email antarleenasengupta@gmail.com for full seminar

1. MANDIBLE:
GROWTH,
DEVELOPMENT &
ANATOMICAL
CONSIDERATIONS
By
DR. ANTARLEENA SENGUPTA
I YR PG,
DEPTT. OF PERIODONTOLOGY &
IMPLANTOLOGY,
MCODS MANGALORE

2. CONTENTS
 INTRODUCTION
 ANATOMY
 BODY OF MANDIBLE
 OUTER SURFACE
 INNER SURFACE
 RAMUS
 LATERAL SURFACE
 MEDIAL SURFACE
 CORONOID PROCESS
 CONDYLAR PROCESS
 ATTACHMENTS & RELATIONS
 MUSCLE ATTACHMENTS
 FORAMINA
 BLOOD SUPPLY
 NERVE SUPPLY
 LYMPHATICS
 STRUCTURES RELATED TO MANDIBLE
2

3. contd.
 GROWTH OF MANDIBLE
 PRENATAL EMBRYOLOGY
 MECKEL’S CARTILAGE
 ENDOCHONDRAL BONE
FORMATION
 CONDYLAR PROCESS
 CORONOID PROCESS
 MENTAL REGION
 POST-NATAL EMBRYOLOGY
 RAMUS
 BODY
 ANGLE
 LINGUAL TUBEROSITY
 ALVEOLAR PROCESS
 CHIN
 CONDYLAR PROCESS
 CORONOID PROCESS
 THEORIES OF GROWTH
 ENLOW’S EXPANDING V PRINCIPLE
 ENLOW’S COUNTERPART
PRINCIPLE
 AGE CHANGES IN MANDIBLE
 INFANTS & CHILDREN
 ADULTS
 OLD AGE
 ANATOMIC CONSIDERATIONS
 DEVELOPMENTAL ANOMALIES
 SURGICAL CONSIDERATIONS
 ANATOMIC SPACES
 CONCLUSION
 REFERENCES
3

4. INTRODUCTION
4
ANTERIOR VIEW LATERAL VIEW

5. ANTERIOR VIEW LATERAL VIEW
5

6. POSTERIOR VIEW
6

7. 7
ANTERIOR VIEW

8. 8
MENTAL PROTUBERANCE MENTAL TUBERCLES
ANTERIOR VIEW

9.  BODY
 Each half of the body has outer and inner surfaces, and
upper and lower borders.
 The outer surface presents the following features:
1. The symphysis menti
2. The mental protuberance
3. The mental foramen
4. The oblique line
9

10. OUTER SURFACE
Anterior border
LATERAL VIEW
10

11. 11
FRONTAL VIEW
symphysis menti

12. INNER SURFACE has the following
features:
 Mylohyoid Line
 Submandibular fossa
 Sublingual fossa
 Superior and Inferior genial tubercles
 Mylohyoid groove
12

13. INNER SURFACE
13
MEDIAL VIEW

14. UPPER BORDER
The upper or alveolar border bears sockets for the
teeth.
14

15. LOWER BORDER
15
The lower border of the mandible is also called the base. Near
the midline the base shows an oval depression called the
digastric fossa.

16.  RAMUS
16
ANTERIOR VIEW LATERAL VIEW
• LATERAL SURFACE of ramus is flat and bears a
number of oblique ridges.
U
L
P
A

17. MEDIAL SURFACE of ramus has the following:
 Mandibular foramen
 Lingula
 Mylohyoid groove
 Mandibular notch
 Angle of mandible
17
Lingula
Submandibular fossaMylohyoid
groove
Mandibular notch

18.  Coronoid process
 Condyloid process
 Head
 Neck
 Pterygoid fovea
18
Superior view Superior view
Pterygoid fovea
Neck

19. RADIOGRAPHIC VIEW OF MANDIBLE
19

20. ATTACHMENTS & RELATIONS OF
MANDIBLE
 MUSCLE ATTACHMENTS
20
LATERAL VIEW

21. 21
MEDIAL VIEW

22. FORAMINA & RELATIONS OF MANDIBLE
22
Mandibular
foramen
Mental foramen

23. BLOOD SUPPLY
 Central blood supply
 Peripheral blood supply
23
via the INFERIOR ALVEOLAR
ARTERY except the coronoid
process, which is supplied by
temporalis muscle vessels.
via the PERIOSTEAL
VESSELS, which run parallel to
cortical surface of bone, giving
off NUTRIENT VESSELS those
penetrate cortical bone and
anastomose with the branches
of inferior alveolar artery.

