INTRODUCTION ANATOMY PRENATAL GROWTH OF MANDIBLE OSSIFICATION OF MANDIBLE POST NATAL GROWTH OF MANDIBLE DEVELOPMENTAL DEFECTS OF MANDIBLE

1. PRENATAL AND POSTNATAL
GROWTH AND DEVELOPMENT OF
MANDIBLE
DR. SAUMYA PAUL
DEPT. OF
PEDODONTICS

2. CONTENTS
 INTRODUCTION
 ANATOMY
 PRENATAL GROWTH OF MANDIBLE
 OSSIFICATION OF MANDIBLE
 POST NATAL GROWTH OF MANDIBLE
 DEVELOPMENTAL DEFECTS OF MANDIBLE

3. GROWTH
According to Moyers , Growth is defined
as quantitative aspect of biological
development per unit of time.
DEVELOPMENT
According to Moyers ,Development refers
to all the naturally occurring unidirectional
changes in the life of an individual from its
existence as a single cell to its
multifunctional unit terminating to death.
INTRODUCTION

4. FACTORS AFFECTING PHYSICAL GROWTH
 HEREDITARY
 NUTRITION
 ILLNESS
 RACE
 SOCIO-ECONOMIC FACTORS
 FAMILY SIZE AND BIRTH ORDER
 CLIMATIC AND SEASONAL EFFECTS
 PSYCHOLOGICAL DISTURBANCES
 EXERCISE

5. THEORIES OF GROWTH
1. GENETIC THEORY
According to this theory , growth is controlled by genetic
influence and is pre-panned.
2. SUTURAL THEORY
SICHER believed that cranio facial growth occurs at the
sutures.
3. CARTILAGENOUS THEORY
According to James Scott, intrinsic growth controlling
factors are present in cartilage .

6. FUNCTIONAL MATRIX CONCEPT
by-Melvin Moss
The functional matrix hypothesis claims that
the origin, form, position, growth and
maintenance of all the 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 functioning spaces.

8. ANATOMY OF MANDIBLE

9. External
Surfaces
Body
Internal Upper/Alveolar Lower/Basal
Borders

10. Ramus
2 Surfaces
Lateral
4 Borders 2 Processes
Medial
Superior
Posterior
Anterior Inferior
Condylar coronoid

11. GROWTH OF
MANDIBLE
11
Prenatal
growth
Postnatal
growth
Reference-
Human
Embryology,
IB Singh

12. PRENATAL GROWTH
At 4th week of IU
life
12
Developing brain and pericardium form 2
prominent bulges
Separated by stomatodeum or primitive
oral cavity
Floor of stomatodeum
Formed by bucco-pharyngeal membrane
Separating it from foregut

13. 13
6 branchial arches are formed
in the region of head and neck
5th arch disappears soon
Each arch gives rise to-
Muscles
Connective tissue
Vasculature
Skeletal and neural components

14.  In humans, six pharyngeal arches are formed.
 1st arch is known as mandibular arch.
 2nd arch as hyoid arch.
Other arches do not have special names.
14

15. Each arch has
1. Outer covering of ectoderm.
2. An inner covering of
endoderm.
3. Core of mesoderm.
 Arches are separated from
each other by
1.Pharyngeal cleft or groove externally.
2.Pharyngeal pouches internally.
 Each arch contains
1. A cartilaginous supporting element
2. An arch artery
3. An arch-associated cranial nerve
15

17. 17
 The mesoderm covering the developing forebrain
proliferates & forms a downward projection called
FRONTO-NASAL PROCESS. And forms superior
wall of stomodeum.
 Mandibular arch gives of a bud from dorsal end called
MAXILLARY PROCESS

18.  Thus at this stage stomodeum is bounded by frontal process
above,mandibular process below and maxillary process on
either side.
 The ectoderm overlying the fronto nasal process shows bilateral
thickening called NASAL PLACODES
 They soon sinks and forms nasal pit

19.  This divides fronto nasal processs into two parts
1.The medial nasal process
2.The lateral nasal process
 The two mandibular process grows medially and
fuse to form the lower lip and lower jaw
 Maxillary process undergoes growth and fronto
nasal processes narrows so that two nasal pits
comes closer
 The line of fusion of maxillary process and
median nasal process corresponds to naso
lacrimal duct

21. AT 6 WEEKS
•Proliferation of
mesenchymal cells
forms the medial
and lateral nasal
prominence
•Nasal pits develops
in the centre of
nasal placodes

22. AT 7 WEEKS
•The maxillary
prominence enlarge
and push the medial
nasal prominence
toward each other.
•Nasolacrimal groove
develops at the line of
fusion.
•The medial nasal
prominences move
towards each other
,fuse in midline ,and
form the intermaxillary
segment which is the
origin of the philtrum
of upper lip,maxillary
incisors and primary
palate.

