SECTION I
TOPIC WISE SOLVED
QUESTIONS OF
PREVIOUS YEARS
Topic 1

Introduction to Orthodontics ...............................
Topic 23

Removable Orthodontic Appliances ..................................................................................
SECTION

I

Topic wise Solved
Questions of Previous Years

1

Topic

INTRODUCTION TO ORTHODONTICS
LONG ESSAYS

Q. 1. Define...
Quick Review Series for BDS 4th Year: Orthodontics
4

All the above three objectives put together are popularly
known as J...
Topic wise Solved Questions of Previous Years
5

xi. Malocclusion and trauma: One of the most common problems associated w...
Quick Review Series for BDS 4th Year: Orthodontics
6

Ans.
According to Graber, interceptive orthodontics is ‘the
phase of...
Topic wise Solved Questions of Previous Years
7

Other concepts/theories related to craniofacial growth
are:
i. Hunter and...
Quick Review Series for BDS 4th Year: Orthodontics
8

which the respective bones arise, grow and are maintained.
The skele...
Topic wise Solved Questions of Previous Years
9

Functional matrix hypothesis was put forward by Melvin
Moss based on the ...
Quick Review Series for BDS 4th Year: Orthodontics
10

iii. Rating and ranking
iv. Opinions.
The quantitative method of me...
Topic wise Solved Questions of Previous Years
11

ii. Maxilla
Hard palate behind deciduous canines
After eruption of maxil...
Quick Review Series for BDS 4th Year: Orthodontics
12

iv. Genital tissue (reproductive organs)
Negligible growth until pu...
Topic wise Solved Questions of Previous Years
13

SHORT ESSAYS
Q. 1. Growth spurts
Or
Growth spurts and two clinical impor...
Quick Review Series for BDS 4th Year: Orthodontics
14

ii. Observations
A method of gathering growth-related information b...
Topic wise Solved Questions of Previous Years
15

Capsular matrix has neurocranial capsule and orofacial
capsule. Each of ...
Quick Review Series for BDS 4th Year: Orthodontics
16

iii. General or visceral (muscle, bone and other organs):
They exhi...
Topic wise Solved Questions of Previous Years
17

Ans.

Various theories of growth are
based on the growth centres.

Growt...
Quick Review Series for BDS 4th Year: Orthodontics
18

Enumerate various tissues for which Scammon’s growth
curves are plo...
Topic wise Solved Questions of Previous Years
19

Q. 8. Neurotrophism
Ans.
A non-impulse transmitting neural function that...
Quick Review Series for BDS 4th Year: Orthodontics
20

The physical growth can be studied by a number of ways:
i. Opinion
...
Topic wise Solved Questions of Previous Years
21

The condyles are low and at the position of the occlusal
plane. The symp...
Quick Review Series for BDS 4th Year: Orthodontics
22

The condyle undergoes reduction of bone on the lateral
aspect of ne...
Topic wise Solved Questions of Previous Years
23

Most of the development of the face takes place between
3rd and 8th week...
Quick Review Series for BDS 4th Year: Orthodontics
24

sutures like the zygomaticomaxillary, frontomaxillary,
pterygopalat...
Topic wise Solved Questions of Previous Years
25

SHORT ESSAYS
Q. 1. Development of palate
Ans.
The palate is formed by co...
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422
Upcoming SlideShare
Loading in …5
×

Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422

8,445 views
8,245 views

Published on

Quick Review Series (QRS) for BDS 4th Year: Orthodontics is an extremely exam-oriented book. The book includes a collection of last 20 years’ solved question papers of Orthodontics from various universities like RGUHS, NTRUHS, MUHS, MGRUHS, etc. according to the new syllabus of BDS 4th year.
The book would serve the requirements of final year BDS students to prepare for their examinations as well as help PG aspirants and PGs for quick review of important topics.

Published in: Health & Medicine, Education
0 Comments
27 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
8,445
On SlideShare
0
From Embeds
0
Number of Embeds
5
Actions
Shares
0
Downloads
554
Comments
0
Likes
27
Embeds 0
No embeds

No notes for slide

Sample chapter quick review series for bds 4th year orthodontics 1e by rao to order call sms at 91 8527622422

