Development of dentition and occlusion

FORMAT
INTRODUCTION
PRENATAL DEV. OF TEETH
1. STAGES OF TOOTH DEV
2. MECHANISM OF TOOTH ERUPTION
DEV. OF DENTITION FROM BIRTH TO
DECID. DENTITION
COMPLETE DECID. DENTITION
www.indiandentalacademy.com

Prenatal Dev. of Tooth
FORMATION OF DENTAL LAMINA
BUD STAGE
CAP STAGE
BELL STAGE
ADVANCED BELL STAGE
ROOT DEV.

INITIATION OF
ODONTOGENESIS
• 3rd
Week of IUL
• 6th
Week of IUL
• 4 Odontogenic zone-Mx
• 2 Odontogenic zone-Mb
• Morphologic change
• 6week IUL4-5 Yrs
IL
SL

DENTAL LAMINA

DEVELOPING TOOTH
BUDS

FORMATION OF TEETH
6TH
WEEK IUL DENTAL LAMINA
8-12 WEEK IUL A,B,C,D,E
4 MONTHS OF IUL 6
5-6 MONTHS OF IUL  1,2,3
9 MONTHS OF IUL  4
9 MONTHS – POSTNATAL  5,7
4TH
YEAR 8

BUD STAGE
7TH
WEEK OF IUL
KNOB LIKE
STRUCTURE
1ST
BUD Mb Antr-
8th
week
STAGE OF
PROLIFERATION

BUD STAGE HISTOLOGICAL
DENTAL LAMINA
ENAMEL ORGAN
MESENCHYMAL
CONDENSATION

CAP STAGE
8TH
WEEK OF IUL
 MITOTIC ACTIVITY OF
ECTOMESENCHYME
PROLIFERATION &
HISTODIFFERENTIATION

CAP STAGE HISTOLOGICAL
OUTER ENAMEL EPITH
DENTAL SAC
DENTAL PAPILLA
INNER ENAMEL EPITH
STELLATE RETICULUM

BELL STAGE
PROLIFERATION
HISTODIFFERENTIATION
MORPHODIFFERENTIATION

BELL STAGE HISTOLOGICAL
OUTER ENAMEL EPITH
STELLATE RETICULUM
STRATUM INTERMEDIUM
DENTAL PAPILLA
DENTAL SAC
INNER ENAMEL EPITH

ADVANCED BELL
STAGE
OEE DENTAL CUTICLE
IEE AMELOBLAST
DENTAL PAPILLA  ODONTOBLAST
DENTAL SAC  PDL, CEMENTUM,
ALVEOLAR BONE
CERVICAL LOOP HERS

ADVANCED BELL STAGE
HISTOLOGICAL
ODONTOBLAST
PRE DENTIN
DENTIN
ENAMEL MATRIX
AMELOBLAST

DEVELOPMENT OF ROOTS

MULTIROOTED TEETH

STAGES-NOLLA1952

POSITION OF DEVELOPING
TEETH

ERUPTION OF TEETH
ERUPTION movement towards occlusal
direction
EMERGENCE perforation of the gums
ERUPTION
PRE EMERGENT
ERUPTION
POST EMERGENT
ERUPTION

PRE EMERGENT ERUPTION
TWO PROCESSES:
RESORPTION
BONE
ROOTS OF PRI. TOOTH
ERUPTION MECHANISM ITSELF
Exp. Studies  dog and child
Failure of tooth eruption:
Cleidocranial dysplasiafailure in bone resorption
Primary failure of eruptionfailure of eruption mech.

Postemergent eruption
Eruption after emergence of tooth in oral cavity.
Postemergent spurt
 Rapid eruption from a time tooth penetrates the
gingiva till tooth reaches occlusal level.
 Eruption - During critical period b/w 8 PM to 1
AM.
 After it attain occlusal contact ,occlusal forces
opposes further eruption

Juvenile Occlusal equilibrium
 Slow phase
 Teeth erupt to fill the space created
by vertical growth of mandibular
ramus.

