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DR. JIGNESH TATE
Ist Year Post Graduate
DEPARTMENT OF PERIODONTOLOGY
CONTENTS
• Introduction
• Pre- natal growth of mandible
• Post- natal growth of mandible
• Fate of Meckel’s cartilage
• Se...
INTRODUCTION
Mandible is the largest and
strongest bone of the face, serves
for the reception of lower teeth.
It consists ...
 About the fourth week of
intrauterine life, the
pharyngeal arches are laid
down.
 The first arch is called the
mandibul...

The first branchial arch, also called the first pharyngeal arch
and mandibular arch, is the first of six pharyngeal arch...
The first structure to
develop in the primodium
of the lower jaw is the
mandibular division of
trigeminal nerve.
Meckel’s cartilage has a close
relationship to the mandibular nerve,
beginning two thirds of the way along the
length of ...
Development of:
 Body or Corpus of
mandible
 Rami of mandible
 Condylar process
 Coronoid process
 Alveolar process
D...

The cartilage of the first arch, Meckel’s cartilage, has a close
relationship to the developing mandible.
At 6 weeks of ...
Its proximal or cranial ends are connected with the ear capsules, and
their distal extremities are joined to one another a...
During the 6th week of embryonic development, on the lateral aspect of
Meckel’s cartilage, a condensation of mesenchyme oc...
From this centre of ossification, bone formation spreads rapidly
anteriorly to the midline and posteriorly to the point wh...

The new bone forms a trough that consist of medial and
lateral plates that unite beneath the nerve.
The trough is soon c...
THE RAMI OF THE
MANDIBLE
The ramus of the mandible develops by a rapid spread of ossification
backwards into the mesenchyme of the first branchial ...

 Thus by 10 weeks of development, the rudimentary
mandible is formed almost entirely by intramembranous
ossification.
Meckel’s cartilage has the following fate:
H & E stained section-Meckel’s cartilage
Prenatal Development of the Human Mand...

 The further growth of mandible is influenced by the
appearance of 3 secondary cartilages:
1) Condylar cartilage
2) Cor...
Carrot shaped cartilage appears (at 12 weeks of development) in the
region of the condyle and occupies most of the develop...
The coronoid cartilage:
It is relatively transient growth cartilage center ( 4th MIU).
It gives riseto:
• Coronoid process...
 They are two in number.
Appear in the connective tissue between the two ends of
Meckel’s cartilage.
They are obliterate...
THE ALVEOLAR PROCESS
 It starts when the deciduous tooth germs reaches the early bell
stage.
 The bone of the mandible begins to grow on each...
GROWTH OF THE MANDIBLE
I. Growth of
secondary
cartilage
II. Development
of the alveolar
process
III. Sub-periosteal
bone apposition
Growth of Man...
Growth by secondary cartilage
Increase in height of the
mandibular ramus
Increase in the overall length of
the mandible
In...
II. Development of the alveolar process:
 The alveolar process develops in response to the presence of
tooth buds.
 As t...
III. Sub-periosteal bone apposition:
Bone deposition Bone resorption Result in
External surface of
the mandible
Inner surf...
AGE CHANGES IN THE
MANDIBLE
At birth
The body of the bone is a mere shell, containing the sockets of the
two incisor, the canine, and the two deciduo...

Childhood
The two segments of the bone become joined at the symphysis,
from below upward, in the first year; but a trace...

 The mandibular canal, after the second dentition, is
situated just above the level of the mylohyoid line; and
the ment...

Adulhood
The alveolar and subdental portions of the body are
usually of equal depth. The mental foramen opens
midway bet...

Old age
The bone becomes greatly reduced in size, for with the
loss of the teeth the alveolar process is resorbed.
The m...
 Developmental disturbances:
Agnathia
Micrognathia
Macrognathia
Facial hemihypertrophy
Facial hemiatrophy
Abnormalities o...

