This include the mandible morphology and also it's development phases Helps students in understanding mandible more better

1. PRENATALAND
POSTNATAL DEVELOPMENT
OF MANDIBLE
Dr.SURESH KUMAR.K
Dept of Orthodontics and Dentofacial
Orthopedics
S.B. Patil intitute for Dental Sciences and
Research

2. INTRODUCTION
 The mandible, or lower jaw – is the largest &
strongest bone of the face .
 It has horse shoe-shaped body which lodges the teeth
& a pair of rami which projects upwards from the
posterior ends of the body & provides attachments to
muscles.
 It is the 2ND bone in the body to ossify.

3. Development
PRE-NATAL EMBRYOLOGY OF
MANDIBLE

4. 1. About 4 week of intra-
uterine life, the
developing brain and
pericardium forms 2
prominent bulge on
the ventral aspect of
the embryo.
2.These bulges are
separated by the
primitive oral cavity or
stomatodaeum.
3.The floor of
stomatodaeum is
formed by bucco-
pharyngeal
membrane, which
separate it from
foregut.

5. 7.The 1st arch is called
mandibular arch and
2nd arch is called hyoid
arch. the other arches
do not have specific
names.
8.The mandibular arch
forms the lateral wall
of stomatodaeum.it
gives off a bud from
its dorsal end. this
bud is called maxillary
process.

6. 7. It grows ventro-
medially,cranial to the
main part of the arch
which is now called
mandibular process.
8.The mandibular
processes of both the
the sides grow
towards each other &
fuse in the midline.

7. Meckels cartilage
1.The meckles cartilage
is derived from the
first brachial arch
around the 41st to 45th
day of intra – uterine
life.
2. It extends from the
cartilaginous otic
capsule to the midline
or symphysis and
provides a template
for guiding the growth
of the mandible.

8. 3. A major portion of the meckels cartilage
disappears during growth and remaining part
develops into the following
a] mental ossicles
b] incus and malleus.
c] spine of sphenoid bone.
d] anterior ligament of malleus.
e] spheno-mandibular ligament.

9. 5.The first structure to develop in to the
primoridium of the lower jaw is the mandibular
division of trigeminal nerve.
6.This is followed by mesenhymal condensation
forming the 1st brachial arch.

10. A single ossification
centre for each half of
the mandible arises in
the 6th week of intra-
uterine life in the
region of the
bifurcation of the
inferior alveolar nerve
into mental &incisive
branches.

12. Further growth of the mandible until birth is influenced by the
appearnce of 3 secondary cartilages (condylar, coronoid,
symphyseal cartilages) & development of muscular
attachments
Condylar cartilage appears at 12th week of development
Coronoid process appears at about 4 months IU
The symphyseal cartilages 2 in number appear in connective
tissue b/w the two ends of Meckel’s cartilage but are entirely
independent of it, they are obliterated with in the 1st year of
the birth.

13. Endo-chondral bone formation
Seen in 3 areas of mandible:-
a] condylar process.
b] coronoid process.
c] mental region

14. Condylar process
1] At about 5th week of
intra uterine life an
area of mesenchymal
condensation can be
seen above the ventral
part of developing
mandible.
2] this develops into a
cone –shaped cartilage
by about 10th week &
starts ossification by
14th week.

15. 3] then it migrates
inferiorly and fuses
with the mandibular
ramus by about 4th
months.
4] much of the cone
shaped cartilage is
replaced by bone by
the middle of fetal life
but its upper end
persists into adulthood
acting both as growth
cartilage and an
articular cartilage.

16. Coronoid process
1] secondary accesssory cartilage appears in the
region of the coronoid process by 10 -14 week.
2]this cartilage is believed to grow in response to
developing temporalis muscle.