24. NERVE SUPPLY
 Derived from mandibular branch (V3) of trigeminal
nerve.
1. Long Buccal Nerve – supplies mucosa opposite
the posterior-most mandibular molars(6,7,8) on
their buccal aspect.
2. Inferior Alveolar Nerve – supplies all lower jaw
teeth, lower lip, buccal mucosa from incisors to
premolar & the skin over the chin.
3. Lingual Nerve – sensory supply to anterior 2/3rd
of tongue, the mucosa on the lingual aspect of
lower teeth & floor of the mouth.
24

25. MANDIBULAR NERVE
25

26. LYMPHATICS
26
Submandibular lymph nodes
Submental lymph nodes
Jugulo-Omohyoid group of
deep cervical lymph nodes
Jugulo-Digastric group of
deep cervical lymph nodes
Mandible + lower teeth
Small wedge
in symphysis
Lower
incisors Extremely posterior

27. STRUCTURES RELATED TO
MANDIBLE
 SALIVARY GLANDS:
 Parotid
 Submandibular
 sublingual
 LYMPH NODES:
 Parotid
 Submandibular
 Submental
 ARTERIES:
 Maxillary
 Superficial temporal
 Masseteric
 Inferior alveolar
 Mylohyoid
 Mental
 Facial
27

28.  NERVES:
 Lingual
 Auriculotemporal
 Masseteric
 Inferior alveolar
 Mylohyoid
 Mental
 MoM: insertions of
 Temporalis
 Masseter
 Medial pterygoid
 Lateral pterygoid
 LIGAMENTS:
 Lateral ligament of TMJ
 Stylomandibular
 Sphenomandibular and
 Pterygomandibular raphe
28

29. PRENATAL DEVELOPMENT OF
MANDIBLE
 MECKEL’S CARTILAGE
 Derived from 1st branchial arch
 41st-45th day IU
 Extends from cartilaginous otic capsule to
midline(symphysis)
 Provides template for guiding growth of mandible
 MANDIBULAR DIVISION, TRIGEMINAL NERVE(V3)→
first structure to develop
 2 ossification centres: 1 for each half; arises 6th wk. IU
29

30.  Ossifying membrane located lateral to the
Meckel’s Cartilage
 Spreads below & around IAN and incisive
branch and upwards to form a trough to
accommodate developing tooth buds
 Dorsally and ventrally spreads to form body and
ramus of mandible
 Ossification continues→ Meckel’s cartilage
surrounded by bone→ invaded by bone→
ossification stops at lingula
30
Continued growth into middle ear : develops
auditory ossicles
To sphenoid bone to
form a remnant of
Meckel’s cartilage
Sphenomandibular ligament

31.  ENDOCHONDRAL BONE FORMATION
 THE CONDYLAR PROCESS:
 5th wk. IU
 10th- 14th wk. IU
 THE CORONOID PROCESS:
 10th – 14th wk. IU
 Accessory cartilage gets incorporated into
expanding ramus; disappears before birth.
31
Area of mesenchymal condensation
seen above ventral part of the
developing mandible
Develops into a cone-shaped
cartilage → replaced by mid-fetal
life; upper end persists into
adulthood
Secondary cartilage of coronoid
process grows in response to
developing temporalis muscle.

32.  MENTAL REGION:
 2 small cartilages appear on either side of
symphysis
 7th wk. IU
 1st yr. postnatal
32
Formation of mental ossicles
Incorporated in intramembranous
ossification
Complete ossification

33. POSTNATAL DEVELOPMENT OF MANDIBLE
 Divided into development of following
functional parts:
 Ramus
 Corpus or Body of mandible
 Angle of the mandible
 Lingual tuberosity
 Alveolar process
 Chin
 Condyle
 Coronoid process
33
THREE FORMS OF GROWTH can be seen in
the mandible:
o Vertical
o Transverse
o rotational

34.  VERTICAL GROWTH
of the mandible is quite
pronounced. The
mandible has to keep
pace with the descent of
the maxilla and must
also maintain the
interocclusal vertical
direction.
34

35.  TRANSVERSE
GROWTH of the
mandible is achieved
principally by the
divergence of the
condyles as they grow
posteriorly(Enlow’s V
principle)
 Buccal bone deposition
on the body and ramus
35

36.  In ROTATIONAL
GROWTH, the matrix
surrounding the
mandible acts to
moderate the shape
changes of the bone
rotating with it.
36

37. THEORIES OF GROWTH
 ENLOW’S EXPANDING ‘V’ PRINCIPLE
 ENLOW’S COUNTERPART PRINCIPLE
37
States that the growth of any given facial/cranial part
relates specifically to other structural and geometric
counterparts in the face and cranium.
The growth, movement &
enlargement of these
bones occur towards the
wide ends of the ‘V’ as a
result of differential
deposition & selective
resorption.