ADULT OCCLUSAL EQUILBRIUM
EXTREMELY SLOW
COMPENSATES OCCLUSAL WEAR
ANTAGONIST LOSTINCREASED
RATE OF ERUPTION

MECHANISM OF TOOTH
MOVEMENT
BONE REMODELING
ROOT FORMATION
VASCULAR PRESSURE
PERIODONTAL LIGAMENT TRACTION

BONE REMODELING
Exp shows when the tooth germ is
removed and the follicle remained
in position  eruption path created
Result dental follicle is major
determinant not bone

ROOT FORMATION
OPPOSING POINTS
1. Sometimes root is formed but still tooth
doesn’t erupt
2. Root formation and eruption do not coincide
Root formation req a fixed base to move tooth
in occlusal direction
No such fixed basebone gets resorbed
Presence of cushion hammock ligfixed
base
Discarded pulp delineating membrane, runs
across apex of tooth & has no bony
insertion cannot act as fixed basewww.indiandentalacademy.com

VASCULAR PRESSURE
Tooth moves with synchrony of
arterial pressure
Debatable on surgical excision of
the roots  no blood supply to the
dev tooth doesn’t prevent tooth
eruption

PDL LIGAMENT TRACTION
Presence of dental follicle is only necessary not
tooth germ--?
Dental follicle  PDL having fibers & matrix
Fibers  Collagen
Matrix Fibronexous gel
Fibroblasts of PDL contracts Force on
fibronexous gel  collagen fibers  eruption
Exp done Silicone replica erupts

PRECAUTIOUSLY
ERUPTED TEETH
NATAL TEETH
NEONATAL TEETH
PRE ERUPTED TEETH

NATAL TOOTH

TIME OF ERUPTION OF PRI.
TEETH
6-8 MONTHS  Mb C.I
9-10 MONTHS  Mx C.I
10-14 MONTHS  L.I
14-18 MONTHS  1ST
MOLAR
18-24 MONTHS  CANINE
24-30 MONTHS  2ND
MOLAR

MOUTH OF THE NEONATE
GUM PADS:
THICKENING OF OMM
PINK & FIRM
DENTAL GROOVE
PARTSLABIO/ BUCCAL
LINGUAL
TRANSVERSE GROOVE
LATERAL SULCUS

RELATIONSHIP OF GUM PADS
Mx  More ant.
In relation to mb
Contact at molar
region
Tongue protrude
at ant. Region

AT BIRTH
• Jaws are
relatively small
• Decid. Incisors and
canine are crowded
• Molars w/o crowding
often space b/w them

6-8 M0NTHS
Both jaw grow from birth
to 6-8 months
Marked ventral
dev.More antr. Position
of lower jaw in relation to
upper
Relatively dorsal position
of Mb initially present has
changed by the time
incisor erupt

9-10 MONTHS
Max. Central
incisors emerge
few months
after the
mandibular
ones

10-14 MONTHS
Decid. lateral
incisors emerge
at about 1yr
Mb ones are
usually precede
the Mx ones

14 -18 MONTHS
Transverse and
ventral dev of both
arches is limited
Postr. Region
keeps on growing
and provide space
for molar
emergence

18-24 MONTHS
Emergence of
canine
Mb teeth 
ventrally as the
antr. dev of the Mb
exceeds Mx

24-30 MONTHS
Eruption of 2nd
decid molar

Complete Decid. Dentition

Displacement of U & L Dm1
to establish occlusion :
Cone-funnel mechanism
Palatal cusp of
max. 1st
molar
– cone
Crater in mand.
1st
molar –
funnel

The Complete
Deciduous Dentition
A B C D E
A B C D E

The Complete Deciduous
Dentition
Competed at 2.5 yrs of age after dm2 erupts
and lasts till 5 yr of age
Physiological spaces in primary
dentition-
 Primate spaces
 Developmental spaces

PRIMATE SPACES

Spacing in Deciduous
dentition
 Gap toothed smile - normal
 Hollywood smile with teeth in contact - not normal

SPACING IN DECID.
DENTITION

Occlusal relationship of U & L
Dm2
3 types of terminal planes –
 Flush terminal plane
 Mesial step
 distal step

SHALOW OVERJET &
OVERBITE

CLINICAL IMPLICATIONS
OF DECIDOUS TEETH

DEEP BITE
Occur in initial stages development
Incisors are upright
Later reduced by
1. Eruption of decidous molars
2. Attrition of incisors
3. Forward movement of mandible

