mandibular anatomy for dental implant

1. Dr Bindu kumari ( BDS)

2.  A proficient knowledge of oral anatomy is
needed to provide effective implant dentistry.
 The study of anatomy familiarizes the implant
surgeon with normal and atypical oral
structures.
 Knowledge of oral structures and ordinary
anatomic variations, which usually differ with
respect to size and shape, enhance patient
evaluations and facilitate precise surgical
procedures.

3.  Mandibular foramen
 Inferior alveolar canal
 Mental foramen and nerve
 Mandibular incisive canal
 Lingual foramen and lateral canal
 Submental and sublingual arteries

4.  Submandibular and sublingual fossae
 Lingual and mylohyoid nerve
 Long buccal nerve
 Muscles attached to mandible

5. Mandibular foramen
The location of the mandibular foramen may
vary based on race and ethnicity, and this can
affect the success of block injections.
It is advisable to inject patients 6 to 10 mm
superior to the occlusal plane, which usually
accounts for anatomic variations.

6.  Mandibular foramen

7. Inferior alveolar canal
The trigeminal nerve, the fifth cranial nerve, has
three main branches: ophthalmic, maxillary, and
mandibular.
The mandibular nerve gives rise to the inferior
alveolar nerve (IAN).

9.  Thickness of IAN canal= 3.4mm wide
2.2mm thick
 Within the canal there is a nerve, an artery, a
vein, and lymphatic vessels.

10.  When developing an osteotomy over the
mandibular canal, cortical bone is penetrated
first, and the preparation terminates within
softer cancellous bone.
 The mandibular canal usually has cortical
bone around it, which may provide some
resistance to drilling.

13.  The IAN may present in different anatomic
configurations.
 The nerve may lower gently as it proceeds
anteriorly, or there can be a sharp decline or the
nerve can drape downward in catenary fashion
(curled as hanging between two points).

14.  The IAN crosses from the lingual to the
buccal side of the mandible and often ,by the
first molar, it is located midway between the
buccal and lingual cortical plates of bone.

16.  The IAN divides into the mental and incisive
nerves in the premolar molar region.
 The mental nerve emerges from the mental
canal, and anterior to the mental foramen the
mandibular canal is referred to as the incisive
canal.

18. Mental foramen and nerve
 Commonly, three nerve branches of the
mental nerve emerge from the mental
foramen
 They supply innervation to the skin of the
mental foraminal area, the lower lip, chin,
mucous membranes, and the gingiva until the
second premolar

20.  The anterior loop of the mental foramen
refers to the IAN when it courses inferiorly
and anteriorly to the foramen and then loops
back to emerge from the foramen.

21.  Several methods and techniques for
identifying the extent of the AL( anterior
loop) of the neurovascular bundle have
been proposed using panoramic
radiographs, computed tomography, and
determination of the AL during surgery
using a curved explorer.

23.  If placement of the probe into the mental
foramen on the distal side reveals that the
mental canal is patent, then the anterior loop is
not present.
 If placement of a probe into the mental foramen
on the distal side reveals that the mental canal is
not patent, then an anterior loop of the mental
nerve exists.
 The nerve must have traversed inferiorly and
looped back to the foramen creating an anterior
loop.

24. Mandibular incisive canal
 Numerous investigations reported that there
is a ‘‘true’’ incisive canal mesial to the mental
foramen, which is a continuation of the
mandibular canal.
 The incisive nerve supplies innervation to
teeth (first bicuspid, canine, and lateral and
central incisors).

25.  The incisive canal is typically found in the
middle third of the mandible (in 86% of
cases).
 It usually narrows as it approaches the
midline and only reaches the midline 18% of
the time.
 The nerve usually terminates apical to the
lateral incisor and sometimes apical to the
central incisor.

27. Lingual foramen and lateral canal
 Vascular canals are often present in the
midline and lateral to the midline of the
mandible.
 The lingual foramen was detected in 99% of
the mandibles when evaluating skull
dissections.