38. AGE CHANGES IN MANDIBLE
38

39. APPLIED ANATOMY
39

40. AGNATHIA
 Characterized by
hypoplasia or absence of
mandible.
 More commonly, only a
portion of jaw is missing.
 Partial absence of
mandible is more
common.
 Entire mandible on one
side may be missing or
more frequently, only the
condyle or the entire
ramus.
 Bilateral agenesis of
condyles and ramus have
also been reported.
40

41. MICROGNATHIA
Means small jaw, either the maxilla or
mandible may be involved.
True micrognathia is classified as:
 Congenital
 Acquired
41

42. CONGENITAL MICROGNATHIA
 Etiology:
I. Idiopathic
II. Assoc’d. with congenital heart disease
III. Pierre-Robin Syndrome
 Follows a hereditary pattern.
 Agenesis of condyles results in true
micrognathia.
 Such cases may be due to posterior
positioning of the mandible with regard to the
skull or to a steep mandibular angle resulting
in apparent retrusion of mandible.
42

43. ACQUIRED MICROGNATHIA
 Postnatal origin.
 Usually results from a
disturbance in the area of
TMJ.
 Since the normal growth of
the mandible depend on
normally developing
condyles as well as
muscles, condylar ankylosis
may result in deficient
mandible.
 Clinically it is characterized
by severe retrusion of the
chin, a steep mandibular
angle, and a deficient chin
button
43

44. MACROGNATHIA
 Macrognathia refers to
the condition of
abnormally large jaws.
 An increase in both the
jaws is frequently
proportional to
generalized increase in
entire skeleton.
 Often associated with
other conditions like:
 Paget’s disease of
bone
 Acromegaly
 Leontiasis ossea
44

45.  Etiology: unknown, although cases may
follow hereditary patterns.
 In many instances the prognathism is due to
disparity in the size of maxilla to mandible.
 The angle between the ramus and the body
influence the relation of mandible to maxilla.
 Thus prognathic patients tend to have long
rami which form a steep angle with the body
of the mandible.
45

46. FACIAL HEMIHYPERTROPHY
 One of the rare
developmental disorder.
 Asymmetric over growth of
one or more body parts.
 Represents hyperplasia
rather than hypertrophy.
 It is of 3 types, namely:
 Simple hyperplasia
 Complex hyperplasia
 Hemifacial hyperplasia
 F:M > 2:1, often affecting on
right side.
46

47.  Asymmetry starts at birth.
 Enlargement is more accentuated at the age of 6 and
continues ‘til the overall growth ceases.
 Enlargement of mandible and teeth on the affected side.
 The bone is wider and thicker.
 Premature shedding of the deciduous teeth.
 Roots of teeth are sometimes proportionately enlarged
but maybe short.
 Permanent teeth on the affected side is often enlarged,
most frequently involving cuspid, premolars, and 1st
molar.
 Permanent teeth on affected side develops more rapidly
and erupt before their counterpart on the uninvolved side.
 Macroglossia
47

48. 48

49. PAGET’S DISEASE
 Characterized by
excessive growth and
abnormal remodeling of
bone.
 Results in bones which are
weak, enlarged and
extensively vascularized.
 Etiology: unknown, there
may be evidence of
genetic link.
 Possible etiologic factors:
 viral infections
 Inflammatory cause
 Autoimmune connective
tissue
49
o Recognized most commonly after
the age of 50 years.
o Its prevalence increases with age.
o Male:female> 1:1
o Jaws are involved more commonly.
o The most common complaint is
bone pain.
o This pain is perceived as dull
aching pain deep below the soft
tissues.
o It may persist or exacerbate during
the night.
o The involved bone becomes warm
to the touch due to increased
vascularity

50. CHERUBISM
 Autosomal dominant
 The gene is mapped to
chromosome 4p16.
 Facial appearance is similar to
plump-cheeked angels, hence the
name cherubism.
 First described in the year 1953 by
Jones.
 Jaw lesions are usually painless and
symmetric.
 Lesions which are firm and non-
tender to palpate involve molar to
coronoid regions, often associated
with cervical lymphadenopathy.
 This contributes to the characteristic
full-faced appearance.
50