  1. 1. SECTION I TOPIC WISE SOLVED QUESTIONS OF PREVIOUS YEARS Topic 1 Introduction to Orthodontics .................................................................................................... 3 Topic 2 General Principles and Concepts of Growth ............................................................................ 6 Topic 3 Growth and Development of Cranial and Facial Structures ................................................... 20 Topic 4 Development of Dentition and Occlusion ............................................................................... 29 Topic 5 Functional Development ......................................................................................................... 40 Topic 6 Occlusion: Basic Concepts .................................................................................................... 44 Topic 7 Classification of Malocclusion ................................................................................................ 47 Topic 8 Aetiology of Malocclusion....................................................................................................... 60 Topic 9 Oral Habits .............................................................................................................................. 71 Topic 10 Orthodontic Diagnosis ............................................................................................................ 82 Topic 11 Cephalometrics..................................................................................................................... 100 Topic 12 Skeletal Maturity Indicators .................................................................................................. 119 Topic 13 Model Analysis...................................................................................................................... 124 Topic 14 Biology and Mechanics of Tooth Movement ........................................................................ 133 Topic 15 Anchorage ............................................................................................................................ 142 Topic 16 Age Factors in Orthodontics ................................................................................................. 149 Topic 17 Preventive Orthodontics ....................................................................................................... 150 Topic 18 Interceptive Orthodontics ..................................................................................................... 159 Topic 19 Methods of Space Gaining ................................................................................................... 166 Topic 20 Arch Expansion ..................................................................................................................... 171 Topic 21 Extractions ............................................................................................................................ 177 Topic 22 Orthodontic Appliances: General Principles ......................................................................... 181 Orthodontics-Part-I-2013.indd 1 12/3/2013 2:49:10 PM
  2. 2. Topic 23 Removable Orthodontic Appliances ..................................................................................... 183 Topic 24 Fixed Orthodontic Appliances .............................................................................................. 199 Topic 25 Myofunctional and Orthopaedic Appliances ........................................................................ 210 Topic 26 Management of Common Malocclusions ............................................................................. 229 Topic 27 Management of Class II Malocclusion.................................................................................. 236 Topic 28 Management of Class III Malocclusion ................................................................................. 241 Topic 29 Management of Open Bite, Crossbite and Deep Bite .......................................................... 245 Topic 30 Cleft Lip and Palate .............................................................................................................. 256 Topic 31 Surgical Orthodontics ........................................................................................................... 263 Topic 32 Retention and Relapse ......................................................................................................... 267 Topic 33 Genetics in Orthodontics ...................................................................................................... 275 Topic 34 Lab Procedures .................................................................................................................... 277 Topic 35 Materials Used in Orthodontics ............................................................................................ 281 Orthodontics-Part-I-2013.indd 2 12/3/2013 2:49:10 PM
  3. 3. SECTION I Topic wise Solved Questions of Previous Years 1 Topic INTRODUCTION TO ORTHODONTICS LONG ESSAYS Q. 1. Define orthodontics. Describe aims and science of orthodontics. Or Describe briefly the aims, objectives, scope and limitations of orthodontic treatment. Ans. Orthodontics is the study of growth and development of the masticatory apparatus and the prevention and treatment of abnormalities of this development. According to British Society for the Study of Orthodontics (BSSO), ‘Orthodontics includes the study of growth and development of the jaws and face particularly, and the body generally, as influencing the position of the teeth; the study of action and reaction of internal and external influences on the development, and the prevention and correction of arrested and perverted development’. The aims of orthodontic treatment are as follows: All the branches of dentistry have one common aim, the establishment of as good an occlusion as possible, not only in the functional but also in the aesthetic sense. The aim of orthodontics is to achieve a functional and aesthetically harmonious occlusion by permanently altering the positions of the natural teeth. This is accomplished by careful stimulation of alveolar bone tissue to alter its shape and support the teeth in a more favourable position. The goal of modern orthodontics is to create the best possible occlusal relationship within the framework of acceptable facial aesthetics and stability of the occlusion. Orthodontics-Part-I-2013.indd 3 It may be said that orthodontics seek: ❍ To intercept departures from normal development of the masticatory organs. ❍ To restore conditions to normal development at the earliest when required. ❍ To establish as good an occlusion as possible both in functional and aesthetic senses. It is important that to achieve the results, we do not interfere with normal function for more than what is required. The use of appliances should be kept to minimum possible to attain the desired result, lest they interfere with normal growth changes and produce further abnormality. It has been found (Gardiner, 1956) that at least 50% of all school children may benefit from orthodontic treatment, and dental surgeons in general family practice are often requested by parents to provide such treatment. The objectives of orthodontic treatment are summarized by Jackson into: i. Functional efficiency ii. Structural balance iii. Aesthetic harmony. Aesthetic harmony Functional efficiency Structural balance Fig. 1.1 Jackson’s triad. 12/3/2013 2:49:10 PM
  4. 4. Quick Review Series for BDS 4th Year: Orthodontics 4 All the above three objectives put together are popularly known as Jackson’s triad (Fig. 1.1). i. Establishing functional efficiency: Correction of malocclusion eliminates all the unfavourable sequelae of malocclusion and thereby restores the functional efficiency of the masticatory apparatus. ii. Restoring structural balance Achieving structural balance between the hard and soft tissues maintains stability of the corrected malocclusion. Failure to achieve structural balance will lead to relapse or loss of correction achieved. iii. Aesthetic harmony: The prime objective of orthodontic treatment is the improvement of the facial aesthetics and is the single most common reason for the patients to approach an orthodontist. Q. 2. What is orthodontia? Describe various sequelae of malocclusion of teeth. Ans. Orthodontics is the study of growth and development of the masticatory apparatus and the prevention and treatment of abnormalities of this development. The various problems or sequelae of malocclusion are as follows: i. Psychological and social problems ii. Poor appearance iii. Interference with normal growth and development like crossbites causing asymmetry and influences of overbite and overjet. iv. Improper or abnormal muscle functions like hyperactive mentalis, hypoactive upper lip, increased buccinator pressures, tongue thrust and associated muscle habits like lip biting, nail biting, finger sucking, etc. v. Abnormal deglutition vi. Mouth breathing vii. Improper mastication viii. Speech defects ix. Increased caries activity x. Predisposition to periodontal disease xi. Temporomandibular joint (TMJ) problems xii. Impacted and unerupted teeth leading to pathologies like cysts and damage to other teeth xiii. Risk of trauma or accidents xiv. Prosthetic rehabilitation complications. i. Psychological and social problems Irregular and protruding teeth have a negative impact on a patient’s psychology. Children with malocclusion become introvert and their social behaviour is immature. Example: Introversion or self-consciousness and response to nicknames like ‘bugs bunny’, ‘buck teeth’, etc. Orthodontics-Part-I-2013.indd 4 ii. Poor appearance Poor appearance due to malocclusion forms a hindrance to the child’s performance in school as well as in other extracurricular activities like play. Preventive or interceptive measures should be attempted to correct the malocclusion, if it is detected in early stages of child development. iii. Interference with growth and development Perverted perioral muscle activity due to abnormal finger sucking habit could cause morphological and functional changes to the dentition. Common effect of abnormal perioral muscle activity is development of posterior crossbites. Many a time functional aberrations may lead to unilateral crossbite, which in turn, may cause facial asymmetry. Flattening of mandibular anteriors may be caused due to increased deep bite and abnormal lip posture. Anterior occlusal interferences may cause pseudo class III. iv. Abnormal muscle function Abnormal muscle activity could be contributing to malocclusion. In case of lip trap, cushioning of lower lip behind the proclined upper incisors may aggravate the proclination. v. Improper deglutition: Many malocclusions result in abnormal functioning of stomatognathic system like improper deglutition. vi. Mouth breathing: Malocclusions like increased overjet can result in mouth breathing usually correction of increased overjet can make lip closure possible, establishing anterior oral seal and making nasal breathing possible. vii. Improper mastication: Malaligned teeth change the pattern of chewing, which can lead to TMJ problems, periodontal problems, etc. viii. Speech defects Malocclusion affects the speech pattern of individuals. Effect of cleft lip: Speech problem in cleft patients is due to velopharyngeal incompetence, naso-oral communication, abnormal tongue posture and function, and lip tissue inadequacy. ix. Increased predilection to caries and periodontal diseases Irregular teeth make self-cleansing of oral cavity less effective and may lead to increased susceptibility to caries and periodontal diseases. Loss of proper contact between teeth and abnormal axial inclinations could lead to uneven distribution of functional stresses, which in turn can lead to periodontal problems. x. TMJ disorders: Malocclusion causes TMJ problems like clicking, crepitus, pain and dysfunction. 12/3/2013 2:49:10 PM
  5. 5. Topic wise Solved Questions of Previous Years 5 xi. Malocclusion and trauma: One of the most common problems associated with class II division 1 malocclusion is high risk of trauma to maxillary anterior teeth. xii. Impacted and unerupted tooth Impacted teeth may interfere with eruption of the successor or neighbouring tooth, and may also cause resorption of the roots of the adjacent tooth. Possibility of development of pathologies like cysts due to impacted or unerupted tooth is most likely. xiii. Prosthetic rehabilitation problems: Supraeruption of the tooth into opposing edentulous area and tipping of teeth into adjacent edentulous area causes space problems for prosthetic rehabilitation. SHORT ESSAYS Q. 1. Objectives of orthodontics Ans. The objectives of orthodontic treatment are summarized by Jackson into: i. Functional efficiency ii. Structural balance iii. Aesthetic harmony. All the above three objectives put together are popularly known as Jackson’s triad. i. Establishing functional efficiency: Correction of malocclusion eliminates all unfavourable sequelae of maloc- clusion and thereby restores the functional efficiency of the masticatory apparatus. ii. Restoring structural balance Achieving structural balance between the hard and soft tissues maintains stability of the corrected malocclusion. Failure to achieve structural balance will lead to relapse or loss of correction achieved. iii. Aesthetic harmony: The prime objective of orthodontic treatment is improvement of the facial aesthetics and is the single most common reason for the patients to approach an orthodontist. SHORT NOTES Q. 1. Aims of orthodontics Or Aims and scope of orthodontics Ans. The aims of orthodontics are as follows: i. To intercept departures from normal development of the masticatory apparatus ii. To restore conditions for normal development at the earliest when required iii. To establish as good an occlusion as possible—both in functional and aesthetic senses. The goal of modern orthodontics is to create the best possible occlusal relationship within the framework of acceptable facial aesthetics and stability of the occlusion. Q. 2. Jackson’s triad Or Describe Andrews Jackson’s triad. Orthodontics-Part-I-2013.indd 5 Ans. The objectives of orthodontic treatment are briefly summarized by Jackson into: i. Functional efficiency ii. Structural balance iii. Aesthetic harmony. All the above three objectives put together are popularly known as Jackson’s triad. i. Establishing functional efficiency: Correction of malocclusion eliminates all unfavourable sequelae of malocclusion and thereby restores the functional efficiency of the masticatory apparatus. ii. Restoring structural balance: Achieving structural balance between the hard and soft tissues maintains stability of the corrected malocclusion. iii. Aesthetic harmony: The prime objective of orthodontic treatment is improvement of the facial aesthetics and is the most common reason for the patients to approach an orthodontist. Q. 3. Define interceptive and preventive orthodontics. 12/3/2013 2:49:10 PM