Agnathia
• Hypoplasia or absence of mandible.
• The entire mandible or one side
may be missing or only the
condyle or th...
Micrognathia

• Means small jaw.
• Maxilla or mandible
may be affected.
• Can be due to small jaw
or to an abnormal
posit...

Macrognathia
• Abnormally large jaws.
• Increased height of ramus.
• Increased mandibular body length.
• Increased gonia...

Exhibit an enlargement which is confined to one side of the
body, unilateral macroglossia, and premature development,
an...

Progressive wasting of subcutaneous fat accompanied by
atrophy of skin, cartilage, bone and muscle.
Facial hemiatrophy

 Class II
 Class III
Abnormalities of dental arch relations
 Median mandibular cyst
- Originate from proliferation of epithelial remnants
entrapped in the median mandibular fissure ...

 Alveolar cyst of newborn
- Arise from epithelial remnants of deeply budding
dental lamina during tooth development.
All the events taking place during development of mandible
play an important role in determining the final structure of
ma...
1) Ten Cate’s Oral Histology, Development, Structure And Function, 7th
Edition.
2) Orban's Oral Histology And Embryology, ...
THANK YOU !
Development of mandible
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Development of mandible

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Development of mandible

  1. 1. DR. JIGNESH TATE Ist Year Post Graduate DEPARTMENT OF PERIODONTOLOGY
  2. 2. CONTENTS • Introduction • Pre- natal growth of mandible • Post- natal growth of mandible • Fate of Meckel’s cartilage • Secondary cartilages • Age changes in mandible • Clinical considerations • Conclusion • References
  3. 3. INTRODUCTION Mandible is the largest and strongest bone of the face, serves for the reception of lower teeth. It consists of curved, horizontal portion, the body; and two perpendicular portions the rami, which unite with the ends of the body nearly at right angles.
  4. 4.  About the fourth week of intrauterine life, the pharyngeal arches are laid down.  The first arch is called the mandibular arch. Courtesy:Human Embryology,I.B.Singh
  5. 5.  The first branchial arch, also called the first pharyngeal arch and mandibular arch, is the first of six pharyngeal arches. This arch divides into a maxillary and a mandibular process, giving rise to structures including the bones of the lower two-thirds of the face and the jaw. The maxillary process becomes the maxilla (or upper jaw), and palate while the mandibular process becomes the lower jaw. This arch also gives rise to the muscles of mastication.
  6. 6. The first structure to develop in the primodium of the lower jaw is the mandibular division of trigeminal nerve.
  7. 7. Meckel’s cartilage has a close relationship to the mandibular nerve, beginning two thirds of the way along the length of the cartilage. At this point the mandibular nerve divides into lingual and inferior alveolar branches, which run along the medial and lateral aspects of the cartilage, respectively. The inferior alveolar nerve further divides into incisive and mental branches more anteriorly.
  8. 8. Development of:  Body or Corpus of mandible  Rami of mandible  Condylar process  Coronoid process  Alveolar process DEVELOPMENT OF MANDIBLE
  9. 9.  The cartilage of the first arch, Meckel’s cartilage, has a close relationship to the developing mandible. At 6 weeks of development, this cartilage extends as a solid hyaline cartilagenous rod surrounded by a fibrocellular capsule. Body of mandible
  10. 10. Its proximal or cranial ends are connected with the ear capsules, and their distal extremities are joined to one another at the symphysis by mesodermal tissue. The two cartilages of each side do not meet at the midline but are separated by a thin band of mesenchyme.
  11. 11. During the 6th week of embryonic development, on the lateral aspect of Meckel’s cartilage, a condensation of mesenchyme occurs in the angle formed by the division of inferior alveolar nerve and its incisive and mental branches. At, 7th week intramembranous ossification begins in this condensation, forming the first bone of the mandible.
  12. 12. From this centre of ossification, bone formation spreads rapidly anteriorly to the midline and posteriorly to the point where the mandibular nerve divides into lingual and inferior alveolar branch. Courtesy: Ten Cate
