Most imp structures to study !!

1. GROWTH AND DEVELOPMENT OF
MAXILLA AND MANDIBLE
Priyanka Doshi
M.D.S Part 1

2. According to TODDAccording to TODD
“Growth is an increase in size & ,Development is
progress towards maturity

3. Mechanism Of Bone GrowthMechanism Of Bone Growth
•Bone is a specialized tissue of mesodermal origin. It forms theBone is a specialized tissue of mesodermal origin. It forms the
structural framework of the body.structural framework of the body.
•Bone is calcified tissue that supports the body & gives points ofBone is calcified tissue that supports the body & gives points of
attachment to the musculature.attachment to the musculature.
•Normal bone contains between 32-36% of organic matter.Normal bone contains between 32-36% of organic matter.
•Growth movements are of 3 types:-Growth movements are of 3 types:-
-Bone deposition & resorption-Bone deposition & resorption
-Cortical drift-Cortical drift
-Displacement-Displacement

4. TYPES OF OSSIFICATIONTYPES OF OSSIFICATION
Accordingly 2 types of bone growth ossification are normally seen.
1. Intramembranous ossification: TheThe
transformation of mesenchymal connectivetransformation of mesenchymal connective
tissue usually in membranous sheets, intotissue usually in membranous sheets, into
osseous tissues.osseous tissues.

5. 2. Endochondral ossification:
The conversion of hyaline cartilage
prototype models into bone.

6. Growth and development of an individual can beGrowth and development of an individual can be
divided into PRENATAL & the POSTNATALdivided into PRENATAL & the POSTNATAL
periods. The pre-natal life can be arbitrarily dividedperiods. The pre-natal life can be arbitrarily divided
into three periods.into three periods.
1. Period of the Ovum1. Period of the Ovum
2. Period of the Embryo2. Period of the Embryo
3. Period of the Fetus3. Period of the Fetus

7. Period of the ovumPeriod of the ovum::
This period extends for a period ofThis period extends for a period of
approximately two weeks from the time of fertilization.approximately two weeks from the time of fertilization.
During this period the cleavage of the ovum and theDuring this period the cleavage of the ovum and the
attachment of the ovum to the intra-uterine wallattachment of the ovum to the intra-uterine wall
occurs.occurs.

8. Period of the embryoPeriod of the embryo::
This period extends from the fourteenth day to the fifty sixthThis period extends from the fourteenth day to the fifty sixth
day of intra-uterine life.day of intra-uterine life.
During this period the major part of the development of theDuring this period the major part of the development of the
facial & the cranial region occurs.facial & the cranial region occurs.
..

9. Period of the fetusPeriod of the fetus::
This phase extends between the fifty sixthThis phase extends between the fifty sixth
day of intra-uterine life till birth. In this period ,acceleratedday of intra-uterine life till birth. In this period ,accelerated
growth of the cranio-facial structures occurs resulting in angrowth of the cranio-facial structures occurs resulting in an
increase in their size. In addition, a change in proportionincrease in their size. In addition, a change in proportion
between the various structures also occursbetween the various structures also occurs

10. PRENATAL GROWTH OF MAXILLA

11. •Around the fourth week of intra-uterine life, a prominent bulge appears onAround the fourth week of intra-uterine life, a prominent bulge appears on
the ventral aspect of the embryo corresponding to the developing brain.the ventral aspect of the embryo corresponding to the developing brain.
•Below the bulge a shallow depression which corresponds to the primitiveBelow the bulge a shallow depression which corresponds to the primitive
mouth appears called “ STOMODAEUM”.mouth appears called “ STOMODAEUM”.
•The floor of the stomodeum isThe floor of the stomodeum is
formed by the buccopharyngealformed by the buccopharyngeal
membrane which separates themembrane which separates the
stomodeum from the foregut.stomodeum from the foregut.

12. By around the 4th week of intra-uterine life, five branchialBy around the 4th week of intra-uterine life, five branchial
arches form in the region of the future head & neck.arches form in the region of the future head & neck.
Each of these arches gives rise to muscles, connective tissue,Each of these arches gives rise to muscles, connective tissue,
vasculature, skeletal components & neural components of thevasculature, skeletal components & neural components of the
future face.future face.