  6. 6. Quick Review Series for BDS 4th Year: Orthodontics 6 Ans. According to Graber, interceptive orthodontics is ‘the phase of the science and art of orthodontics employed to recognize and eliminate potential irregularities in the developing dentofacial complex’. Graber defined preventive orthodontics as ‘the action taken to preserve the integrity of what appears to be the normal occlusion at a specific time’. Q. 4. Define orthodontics. Or Give the BSSO definition of orthodontics. Ans. Orthodontic treatment for adults is broadly classified into two types: i. Adjunctive orthodontic treatment ii. Comprehensive orthodontic treatment. Adjunctive orthodontic treatment procedures are carried out to facilitate other dental procedures to control disease and restore function. For example, uprighting of molars, forced eruption, crossbite correction, diastema closure, etc. Comprehensive orthodontic treatment is an essential treatment procedure carried out in children for correction of malocclusion. Response to orthodontic force is slightly slower in adults as compared to children. Q. 6. Contributions of EH Angle to orthodontics Orthodontics is the study of growth and development of the masticatory apparatus and the prevention and treatment of abnormalities of this development. According to British Society for the Study of Orthodontics (BSSO), ‘orthodontics includes the study of growth and development of the jaws and face particularly, and the body generally, as influencing the position of the teeth; the study of action and reaction of internal and external influences on the development, and the prevention and correction of arrested and perverted development’. Q. 5. Adult orthodontics Ans. Ans. Edward H Angle is considered as the ‘father of modern orthodontics’ for his numerous contributions to the speciality of orthodontics, which are as follows: i. Publication of book on orthodontics in 1887 ii. Concept of ‘occlusion in orthodontics’ iii. Hypothesis of ‘key of occlusion’ iv. Classification of malocclusion v. Various appliances like a. Angle’s E-arch, b. Pin and tube, c. Ribbon arch appliance and d. Edgewise appliance. Orthodontic treatment of adults is known as adult orthodontics. Topic 2 GENERAL PRINCIPLES AND CONCEPTS OF GROWTH LONG ESSAYS Q. 1. Define growth and development. Mention various theories of growth and write in detail about functional matrix hypothesis. Or Enumerate various theories of growth. Explain in detail the functional matrix theory. Or Enumerate various theories of growth. Describe functional matrix theory of Moss. Orthodontics-Part-I-2013.indd 6 Or Enumerate theories of bone growth. Ans. Based on the expression of intrinsic genetic potential various theories of craniofacial growth are: i. Genetic theory by Brodie ii. Sutural dominance theory by Sicher iii. Cartilaginous theory by Scott iv. Functional matrix theory by Melvin Moss v. Van Limborgh’s theory. 12/3/2013 2:49:10 PM
  7. 7. Topic wise Solved Questions of Previous Years 7 Other concepts/theories related to craniofacial growth are: i. Hunter and Enlow’s growth equivalent concept ii. Petrovic’s cybernetic theory. Functional matrix theory (Melvin Moss) The functional matrix concept attempts to comprehend the relation between form and function. Functional matrix hypothesis was put forward by Melvin Moss based on the work of Van der Klaauw. The theory is simply stated as ‘there is no direct genetic influence on the size, shape or position of skeletal tissues, only the initiation of ossification. All skeletogenic activities are primarily based upon the functional matrices.’ According to original version of functional matrix hypothesis: Head is a composite structure—operationally consisting of number of relatively independent functions. For example, digestion, respiration, vision, olfaction, speech equilibrium and neural integration, etc. Each function is carried out by a group of soft tissues, which are supported and protected by related skeletal elements. Soft tissues and skeletal elements related to single function are known as functional cranial component. Associated with one single function, totally all the i. skeletal elements are known as skeletal unit. ii. soft tissues are known as functional matrix. It was demonstrated that the origin, growth and maintenance of the skeletal unit depends almost exclusively upon its functional matrix. 1968 Updated version of Melvin Moss’s hypothesis Functional matrix hypothesis claims that the origin, form, position, growth and maintenance of all skeletal tissues and organs is always secondary, compensatory and necessary response to chronologically and morphologically prior events or processes that occur in specifically related non-skeletal tissues, organs or functional spaces. Each of independent function in craniofacial region is carried out by: functional cranial component (consists of all tissues + organs + spaces and skeletal parts necessary to carry out given function). Functional cranial component is divided into: i. Functional unit: Comprises all the tissues, organs and functioning spaces as a whole. ii. Skeletal unit: Skeletal tissues related to specific function matrix. Skeletal unit It is comprised of bone, cartilage and tendinous tissue. It is nothing but all skeletal tissues associated with a single function. Orthodontics-Part-I-2013.indd 7 It is divided into: i. Microskeletal unit ii. Macroskeletal unit. Microskeletal unit Macroskeletal unit When a bone is comprised of several contiguous skeletal units, it is known as microskeletal units. Example: i. Mandible has following microskeletal units: alveolar, angular, condylar, gonial, mental, coronoid and basal. ii. Maxilla has following microskeletal units: orbital, pneumatic, palatal and basal. When adjoining portions of a number of neighbouring bones are united to function as a single cranial component, it is termed as macroskeletal unit. Example: i. Entire endocranial surface of the calvarium. Functional matrix It consists of muscles, glands, nerves, vessels, fat, teeth and functioning spaces. Functional matrix is divided into: i. Periosteal matrix ii. Capsular matrix. Periosteal matrix Capsular matrix It includes muscles, blood ves- It includes neurocranial capsule sels, nerves and glands. and orofacial capsule. They act directly and actively upon their related skeletal units bringing about transformation in their size and shape by bone deposition and resorption. They act indirectly and passively on their related skeletal units producing a secondary compensatory translation in space. Capsular matrix Neurocranial capsule Orofacial capsule It is made up of skin, connective tissue, aponeurotic layer, loose connective layer, periosteum, base of the skull and two layers of dura mater, which surround and protect neurocranial capsular functional matrix, which is brain, leptomeninges and cerebrospinal fluid. Surrounds and protects the oronasopharyngeal spaces, which constitute the orofacial capsular matrix. The growth of facial skull is influenced by volume and patency of these spaces. Each of the neurocranial and orofacial capsule is an envelope that contains series of functional cranial components (i. e. skeletal units and functional matrix), which as a whole is sandwiched between two covering layers. The alterations in special position of skeletal units is brought about by the expansion of these capsules within 12/3/2013 2:49:10 PM
  8. 8. Quick Review Series for BDS 4th Year: Orthodontics 8 which the respective bones arise, grow and are maintained. The skeletal units are passively and secondarily moved in space, as their enveloping capsule is expanded. This kind of translative growth is not brought about by deposition and resorption. Clinical implications of functional matrix theory Orthodontic corrections of teeth are done either by intraoral or extraoral appliances. The forced application by these appliances tends to alter the functional matrix. Alteration of periosteal functional matrix produces changes in microskeletal unit, i.e. alveolar bone while the alteration of capsular functional matrix produces changes in macroskeletal unit, i.e. jaws. Q. 2. Define growth and enumerate various theories of bone growth. Ans. Growth has been defined by various clinicians in different ways as follows: JS Huxley defined growth as ‘the self-multiplication of living substance.’ Krogman defined growth as ‘increase in size, change in proportion and progressive complexity.’ Todd defined growth as ‘an increase in size.’ Meredith defined growth as ‘entire series of sequential anatomic and physiologic changes taking place from the beginning of prenatal life to senility.’ Moyers defined growth as ‘quantitative aspect of biological development per unit of time.’ Moss defined growth as ‘change in any morphological parameter that is measurable.’ Based on the expression of intrinsic genetic potential various theories of craniofacial growth are: i. Genetic theory by Brodie ii. Sutural dominance theory by Sicher iii. Cartilaginous theory by Scott iv. Functional matrix theory by Melvin Moss v. Van Limborgh’s theory. Other concepts/theories related to craniofacial growth are: i. Hunter and Enlow’s growth equivalent concept ii. Petrovic’s cybernetic theory. i. Genetic theory This is one of the earliest theories put forward by Brodie in 1941. Brodie stated simply that all growth is controlled by the genes and is preplanned. This theory is more of an assumption and is not proved. Primary genetic control determines only certain features and does not have complete influence on overall growth. Orthodontics-Part-I-2013.indd 8 ii. Sicher’s sutural dominance theory/Sicher’s hypothesis/ Sutural theory Sutural dominance theory was put forward by Sicher. According to him bone growth within the various craniofacial units is the result of growth taking place in sutures. According to Sicher, the growth of the skull tissue is controlled by its own genetic potential. According to him, all bone-forming elements like cartilage, sutures and periosteum are growth centres. This theory is also known as sutural dominance theory because proliferation of connective tissue and its replacement by bone in the suture is considered to be the primary event. Growth taking place in the sutures that connect maxillary complex to the cranium causes downward movement of the midface. Drawbacks of sutural theory Any unusual pressure on suture initiates bone resorption and not bone’s deposition as it is a tension-adapted tissue. Sutures do not act as primary growth centres. Growth in the sutural area is a secondary response to functional needs. Evidence in favour of secondary role of sutural growth is more. Based on various experimental studies it was shown that extirpation or removal of facial sutures had no effect on the growth of skeleton. iii. Cartilaginous theory Cartilaginous theory is also known as Scott’s hypothesis or nasal septal theory, and is put forward by James Scott. This theory is based on the principle that intrinsic growth controlling factors are present in cartilage and periosteum. According to Scott, cartilaginous sites throughout the skull are primary growth centres and growth of cartilage in nasal septum provides force that displaces maxilla downwards and forwards. Nasal septum is considered to be the major contributor in maxillary growth. In mandible, condylar cartilage is considered to be the growth centre present bilaterally with the horseshoeshaped mandible in between. Experimental evidence in favour of this theory are: Removal of nasal septal cartilage in rats and rabbits resulted in deficient snout of these animals. Transplantation of part of epiphyseal plate and synchondroses to a different location results in continued growth in the new location, which indicates innate growth potential of the cartilage. Nasal septum also shows innate growth potential on being transplanted to a different location. iv. Functional matrix theory (Melvin Moss) The functional matrix concept attempts to comprehend the relation between form and function. 12/3/2013 2:49:10 PM