51. CHERUBISM- RADIOGRAPHIC
APPEARANCE
 Bilateral multilocular
radiolucencies in the
posterior mandible.
 These lesions tend to
show varying degree of
remission and involution
after puberty.
 There maybe
displacement, rotation of
the teeth.
 Premature exfoliation,
delayed eruption.
51

52. EXOSTOSES
 Normal anatomic
variation.
 Hinders removal of
plaque by patient.
 May have to be removed
to improve the prognosis
of neighbouring teeth.
 Most common in lingual
area of canine and
premolars, above
mylohyoid muscle.
 Also found on
buccal/labial surfaces of
mandibular teeth.
52

53. ANATOMIC SPACES
 Several anatomic spaces or compartments
are found close to the operative field of
periodontal & implant surgery sites.
 Contain loose connective tissue– easily
distended by hemorrhage, inflammatory fluid,
and infection.
 Surgical invasion of these areas may result in
dangerous hemorrhage (intraoperative) or
infections (postoperative) & should be
carefully avoided.
53

54. ANATOMIC SPACES
54
A. SUBMENTAL SPACE: between mylohyoid muscle
superiorly and platysma inferiorly. Infection results in
swelling of the region; more dangerous as it proceeds
posteriorly.
B. MASTICATOR SPACE: contains masseter, pterygoid
(lat. and med.), tendon of insertion of temporalis, ramus
and posterior mandible. Infection leads to swelling of
face, severe trismus and pain.
C. SUBLINGUAL SPACE: below the oral mucosa in
anterior part of floor of mouth. Infection of this space
raises floor of mouth, displacing the tongue, resulting in
pain & difficulty swallowing.
D. SUBMANDIBULAR SPACE: external to sublingual
space below mylohyoid and hyoglossus muscle.
Contains the submandibular gland and connected with
sublingual space. Infections lead to obliterated
submandibular line+ pain in swallowing.

55. SURGICAL CONSIDERATIONS
 Surgical trauma (pressure, manipulation and
postsurgical swelling) to the mental nerve
produces paresthesia of lip– recovers slowly.
 Partial/complete cutting of the nerve can
result in permanent paresthesia/dysesthesia.
55

56. SURGICAL CONSIDERATIONS
 In partially/completely edentulous patients,
disappearance of alveolar portion brings
mandibular canal and mental foramen closer
to superior border.
 In such patients, during evaluation for
placement of implants, the distance
between canal and superior surface of the
bone as well as location of mental foramen
must be carefully determined to avoid surgical
injury to the nerve.
56

57. SURGICAL CONSIDERATIONS
 The lingual nerve lies close to the surface of
the oral mucosa in the third molar area and
goes deeper as it travels forward.
 It can be damaged during anesthetic
injections (and during extraction
procedures).
 It can be injured when a periodontal partial-
thickness flap is raised in third molar region
or when releasing incisions are made in the
area.
57

58. SURGICAL CONSIDERATIONS
 The alveolar process, which provides the supporting
bone to the teeth, has a narrower distal curvature than
the body of mandible, creating a flat surface in the
posterior area between the teeth and the anterior border
of the ramus.
 This results in the formation of external oblique ridge,
which runs downward and forward to region of
second/first molar, creating a shelflike bony area.
 Resective osseous therapy may be difficult in this area
because of the amount of bone that must be removed
distally toward ramus to achieve resection of a
periodontal osseous defect on the distal aspect of
mandibular 2nd/3rd molar.
58

59. SURGICAL CONSIDERATIONS
 Distal flap procedures in distal to the last molar
can be performed effectively only if there exists
sufficient space.
59

60. CONCLUSION
 Familiarity with the location and appearance
of the mental nerve reduces likelihood of
injury to the nerve.
 Determining the amount of available bone is
critical for placement of implants.
60

61. REFERENCES
1. B D Chaurasia’s Human Anatomy vol. 3
2. Human Embryology, Inderbir Singh
3. Clinical Periodontology by Carranza, 10th edition,
vol 2
4. Shafer’s Textbook of Oral Pathology
5. Contemporary Orthodontics by W R Profitt
6. Handbook of Local Anesthesia, S F Malamed
7. Image references:
 Wikimedia Commons
 Gray’s anatomy, 41st edition
61

62. 62