NORMAL VARIATION IN
POSITION OF TEETH
ANTERO-POSTERIOR VARIATIONS
TRANSVERSE/LATERAL VARIATIONS

Antero-posterior variations
Lower canines may be hidden by
upper canines upto age of 31/2
years  corrected by relative
forward movement of Mb arch
Spaces b/w the molars may be
present upto the age of 5 years
There may be space b/w the lower
canine and 1st
decid molar upto the
age of 9 years

Transverse/ lateral variations
Arch width increases b/w 5-8 yrs more in
upper arch than the lower allow forward
movement of Mb
The breadth of the arch in Mx 1st
perm
molar region inc by 1-2 mm upto 11 yrs
and may inc a small amount after this age
Decid incisors may be rotated but this
condition esp. in the lower incisor
improves by 4 yrs of age

CROWDING
 Rare in decid. dentition
 If present, definitely perpetuate
in perm teeth
CROSS BITE
 Should be treated as early as
possible
 Can impede the Mx. growth

Caries in decid dentition
Regular supervision should begin from
about 2 yrs of age  use of fluoride & pit
and fissure sealants
Proximal caries on decid 2nd
molar loss
of space  due to mesial migration of
perm 1st
molar
If perm 1st
molar not erupted space loss
is more
Space maintainers are given

Premature loss of decid teeth
Loss in arch length  mesial drifting of
perm molar
Perm molars are mesially inclined so on
eruption they move mesially and
occlusally
Exp. Data suggest in absence of opposing
occlusal contact, perm molar drift more
mesially  shows forces from occlusion
opposes mesial drifting of molars

Mesial drift of perm molar after
premature loss of pri 2nd
molar 
crowding in post. region
On premature loss of canine &1st
pri
molar  distal drifting of incisors occur
due to
 pull from trans-septal fibers
 lip pressure
if it occur on one side  perm teeth
drift distally only on that side
crowding & mid line shift

Trauma to primary teeth
1. Damage to permanent tooth buds
2. Drift of permanent teeth
3. Direct injury to permanent teeth

TRAUMA OF DEV PERM TEETH
When crown is forming When roots are forming
Disturbed enamel formation Root formn may stop
Defect in crown If continue, remaining
Part of root forms an angle
DILACERATION
Mech interference on eruption
Traumatically displaced tooth buds in children
Repositioned as early as possible normal root
Formation resume.www.indiandentalacademy.com

IF PERM TEETH ARE DISPLACED BY
TRAUMA :
Displaced labially or lingually
Immediate intact tooth should be moved
back to its original position during
treatment
After healing (2-3 weeks later), difficult to
reposition due to ankylosis

Retained deciduous teeth
Abnormal erup path of perm teeth e.g. lingual erup
of incisors on over retained decid incisors
If persists too long  entire obstn of erup of
successors
If R/F confirm the presence of successors retained
decid teeth may be extracted immediately
Where a pre molar successor is absent  try to
retain decid molar
If it is impossible, the space should be maintained
until tooth replaced artificially

Cuspal interferences
Happens freq if minor malocclusion of
individual decid tooth  deviation of Mb
path of closure
Normally this is corrected by attrition of
cusps
But if not corrected itself, selective
cuspal grinding is done  occlusal
equilibration

Supplemental decid teeth
If they are causing malocclusion 
extraction
Defect may repeat in perm dentition 
R/F examination should be carried out
before supernumerary teeth affect perm
teeth to erupt
Complete anodontia
Rare in decid dentition
If occur  anodontia of perm successor

CROWDING

THE FIRST
TRANSITION
PERIOD

The First transition
period
The emergence of 1st
permanent
molar (A B C D E 6)
Transition of the incisors

The emergence of 1st
permanent molar
1st
teeth to emerge in permanent dentition.
In mand. 6 –7 yr In maxillary arch 7- 8 yr
The A-P relation b/w two opposing
permanent molars depend upon –
 Their previous position within the jaw
 Sagittal relation b/w maxilla and mandible
 Terminal planes of 2nd
decid molars.