  9. 9. Topic wise Solved Questions of Previous Years 9 Functional matrix hypothesis was put forward by Melvin Moss based on the work of van der Klaauw. The theory is simply stated as ‘there is no direct genetic influence on the size, shape or position of skeletal tissues, only the initiation of ossification. All skeletogenic activity is primarily based upon the functional matrices.’ Head is a composite structure. Each function is carried out by a group of soft tissues supported and protected by related skeletal elements. Soft tissues and skeletal elements related to single function are known as functional cranial component. Associated with one single function, totally all the i. skeletal elements are known as skeletal unit. ii. soft tissues are known as functional matrix. It was demonstrated that the origin, growth and maintenance of the skeletal unit depends almost exclusively upon its functional matrix. 1968 Updated version of Melvin Moss hypothesis Functional matrix hypothesis claims that the origin, form, position, growth and maintenance of all skeletal tissues and organs are always secondary, compensatory and necessary responses to chronologically and morphologically prior events or processes that occur in specifically related non-skeletal tissues, organs or functional spaces. Each of the independent functions in craniofacial region are carried out by functional cranial component, which consists of all tissues, organs, spaces and skeletal parts necessary to carry out given function. v. van Limborgh’s theory van Limborgh in 1970 put forward a multifactorial theory. He explained the process of growth and development in a view that combines all three existing theories: (i) functional matrix theory, (ii) sutural theory by Sicher and (iii) genetic theory. According to van Limborgh the five factors that control the growth are as follows: i. Intrinsic genetic factors: They are genetic control of the skeletal units themselves. ii. Local epigenetic factors: Bone growth is determined by genetic control originating from adjacent structures like brain, eyes, etc. iii. General epigenetic factors: They are genetic factors determining growth from distant structures, e.g. sex hormones, growth hormones. iv. Local environmental factors: Non-genetic factors from local external environment, e.g. habits, muscle force. v. General environmental factors: Non-genetic general environment, e.g. nutrition, O2. Views expressed by van Limborgh can be summarized as follows: Chondrocranial and desmocranial growth are controlled by ‘intrinsic genetic factors.’ Orthodontics-Part-I-2013.indd 9 Cartilaginous parts of skull are considered as growth centres. Sutural and periosteal growths are additionally governed by local non-genetic environmental infamies. Sutural growth is controlled by influences originating from skull cartilages and other adjacent skull structures. Periosteal growth to a large extent depends on growth of adjacent structures. Other concepts/theories related to craniofacial growth are: Hunter and Enlow’s growth equivalent concept According to Enlow’s expanding ‘V’ principle: Many facial bones or parts of bone have a ‘V’-shaped pattern of growth. In these bones, the growth movements and enlargement occurs towards the wide ends of the ‘V’ as a result of differential deposition and selective resorption of bone. Bone deposition occurs on the inner side of the wide end of the ‘V’ and bone resorption on the outer surface. Deposition also takes place at the ends of the two arms of the ‘V’ resulting in growth movement towards the ends. The ‘V’ pattern of the growth occurs in a number of regions such as the base of the mandible, ends of long bones, mandibular body, palate, etc. Q. 3. Enumerate the various methods of measuring growth. Discuss the clinical importance of the knowledge of growth and development in orthodontics. Or What are the methods of measuring growth and discuss the importance of the knowledge of growth and development in orthodontics? Ans. Various methods of measuring growth are as follows: i. Proffit’s classification ii. Moyer’s classification Proffit’s classification i. ii. iii. iv. v. vi. Measurement approaches Anthropometry Craniometry Cephalometry Arcial growth Logarithmic spiral Finite element analysis i. ii. iii. iv. Experimental approaches Vital staining Radioactive tracer Autoradiography Implant radiography Moyer’s classification It is of following types: i. Quantitative ii. Observations 12/3/2013 2:49:11 PM
  10. 10. Quick Review Series for BDS 4th Year: Orthodontics 10 iii. Rating and ranking iv. Opinions. The quantitative method of measuring growth is again of following types: Direct measurements Indirect measurements Combination i. Anthropometry i. Study casts i. Radiography and implants ii. Craniometry ii. Radiographs ii. Radiograph + metaphysic bands iii. Vital staining iii. Photographs iii. Autoradiography iv. Implant markers v. Histochemistry The various methods of measuring growth in detail are as follows: I. Craniometry and anthropometry Craniometry is the art of measuring skulls so as to discover their specific differences. Precise measurements can be made with craniometry. It is a cross-sectional type of study. Site, amount and rate of growth cannot be elicited by craniometry but gives information about direction of growth to some extent. Anthropometry is the measurement of skeletal dimensions on living individuals. It is a longitudinal study. Anthropometry gives little information about amount of growth and to some extent rate of growth, whereas it gives relatively accurate information about direction of growth. Clinical uses Cranial index and facial index are two important indices used in orthodontics. Index is the ratio of smaller to a larger linear measurement expressed by means of percentage. Cranial index = Maximum cranial breadth × 100 Maximum cranial length Maximum cranial breadth is the measured distance between the two most prominent points on either side of the head. Maximum cranial length is the measured distance from glabella to opisthocranion—the most prominent point of the occipital bone in the midline. The values of cranial index are more for brachycephalic/ short and round head types around 80–85 and less for dolichocephalic/long narrow head type around 70–75, while for mesocephalic/middle type the values are in between the above two. Facial index = Orthodontics-Part-I-2013.indd 10 Facial height × 100 Zygomatic breadth Facial height is the measured distance from nasion to gnathion whereas zygomatic breadth is the distance between two zygomas. The values of facial index are more for leptoprosopic, i.e. high and narrow facial type 90–95 and less for euryprosopic, i.e. broad and round facial type 80–85 and average in between these two values for mesoprosopic, i.e. middle type around 85–90. II. Vital staining Vital staining is an experimental method of measuring growth introduced by John Hunter in 18th century. Commonly used dyes for vital staining are: Alizarin S Radioactive tracers Fluorochrome Tetracycline Trypan blue Procedure This technique involves injecting certain dyes that stain the mineralizing tissues and get incorporated in the bones and teeth. Animals are sacrificed and tissues are studied histologically for manner in which bone is laid down, the site of growth, the direction, duration and amount of growth at different sites in the bone. Disadvantage of this method is that it is not a longitudinal study; hence, repeated data of the same individual cannot be obtained. III. Implant radiography Use of implant radiograph to study bone growth was introduced by Professor Bjork in 1969. It is an experimental method for studying physical bone growth. Procedure It involves inserting small bits of biologically inert metal alloys into growing bone of either mandible or maxilla. Very tiny metallic implants of size 1.5 mm long and 0.5 mm diameter made of tantalum are used. Osseointegrated implants serve as reference points; and serial cephalometric radiographs are taken repeatedly over a period of time and compared. Preferable site of implants in mandible and maxilla are as follows: i. Mandible Anterior aspect of symphysis in the midline below roots. Two pins on the right side body of mandible: one below first premolar and another below second premolar or first molar. External surface of ramus on the right side at the level of occlusal surface of molars. 12/3/2013 2:49:11 PM
  11. 11. Topic wise Solved Questions of Previous Years 11 ii. Maxilla Hard palate behind deciduous canines After eruption of maxillary incisors below the anterior nasal spine Bilaterally one implant on either side of zygomatic process of maxilla The patterns are the controlling or restricting mechanisms to preserve the integration of parts of the body under varying conditions. Differential growth (cephalocaudal growth, Scammon’s growth) and predictability are the contributors to pattern. Junction of hard palate and alveolar process medial to first molar: Implant radiography gives very accurate information about the site, amount and direction of growth while a relatively accurate information about rate of growth. Drawbacks of this method are that it is a two-dimensional study of three-dimensional process and radiation hazard. Throughout life human body does not grow at the same rate; different organs grow at different rates to a different amount and at different times. This is known as differential growth. The concepts of differential growth are more clearly understood by two important aspects of growth: a. Cephalocaudal gradient of growth b. Scammon’s curve of growth. Q. 4. Define growth. Discuss briefly clinical application of knowledge of growth and development in orthodontics. Ans. Growth has been described in so many terms. Todd defined growth as ‘increase in size.’ Krogman defined it as ‘increase in size and change in spatial proportion over time.’ Huxley defined it as ‘self-multiplication of the living tissues.’ Moss defined growth as ‘any change in morphology that is within measurable parameter.’ Meredith defined growth as ‘the entire series of anatomic and physiologic changes taking place between the beginning of prenatal life and the close of senility.’ Moyer defined growth as ‘the biologic process by which living matter gets larger.’ Development is defined in simple words as ‘progression towards maturity.’ According to Melvin Moss, ‘development can be considered as a continuum of causally related events from the fertilization of ovum onwards.’ Importance of knowledge of growth and development in orthodontics is as follows: Craniofacial growth is a complex phenomenon. A thorough knowledge of the normal pattern of growth and normal variations will help in identifying the problems and also utilize the normal growth to advantage in treatment. Clinical implications of growth and development can be studied under the following headings: i. Growth pattern ii. Differential growth iii. Variability iv. Timing variations v. Safety valve mechanism. i. Growth pattern Definite arrangement of designs in definite proportional relationship is known as pattern. In relation to growth, pattern can be defined as proportional relationship over time. Orthodontics-Part-I-2013.indd 11 ii. Differential growth a. Cephalocaudal gradient of growth An axis of increased growth gradient extending from head towards the feet is called ‘cephalocaudal growth.’ In fetal life, head constitutes 50% of total body length while limbs are primitive (30%). At the time of birth head constitutes 25–30% and there is an increased growth of body and limbs. In an adult the head constitutes only 12%, while limbs account to 50%. These changes in the pattern of growth are because of cephalocaudal gradient. Cephalocaudal growth of face: At the time of birth jaws and face are less developed compared to skull. Maxilla being closer to head grows faster and growth is completed before mandibular growth. Mandible being away from the brain grows more and growth completes later than maxilla. b. Scammon’s curve of growth Major tissues of the human body are divided into four types: i. Lymphoid tissue ii. Neural tissue iii. General tissue iv. Genital tissue. These different tissues grow at different time and at different rates. i. Lymphoid tissue: It proliferates rapidly in late childhood to almost 200% of adult size. Adaptation to protect child from infection—by 18 years it undergoes involution to reach adult size. ii. Neural tissue: Grows very rapidly and almost reaches adult size by 6–7 years of age after that a very little growth occurs in neural tissue. iii. General/visceral and muscle, bone and other organs: They exhibit ‘S’-shaped curve of rapid growth up to 2–3 years of age: a. followed by slow phase between 3 and 10 years of age. b. followed by rapid phase of growth occurring after 10th year, and terminating between 18 and 20 years. 12/3/2013 2:49:11 PM