  13. 13.  The new bone forms a trough that consist of medial and lateral plates that unite beneath the nerve. The trough is soon converted into a canal as bone forms over the nerve, joining the lateral and medial plates.
  14. 14. THE RAMI OF THE MANDIBLE
  15. 15. The ramus of the mandible develops by a rapid spread of ossification backwards into the mesenchyme of the first branchial arch diverging away from Meckel’s cartilage. This point of divergence is marked by the lingula in adult mandible, where the inferior alveolar nerve enters mandibular foramen.
  16. 16.   Thus by 10 weeks of development, the rudimentary mandible is formed almost entirely by intramembranous ossification.
  17. 17. Meckel’s cartilage has the following fate: H & E stained section-Meckel’s cartilage Prenatal Development of the Human Mandible. THE ANATOMICAL RECORD 263:314–325(2001) Its posterior end forms the malleus and incus of the inner ear and the sphenomandibular ligament; but its fibrocellular capsule persists to form the sphenomandibular ligament . From the lingula forward to the division of the alveolar nerve into its incisive and mental branches, Meckel’s cartilage degenerates.
  18. 18.   The further growth of mandible is influenced by the appearance of 3 secondary cartilages: 1) Condylar cartilage 2) Coronoid cartilage 3) Symphyseal cartilage
  19. 19. Carrot shaped cartilage appears (at 12 weeks of development) in the region of the condyle and occupies most of the developing ramus. It is rapidly converted to bone by endochondral ossification. It gives rise to: • Condyle head and neck of the mandible. • The posterior half of the ramus to the level of inferior dental foramen. At 20 weeks a thin layer of cartilage remains in the condylar head. Remnants of cartilage persists until the end of 2nd decade of life. The condylar cartilage
  20. 20. The coronoid cartilage: It is relatively transient growth cartilage center ( 4th MIU). It gives riseto: • Coronoid process. • The anterior half of the ramus to the level of inferior dental foramen. Disappears long before birth.
  21. 21.  They are two in number. Appear in the connective tissue between the two ends of Meckel’s cartilage. They are obliterated within the 1st year afterbirth.   Symphyseal cartilage:
  22. 22. THE ALVEOLAR PROCESS
  23. 23.  It starts when the deciduous tooth germs reaches the early bell stage.  The bone of the mandible begins to grow on each side of the tooth germ.  By this growth the tooth germs come to be in a trough or groove of bone, which also includes the alveolar nerves and blood vessels.  Later on, septa of bone between the adjacent tooth germs develop, keeping each tooth separate in its bony crept.  The mandibular canal is separated from the bony crypts by a horizontal plate of bone.  The alveolar processes grow at a rapid rate during the periods of tooth eruption.
  24. 24. GROWTH OF THE MANDIBLE
  25. 25. I. Growth of secondary cartilage II. Development of the alveolar process III. Sub-periosteal bone apposition Growth of Mandible
  26. 26. Growth by secondary cartilage Increase in height of the mandibular ramus Increase in the overall length of the mandible Increase in the inter-condylar distance I. Growth of secondary cartilage
  27. 27. II. Development of the alveolar process:  The alveolar process develops in response to the presence of tooth buds.  As the teeth erupt the alveolar process develops and increases in height by bone deposition at the margins.  The alveolar bone 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.
  28. 28. III. Sub-periosteal bone apposition: Bone deposition Bone resorption Result in External surface of the mandible Inner surface of the mandible Increase the transeverse dimension Posterior border of the ramus Anterior border of the ramus Adjust the thickness of the ramus Anterior border of the coronoid process Posterior border of the coronoid process Displacement of the coronoid process Chin region ‫ــــــــــــــــــــــــ‬ Modeling of the lower face
  29. 29. AGE CHANGES IN THE MANDIBLE