FLUSH TERMINAL PLANE
Distal surface of upper & lower 2nd
molar
are in one vertical plane
So erupting 1st
p molar flush or end on
relationship
To achieve class I molar relation lower
molar have to move 3-5 mm forward in
relation to upper molar

Utilization of physiologic spaces
and leeway space in lower arch
By differential forward growth of
mandible

EARLY MESIAL SHIFT
Occur early
Utilize primate space

LATE MESIAL SHIFT
In late mixed dentition
Utilize leeway space

MESIAL STEP
Distal surface of lower molar is more
mesial to upper
Occur due to early forward growth of mb
If growth persist in forward direction 
angle class III
If growth minimal  angle class I

DISTAL STEP
Distal surface of lower 2nd
decid molar is
more distal to upper
Erupting permanent 1st
molar is in class
II or end on

Influence of terminal
plane on the position of
1st
permanent molar

EXCHANGE OF INCISORS
Normally mb incisor erupt first
Incisor liability/ early incisor crowding
In mx – 7.6 mm in mb – 6 mm
Corrected by following way

utilization of interdental spaces
increase in anterior arch length
increase in inter-canine arch width

Inter canine arch width
Increase in both jaws
at the time of eruption
 3mm
Increase at the time of
canine eruption  1.5
mm

Role of tongue and lip
muscles
mx lat. incisor 
labially
mb lat. incisor 
lingually

Change in inclination of
permanent incisors
150
123

Overjet and overbite

Sequence of normal transition of incisors
At 5 yr. At 6 –7 yr
At 7 –8 yr.
At 8 – 9 yr
At 5 yr.
At 7 –8 yr.

Loss of decid. tooth is caused by-
 Resorption of its root
 By reduction of bone cervically
Several week passes b/w shedding of decid and
eruption of successor
A perm. teeth starts eruption after ¼ of its root
formed
Perm .teeth emerge in oral cavity when ¾ root is
formed..
Transition of incisors

DEVELOPMENT
OF DENTITION
AND OCCLUSION
Dr. ASHISH Kr. SINGH

Clinical considerations
UGLY DUCKLING STAGE
TERM  BROADBENT
TRANSIENT OR SELF CORRECTING

If m-d dimension of mb lat incisor is very large
 exfoliation of pri canine lingual tipping of
incisors  antr arch less stable
Frequently found in classII/1
Lingual tipping of incisors  permanent canine
slide labially  labioversion
Before applying ortho force  ¾ root formed

1 2 C D E 6
THE INTER
TRANSITIONAL
PERIOD

INTERTRANSITIONAL PERIOD
consist of both decid & permanent dentition
teeth present are 1 2 c d e 6
ugly duckling stage persist
under influence of tongue mb incisors attain
proper sites from their lingual position
decid teeth present are worn out
stable phase with little changes in dentition

INTERTRANSITIONAL
PERIOD

The Second
transitional period
Transition of Canine & premolar
Eruption of Second permanent molar

Transition of Canine&
Premolar
Transition of C D E with 3 4 5
For smooth exchange following are conditions
LEEWAY SPACE OF NANCE
Sum of M-D dimension of 3,4,5<C D & E
Space available
22.3 – 21.5= 0.8(U)
22.3 – 21.1=2.4(L)

Order of exchange of decid
canines and molars to permanent
canines & premolars
Takes 11/2 yrs to
complete
Sequence of eruption
Mx  4 5 3
Mb  3 4 5

Eruption of 2nd
molar
After loss of all
decid teeth
Sometimes it
erupts before E
sheds crowding

Transition of canine,pmolar &
erupn of 2nd
perm molar
At 10 – 11 yrs.
At 11 – 12 yrs
At 9- 10 yrs
At 10 – 12 yrs.
At 12 – 13 yrs.

The Permanent Dentition
1 2 3 4 5 6 7
1 2 3 4 5 6 7

The Permanent
Dentition
At around 13 yr of
age all permanent
teeth (except 3rd
molar) are
erupted.
Situation in normal
permanent dentition

Normal bucco-lingual
inclination of perm teeth in
both jaws

DISORDERS OF DEV
OF DENTITION

At time of eruption of Deciduous
dentition –
Teething disorder - most of infants exhibit
fever, diarrohea, vomiting , irritability etc
before tooth eruption.
Anomolies
Its rare for primary teeth to be congenitally
missing.
Primary tooth resorption
Hastened by inflammation and occlusal
trauma
Delayed by splinting and absence of
successor