13. The first branchial arch plays an important role in theThe first branchial arch plays an important role in the
development of the naso- maxillary region.development of the naso- maxillary region.
The mesoderm covering the developing forebrain proliferates &The mesoderm covering the developing forebrain proliferates &
forms a downward projection that overlaps the upper part offorms a downward projection that overlaps the upper part of
stomodeum .This downward projection is calledstomodeum .This downward projection is called “FRONTO-“FRONTO-
NASAL PROCESS”.NASAL PROCESS”.

14. The stomodeum is thus overlapped superiorly by the fronto-The stomodeum is thus overlapped superiorly by the fronto-
nasal process. The mandibular arches of bothnasal process. The mandibular arches of both
The sides form the lateral walls of the stomodeum.The sides form the lateral walls of the stomodeum.
The mandibular arch gives off a bud from its dorsal end calledThe mandibular arch gives off a bud from its dorsal end called
the “MAXILLARY PROCESS”.the “MAXILLARY PROCESS”.

15. The maxillary process grows ventro-medio-cranial to the mainThe maxillary process grows ventro-medio-cranial to the main
part of the mandibular arch which is now called thepart of the mandibular arch which is now called the
“MANDIBULAR PROCESS”.“MANDIBULAR PROCESS”.
Thus at this stage the primitive mouth or stomodeum isThus at this stage the primitive mouth or stomodeum is
overlapped from above by the frontal process,below by theoverlapped from above by the frontal process,below by the
mandibular process & on either side by the maxillary process.mandibular process & on either side by the maxillary process.

16. The ectoderm overlying the fronto-nasal process shows bilateral localizedThe ectoderm overlying the fronto-nasal process shows bilateral localized
thickenings above the stomodeum. These are called the “NASALthickenings above the stomodeum. These are called the “NASAL
PLACODES”.These placodes soon sink and form the nasal pits.PLACODES”.These placodes soon sink and form the nasal pits.
The formation of these nasal pits divides the fronto-nasal process into twoThe formation of these nasal pits divides the fronto-nasal process into two
parts:parts:
a)The medial nasal process &a)The medial nasal process &
b)The lateral nasal processb)The lateral nasal process

17. The two mandibular processes grow medially & fuse to formThe two mandibular processes grow medially & fuse to form
the lower lip & lower jaw.the lower lip & lower jaw.
As the maxillary processes become narrow so that the twoAs the maxillary processes become narrow so that the two
nasal pits come closer. The line of fusion of the maxillarynasal pits come closer. The line of fusion of the maxillary
process & the medial nasal process corresponds to the naso-process & the medial nasal process corresponds to the naso-
lacrimal duct.lacrimal duct.

18. DEVELOPMENT OF PALATE
The palate is formed by the
contribution of:
• Maxillary process.
• Palatal shelves given off by the
maxillary process
• Fronto-nasal process

19. PRIMARY PALATE
• By the fusion of the maxillary and nasal processes in the roof of the stomodeum
the primitive palate (or primary palate) is formed, and the olfactory pits extend
backward above it.
• It consists of the maxillary process and medial nasal process.

20. SECONDARY PALATE
The development of the secondary palate commences in
the sixth week of human embryological development. It is
characterised by the formation of two palatal shelves on
the maxillary prominences

21. • As the palatal shelves grow medially their, their union is prevented
by the presence of tongue
• Initially the developing palatal shelves grow vertically toward the
floor of mouth
• During 7th
week of intrauterine life, a transformation in the position
of the palatine shelf occurs
• They change from a vertical to a horizontal position

22. • The 2 palatal shelves, by 8 ½ weeks of intra uterine life are in
close approximation to each other
• Initially the 2 palatal shelves are covered by an epithelial lining.
As they join the epithelial cells degenerate
• Initially the contact occurs in the central region of the secondary
palate posterior to the premaxilla
• From this point, closure occurs both anteriorly and posteriorly

23. OSSIFICATION OF PALATE
• Ossification of the palate occurs from the 8th
week of
intra- uterine life. This is an intramembranous type of
ossification
• The palate ossifies from a single centre derived from the
maxilla
• The most posterior part of the palate does not ossify. This
forms the soft palate
• The mid palatal suture ossifies by 12-14 yrs

24. POST NATAL GROWTH OF MAXILLA

25. ..The growth of naso-maxillary complex is
produced by the following mechanisms:
• Displacement
• Growth at sutures
• Surface remodelling

26. DisplacementDisplacement
It is the movement of the whole bone as a unit.It is the movement of the whole bone as a unit.
Displacement can be of two types:-Displacement can be of two types:-

27. PRIMARY DISPLACEMENT
1.Primary displacement: It occurs by growth of
maxillay tuberosity in a posterior direction. This
results in whole maxilla being carried anteriorly. The
amount of this forward displacement equals the
amount of posterior lengthning. This is primary type
of displacement as the bone is displaced by its own
enlargement.

