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SAIRA ELIZABETH DENNY
I MDS
DEPT. OF ORAL AND MAXILLOFACIAL PATHOLOGY

INTRODUCTION
 Mandible is the largest
and strongest bone of the
face, serves for the
reception of the lower
teeth. It c...
 About the fourth
week of intrauterine
life, the
pharyngeal arches are
laid down
 The first arch is
called the mandibula...

 The first branchial arch, also called the first pharyngeal
arch and mandibular arch, is the first of six pharyngeal
ar...
The first structure to
develop in the
primodium of the
lower jaw is the
mandibular division
of trigeminal nerve.
Courtesy:...

 Meckel’s cartilage has a close, relationship to the
mandibular nerve, at the junction between posterior
and middle thi...

Development of
 Body of mandible
 Rami of mandible
 Condylar process
 Coronoid process
 Alveolar process
DEVELOPMEN...

The cartilage of the first arch, Meckel’s cartilage, has a
close, relationship to the developing mandible.
At 6 weeks of...
Their proximal or cranial ends are connected with
the ear capsules, and their distal extremities are
joined to one another...

On the lateral aspect of Meckel’s cartilage, during the 6th
week of embryonic development, a condensation of
mesenchyme ...

 From this centre of ossification, bone formation spreads
rapidly anteriorly to the midline and posteriorly to the
poin...

 The new bone forms a trough that consist of medial
and lateral plates that unite beneath the nerve. The
trough is soon...

Relationship between Meckel’s cartilage and
mandible in human embryo
H&E tained section - human embryo
Courtesy: . Prena...
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:
 Its posterior end forms the malleus and incus of the
inner ear and the sphe...

 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 develo...
The coronoid cartilage:
It is relatively transient growth cartilage center ( 4th MIU). it gives rise to:
•Coronoid process...

 2 in number, appear in the connective tissue between
the 2 end of Meckel’s cartilage
 They are obliterated within the...
The alveolar process
It starts when the deciduous tooth germs reach the early
bell stage. The bone of the mandible begins to grow on
each side ...
GROWTH OF THE MANDIBLE
Growth of the mandible
I. Growth by
secondary cartilage
II. Development of
the alveolar
process
III. Subperiosteal
bone
ap...
I. Growth by
secondary cartilage
( mainly condylar
cartilage )
Increase in height
of the mandibular
ramus
Increase in the ...
II. Development of the alveolar process:
Due to the increase in the space between the upper and
lower jaws a space is crea...
III. Subperiosteal bone apposition and bone
resorption:
Bone deposition Bone resorption Result in
External surface of
the ...

Age changes in the
mandible
At birth
 The body of the bone is a mere shell, containing the
sockets of the two incisor, ...

Childhood
 The two segments of the bone become joined at the symphysis,
from below upward, in the first year; but a tra...

 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 b...

Old age
 The bone becomes greatly reduced in size, for with the
loss of the teeth the alveolar process is absorbed, and...


-Developmental disturbances:
 Agnathia
 Micrognathia
 Macrognathia
 Facial hemihypertrophy
 Facial hemiatrophy
 Ab...

-Hypoplasia or absence of mandible
-The entire mandible or one side may
be missing or only the condyle or the
entire ram...

Micrognathia
- Means small jaw
- Maxilla or mandible
may be affected
- Can be due to small jaw
or to an abnormal
positio...

-abnormally large jaws
Factors that favor mandibular prognathism:
- Increased height of ramus
- Increased mandibular bod...

-exhibit an enlargement which is confined to one side of
the body, unilateral macroglossia, and premature
development, a...

-progressive wasting of subcutaneous fat accompanied
by atrophy of skin,cartilage , bone and muscle.
Facial hemiatrophy
...

 Class I
 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 dermining the final
structure of ma...

1.Ten Cate’s Oral Histology, Development, Structure
And Function-Seven Edition .
2. Oral Anatomy, Histology And Embryolo...
THANK YOU !
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Development of mandible ppt