Ankylosis of primary teeth
In Primary molars, esp during physiologic
resorption
Disorders of primary Occlusion –
Its less compared to permanent occlusion.
Thumb sucking and other oral habits
Posterior crossbite
Open bites
Class II malocclusion
Excessive overjet
Bruxism – functional malocclusion

Factors affecting transition of teeth
Dental caries in primary teeth
Disturbance in root resorption due to
pulpal or periodontal disturbances
A periapical lesion
Premature loss of primary molar

Anomolies in Permanent dentition
Microdontia, macrodontia
Gemination ,Fusion, Dilaceration, Talon
cusp, Dens evaginatus
Supernumerary roots
Dentinogenesis & Amelogenesis imperfecta
Enamel Hypoplasia

Abnormalities in dental
arch
Arch Length Discrepancy
 Crowding
 Spacing
Deviation in no. of teeth-
 Absence of teeth ( Agenesis)
 Supernumerary teeth

Absence of teeth
( Agenesis)
Sequece of agenesis is –
3rd molar > Mand. 2nd premolars >
Max Lateral Incisors > Max. 2nd
Premolar

Supernumerary teeth

Deviation in tooth size
Its relative in nature
All teeth combined > or < relative
to size of jaws or head.
 Crowding
 Spacing
Deviation in size of individual teeth
 Tooth size Discrepancy

Tooth size
Discrepancy

Deviation in individual
teeth position

Ankylosis
Frequent in mand deciduous molars.
In permanent 2 types
 Due to abnormal position within
jaw
 Max perm. Canine
 Due to lack of space
Mand 3rd molar

Angle’s classification
of Malocclusion
Class I
ClassII
Class II div 1
 Class II div 1 subdivison
Class II div 2
 Class II div 2 subdivison
Class III
 Class III subdivison

Development of
dentition in Class II/ 1
malocclusion

In Deciduous
dentition
Mand dental arch
dorsally placed irt
maxillary
Limited increase in
overbite
Distal step

In Intertransitional
period
Increased overbite
Mand 1st
perm molar
occludes dorsally to max

In Permanent Dentition
Increased overbite
Class II molar relation

Change in Incisor and Molar region in Class
II /1 , from deciduous to permanent
child
Adult
•Distal step
•Decid incisor labially
inclined.
•Lower lip dorsally
placed.
•Class II molar relation
•Max incisor erupts
labially.
• Mand incisor touches
the palate.
• Max incisor situated
infront of lower lip
•Mand incisor erupts
normally
•Mand incisor
continue to erupt .
• lower lip supports
max incisor.
• Secondary covering
of protruding max
incisors by lips.

Development of dentition in Class
II/2 malocclusion

Change in Incisor and Molar region in Class
II /2 , from deciduous to permanent
Lower lip – lingual
tipping of L. Incisor
In decid dentition
Less overjet
high lip line
Continued eruption
– till vertical contact
Mand incisor erupt
normally ,Max erupts
slightly upright
Lower lip – lingual tipping
of U. Incisor
In adult, U. C. incisor
tipped severely palatally

Class II /2 with more
space in anterior segment
U L P incisor erupt in
normal orientation as
sufficient space available
•Palatal tipping of U L P
incisor by L lip.
•Lingual tipping of lower
incisors.
•Rectangular arch form
Palatal tipping ( By L Lip)
U C P incisor - Continuous
arch with B & C

Class II /2 with less space
in anterior segment
•Palatal tipping ( By L Lip)
•U C P incisor - Continous
Arch with B & C
• Lateral erupts labially
• L lip placed lingual to laterals
•Max. laterals rest on the L lip.
•Max Central and Mand incisors
are perpendicular to Occ plane

Development of
dentition in Class III
malocclusion

In Deciduous dentition
Lower ant placed ventrally to
max. less overbite
Large mesial step

In Intertransitional
period
Incisal surface of
U incisor contact ligual
surface of lower
Mand perm !st molar
occludes too far
mesially to max
Mand dental arch ventrally
placed, reverse overjet

In Permanent dentition
Incisal surface of U incisor
contact lingual surface of
lower
Mand perm !st molar
occludes too far
mesially to max
Mand dental arch ventrally
placed, reverse overjet

Development of Open
bite

Anterior open bite
Asymmetrical open bite
due to thumb sucking
in Deciduous dentition
Open bite due to abnormal
Tongue position
(symmetrical)

Posterior open bite
Open bite due to incomplete
eruption of teeth.
Resulting in
interpositioning of tongue
Open bite combined with
inadequate contacts.