28. 2. Secondary displacement: A passive or secondary
displacement of the naso-maxillary complex occurs
in a downward and forward direction as the cranial
base grows.

29. GROWTH AT SUTURES
The maxilla is connected to the cranium and cranial base
by a number of sutures. These sutures include:
• Fronto-nasal suture
• Fronto-maxillary suture
• Zygomatico-maxillary suture
• Zygomatico-temporal suture
• Pterygopalatine suture

30. Sutures are oblique and parallel to each other. This allows the downward
and forward repositioning of maxilla as growth occurs at these sutures. As
growth of surrounding soft tissue occurs, the maxilla is carried downwards
and forward. This leads to opening up of space at the sutural attachments.
New bone is formed on either side of the suture. Thus the overall size of the
bones on either side increases.

31. SURFACE REMODELING
Remodeling occurs by bone deposition &Remodeling occurs by bone deposition &
resorption to bring about:resorption to bring about:
a) Increase in size
b) Change in shape
c) Change functional relationship

32. Bone deposition & resorption:Bone deposition & resorption:
Bone changes in shape & size by two basic mechanisms,Bone changes in shape & size by two basic mechanisms,
bone deposition & bone resorption. The bone deposition &bone deposition & bone resorption. The bone deposition &
resorption together is called “resorption together is called “ BONE REMODELINGBONE REMODELING”.”.
The changes that bone deposition & resorption can produceThe changes that bone deposition & resorption can produce
are:are:
• Change in sizeChange in size
• Change in shapeChange in shape
• Change in proportionChange in proportion
• Change in relationship of the bone with adjacent structures.Change in relationship of the bone with adjacent structures.

33. Bone remodeling seen in the midfacial regionBone remodeling seen in the midfacial region

34. Bone remodeling of the palate resulting inBone remodeling of the palate resulting in
its downward displacementits downward displacement

35. Growth of the palate exhibiting V pattern of growthGrowth of the palate exhibiting V pattern of growth

36. EXPANDING “V” PRINCIPLE OF MAXILLA
As the maxilla descends, transversely, additive growth on the free ends
increases the distance between them. The buccal segments move
outward and downward, as the maxilla itself is moving downward and
forward, following the principle of expanding

37. DEVELOPMENTAL ANOMALIES AFFECTING
MAXILLA
• Cleft palate.
• Micrognathia.
• Macrognathia.
• Cleidocranial dyplasia
• Craniofacial dysostosis

39. PRENATAL GROWTH OF MANDIBLE

40. The first structure to develop in the primordium of the lower
jaw is the mandibular division of trigeminal nerve that
preceeded the mesenchymal condensation forming the
first arch (mandibular).

41. MECKEL’S CARTILAGE
Meckel’s cartilage is derived from the first branchial arch
around the 41st
-45th
day of intra uterine life.
It extends from the cartilaginous otic capsule to the midline
or symphysis and provides a template for guiding the
growth of the mandible.

42. A major portion of the Meckel’s carlitage disappears during
growth and the remaining part develop into the
following structures:-
• The mental ossicles
• Incus and malleus
• Spine of sphenoid bone
• Anteriorligament of malleus
• Spheno mandibular ligament

43. • As a result mandibular
length increases, the
external auditory meatus
appears to move posteriorly.
• Bone begins to develop
lateral to Meckel’s cartilage
during the 7th
week and
continues until the posterior
aspect is covered with bone.
• This is the marked
acceleration of the
mandibular growth between
the 8th
and 12th
week IU

44. • Ossification stops at the
point, which will later become
the mandibular lingula and,
the remaining part of meckel’s
cartilage continues on its own
to form sphenomandibular
ligament and the spine
process of sphenoid
ossification.
• Meckel’s cartilage does,
however, persist until as long
as the 24th
week IU, before it
disappears.

45. ENDOCHONDRAL BONE FORMATION
Endochondral bone formation is seen in 3 areas of mandible-
1) The condylar process
2) The coronoid process
3) The mental process

46. • At fifth week of intrauterine life , an area of mesenchymalAt fifth week of intrauterine life , an area of mesenchymal
condensation is seen above the ventral part of developingcondensation is seen above the ventral part of developing
mandible.mandible.
• At about tenth week it develops in cone shaped cartilage.At about tenth week it develops in cone shaped cartilage.
• It migrate inferior & fuses with mandibular ramus at about 4It migrate inferior & fuses with mandibular ramus at about 4
month.month.