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Development of mandible ppt

  1. 1. SAIRA ELIZABETH DENNY I MDS DEPT. OF ORAL AND MAXILLOFACIAL PATHOLOGY
  2. 2.  INTRODUCTION  Mandible is the largest and strongest bone of the face, serves for the reception of the lower teeth. It consists of a curved, horizontal portion, the body;and two perpendicular portions, the rami, which unite with the ends of the body nearly at right angles.
  3. 3.  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
  4. 4.   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 process 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.
  5. 5. The first structure to develop in the primodium of the lower jaw is the mandibular division of trigeminal nerve. Courtesy:Google
  6. 6.   Meckel’s cartilage has a close, relationship to the mandibular nerve, at the junction between posterior and middle thirds, where the mandibular nerve divides into the lingual and inferior dental nerve. The lingual nerve passes forward, on the medial side of the cartilage, while the inferior dental lies lateral to its upper margins & runs forward parallel to it and terminates by dividing into the mental and incisive branches. Courtesy:Google
  7. 7.  Development of  Body of mandible  Rami of mandible  Condylar process  Coronoid process  Alveolar process DEVELOPMENT OF MANDILLE Courtesy:Google
  8. 8.  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 Courtesy:Google
  9. 9. Their 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. Courtesy:Google
  10. 10.  On the lateral aspect of Meckel’s cartilage, during the 6th week of embryonic development, a condensation of mesenchyme occurs in the angle formed by the division of inferior alveolar nerve and its incisor and mental branches. 7th week-ossification begins in this condensation + Courtesy: Ten Cate
  11. 11.   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
  12. 12.   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.
  13. 13.  Relationship between Meckel’s cartilage and mandible in human embryo H&E tained section - human embryo Courtesy: . Prenatal Development of the Human Mandible. THE ANATOMICAL RECORD 263:314–325 (2001)
  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. Courtesy:Google
  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:  Its posterior end forms the malleus and incus of the inner ear and the sphenomalleolar ligament; but its fibrocellular capsule persists to form the sphenomandibular ligament .  From the lingula forward to the devision of the alveolar nerve into its incisor and mental branches, Meckel’s cartilage degenerates. H & E stained section-Meckel’s cartilage Prenatal Development of the Human Mandible. THE ANATOMICAL RECORD 263:314–325 (2001)
  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 Courtesy:Google
  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 rise to: •Coronoid process. •The anterior half of the ramus to the level of inferior dental foramen Disappears long before birth Courtesy:Google
  21. 21.   2 in number, appear in the connective tissue between the 2 end of Meckel’s cartilage  They are obliterated within the 1st year after birth. Symphyseal cartilage
  22. 22. The alveolar process
  23. 23. It starts when the deciduous tooth germs reach 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. Growth of the mandible I. Growth by secondary cartilage II. Development of the alveolar process III. Subperiosteal bone appositionand bone resorption
  26. 26. I. Growth by secondary cartilage ( mainly condylar cartilage ) Increase in height of the mandibular ramus Increase in the over all length of the mandible Increase of the inter condylar distance
  27. 27. II. Development of the alveolar process: Due to the increase in the space between the upper and lower jaws a space is created between the opposing teeth to erupt. At the same time bone apposition occurs at the crest of the alveolar process and the fundus of the alveolus. This means that bone deposition contributes to the growth of the body of the mandible in height.
  28. 28. III. Subperiosteal bone apposition and bone resorption: Bone deposition Bone resorption Result in External surface of the mandible Inner surface of the mandible Increase the transeverse dimension Posterior border of the remus 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 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.
  30. 30.  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; but the alveolar portion is the deeper of the two, and, consequently, the chief part of the body lies above the oblique line.
  31. 31.   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°.
  32. 32.  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°.
  33. 33.  Old age  The bone becomes greatly reduced in size, for with the loss of the teeth the alveolar process is absorbed, and the chief part of the bone is below the oblique line.  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.
  34. 34.
  35. 35.  -Developmental disturbances:  Agnathia  Micrognathia  Macrognathia  Facial hemihypertrophy  Facial hemiatrophy  Abnormalities of dental arch relation -Developmental cyst  Median mandibular cyst  Alveolar cyst of newborn Clinical consideration
  36. 36.  -Hypoplasia or absence of mandible -The entire mandible or one side may be missing or only the condyle or the entire ramus. Agnathia Courtesy:Google
  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. Courtesy:Google
  38. 38.  -abnormally large jaws Factors that favor mandibular prognathism: - Increased height of ramus - Increased mandibular body length - Increased gonial angle Macrognathia Courtesy:Google
  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 Courtesy:Google
  40. 40.  -progressive wasting of subcutaneous fat accompanied by atrophy of skin,cartilage , bone and muscle. Facial hemiatrophy Courtesy:Google
  41. 41.   Class I  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 cyst
  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 dermining 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-Seven Edition . 2. Oral Anatomy, Histology And Embryology- Berkovitz,4th Edition 3. Orban's Oral Histology And Embryology-12th Edition 4. Histology and embryology-James Avery 5. Prenatal Development of the Human Mandible. THE ANATOMICAL RECORD 263:314–325 (2001) Reference
  46. 46. THANK YOU !

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