23. AT 10 WEEK

24. >The cartilage of 1st arch is called as
Meckel’s cartilage.
> Provides a template for guiding the growth
of mandible.
> 41th- 45th day of I.U.L
> Extents from otic capsule to Midline or
Symphysis
MECKEL'S CARTILAGE

26.  The mandibular branch of trigeminal nerve appears 1st at about
2/3rd length of meckel’s cartilage level.
 This nerve bifucates into medially lingual nerve and laterally
inferior alveolar branches.
 Further bifurcates into incisive and mental branch more
anteriorly.

27. OSSIFICATION OF MECKEL’S CARTILAGE
At 6th week of IU life → a single ossification centre for each
half of mandible develop in the region of the bifurcation of
inferior alveolar nerve.
Neurotrophic factors produced by the nerve induces
osteogenesis in the ossification centre.
27

30. • From center of ossification bone formation spreads:
Anteriorly - towards midline
Posteriorly – till the place where mandibular nerve divides
into lingual and inferior alveolar branch and forms the
body of mandible.
And bone formation posterior to this division forms ramus
of mandible.
.

31. • Ossification spread further
posteriorly to form ramus of
mandible, turning away from
meckel’s cartilage.
• This point of divergence is
marked by lingula in adult
mandible.
• A major portion of the
Meckel’s cartilage disappears.
31

32. Remaining part of Meckel’s
cartilage develops :
1. Incus & Malleus.
2. Spine of sphenoid bone.
3. Anterior ligament of malleus.
4. Spheno – mandibular ligament.
32

33. OSSIFICATION OF MANDIBLE
ENDOCHONDRAL
 Cartilage template is
replaced by
endochondrial bone
 Indirect bone growth
 Slow expansion
INTRAMEMBRANOUS
Direct deposition of osseous
tissue in periosteal membrane
Direct bone growth
Rapid expansion

35. OSSIFICATION OF
MANDIBLE
 Bone of the body and ramus .
 Mineralization of primitive bone begins in 7th
week.
 Primitive mandible is termed as os dentale.
INTRAMEMBRANOUS OSSIFICATION

36. Further growth of mandible untill birth is influenced strongly by
appearance of three secondary cartilages.
• Condylar cartilage
• Coronoid cartilage
• Symphyseal cartilage
36
ENDOCHONDRAL BONE FORMATION

37. • At fifth week of intrauterine life , an area of mesenchymal
condensation is seen above the ventral part of developing
mandible.
• At about tenth week it develops in cone shaped cartilage.
• It migrate inferior & fuses with mandibular ramus at about 4
month and
persists untill
end of second
decade.
37
CONDYLAR CARTILAGE
Textbook of orthodontics, 1st edition, S Gowri Sankar, Page 54

38. CORONOID CARTILAGE
• Secondary accessory cartilage appear in region of coronoid
process at about 10- 14 week of intrauterine life.
• Cartilage grow is believed to grow as a response of developing
temporalis muscle.
• This cartilage become incorporated into expanding
intramembranous bone of ramus & dissappear by birth.
38

39. SYMPHYSEAL CARTILAGE
• Two in number.
• Appear in between the two end of Meckel’s cartilage.
• At about 7th month of IUL theses undergo ossification and form
mental ossicles.
• Later these ossicles merge with symphysis region.
• Ossification of symphysis will be completed by the end of 1 yr
after birth.
39

40. POST NATAL GROWTH OF
MANDIBLE
 Mandibular bone is one of the bones which
exhibits a wide variation in their
morphology.
 This is due to the fact that of all the facial
bones, it is the one which undergoes
largest amount of growth postnatally.
 Basically mandible does not grow, it
remodels and simultaneously displace
downward and forward.

