PERIODONTAL INTEREST

2. UNDER THE GUIDANCE:
Prof.Dr.C.S. SAIMBI(H.O.D)
DR.VIKASH
KUMAR(ASST.PROF)
 PRESENTED BY –Dr.SONI BISTA
(1st year PG student)
Periodontology and
Oral Implantology

4.  The word mandible is derived from
Latin word mandibula- "jawbone"
or inferior maxillary bone.
 It forms the lower jaw and holds the
lower teeth in place.
 It is the largest, strongest and lowest
bone in the face.

5.  Only movable bone in the skull
 It consists of an anterior Horseshoe-shaped
body, and of two rami that project
upwards from the posterior part of the
body.
 It provides structural and protective
support for the oral cavity.
 The mandible is articulated in ball and
socket fashion at the condylar process.
 Strength resides in its dense cortical
plates.

6. ANATOMY
OF
MANDIBLE

7. Mandible
Body Two Rami
Surfaces SurfacesBorders Borders Processes
External/
Outer
Internal/
Inner
Superior/
Alveolar
Inferior/
Base
CoronoidCondyloidLateral/
External
Medial/
Internal
Anterior Posterior Superior Inferior

8.  Horseshoe-shaped BODY
 Has two surfaces
EXTERNAL and INTERNAL surfaces
 Two borders UPPER and LOWER borders.

9. 1. SYMPHYSIS MENTI : The line at
which the right and left halves of
the bone meet each other. It is
marked by a faint ridge.
2. MENTAL PROTUBERANCE :
median triangular projecting area
in the lower part of the midline.
3. MENTAL FORAMEN : It lies
below the interval between the
premolar teeth
4. EXTERNAL OBLIQUE LINE :
Continuation of the sharp anterior
border of the ramus of mandible.
5. INCISIVE FOSSA : Depression that
lies just below the incisor teeth

11. 1. MYLOHYOID LINE : Prominent
ridge that runs obliquely
downwards and forwards from
below the third molar tooth to
the median area below genial
tubercle.
2. SUBMANDIBULAR FOSSA : It
lies below the mylohyoid line,
which lodges the submandibular
gland
3. SUBLINGUAL FOSSA : It lies
above the mylohyoid line, which
lodges the sublingual gland
4. GENIAL TUBERCLES : Posterior
surface of the symphysis menti is
marked by four small elevations
called the superior and inferior
tubercle

12. 5. MYLOHYOID GROOVE :
Extends from ramus to the
body below the posterior
end of the mylohyoid line.
6.UPPER ALVEOLAR BORDER
: It bears socket for the
teeth.
7. LOWER BORDER /BASE :
8. DIGASTRIC FOSSA : Near
the midline the base shows
an oval depression.

13. UPERIORBORDER (ALVEOLAR
BORDER)
t is hollowed into cavities for the reception of
the teeth, these cavities are sixteen in number,
and vary in depth and size according to the
teeth which they contain.
is rounded, longer than the
superior, and thicker in
front than behind.

14.  Is quadrilateral
 2 surfaces
1. Lateral
2. Medial
 4 borders
1. Superior
2. Inferior
3. Anterior
4. Posterior
 2 processes
1. Coronoid
2. Condylar

15.  Lateral surface – flat with
oblique ridges
 Medial surface Features-
1. MANDIBULAR FORAMEN : It lies little
above the centre of ramus at the
level of occlusal plane. It leads into
mandibular canal.
2. LINGULA : Anterior margin of
foramen marked by tongue
shaped projection
3. MYLOHYOID GROOVE : Begins
just below mandibular
foramen, runs forwards and
downwards to be gradually
lost over the submandibular
fossa.
4. UPPER BORDER -Forms
mandibular notch
5. LOWER BORDER- Forms angle
( junction of the body and
ramus )

16. straight, and continuous
with the inferior
border of the body of
the bone. At its
junction with the
posterior border is the
angle of the mandible,
and is marked by
rough, oblique ridges on
each side.
 The upper border is
thin, and is surmounted
by two processes, the
coronoid in front and
the condyloid behind,
separated by a deep
Anterior border- thin &
continuous with
coronoid process
Posterior border- thick
& extends from

17. CORONOID PROCESS
 Flat ,triangular
 Upward and forward
projection from
anterolateral part of ramus
 Anterior border continuous
with anterior border of
ramus
 Posterior border bounds
the mandibular notch