  12. 12. Quick Review Series for BDS 4th Year: Orthodontics 12 iv. Genital tissue (reproductive organs) Negligible growth until puberty. They grow rapidly at puberty reaching adult size, after which growth ceases. Effect of Scammon’s growth in facial region: ❍ Mandible follows somatic growth pattern. Longtime growth is seen until about 18–20 years in males. ❍ Maxilla follows neural growth pattern and growth ceases earlier; hence skeletal problems of the maxilla should be treated earlier to mandible. iii. Variability of growth Variability of growth is the law of nature. No two individuals mimic alike, and no two individuals grow in the same pattern. The reasons for variability of growth are as follows: a. Variation within normal range: Evaluated by Wetzel’s grid. b. Variation due to other influences includes the following: i. Heredity ii. Nutrition iii. Racial difference iv. Climate v. Exercise vi. Socioeconomic factors vii. Psychological factors viii. Size of the family ix. Hormonal changes. c. Variation due to timing effects is due to the following: i. Body build ii. Sex difference iii. Growth spurts. Variation within normal range It is evaluated by Wetzel’s grid. The resultant curve obtained by plotting the height and weight of an individual against the age over a period of time is compared with normal range. Any unexpected growth pattern changes should be evaluated and investigated for growth abnormality. b. Variation due to other influences Heredity: On rate of growth and onset of menarche, there is genetic control. Nutrition: Certain parts of the body may be affected by malnutrition and show retardation of growth. Racial differences: Differences in skeletal maturity are exhibited by different races. Orthodontics-Part-I-2013.indd 12 Climate and seasonal effects: People living in cold places have more of fat or adipose tissue. Exercise: Increases muscle mass and physique. c. Variation due to timing effects Timing variations in growth is nothing but occurrence of same events at different times for different individuals. iv. Timing variation in growth i. Body build ii. Sex difference iii. Growth spurts Body build Ectomorphic: Late-maturing individuals grow for a longer period. Mesomorphic: Individuals exhibiting average growth period. Endomorphic: Early-maturing individuals, where growth completes much faster. Sex differences Boys and girls exhibit variation between onset of menarche and rate of growth. In girls, there is early onset of menarche and growth completes faster than boys of the same age. In the boys, there is delayed onset of puberty and growth occurs over a longer period. Growth spurts Growth does not take place uniformly at all times. There seem to be periods when a sudden acceleration of growth occurs. This sudden increase in growth is termed growth spurt. The growth spurts can be utilized for growth modulation treatment. v. Safety valve mechanism Safety valve mechanism is a nature’s attempt to maintain proper occlusion. To compensate for the horizontal growth in mandible, the maxillary intercanine width serves as a safety valve. In mandible the intercanine width is completed at 9 years of age in girls and at around 10 years of age in boys. In the maxilla the intercanine width is completed by 12 years in girls and at 18 years in boys. The delay in growth of maxillary intercanine arch width serves as a ‘safety valve’ for pubertal growth spurts in mandible. Maxillary intercanine width adjusts to the mandibular dentition as it is brought forward. This is called ‘safety valve mechanism.’ 12/3/2013 2:49:11 PM
  13. 13. Topic wise Solved Questions of Previous Years 13 SHORT ESSAYS Q. 1. Growth spurts Or Growth spurts and two clinical importance Or Pubertal growth spurts Ans. Growth does not take place uniformly at all times. There seems to be periods when a sudden acceleration of growth occurs. This sudden increase in growth is termed growth spurt. Aetiology The physiologic alteration in hormonal secretion. The timing of the growth spurts differ in boys and girls. They are as follows: i. Just before birth ii. One year after birth iii. Mixed dentition growth spurt (boys 8–11 years and girls 7–9 years) iv. Prepubertal growth spurt (boys 14–16 years and girls 11–13 years). Clinical importance Knowledge of growth spurts is essential for successful treatment planning in orthodontics. Growth modulation by means of functional and orthodontic appliances elicits better response during growth spurts. Surgical correction involving maxilla and mandible should be carried out only after cessation of the growth spurts. During pubertal growth spurts there is change in growth direction from vertical to horizontal. Periods of maximum growth are suitable for arch expansion and rapid skeletal expansion procedures. Growth spurt period is the best time for interceptive orthodontic procedures. Q. 2. Methods of gathering growth data Or Methods of studying growth Or What are growth studies? Ans. The various growth studies are as follows: i. Longitudinal studies Orthodontics-Part-I-2013.indd 13 ii. Cross-sectional studies iii. Semilongitudinal studies. Longitudinal studies This type of study consists of the observation and measurements pertaining to growth made on a person or a group of persons at regular intervals over a prolonged period of time. The longitudinal studies are long-term studies where the same sample is studied by means of follow-up examination. Advantages The specific developmental pattern of an individual can be studied and compared, as the same subjects are followed up over a long period. Developmental variations among individuals within the sample can be studied. Disadvantages A long period of time is involved; it often takes years or decades to complete a study. These studies require maintenance of laboratory research personnel and data storage systems for a long period of time. They can be expensive. As these studies are performed over prolonged periods of time, there is a risk of the reduction of sample size due to change of place or other unforeseen events. 2. Cross-sectional studies Cross-sectional studies are carried out by observation and measurement made of different samples and studied at different periods. Advantages These studies are of short duration. They are less expensive. It is possible to repeat the study in case of any flaw. 3. Semilongitudinal studies In these studies, it is possible to combine the cross-sectional and longitudinal methods to derive the advantages of gathering growth data. Types of growth data The physical growth can be studied by a number of ways: i. Opinion It is a clever guess of an experienced person and is the crudest means of studying growth. This method of studying growth is not very scientific and should be avoided when better methods are available. 12/3/2013 2:49:11 PM
  14. 14. Quick Review Series for BDS 4th Year: Orthodontics 14 ii. Observations A method of gathering growth-related information by observation. They are useful in studying all or none of the phenomena such as presence or absence of disease. Example: Presence or absence of a caries, class II molar relation. iii. Ratings and rankings Rating makes use of standard, conventionally accepted scales for classification. Ranking involves the arrangement of data in an orderly sequence based on the value. Whenever it is difficult to quantify a particular data, it is possible to adopt a method of rating and ranking. resulting in the displacement of maxilla in forward and downward direction. ii. Secondary displacement: If a displacement of bone occurs as a result of growth and enlargement of adjacent bone, it is known as secondary displacement. Example: Growth of the cranial base results in the forward and downward displacement of the maxilla. Q. 4. Functional matrix theory Or Functional matrix theory of growth and development Quantitative measurements Ans. A scientific approach to study growth is based on accurate measurements, which are of three types: i. Direct data: Direct data are obtained from measurements that are taken on living persons or cadavers by means of scales, measuring tapes or callipers. ii. Indirect data: The growth measurements derived from images, photographs, radiographs or dental casts of a person. iii. Derived data: The data that is derived after comparing two measurements. These two sets of measurements can be of different time frames or of two different samples. Functional matrix hypothesis was put forward by Melvin Moss based on the work of van der Klaauw. The theory is simply stated as ‘there is no direct genetic influence on the size, shape or position of skeletal tissues, only the initiation of ossification. All skeletogenic activities are is primarily based upon the functional matrices.’ According to original version of functional matrix hypothesis: Head is a composite structure operationally consisting of number of relatively independent functions. Example: digestion, respiration, vision and neural integration. Each function is carried out by a group of soft tissues, which are supported and protected by related skeletal elements. Soft tissues and skeletal elements related to single function are known as functional cranial component. Functional cranial component is divided into: i. Functional matrix comprises all the tissues, organs and functioning spaces as a whole. ii. Skeletal unit comprises skeletal tissues related to specific functional matrix. It was demonstrated that the origin, growth and maintenance of the skeletal unit depends almost exclusively up on its functional matrix. Q. 3. Discuss drift and displacement with examples. Ans. Drift and displacement are two basic modes of movements involved during growth. Overall process of craniofacial enlargement is a combination of drift and displacement. Cortical drift Growth of most bones occurs due to interplay of bone deposition and resorption. A combination of bone deposition and resorption resulting in a growth movement towards the depositing surface is called cortical drift. If bone deposition and resorption on either side of a bone are equal, the thickness of the bone remains constant. If in case more bone is deposited on one side and less bone resorbed on the opposite side the thickness of the bone increases. Drift occurs in all the regions of growing bones producing generalized enlargement as well as relocation of parts. Displacement The movement of the whole bone as a unit is known as displacement. It can be of two types: (i) primary and (ii) secondary. i. Primary displacement: If a bone gets displaced as a result of its own growth, it is known as primary displacement. Example: Growth of the maxilla at the tuberosity region causes pushing of the maxilla against the cranial base Orthodontics-Part-I-2013.indd 14 Functional matrix It consists of muscles, glands, nerves, vessels, fat, teeth and functioning spaces. It is divided into two types: i. Periosteal matrix ii. Capsular matrix. Periosteal matrix Capsular matrix It includes muscles, blood ves- It includes neurocranial capsule sels, nerves, glands, etc. and orofacial capsule. It acts directly and actively upon its related skeletal units, and brings about transformation in their size and shape by bone deposition and resorption. It acts indirectly and passively on its related skeletal units producing a secondary compensatory translation in space. 12/3/2013 2:49:11 PM
  15. 15. Topic wise Solved Questions of Previous Years 15 Capsular matrix has neurocranial capsule and orofacial capsule. Each of the neurocranial capsule and orofacial capsule is an envelope that contains series of functional cranial components (i.e. skeletal units and functional matrix), which as a whole is sandwiched between two covering layers. The alterations in special position of skeletal units is brought about by the expansion of these capsules, within which the respective bones arise, grow and are maintained. The skeletal units are passively and secondarily moved in space as their enveloping capsule is expanded. This kind of translative growth is not brought about by deposition and resorption. Clinical implications of functional matrix theory The force application by orthodontic appliances tends to alter the functional matrix. Alteration of periosteal functional matrix produces changes in microskeletal unit, i.e. alveolar bone while the alteration of capsular functional matrix produces changes in macroskeletal unit, i.e. jaws. Q. 5. Neurotrophism Ans. A non-impulse transmitting neural function that involves axoplasmic transport and provides for long-term interaction between neurons and innervated tissues that homeostatically regulate the morphological, compositional and functional integrity of those tissues is known as neurotrophism. Presently, the nature of neurotrophic substances and the process of their introduction into the target tissue is unknown. The various types of neurotrophic mechanisms are: i. Neuroepithelial trophism ii. Neurovisceral trophism iii. Neuromuscular trophism. Neuroepithelial trophism: There is a neurotrophic control over epithelial mitosis and synthesis. Certain neurotrophic substances released by the nerve synapses control the normal epithelial growth. If this neurotrophic process is lacking or deficient, abnormal epithelial growth, orofacial hypoplasia and malformation, etc. occur. Example: The presence of taste buds is dependent upon an intact innervation. The nerves are not only important for the sensation of taste but also for healthy growth of the taste buds. If the taste buds are deinnervated, they become atrophic. Neuromuscular trophism: Embryonic myogenesis is independent of neural innervation and trophic control. The neural innervation is established approximately at the myoblast stage of differentiation, without which further continuation of myogenesis usually does not occur. Orthodontics-Part-I-2013.indd 15 Neurovisceral trophism: Visceral organs like the salivary glands, fat tissue and other organs are trophically regulated, at least in part. Q. 6. Scammon’s curve Or Explain differential growth and Scammon’s growth curve. Or Cephalocaudal gradient of growth Ans. Human body does not grow at the same rate human body does not grow at the same rate throughout life; different organs grow at different rates to a different amount and at different times. This is known as differential growth. The concepts of differential growth are more clearly understood by two important aspects of growth: i. Cephalocaudal gradient of growth ii. Scammon’s cure of growth. i. Cephalocaudal gradient of growth An axis of increased growth gradient extending from head towards the feet is called ‘cephalocaudal growth.’ In fetal life, head constitutes 50% of total body length while limbs are primitive (30%). At the time of birth, head constitutes 25–30% and there is increased growth of body and limbs. In an adult, the head constitutes only 12%, while limbs accounts to 50%. These changes in the pattern of growth are because of cephalocaudal gradient. Cephalocaudal growth of face: At the time of birth, jaws and face are less developed compared to skull. Maxilla being closer to head grows faster and growth is completed before mandibular growth. Mandible being away from the brain grows more and growth completes later than maxilla. ii. Scammon’s curve of growth Major tissues of the human body are divided into four types: i. Lymphoid tissue ii. Neural tissue iii. General tissue iv. Genital tissue. These tissues grow at different time and at different rates. i. Lymphoid tissue: It proliferates rapidly in late childhood to almost 200% of adult size. Adaptation to protect child from infection—by 18 years it undergoes involution to reach adult size. ii. Neural tissue: Grows very rapidly and almost reaches adult size by 6–7 years of age; after that a very little growth occurs in neural tissue. 12/3/2013 2:49:11 PM