41. MECHANISM OF MANDIBULAR GROWTH
Growth Of The Mandible Primarily Involve
1. Bone remodeling
Process Of Bone Deposition And Resorption
2. Cortical drift
Combination of bone deposition and resorption resulting in
growth movement towards deposition surface
3. Displacement
Movement of whole bone as a unit
I) Primary displacement
II) Secondary displacement

42. NEONATAL MANDIBLE
 Ascending Ramus low and wide
 Poorly developed condyles
 Large Coronoid process
 Body – open shell containing tooth buds
and partially formed deciduous teeth
 Mandibular canal that runs low in the
body

43. MANDIBULAR GROWTH AFTER
1ST YEAR OF LIFE
 More selective.
 Definitive sequence –
Growth in width is completed first
Then, growth in length and
finally growth in height completed.

45. Effect of trauma on condyle

47. ANKYLOSIS

48. MANDIBULAR REMODELLING

49. Remodelling in terms of various anatomical units.
• Ramus
• Lingual Tuberosity
• Body of mandible
• Condylar process
• Condylar neck
• Coronoid process
• Angular process
• Mandibular foramen
• Alveolar process
• Mental foramen
• Chin
49

50. GROWTH AT RAMUS
 Resorption the anterior
part of the ramus.
 Deposition posterior
region.
Results in
Drift of the ramus in a posterior
direction.
 This resorptive nature is usually
described as “making room for
the last molars”. Textbook of orthodontics, 1st edition, S Gowri Sankar, Page 68

51.  This leads to growth of ramus in posterior,
superior and lateral position. 51
(Facial Growth – Donald H. Enlow third edition)
Superior part of ramus
below sigmoid notch
Lower part of ramus
below the Coronoid
process
lingual-deposition
Buccal-resorption
Buccal-deposition
Lingual-resorption

52. LINGUAL TUBEROSITY
 Just as maxillary tuberosity in maxilla,
lingual tuberosity in mandible is the
growth site.
 Grows posterior and medial by bone
deposition.
 Resorptive field below tuberosity
makes it more prominent.
 This resorptive field below is called as
Lingual fossa

53. BODY OF THE MANDIBLE
53
 The increase in width of the
mandible occurs primarily
due to resorption on the
inside and deposition on the
outside
 Increase in length occurs
due to drift of the ramus
posteriorly
 Increase in height occurs
due to eruption of the teeth

54. THE MANDIBULAR CONDYLE
 It is a major site of growth.
 Endochondral growth occurs at the condyle because of condylar cartilage.
 Condyle grows upwards & backwards resulting in downward and forward
growth of mandible.
 Selective remodeling of condyle follows Enlow ‘V’ principle.
 Condylar growth reaches peak at pubertal growth spurt (12-15 yrs)
54

55. 55
CONDYLAR NECK
> Since the circumference of the condyle is greater than the
circumference of neck, the lingual and buccal sides of the neck
have resorptive surfaces.
> In the mandible of an adult, both the outer and inner surfaces of
the cortices of the condylar neck are composed of endosteal bone.
> This is another example of the V principle

56. CORONOID PROCESS
56
 Deposition on lingual side
 Resorption on buccal surface
 Follows V Principle

57. ANTEGONIAL NOTCH
 A single field of surface resorption is present on the inferior edge
of mandible at the ramus corpus junction. This forms the
Antegonial notch.
 In Vertical growth it is deep
and
 Horizontal growth –shallow
57

58. THE MANDIBULAR FORAMEN
 With the remodelling of ramus posteriorly, the mandibular
foramen maintains its position by deposition in anterior rim and
resorption in posterior rim.
 It also shifts posteriorly and maintains its central position on
medial surface of ramus.
Textbook of craniofacial growth, Sridhar Premkumar, 1st edition, Page-99

59. THE ALVEOLAR PROCESS
59
 As teeth erupt the alveolar process develops and increase in height
by bone deposition at the margins.
 If teeth are absent, alveolar process
fails to develop.
 If teeth are extracted, alveolar process
resorbs.

60. MENTAL FORAMEN
 Newborn- Mental foramen points forward.
 At 5 years of age- Mental foramen points upwards.
 Adult- Mental foramen points backwards.
This is because of difference in growth rate of buccal and
lingual periosteum of body of mandible.
Textbook of craniofacial growth, Sridhar Premkumar, 1st edition,
Page-74

61. THE CHIN
61
 In infancy, the chin is usually under developed.
 As age advances the growth of chin become significant.
 The mental protuberance formed by bone deposition during
childhood.
 Its prominence is accentuated by resorption that occurs in the
alveolar region above it.