18. CONDYLAR PROCESS
 Upward projection from
postero superior part of
ramus
 Apically enlarged as head of
condyle.
 Articulates with temporal
bone’s mandibular fossa to
form temperomandibular
joint
 Lateral aspect palpable in
front of tragus
 Pterygoid fovea anterior to
neck

19. 1. External oblique line-
origin to buccinator,
depressor inferioris,
depressor anguli oris
2. Incisive fossa -origin of
mentalis, mental slips of
orbicularis oris
3. Mylohyoid line – origin
to mylohyoid muscle ,
attachment to superior
constrictor of pharynx,
pterygomandibular

20. 5. Lower genial
tubercles –origin to
geniohyoid
6. Diagastric fossa-
anterior belly of
diagastric
7. Lower border -deep
cervical fascia and
platysma
8. Lateral surface of
ramus - insertion for
masseter

21. 10. Lingula-sphenomandibular
ligament
11. Medial surface of ramus-
medial pterygoid muscle
attachment
12. Apex of coronoid process -
temporalis attachment
13. Pterygoid fovea - lateral
pterygoid muscle
14. Lateral surface of neck -

22. MUSCLES OF MASTICATION
MUSCLES OF FACIAL EXPRESSION

23. ARTERY SUPPLY OF MANDIBLE; Mainly by Maxillary
artery, Branch of external carotid artery By
its branches, mainly through inferior alveolar
artery
INFERIOR ALVEOLAR ARTERY
Lingual
branch
Mental
branch
Mylohyoid
branch
Incisive
artery

25.  Drains into
Internal jugular
vein and external
jugular vein
through maxillary
vein, facial vein and
pterygoid plexus

26.  Mainly through the trigeminal nerve -
V cranial nerve
MANDIBULAR NERVE
 Main trunk
 Anterior trunk
 Posterior trunk

27. Posterior division of the mandibular nerve
Mylohyoid
nerve
Inferior alveolar nerve
Mental
nerve
Incisive nerve
Auriculotemporal
nerve
Lingual

29. 1. Mental foramina - mental
nerve and vessels
2. Mandibular notch -
massetric nerve and
vessels
3. Medial side of neck -
auriculo temporal nerve
4. Mylohyoid groove -
mylohyoid nerve and
vessels
5. Mylohyoid groove in front
of ramus - lingual nerve
6. Mandibular canal and
foramina - inferior
alveolar nerve and
vessels

30. Articulation
 Mandibular process of
temporal bone and
condylar part of
mandible articulate
to form
temporomandibular
joint.

32. •Forms from the 1st arch within the mandibular process.
• Meckel’s cartilage (cartilage of 1st arch) forms lower jaw in
primitive vertebrates.
• In humans, it has a close relation to the developing mandible
but makes no direct contribution to it.

33.  Forms at 6th week of development.
• It is a solid hyaline cartilage surrounded by a
fibro-cellular capsule.
• Extends from otic capsule to the midline of the
fused mandibular processes.
• Cartilages of each side do not meet at midline;
they are separated by a thin band of
mesenchyme. Formation of the mandibular division of trigeminal
nerve begins two thirds along the length of the cartilage.
• It divides into two branches at this point:
Lingual nerve Inferior alveolar nerve (IAN)
• Lingual nerve runs along the medial aspect of the
cartilage.
• Inferior alveolar nerve runs along the lateral aspect of the

34.  Mandible is the second bone to ossify in the body.
 It is partly membranous & partly cartilaginous in
ossification.
• Incisive part below symphysis menti
• Coronoid
• Condyloid process
• Upper half of ramus
Cartilage
• Whole of body except lower incisive
part
• Lower half of ramus upto
mandibular foramen
Membrane

35.  Condensation of mesenchyme occurs lateral to
Meckel’s cartilage in the 6th week gestation.
 This condensation begins at the angle formed
by division of the IAN into incisive and
mental branches.
 Intra-membranous ossification begins in this
condensation during the 7th week.
Ossification begins in the membrane covering
the outer surface of Meckel’s cartilage.
 From this centre, bone formation spreads
rapidly, anteriorly to the midline, posteriorly
to the point of division of the mandibular
nerve into lingual nerve and inferior alveolar
nerve.