47. THE CORONOID PROCESS-THE CORONOID PROCESS-
Secondary accessory cartilage appear in region of coronoidSecondary accessory cartilage appear in region of coronoid
process at about 10- 14 week of intrauterine life.process at about 10- 14 week of intrauterine life.
This cartilage become incorporated into expanding intramembranousThis cartilage become incorporated into expanding intramembranous
bone of ramus & dissappear before birth.bone of ramus & dissappear before birth.

48. THE MENTAL REGION-THE MENTAL REGION-
In mental region , on either side of symphysis , one or two smallIn mental region , on either side of symphysis , one or two small
cartilage appear and ossify in seventh week of intrauterine life tocartilage appear and ossify in seventh week of intrauterine life to
become mental ossicles.become mental ossicles.
These ossicles become incorporated into intramembranous boneThese ossicles become incorporated into intramembranous bone
when symphysis ossify completely.when symphysis ossify completely.

49. POST NATAL GROWTH OF MANDIBLE

50. RAMUS
• The ramus moves progressively posterior by a combination of
deposition and resorption
• Resorption occurs on the anterior part of the ramus while bone
deposition occurs on the posterior region. This results in drift of
ramus in a posterior direction

51. CORPUS or the BODY OF MANDIBLE
Body of the mandible lengthens as the ramus exhibits bone
deposition on the posterior aspect and resorption on the
anterior aspect

52. ANGLE OF THE MANDIBLE
• On the lingual side of the angle of the mandible, resorption takes
place on the posterio-inferior aspect while deposition occurs on the
antero-superior aspect
• On the buccal side, resorption occurs on the anterio-superior part
while deposition takes place on the postero-inferior part. This results
in flaring of the angle of the mandible as age advances

53. THE LINGUAL TUBEROSITY
• The lingual tuberosity moves
posteriorly by deposition on its
posterior facing surface
• Lingual tuberosity protrudes
noticeably in a lingual direction
and that it lies well toward the
midline of the ramus.
• The prominence of the tuberosity
is increased by the presence of a
large resorption field just below it
• The resorption field produces a
sizeable depression, the lingual
fossa

54. THE ALVEOLAR PROCESS
• As the teeth erupt the alveolar
process develops and increases in
height by bone deposition at the
margins
• The alveolar process adds to the
height and thickness of the body of
the mandible
• In case of absence of teeth, the
alveolar bone fails to develop and it
resorbs in the event of tooth
extraction

55. THE CONDYLE
The role of condyle in the growth of mandible has
remained a controversy. There are 2 schools of thought
regarding the role of the condyle:
• It was earlier believed that growth occurs at the surface
of condylar cartilage by means of bone deposition

56. • It is now believed that the gowth of soft tissues including
the muscles and connective tissues carries the mandible
forward away from the cranial base( carry away
phenomenon)

57. THE CORONOID PROCESS
The growth of th coronoid process follows the enlarging “V” principle
• Viewing the longitudinal section of the coronoid process from the
posterior aspect, deposition occurs on the lingual surfaces of the left
and right coronoid process
• Viewing it from the occlusal aspect, the deposition on the lingual of
the coronoid process brings about a posterior growth movement in the
“V” pattern.

58. THE CHINTHE CHIN ––
Enlow & harris feel that chin is “associatedEnlow & harris feel that chin is “associated
with a generalised cortical recession in thewith a generalised cortical recession in the
flattened regions positioned between theflattened regions positioned between the
canine teeth. The process involves acanine teeth. The process involves a
mechanism of endosteal cortical growth.”mechanism of endosteal cortical growth.”
As the age advances the growth of chinAs the age advances the growth of chin
becomes significantbecomes significant
Usually males have prominent chin asUsually males have prominent chin as
compared to femalescompared to females
Prominence of mental protuberance isProminence of mental protuberance is
accentuated by bone resorption that occursaccentuated by bone resorption that occurs
in the alveolar region above it, creating ain the alveolar region above it, creating a
concavityconcavity

59. DEVELOPMENTAL ANOMALIES AFFECTING
MANDIBLE
•Agnathia
•Micrognathia
•Macrognathia
•Facial hemihypertrophy
•Facial hemiatrophy