  16. 16. Quick Review Series for BDS 4th Year: Orthodontics 16 iii. General or visceral (muscle, bone and other organs): They exhibit ‘S’-shaped curve with rapid growth up to 2–3 years of age: a. followed by slow phase between 3 and 10 years of age. b. followed by rapid phase of growth occuring after 10th year and terminating between 18 and 20 years. iv. Genital tissue (reproductive organs): Negligible growth until puberty. They grow rapidly at puberty, reaching adult size; after which growth ceases. Effect of Scammon’s growth in facial region Mandible follows somatic growth pattern. Long-time growth is seen until about 18–20 years in males. Maxilla follows neural growth pattern and growth ceases earlier; hence skeletal problems of the maxilla should be treated earlier to mandible. Q. 7. Safety valve mechanism Ans. Safety valve mechanism is a nature’s attempt to maintain proper occlusion. To compensate for the horizontal growth in mandible, the maxillary intercanine width serves as a safety valve. In mandible the intercanine width is completed at 9 years of age in girls and at around 10 years of age in boys. In the maxilla the intercanine width is completed by 12 years in girls and at 18 years in boys. The delay in growth of maxillary intercanine arch width serves as a ‘safety valve’ for pubertal growth spurts in mandible. Maxillary intercanine width adjusts to the mandibular dentition as it is brought forward. This is called ‘safety valve mechanism.’ Q. 8. Endochondral and intramembranous bone formation Ans. The process of bone formation occurs by two basic methods: i. Endochondral bone formation ii. Intramembranous bone formation. i. Endochondral ossification (cartilaginous ossification/indirect ossification/endochondral bone formation) In this type of osteogenesis the bone formation is preceded by formation of a cartilaginous model, which is subsequently replaced by bone. Endochondral bone formation occurs as follows: At the site of bone formation; the condensation of mesenchymal cells takes place and some of them differentiate into chondroblasts and lay down hyaline cartilage. Orthodontics-Part-I-2013.indd 16 The cartilage is surrounded by a membrane called perichondrium, which is highly vascular and contains osteogenic cells. The intercellular substance surrounding the cartilage cells becomes calcified due to an enzyme alkaline phosphatase secreted by the cartilage cells. The cartilage cells are deprived of nutrition leading to their death. This results in the formation of empty spaces called primary areolae. The blood vessels and osteogenic cells from the perichondrium invade the calcified cartilaginous matrix, which is now reduced to bars or walls due to eating away of the calcified matrix. This leaves large empty spaces between the walls called secondary areolae. The osteogenic cells of perichondrium become osteoblasts, arrange themselves along the surface of these bars of calcified matrix and lay down osteoid, which later becomes calcified to form a lamella of bone. The calcified matrix of cartilage acts as a support for bone formation and layers of osteoid are secreted one upon other. The entire process of endochondral ossification is continuous and repetitive. Importance of endochondral ossification Cartilage behaves like a soft tissue, and growth takes place both by interstitial growth and appositional growth. Cartilage can grow in heavy pressure areas, as it is a pressure-adapted tissue unlike bone, e.g. cranial base. Linear growth takes place allowing lengthening of bones. ii. Intramembranous bone formation In this case, the formation of bone is not preceded by formation of a cartilaginous model. Instead, bone is laid down directly in a fibrous membrane. The intramembranous bone is formed in the following manner: At the site of bone formation, mesenchymal cells become aggregated and some of them lay down bundles of collagen fibres. Some mesenchymal cells enlarge and form osteoblasts, which secrete a gelatinous matrix called osteoid around the collagen fibres. The osteoid is converted into bone lamella by deposition of calcium salts in it; and now the osteoblasts move away from the lamellae and a new layer of osteoid is secreted, which also gets calcified. Some of the osteoblasts get entrapped between two lamellae. They are called osteocytes. Q. 9. Growth site versus growth centre Or Distinguish between growth centre and growth site by giving examples. 12/3/2013 2:49:11 PM
  17. 17. Topic wise Solved Questions of Previous Years 17 Ans. Various theories of growth are based on the growth centres. Growth sites do not control the overall growth of the bone. Differences between growth site and centre are as follows: Theories of growth are not based on growth site. The overall growth of the bone is controlled by growth centre. Growth site Growth centre It is any location or site where growth takes place. It is a location or place where genetically controlled growth takes place. Q. 10. Expanding ‘V’ principle It is a region where periosteal or sutural bone formation and remodelling resorption adaptive to environment occurs. It is a place of ossification with tissue-separating force. Ans. Sites of growth does not continue to grow when transplanted to another area. Centres of growth continue to grow when transplanted to another area. It markedly responses to external influences. Its response to external influence is less whereas response to functional needs is more. It is the place where exaggerated growth takes place but does not cause growth of the whole bone. It causes growth of the major part of the bone. All growth sites are not growth centres. All growth centres are growth sites. Expanding ‘V’ principle is one of the concepts/theories related to craniofacial growth, put forward by Enlow. According to Enlow’s expanding ‘V’ principle many facial bones or parts of bone have a ‘V’-shaped pattern of growth. In these bones the growth movements and enlargement occurs toward the wide ends of the ‘V’ as a result of differential deposition and selective resorption of bone. Bone deposition occurs on the inner side of the wide end of the ‘V’ and bone resorption on the outer surface. Deposition also takes place at the ends of the two arms of the ‘V’, resulting in growth movement towards the ends. In a number of regions such as the base of the mandible, ends of long bones, mandibular body, palate, etc., the ‘V’ pattern of the growth occurs. SHORT NOTES Q. 1. Growth spurts Or Growth spurts and two clinical importance Or Prepubertal growth spurt Ans. Growth does not take place uniformly at all times. There seems to be periods when a sudden acceleration of growth occurs. This sudden increase in growth is termed growth spurt. The timing of the growth spurts differs in boys and girls as follows: i. Just before birth ii. One year after birth iii. Mixed dentition growth spurt (boys 8–11 years and girls 7–9 years) iv. Prepubertal growth spurt (boys 14–16 years and girls 11–13 years). Clinical importance Knowledge of growth spurts is essential for successful treatment planning in orthodontics. Orthodontics-Part-I-2013.indd 17 Growth modulation by means of functional and orthodontic appliances elicits better response during growth spurts. Q. 2. Growth sites Ans. Growth site is any location or site where growth takes place. It is a region where periosteal or sutural bone formation, remodelling and resorption adaptive to environment occurs. Sites of growth do not continue to grow when transplanted to another area. They markedly respond to external influences. They are the places where exaggerated growth takes place; but they do not control the overall growth of the bone. All growth sites are not growth centres. Q. 3. Growth curve Or Scammon’s growth curves Or 12/3/2013 2:49:11 PM
  18. 18. Quick Review Series for BDS 4th Year: Orthodontics 18 Enumerate various tissues for which Scammon’s growth curves are plotted. Ans. Scammon’s growth curve indicates that growth rate of different tissues is different at different ages. Example: The various tissues for which Scammon’s growth curve is plotted is lymphoid tissue, neural tissue, general or visceral tissue, and genital tissue. Lymphoid tissue proliferates rapidly in late childhood to almost 200% of adult size. By 18 years it undergoes involution to reach adult size. Neural tissue grows very rapidly and almost reaches adult size by 6–7 years of age; after that a very little growth occurs in neural tissue. General or visceral tissue exhibits ‘S’-shaped curve, which indicates rapid growth up to 2–3 years of age followed by slow phase between 3 and 10 years of age, followed again by rapid phase of growth occurring after 10th year and terminating by 18–20 years. Genital tissue shows negligible growth until puberty. They grow rapidly at puberty reaching adult size after which growth ceases. Q. 4. Capsular matrix Ans. Capsular matrix is a component of functional matrix. It has neurocranial capsule and orofacial capsule. Each of the neurocranial capsule and orofacial capsule is an envelope that contains series of functional cranial components, which as a whole is sandwiched between two covering layers. The alterations in special position of skeletal units is brought about by the expansion of these capsules with in which the respective bones arise, grow and are maintained. The skeletal units are passively and secondarily moved in space, as their enveloping capsule is expanded. This kind of translative growth is not brought about by deposition and resorption. Q. 5. Functional matrix theory Ans. Functional matrix hypothesis was put forward by Melvin Moss based on the work of van der Klaauw. The theory is simply stated as, ‘there is no direct genetic influence on the size, shape or position of skeletal tissues, only the initiation of ossification. All skeletogenic activity is primarily based upon the functional matrices.’ Functional cranial component is divided into functional matrix and skeletal unit; functional matrix comprises Orthodontics-Part-I-2013.indd 18 all the tissues, organs and functioning spaces as a whole, while skeletal unit comprises skeletal tissues related to specific function matrix. It was demonstrated that the origin, growth and maintenance of the skeletal unit depends almost exclusively upon its functional matrix. Clinical implications of functional matrix theory The forced application by orthodontic appliances tends to alter the functional matrix. Alteration of periosteal functional matrix produces changes in microskeletal unit while the alteration of capsular functional matrix produces changes in macroskeletal unit. Q. 6. Methods of measuring or studying growth Ans. Various methods of measuring growth are as follows: A. Proffit’s classification B. Moyer’s classification. A. Proffit’s classification Measurement approaches i. Anthropometry ii. Craniometry iii. Cephalometry iv. Arcial growth v. Logarithmic spiral vi. Finite element analysis B. Moyer’s classification i. ii. iii. iv. Experimental approaches Vital staining Radioactive tracer Autoradiography Implant radiography i. Quantitative method a. Direct measurements, e.g. craniometry, vital staining, etc. b. Indirect measurements, e.g. study casts, radiographs, etc. ii. Observations iii. Rating and ranking iv. Opinions. Q. 7. Twin studies Ans. In twin study, twins are compared. Comparing monozygotic twins with dizygotic twins is the best way to determine the extent of genetic effect on malocclusion. The heritability of malocclusion can be determined by comparing the ordinary siblings, monozygotic twins and dizygotic twins. In case of monozygotic twins, any change in occlusion or features could be attributed to environmental factors as both of them have similar DNA, whereas in dizygotic twins interplay of genetic and environmental factors is responsible. 12/3/2013 2:49:11 PM