36.  Ossification grows medially beneath the incisive
nerve, then spreads beneath this nerve and
Meckel’s cartilage.
 • Incisive nerve is contained within this trough or
groove of bone formed by lateral and medial
plates which are united below the nerve.
 • This trough comes in close contact with a
similar trough from the opposite side. The two
fuse shortly after birth. Trough converted into
canal when bone forms over the nerve.
 • Spread of ossification in the backward
direction produces at first a troughlike gutter of
bone in which lies the inferior alveolar nerve up
to the level of the future lingula.
 • Later this gutter is converted to bone.

37. BODY OF MANDIBLE
• Above bony canal, medial
and lateral alveolar plates
develop.
• Odontogenic epithelium
forming the tooth germs lies
superiorly.
• Medial and lateral plates
develop around these germs
and they come to lie in a
secondary trough.
• Trough is partitioned by
developing individual tooth
germs.
• Alveolar plates completely
enclose the tooth germs.
RAMUS OF MANDIBLE
• Ossification spreads
posteriorly into mesenchyme
of the 1st arch.
• Spreads away from
Meckel’s cartilage and this
point of turning away is the
future lingula.
• By 10th week, primitive
mandible is formed almost
entirely by membranous
ossification.

39. CONDYLAR CARTILAGE
• Appears during 12th week.
• Rapidly forms cone/carrot shaped mass occupying
most of ramus area.
• Converted to bone by endochondral ossification. •
By 20th week, only a thin layer of cartilage remains in
the condylar head.
• This remnant of cartilage persists till the 2nd decade
of life.
• Provides a growth mechanism for the mandible in
the same way as an epiphyseal cartilage does in the
limbs.

40. CORONOID
CARTILAGE
• Appears at about
4th month of
development.
• Forms near
anterior border and
top of the coronoid
process.
• It is a transient
cartilage.
• Disappears long
before birth.
SYMPHYSEAL
CARTILAGE
• Two in number.
• Appear in the
connective tissue
between two ends
of the Meckel’s
cartilage.
• Get obliterated
within the first year
of birth.

41. AT BIRTH :
 The two halves of the mandible are united by a
fibrous symphysis menti.
 At this stage the body is a mere shell, enclosing
imperfectly separated sockets of deciduous
teeth.
 The mandibular canal is near the lower border
 The mental foramen opens below the first
deciduous molar and is directed forwards.
 The coronoid process projects above the condyle
 The angle of the mandible is obtuse (above
140degrees or more) because the head is in line
with the body.

42. IN ADULTS :
 The mental foramen opens midway between
the upper and lower borders as the alveolar
and sub-alveolar regions are about equal in
depth.
 The mandibular canal nearly parallels the
mylohyoid line
 The angle between the lower border of the
body and a plane touching the posterior
surface of the condyle above and ramus
below diminishes as ramal height increases
with age (about 110 –120degrees)

43. In OLD AGE :
 Bone is reduced in size as
teeth are lost and
alveolar region resorbed
 The mandibular canal and
the mental foramen are
nearer the superior border
 The ramus becomes
oblique as angle becomes
obtuse (140degrees) and
the neck inclined backwards.

45. At Birth
Adult MandibleGeriatric Mandible
In Childhood

47. MANDIBULAR
CANAL
MANDIBULAR
CANAL
MENTAL
FORAMEN
In partially/totally edentulous jaws:
the disappearance of alveolar portion of
the mandible brings the mandibular canal
close to the superior border.When these
patients are evaluated for placement of
implants,the distance between the canal
and the superior surface of bone must be
carefully determined to avoid surgical
injury to nerve.

48. LINGUAL NERVE
Lingual nerve may be injured when
periodontal partial thickness flap
is raised in the third molar region/
when releasing incisions are made..
EXTERNAL
OBLIQUE RIDGE
Resective
osseous
surgery
may be
difficult.
RETROMOLAR
TRIANGLE Distal wedge
procedure

50.  Inderbersingh :text book of human osteology.
 B.D.Chaurasia: human osteology.
 Inderbersingh : human embryology.
 Warren .H.Lewis.-Gray’s anatomy of the human body.2000:20th
edition
 Langman’s medical embryology – T.W. Sadler, 5th edition.
 Oral histology, development, structure and function– a.R. Ten cate,
4th edition