62. J Craniofac Surg. 2007 Jan;18(1):146-50.
Morphology and growth of the
mandible in Crouzon, Apert, and
Pfeiffer syndromes.
Boutros S1, Shetye PR, Ghali S, Carter
CR, McCarthy JG, Grayson BH
purpose
To examine mandibular morphology and growth in patients with Crouzon,
Pfeiffer, and Apert syndromes using PA cephalograms
All patients had serial cephalograms at 5, 10, and 15
years of age.
The bicondylar width, bigonial width, bicondylar/bigonial
ratio, and ramus to IC plane angle were measured on the
cephalograms and compared with age-match controls.
An analysis was carried out to detect differences between
patients and controls and sex differences between
patients.
METHOD

63. RESULT
1. In both male and female patients, significant reduction in
bicondylar width was seen.
2. Male patients also had a significant increase in bigonial
width compared with controls and female patients at 10
and 15 years.
3. The resulting bicondylar/bigonial ratios were significantly
reduced.
4. Ramus to IC plane angles were significantly increased in
both male and female patients compared with controls.
CONCLUSION
These findings suggest a narrowing at the cranial base with resulting
restriction of normal transverse mandibular growth at the condyle.
Consequently, the ramus appears torqued inward, forming a greater
angle with the cranial base.

65. DEVELOPMENTAL DEFECTS
OF MANDIBLE

68. AGNATHIA
68
 Autosomal recessive disorder .
 Characterised by hypoplasia or absence of
mandible.
 It is probably due to absence of neural
crest mesenchyme in lower part of face.

69. MICROGNATHIA
69
 Characterised by small jaw either the maxilla or the
mandible.
 Severe retrusion of chin.
 Steep mandibular plane angle.

70. MACROGNATHIA
70
 Abnormally large jaw
 E.g.
Paget’s disease of bone.
Acromegaly.

71. CORONOID HYPERPLASIA
71
 Rare developmental anomaly.
 Unknown etiology.
 M:F ratio 5:1
 May be unilateral or bilateral.
 Result in limited mandibular movement

72. CONDYLAR HYPERPLASIA
72
 Excessive growth of one of the condyles.
 Cause is unknown.
 Endocrine disturbances, and trauma have been suggested as
possible etiologic factors.

73. CONDYLAR HYPOPLASIA
73
 Congenital:
Mandibulofacial dysostosis.
Hemifacial microsomia .
 Acquired

74. BIFID CONDYLE
74
 Rare & cause is uncertain
 Bifid condyle generally has medial and
lateral head but may be divided into anterior
and posterior head.

75. TORUS MANDIBULARIS
75
 It is excessive growth of bone
along the lingual aspect of the
mandible.
 Generally above the
mylohyoid ridge.
 Causes includes both genetics
and environmental influences.

76. CLINICAL IMPLICATIONS
 Certain growth factors are of vital importance to orthodontist.
 There is no width change in denture area after 06 yrs of life .
 Mandibular intercanine width is completed by 9-10 yrs of age
in both females and males.
 In maxilla intercanine width is completed by 12 yrs in females
and 18 yrs in males.
 So the maxillary intercanine dimension serve as safety valve
for basal bone discrepancy.

77. RECENT ADVANCES TO STUDY
THE GROWTH AND
DEVELOPMENT OFMANDIBLE
 Genex 3D camera
 3D digital photogrammeric images
 3D digitizer screening
 Aid of metallic implants
 3D facial imaging system

78. CONCLUSION
This overall picture of maxillary and mandibular
growth will hopefully serve the clinician a useful aid
when he/she uses growth modulation procedures as a
treatment modality…

79. REFERENCES
1. Contemporary Orthodontics – William R. Proffit, 4th
Edition.
2. An introduction to human embryology for medical
students – Inderbir Singh, 5th Edition.
3. Human anatomy, Regional and applied – Head, Neck and
Brain – B.D. Chaurasia, 3rd Edition.
4. Orban’s oral histology and embryology – S.N. Bhaskar,
11th Edition

80. Thank you…