ClassII /1 Subdivison
• Class I on right side, class II on left
• Overjet overbite too large
• Midline shift.

ClassIII Subdivison
• Class I on right side, class III on left
• Anterior crossbite exists
• Midline shift.

Unilateral Crossbite
Maxillary dental arch crosses the mandibular
arch, distal to maxillary left canine

Bilateral Crossbite
On both sides maxillary molars occlude with their
buccal cusps instead of their palatal ones

Total exo-occlusion in ClassII/1
 All maxillary teeth positioned exteriorly to mandibular
 Brodie Syndrome or Telescope bite

Total endo-occlusion in Class III
All maxillary teeth positioned interiorly to mandibular
ones

Concept of occlusion
occ = upward clusion = closure
The act or process of closure or of
being closed or shut off.
The static relationship between the
incising or masticating surfaces of the
Mx & Mb teeth
GPT-7

OCCLUSION includes a integrated system of
functional units involving teeth, joints and
muscles of head & neck
-Wheelers
Normal relation of occlusal inclined planes of
teeth when the jaws are closed
-Angle

The curvatures of teeth
and arches
Curve of Spee.
Curve of Wilson
Curve of Monson

CURVE OF SPEE
Ferdinand graf spee (1890)
“The anatomic curve established by the occlusal
alignment of teeth, as projected onto the median plane
beginning with the cusp tip of Mb canine and following
the buccal cusp tips of PM & M teeth, continuing
through the ant. border of ramus , ending in the
condyle”
GPT-7

ORTHODONTIC IMPLICATION
Should be flat or slight curve
 vertical overlap
 decrease relapse
Inc COS Compensates for small Mx. teeth
Deeper the COS, more difficult to make &
adjust interocclusal app.(bruxism)

Leveling the curve of spee
Baldridge W.Dolye (1969)
2 ways of leveling
1. Intrusion of anteriors
2. Extrusion of pre molars
Limiting factors of leveling
1. Availability of alveolar bone
2. Root morphology

Curve of wilson
George H. wilson
Eponym for mediolateral curve

“In the theory that occlusion should be spherical,
the curvature of the cusp as projected on the
frontal plane expressed in both arches; the curve
in the lower arch being concave and the one in the
upper arch being convex. The curvature in the
lower arch is affected by an equal lingual inclination
of the right and left molars so that the tip points
of the corresponding cross aligned cusps can be
placed into the circumference of circle. The
transverse cuspal curvature of the upper teeth is
affected by the equal buccal inclination of their
long axis”
GPT-7

CURVE OF MONSON
Visualized the plane to be 3D spherical
curvature
Centre of sphere is vector of masticatory
forces
Dempster et al

SIX KEYS TO NORMAL OCCLUSION
LAWRENCE F.ANDREWS(1972)
Criteria for selection
1. Had never undergone ortho treatment
2. Were straight & pleasing in appearance
3. Had a bite which looked generally correct
4. In his judgement, would not benefit from
ortho treatment

ANDREWS SIX
KEYS OF OCCLUSION
1. MOLAR RELATIONSHIP
2. CROWN ANGULATION
3. CROWN INCLINATION
4. ROTATIONS
5. TIGHT CONTACTS
6. OCCLUSAL PLANE

Molar relation

Crown angulation

Crown inclination

Crown inclination of posteriors

Tip and torque

Absence of rotations

Occlusal plane

References
Van der Linden- Development of Dentition
Proffit- Contemporary Orthodontics 3rd
Ed
Moyers- Handbook of Orthodontics 4th
Ed
Glossary of Prosthodontic Terms 7th
Ed
Wheelers- Dental Anatomy Physiology &
Occlusion 7th
Ed
AJO-DO Sept 1972- The Six Keys To Normal
Occlusion
T.M.Graber- Principles & practice Of
orthodontics

Oral Anatomy- Berkovitz
Oral Histology- Orbans
Dentistry for Child- Mc Donalds
Orthodontics for Dental Students- White
& Gardiner, B C Leighton

Development of dentition and occlusion

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