  19. 19. Topic wise Solved Questions of Previous Years 19 Q. 8. Neurotrophism Ans. A non-impulse transmitting neural function that involves axoplasmic transport and provides for long-term interaction between neurons and innervated tissues that homeostatically regulate the morphological, compositional and functional integrity of those tissues is known as neurotrophism. Presently, the nature of neurotrophic substances and the process of their introduction into the target tissue is unknown. The various types of neurotrophic mechanisms are: i. Neuroepithelial trophism ii. Neurovisceral trophism iii. Neuromuscular trophism. Q. 9. Types of bone growth movements Or Cortical drift Ans. Drift and displacement are two basic methods of growth movements. Cortical drift A combination of bone deposition and resorption resulting in a growth movement towards the depositing surface is called cortical drift. It occurs in all the regions of growing bones, producing generalized enlargement as well as relocation of parts. Displacement The movement of the whole bone as a unit is known as displacement. It can be of two types: primary or secondary. i. Primary displacement: If a bone gets displaced as a result of its own growth, it is known as primary displacement. ii. Secondary displacement: If a displacement of bone occurs as a result of growth and enlargement of adjacent bone, it is known as secondary displacement. Q. 10. Growth trends Ans. Three types of growth trends enumerated by Tweed are as follows: i. Type A: Maxilla and mandible grow in unison, both downwards and forwards. ANB shows no change. ii. Type B: Maxilla grows more rapidly than mandible. ANB angle increases. iii. Type C: Mandible grows faster than maxilla. Decrease in ANB angle. Orthodontics-Part-I-2013.indd 19 These growth trends are helpful in planning retention for individual orthodontic cases. Q. 11. Growth centres Ans. Growth centre is a location or place where genetically controlled growth takes place. These are places of ossification with tissue-separating force and cause growth of the major part of the bone. Centres of growth continue to grow when transplanted to another area. Their response to external influence is less, whereas response to functional needs is more. All growth centres are growth sites. The overall growth of the bone is controlled by growth centre. Q. 12. Differential growth Ans. Human throughout life body does not grow at the same rate; different organs grow at different rates to a different amount and at different times. This is known as differential growth. The concepts of differential growth are more clearly understood by two important aspects of growth: i. Cephalocaudal gradient of growth ii. Scammon’s curve of growth i. Cephalocaudal gradient of growth. An axis of increased growth gradient extending from head towards the feet is called ‘cephalocaudal growth.’ In fetal life, head constitutes 50% of total body length while limbs are primitive (30%). At the time of birth, head constitutes 25–30% and there is increased growth of body and limbs. In an adult, the head constitutes only 12%, while limbs accounts to 50%. These changes in the pattern of growth are because of cephalocaudal gradient. Scammon’s growth curve indicates that growth rate of different tissues are different at different ages. Example: The various tissues for which Scammon’s growth curve is plotted are lymphoid tissue, neural tissue, general or visceral tissue, and genital tissue. Q. 13. Methods of gathering growth data Ans. The various methods of gathering growth data are as follows: i. Longitudinal studies ii. Cross-sectional studies iii. Semilongitudinal studies. 12/3/2013 2:49:11 PM
  20. 20. Quick Review Series for BDS 4th Year: Orthodontics 20 The physical growth can be studied by a number of ways: i. Opinion ii. Observations iii. Ratings and rankings. Quantitative measurements: A scientific approach to study growth is based on accurate measurements, which are of three types: i. Direct data ii. Indirect data iii. Derived data. Q. 14. Enumerate the peak periods of postnatal growth. Ans. The peak periods of postnatal growth are as follows: i. One year after birth ii. Mixed dentition growth spurt (boys 8–11 years and girls 7–9 years) Topic 3 iii. Prepubertal growth spurt (boys 14–16 years and girls 11–13 years). Q. 15. Enumerate various theories of growth. Ans. Based on the expression of intrinsic genetic potential various theories of craniofacial growth are: i. Genetic theory by Brodie ii. Sutural dominance theory by Sicher iii. Cartilaginous theory by Scott iv. Functional matrix theory by Melvin Moss v. van Limborgh’s theory. Other concepts/theories related to craniofacial growth are: i. Hunter and Enlow’s growth equivalent concept ii. Petrovic’s cybernetic theory. GROWTH AND DEVELOPMENT OF CRANIAL AND FACIAL STRUCTURES LONG ESSAYS Q. 1. Describe in detail about prenatal and postnatal growth of mandible. Or Discuss prenatal and postnatal growth of mandible and its clinical implications in orthodontics. Or Followed by Mesenchymal condensation forming the first arch (mandibular arch) Define growth and development. Explain the postnatal growth of mandible. Ans. Prenatal growth phases are as follows: i. Period of ovum (from fertilization to 14th day) ii. Period of embryo (from 14th to 56th day) iii. Period of fetus (56th day to birth). Prenatal growth of mandible Mandible is derived from ossification of an osteogenic membrane formed from ectomesenchymal condensation at around 36–38 days Resulting intramembranous bone lies lateral to Meckel’s cartilage of 1st arch (mandibular arch) First structure to develop in primordium of lower jaw is At 6th week of IU life Mandibular division of V nerve (function: presence of nerve is postulated as being necessary to induce osteogenesis by production of neurotrophic factors.) Orthodontics-Part-I-2013.indd 20 In the region of bifurcation of inferior alveolar nerve into mental and incisive branches, a single ossification centre for each half of the mandible arises. 12/3/2013 2:49:11 PM
  21. 21. Topic wise Solved Questions of Previous Years 21 The condyles are low and at the position of the occlusal plane. The symphyseal suture has not ossified. During 7th week of IU life The bone begins to develop lateral to Meckel’s cartilage and continues until the posterior aspect is covered by the bone. Ossification stops at the point that later becomes the mandibular lingula, from where Meckel’s cartilage continues into middle ear and develops into auditory ossicles, i.e. malleus and incus. The remaining part of the Meckel’s cartilage continues on its own to form the sphenomandibular ligament and the spinous process of the sphenoid bone, which are remnants of it. Between 8th and 12th weeks of IU life. There is marked acceleration of mandibular growth and as a result mandibular length increases; the external auditory meatus appears to move posteriorly. Between 10th and 14th weeks of IU life. Secondary accessory cartilages appear to form the head of the condyle, part of the coronoid process and mental protuberance. Soon the growing intramembranous ossification fuses the coronoid process to the ramus. The ossification of the ramus proceeds and the condyle is soon fused to the mandible at about 16 weeks. Meckel’s cartilage persists until as long as 24th week of IU life before it disappears. Postnatal growth of mandible Among all the facial bones, the mandible undergoes largest amount of growth postnatally and also exhibits the largest variability in morphology. Mandibular growth in the postnatal life shows integration of the periosteal and capsular matrices of functional matrix theory by Moss. Capsular matrix involves the oropharyngeal functional spaces and the mandible grows according to the functional needs of the particular functional system. The process of surface remodelling usually involves the activity of the periosteal matrix, i.e. muscle fibres. Mandible at birth Mandible at birth is much smaller in size and varies in shape from the adult form. The infant mandible has a short, more or less horizontal ramus with obtuse gonial angle. Orthodontics-Part-I-2013.indd 21 Growth in the first year It involves growth at the symphyseal suture and lateral expansion in the anterior region to accommodate the erupting anterior teeth. The mental foramen is directed at right angle to the surface of the corpus. There is increased bone deposition in the posterior surface of the ramus of the mandible. The infant mandible is suited for the suckling activity since the condyle and the glenoid fossa is flat, which helps in the anteroposterior movement of the mandible. Mandible in the adult/concept of V principle The adult mandible differs from the mandible of an infant in which: the ramus is longer and the gonial angle is less obtuse. the bone is larger on the whole and the condyle is welldeveloped. All these changes take place in the growth of the mandible in the form of an expanding V. Because of its horseshoe shape, it is easier to visualize mandible as the V-shaped bone than the maxilla. ‘V’ principle of growth According to this principle growth of mandible in length, width and height is as follows: Length The growth of the mandible in length anteroposteriorly is by the deposition of bone at the posterior border of the ramus and resorption at the anterior surface, which helps to lengthen mandible so that the anterior part of the ramus is occupied by the posterior part of the body in the future and accommodates the developing permanent molars. As the articulation of the condyle to the glenoid fossa is constant, the anterior displacement causes displacement of the mandible anteriorly as it grows posteriorly. As the mandible grows anteriorly, the opening of the mental foramen faces backward so that the neurovascular bundle leaves the foramen directed backwards. There is corresponding surface remodelling at the anterior border with deposition in the posterior surface of the symphysis, resorption in the superior part of the anterior surface and deposition in the inferior aspect. Width There is deposition in the lateral surface of the ramus and resorption on the lingual surface of mandible below the mylohyoid ridge. In contrast, the coronoid process undergoes apposition at the medial surface and resorption at the lateral surface. This expands the mandible like a V. 12/3/2013 2:49:11 PM
  22. 22. Quick Review Series for BDS 4th Year: Orthodontics 22 The condyle undergoes reduction of bone on the lateral aspect of neck; and deposition corresponding to the V principle makes the condyle longer at the neck. Following the V principle, the interramal distance is efficiently increased by the growth of mandible, which helps the mandible to keep pace with the growth of the cranial base. The mandible, which is often retrognathic in the newborn, assumes an orthognathic relation with the maxilla during adulthood due to the growth of the bone in length. The condylar cartilage contributes little, if any, to the growth and does not act as primary growth centre. In patients with ankylosis of the temporomandibular joint, the mandible is found to grow to normal length. The muscular processes of the mandible like angle, coronoid and condylar processes are under the influence of the periosteal matrix. Height In the alveolar process, height increases well with eruption of teeth. Bone deposition taking place in the lower border of mandible also contributes to increase in height of the mandible. Rotation of mandible Bjork used implants to study the growth pattern of mandible and found that mandible undergoes growth rotation. It was found that though mandible undergoes rotation the effects seen are minimal due to external compensation. It was concluded that the growth of mandible is largely influenced by the functional matrices; and condylar cartilage has little influence in its overall growth. Summary of mandibular growth Length increases by: i. Surface apposition at posterior border of ramus and resorption at anterior border ii. Deposition at bony chin iii. Growth at condylar cartilage. Height increases by: i. Surface apposition at alveolar border ii. Apposition at the lower border of mandible iii. Growth at the condylar cartilage. Width increases by: i. Sutural growth up to 1st year postnatally ii. Later surface apposition at outer surface. Growth sites in mandible are: i. Mandibular condyle ii. Posterior border of ramus iii. Alveolar process iv. Lower border of mandible v. Suture. Orthodontics-Part-I-2013.indd 22 Q. 2. Define growth and development. Discuss prenatal growth of maxilla. Ans. Growth has been defined by various clinicians in different ways as follows: JS Huxley—‘The self-multiplication of living substance.’ Krogman—‘Increase in size, change in proportion and progressive complexity.’ Todd—‘An increase in size.’ Merdith—‘Entire series of sequential anatomic and physiologic changes taking place from the beginning of prenatal life to senility.’ Moyers—‘Quantitative aspect of biologic development per unit of time.’ Moss—‘Change in any morphological parameter which is measurable.’ Development is defined in simple words as ‘progression towards maturity.’ According to Melvin Moss, “development can be considered as a continuum of causally related events from the fertilization of ovum onwards.” Prenatal growth of maxilla Maxillae, a pair of bones on either side of the middlethird of the face, formed by intramembranous bone formation. Due to its more cranial location, maxilla is ahead of mandible in growth, generally. The cephalocaudal gradient of growth of maxilla closely follows the neural growth curve in the Scammon’s curves. Stages of prenatal growth of craniofacial region The prenatal craniofacial growth develops in three stages: a. The period of the ovum from fertilization till 2nd week b. The period of embryo from 2nd to 8th week c. The period of fetus from the 9th week till birth. The tissues of the face, both hard and soft tissues, are of neural crest cell origin, also called ectomesenchymal origin. The neural crest cell gives rise to diverse structures—both near the site of its origin and at remote sites. In the head and neck region the neural crest cells give rise to facial processes, branchial arches and their cartilages, etc. Frontonasal process The head begins to take shape at around 21 days after conception. The migrating neural crest cells when encounter the lens placode form two streams. The anterior stream of cells forms the mesenchyme of the frontonasal process and the posterior stream migrates to form the structures of the branchial arches. 12/3/2013 2:49:11 PM