17. Mandible
 Mandible undergoes the largest amount of growth post-
natally and also exhibits the largest variability
 The functional parts include-
• Ramus
• Corpus
• Angle of mandible
• Lingual tuberosity
• The alveolar process
• The chin

18. Functions
 Mastication
 Maintenance of airway
 Speech
 Facial expression

19. Ramus
Function
 Provides an attachment base for masticatory
muscles
 Plays key role in placing the corpus and
dental arch into ever-changing fit with the
growing maxilla and the limitless structural
variations of face

20. Corpus
 As anterior border of ramus resorbs – posterior
drift
 Conversion of earlier ramus into posterior part of
the body.
 Thus body of the mandible lengthens

21. RAMUS REMODELLING AND RELOCATION

22. Coronoid process
 Follows V principle
 Lingual surface faces- 3 directions—posterior, superior and
medial
 Lengthens vertically- V oriented vertically

23.  Deposition occurs on lingual surface
 Also posterior movement seen – V oriented
horizontally

24. Angle of the mandible
 Lingual side- resorption antero-inferiorly while
deposition postero-superiorly
 Buccal side vice versa
 This results in flaring of mandible

25. The lingual tuberosity
 Direct equivalent of maxillary tuberosity
 Boundary between ramus and body
 Moves posteriorly by deposition on its posteriorly facing
surface
 Ideally max. tuberosity closely overlies lingual tuberosity

26. Alveolar process

27. Chin
 A specific human characteristic; recent man only
 As age advances the growth of chin becomes significant
 Sexual and genetic factors

28. Condyle
 Anatomic part of special significance
 Evolutionary changes
 Earlier thought to be the master center; now
a regional field of gowth– regional adaptive
growth

29.  poorly vascularised connective tissue covers the articular
surface of condyle
 layer of prechondroblast cells
 hypertrophy
 zone of resoption and bone deposition

30.  This regional, Endochondral bone forming mechanism
develops as a specific response to this particular local
circumstance. The cartilage itself does not contain genetic
programming that directly determines and governs the course
of growth in all other areas of mandible

31. Direction of growth

32.  Mandibular foramen:

33. Mental foramen

34. Vertical relation of mental foramen

35. GROWTH OF MANDIBLE IN DIFFERENT THEORIES
HUNTER AND ENLOW EQUIVALENT CONCEPT

36. Enlow and Bangs expanding “V” principle..

37. WEINMAN AND SICHER

38. KOSKI AND MAKINEN

39.  JAMES.H.SCOTT-
 The Irish anatomist divides the mandible into
basic types of bone -Basal, Muscular, alveolar or
tooth supporting.

40. Functional matrix hypothesis
Functional cranial components
Skeletal units Functional matrix
1)Micro skeletal 2) Macro skeletal 1) periosteal matrix 2)capsular matrix
Moss indicates that the volumetric growth of the spaces is the
primary morphogenetic event in the facial skull growth. 3
functioning spaces(oral,nasal,pharyngeal).

41. Pierre Robin Syndrome
characterized by micrognathia, posterior displacement or
retraction of the tongue (glossoptosis), and upper airway
obstruction. cleft palate,
Anamolies

42. First arch syndrome
insufficient migration of first arch
neural crest cells
e.g., Treacher collins syndrome -
Abnormal external ear.
Anomalies of middle and inner ear
Hypoplasia of molar region and mandible
Defects of lower eyelid.
.

43. AGNATHIA
mandible may be grossly deficient or absent, reflecting a
deficiency of neural crest tissue in the lower part of the
face .

44. MICROGNATHIA-
charectarised by many syndromes including Pierre Robin
and cat’s cry syndromes ,mandibulofacial
dysostosis(Treacher Collins syndrome),progeria,Down
syndrome (trisomy 21 syndrome), Turner syndrome(XO
sex chromosome complement

45. MACROGNATHIA
producing prognathism, is usually an inherited condition,but
abnormal- growth phenomena such as hyperpituitarism may
produce mandibular over growth of increasing severity with age

46. THANK YOU