  30. 30. At birth The body of the bone is a mere shell, containing the sockets of the two incisor, the canine, and the two deciduous molar teeth, imperfectly partitioned off from one another. The mandibular canal is of large size, and runs near the lower border of the bone. The mental foramen opens beneath the socket of the first deciduous molar tooth. The angle is obtuse (175°), and the condyloid portion is nearly in line with the body. The coronoid process is of comparatively large size, and projects above the level of the condyle.
  31. 31.  Childhood The two segments of the bone become joined at the symphysis, from below upward, in the first year; but a trace of separation may be visible in the beginning of the second year, near the alveolar margin. The body becomes elongated in its whole length, but more especially behind the mental foramen, to provide space for the three additional teeth developed in this part. The depth of the body increases owing to increased growth of the alveolar part, to afford room for the roots of the teeth, and by thickening of the subdental portion which enables the jaw to withstand the powerful action of the masticatory muscles.
  32. 32.   The mandibular canal, after the second dentition, is situated just above the level of the mylohyoid line; and the mental foramen occupies the position usual to it in the adult. The angle becomes less obtuse, owing to the separation of the jaws by the teeth; about the fourth year it is 140°.
  33. 33.  Adulhood The alveolar and subdental portions of the body are usually of equal depth. The mental foramen opens midway between the upper and lower borders of the bone, and the mandibular canal runs nearly parallel with the mylohyoid line. The ramus is almost vertical in direction, the angle measuring from 110° to 120°.
  34. 34.  Old age The bone becomes greatly reduced in size, for with the loss of the teeth the alveolar process is resorbed. The mandibular canal, with the mental foramen opening from it, is close to the alveolar border. The ramus is oblique in direction, the angle measures about 140°, and the neck of the condyle is more or less bent backward.
  35. 35.  Developmental disturbances: Agnathia Micrognathia Macrognathia Facial hemihypertrophy Facial hemiatrophy Abnormalities of dental arch relation  Developmental cysts: Median mandibular cyst Alveolar cyst of newborn Clinical consideration 
  36. 36.  Agnathia • Hypoplasia or absence of mandible. • The entire mandible or one side may be missing or only the condyle or the entire ramus.
  37. 37. Micrognathia  • Means small jaw. • Maxilla or mandible may be affected. • Can be due to small jaw or to an abnormal positioning or abnormal relation of one jaw to another.
  38. 38.  Macrognathia • Abnormally large jaws. • Increased height of ramus. • Increased mandibular body length. • Increased gonial angle.
  39. 39.  Exhibit an enlargement which is confined to one side of the body, unilateral macroglossia, and premature development, and eruption as well as increased size of dentition. Facial hemihypertrophy
  40. 40.  Progressive wasting of subcutaneous fat accompanied by atrophy of skin, cartilage, bone and muscle. Facial hemiatrophy
  41. 41.   Class II  Class III Abnormalities of dental arch relations
  42. 42.  Median mandibular cyst - Originate from proliferation of epithelial remnants entrapped in the median mandibular fissure during fusion of the bilateral mandibular arches. - Primodial cyst originating from a supernumerary enamel organ in the anterior mandibular segment. Developmental Cysts 
  43. 43.   Alveolar cyst of newborn - Arise from epithelial remnants of deeply budding dental lamina during tooth development.
  44. 44. All the events taking place during development of mandible play an important role in determining the final structure of mandible, any deviation of which can give rise to various abnormalities in the oro-facial region. CONCLUSION 
  45. 45. 1) Ten Cate’s Oral Histology, Development, Structure And Function, 7th Edition. 2) Orban's Oral Histology And Embryology, 12th Edition. 3) Histology and Embryology, James Avery, 3rd Edition. 4) Human Embryology, Inderbeer Singh, 10th Edition. 5) Shafer’s Textbook of Oral pathology, 7th Edition. 6) Orthodontics- The Art and Science, S.I. Bhalajhi, 6th Edition. 7) Textbook of Oral Madicine, Anil Govindrao Ghom, 3rd Edition. 8) Vishwanathan R. Alveolar cyst of the newborn: a case report. Arch Orofac Sci 2012;7: 85-7. REFERENCES 
  46. 46. THANK YOU !

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