  23. 23. Topic wise Solved Questions of Previous Years 23 Most of the development of the face takes place between 3rd and 8th week of IUL. At around 4th week of IUL, the branchial arches begin to develop. Branchial arches The branchial arches, developing during the late somite period, are formed from the mesoderm of the ventral foregut. There are five pairs of branchial arches, the fifth being transitory. The first arch is the mandibular arch and the second arch is the hyoid arch. The jaws of the face, namely, maxilla and mandible, are derived from the first arch. In the meanwhile, the frontonasal process of the forebrain just above the stomodeum develops bilateral thickenings called nasal placodes. In the middle, there is invagination of the placode to form nasal pits; on both sides of them there are elevations that are medial and lateral nasal processes. Maxillary process By around 4th week of IUL facial process arises from the first arch, which corresponds to the mandibular processes. Later, ventromedially two more swellings grow from the mandibular processes called the maxillary processes. By about 6th week the processes of the face are easily discernible. The stomodeum is bound by the frontonasal process above, the mandibular process below and the sides being occupied by the maxillary processes. The maxillary process grows ventromedially towards the nasal processes. The maxillary process fuses with the lateral nasal process and migrates medially to contact the inferolateral side of the medial nasal process. The maxillary and the medial nasal processes are initially separated by the epithelial nasal fin, which soon degenerates so that the mesenchyme of the two processes fuses. The maxillary and mandibular processes fuse at the sides to form the cheek tissue. The lateral nasal process forms the ala of the nose. The medial nasal process of both sides fuse to form the globular process in the middle, which gives rise to the tip of the nose, columella, philtrum, labial tuberculum of the upper lip, frenulum and entire primary palate. The maxillary process forms the alveolus, which bears teeth distal to the canines and the secondary palate. The area of fusion of the maxillary and mandibular processes forms the commissural corners of the mouth. As the two processes grow towards the fellow of the opposite side, the stomodeum is narrowed. Ossification centres of maxilla Maxilla develops by intramembranous ossification. A primary ossification centre appears at about early 8th week at the termination of the infraorbital nerve situated just above the canine tooth lamina. There are two centres for each maxilla. Orthodontics-Part-I-2013.indd 23 Secondary cartilages appear at the end of the 8th week in the regions of the zygomatic and alveolar processes that ossify and fuse with the primary centre. Around 8th week, two ossification centres appear in the region of the premaxilla on each side. The centres rapidly merge with the primary centres and are overshadowed by the growth of the primary centres. Q. 3. Explain how maxilla increases in width, length and height. Or Explain in detail about postnatal growth and development of maxilla. Ans. Postnatal growth of maxilla The development and growth of maxilla is completed early when compared to the mandible. The growth of maxilla especially in width closely follows the neural growth curve more than the general growth curve in the Scammon’s curve. Growth of maxilla Growth of maxilla occurs by the following processes: 1. Displacement or translation Displacement or translation of a bone is the process by which specific local areas come to occupy new actual positions in succession as the entire bone enlarges. It may be active or passive. Maxilla is attached to the cranial base; hence the growth of the cranial base has a direct bearing on the nasomaxillary growth. A passive or secondary displacement of the nasomaxillary complex occurs in a downward and forward direction as the cranial base grows. This is a secondary type of displacement, the nasomaxillary complex is simply moved anteriorly as the middle cranial fossa grows in that direction. It is an important growth mechanism during the primary dentition period, but becomes less important as growth of cranial base slows down. Active translation takes place when the growth at the tuberosity of the maxilla pushes the maxilla forward. A primary type of displacement is seen in a forward direction, which results in the whole maxilla being carried anteriorly. The amount of this forward displacement equals the amount of posterior lengthening. This is a primary type of displacement as the bone is displaced by its own enlargement. 2. Growth at the sutures by connective tissue proliferation The maxillae articulate with the surrounding bones of cranium and cranial base with the help of number of 12/3/2013 2:49:11 PM
  24. 24. Quick Review Series for BDS 4th Year: Orthodontics 24 sutures like the zygomaticomaxillary, frontomaxillary, pterygopalatine and zygomaticotemporal sutures, etc. According to Sicher, growth at these paired parallel sutures will move the maxilla downward and forward. It is only secondary and not a primary mechanism. As growth of the surrounding soft tissue occurs, the maxilla is carried downwards and forward leading to opening up of space at the sutural attachments. New bone is now formed on either side of the sutures leading to the overall increase in size of the bones on either side. Hence, a tension-related bone formation occurs at the sutures. 3. Remodelling In addition to the growth occurring at the sutures, simultaneous resorption and deposition moves the surfaces of the maxilla while maintaining the integrity and basic shape of the bone. Remodelling by bone deposition and resorption occurs to bring about: a. Increase in size b. Change in shape of bone c. Change in functional relationship. Maxillary growth matures first in width followed by the depth and length. It would be easier to discuss the growth of maxilla in the same order. a. Maxillary width The floor of the orbit faces superiorly, laterally and anteriorly. Growth proceeds in this direction by deposition and resorption on the lateral surface of the orbital rim. Resorption occurs on the lateral surface of the orbital rim leading to lateral movement of the eye ball. To compensate, there is bone deposition on the medial rim of the orbit and on the external surface of the lateral rim. Mid-palatal suture is active till 15 years; but it cannot be generalized. Due to sutural growth there is bone fill in the mid-palatal area and resorption in the lateral aspect. The entire wall of the sinus except the mesial wall undergoes resorption. This results in increase in size of the maxillary sinus. In the zygomatic process and the zygomatic arch, it is more complex. There is deposition on the posterior and lateral aspects and resorption on the anterior and medial surfaces. Thus the zygomatic bone moves in a posterior direction. The face enlarges in width by bone formation on the lateral surface of the zygomatic arch and resorption on its medial surface. The nasal part of the maxilla faces in an anterior, lateral and superior direction. The growth proceeds in the same Orthodontics-Part-I-2013.indd 24 direction. There is surface removal of bone from the periosteum lining the inner aspect of the nasal cavity and deposition on the endosteal surface. This allows expansion of the nasal cavity. b. Anteroposterior depth Zygomatic bone moves posteriorly and laterally by deposition in the posterior and lateral surface and resorption in the medial surface. Bone deposition occurs along the posterior margin of the maxillary tuberosity. This causes lengthening of the dental arch and enlargement of the anteroposterior dimension of the entire maxillary body. This helps to accommodate the erupting molars. The anterior nasal spine prominence increases due to bone deposition. In addition, there is resorption from the periosteal surface of labial cortex. As a compensatory mechanism, bone deposition occurs on the endosteal surface of the labial cortex and periosteal surface of the lingual cortex, and the maxilla moves forward. The zygomatic bone moves in a posterior direction to keep its relation with the maxilla. This happens by resorption in the anterior surface and deposition in the posterior surface. c. Maxillary height Bone resorption is seen on the floor of the nasal cavity. To compensate, there is bone deposition on the palatal side. Thus a net downward shift occurs leading to increase in maxillary height. As the teeth start erupting, bone deposition occurs at the alveolar margins. This increases vertical height of the maxilla and depth of the palate. This increase is seen as long as the teeth erupt. This contributes to early increase in the height of maxilla and accounts for about 40% increase in the maxillary height. Maxillary growth can be summarized as follows: Length increases by—sutural growth and the surface apposition at maxillary tuberosity. Width increases by—growth at the median palatine suture and apposition at zygomatic bone. Height increases by—sutural growth, surface apposition and alveolar growth. Growth sites in maxilla: i. Maxillary tuberosity ii. Sutures iii. Alveolar border iv. Nasal septum v. Lateral walls. 12/3/2013 2:49:11 PM
  25. 25. Topic wise Solved Questions of Previous Years 25 SHORT ESSAYS Q. 1. Development of palate Ans. The palate is formed by contributions of the following maxillary process: i. Palatal shelves of the maxillary process ii. Frontonasal process. The frontonasal process gives rise to the premaxillary region while the palatal shelves form the rest of the palate. As the palatal shelves grow medially, their union is prevented by the presence of the tongue. Thus, initially the developing palatal shelves grow vertically downwards towards the floor of the mouth. During the 7th week of intrauterine life withdrawal of tongue from between palatal shelves aids in transformation of their position from a vertical to a horizontal direction. By 8½ weeks of intrauterine life the two palatal shelves are in close approximation with each other, which are initially covered by an epithelial lining. As they join, the epithelial cells degenerate. The connective tissues of the palatal shelves intermingle with each other resulting in their fusion. The entire palate does not contact and fuse at the same time. Initially contact occurs in the central region of the secondary palate posterior to the premaxilla. From this point, closure occurs both anteriorly and posteriorly. The mesial edges of the palatal processes fuse with the free lower end of nasal septum and thus separates the nasal cavities from each other and the oral cavity. Ossification of the palate occurs from the 8th week of intrauterine life. The palate ossifies from a single centre derived from the maxilla. The most posterior part of the palate does not ossify and forms the soft palate. The midpalatal suture ossifies by 12–14 years. Postnatal growth of the palate follows the concept of expanding ‘V’ by Enlow. It is a more complex process. It is one of the best examples of the expanding ‘V’ principle. Growth at the suture by bone fill contributes more to the increase in width of the palate than remodelling. The width of the palate also increases by the growth of the alveolar process which diverges out. Many bones or parts of the bone are in the form of ‘V’. Bone deposition takes place on the inner side of ‘V’ and resorption takes place on the outer surface. If the outer surface of the expanding ‘V’ is taken, the periosteal surface can be found to be lined with osteoclasts, and endosteal surface is found to be lined with osteoblasts. Orthodontics-Part-I-2013.indd 25 In young child the maxillary arch and the nasal floor are very close to the inferior orbital rim. By deposition on the palatal periosteal surface and resorption on the nasal floor, the palate comes to occupy a lower position. When viewed in the cross-section, the deposition of the bone occurs along the whole of the periosteal surface of the palate in such a way that the bone expands in a lateral direction and also downwards. The nasal floor due to resorption increases in volume and descends down from the level of infraorbital rim. In conjunction with the ‘V’ principle, half of the external surface involved in this growth is depository and other half is resorptive; thus, half of the bone tissue of the palate is endosteal and other half is periosteal. The same concept is seen even in the anteroposterior growth of the palate or midsagittal section of the palate. There is deposition on the palatal surface and resorption along the anterior surface or incisor area and superior surface, expanding the palate like a ‘V’. Q. 2. Describe the developmental defects of maxilla. Ans. The developmental defects of maxilla are as follows: The most prominent defect in the development of maxilla is the cleft lip—either unilateral or bilateral. The cleft lip can be complete or partial. The most common is unilateral cleft lip (1 in 800 births). Bilateral cleft lip is rare and produces a protuberant, freehanging middle part of the lip. The cleft lip occurs due to failure of the fusion of maxillary and medial nasal processes. The failure of fusion of the medial nasal processes produces the midline cleft—the ‘true hare lip’, which is exceedingly rare. Lateral facial cleft or oblique facial cleft is occasionally seen in condition of failure of fusion of lateral nasal process with the maxillary process. Cleft lip/palate and other facial clefts develop during the period of organ formation in the craniofacial development. This approximates to about 28–55 days of IUL. Over fusion of the maxillary and mandibular processes leads to a small mouth called microstomia. Q. 3. Postnatal growth and development of the mandible. Ans. Postnatal growth of mandible is as follows: 12/3/2013 2:49:11 PM

×