28.  The lingual foramen harbors an artery that
corresponds to an anastomosis of the right
and left sublingual arteries.

30. Submental and sublingual arteries
The submental artery (2-mm average
diameter) is derived from the facial artery,
And the sublingual artery (2-mm average
diameter) is a branch of the lingual artery.

31.  The sublingual artery is found above the
mylohyoid muscle and is the major nutrient
vessel in the floor of the mouth.
 The submental artery frequently traverses
inferiorly to the mylohyoid muscle

32.  Hofschneider et al also reported that the
sublingual and submental arteries may
course anteriorly in close proximity to the
lingual plate, and branches of these blood
vessels enter accessory foramina along the
lingual cortex.

33.  Inadvertent penetration through the lingual
cortical plate into the floor of the mouth
while preparing an osteotomy can cause
arterial trauma, there by resulting in
development of a sublingual or
submandibular hematoma.

34. Submandibular and sublingual fossae
The submandibular fossa is a depression on the
medial surface of the mandible inferior to the
mylohyoid line, and it contains the
submandibular gland.
 The sublingual gland is found in the
sublingual fossa.

35.  This fossa is a shallow depression on the
medial surface of the mandible on both sides
of the mental spine, superior to the
mylohyoid line.

37.  The submandibular and sublingual fossae
must be palpated prior to osteotomy
development; if there is a large undercut, the
lingual bony plate can be perforated
inadvertently, resulting in hemorrhaging.

38.  If there is a large undercut, an instrument can
be placed into and parallel to the undercut to
visualize and measure the extent of the
depression.

39. Lingual and mylohyoid nerve
 The mandibular branch of the trigeminal
nerve gives rise to the lingual nerve.
 This nerve provides sensory innervation to
the mucous membranes of the anterior two-
thirds of the tongue and the lingual tissues.

41.  At the time of implant surgery in the
posterior mandible, the lingual nerve can be
injured if the lingual flap is not reflected
cautiously.
 The lingual nerve is usually located 3 mm
apical to the osseous crest and 2 mm
horizontally from the lingual cortical plate in
the flap

42.  However, in 15% to 20% of cases, the nerve
may be situated at or above the crest of
bone, lingual to the mandibular third molars.

43.  The mylohyoid nerve is a branch of the
inferior alveolar nerve.

44.  It arises just prior to where the IAN enters the
mandibular foramen.
 On the deep surface of the ramus, it moves
down in a groove to reach and innervate the
mylohyoid muscle and the anterior belly of
the digastric muscle.

45. Long buccal nerve
 The buccal nerve is a branch of the
mandibular nerve that is derived from the
trigeminal nerve, and it begins high in the
infratemporal fossa.

46.  It transmits sensory innervation to the buccal
gingiva and mucosa of the cheek from the
retromolar area to the second premolar.

47. Muscles attached to mandible
There are 26 muscles attached to the mandible.
There are two single muscles (orbicularis oris
and platysma) and 12 pairs of bilateral
muscles.

48.  Which are listed in alphabetic order:
anteriorbelly of digastric, buccinator,
depressor anguli oris, depressor labii
inferioris, genioglossus, geniohyoid,
masseter, mentalis, mylohyoid, lateral
pterygoid, medial pterygoid, and temporalis.

49. 1. Mentalis Muscle
2. Mylohyoid Muscle
3. GenialTubercles (genioglossus and
geniohyoid muscles)
4. Depressor Anguli Oris and Depressor Labii
Inferiorus
5. Buccinator and Orbicularis Oris Muscles
6. Masseter Muscle

50.  Mentalis Muscle
 The mentalis muscle is a paired small muscle
that originates in the incisive fossa of the
mandible and inserts into the integument of
the chin.

51.  When a flap is raised in this region, the entire
mentalis muscle should not be released off
from the mental protuberances, because
the muscle may fail to reattach well.
 This can result in an appearance referred to
as a witch’s chin (double chin).

52.  Mylohyoid Muscle
 Two flat mylohyoid muscles form a sling
inferior to the tongue, supporting the floor of
the mouth.
 Their origin is the mylohyoid line on the
medial aspect of the mandible, which extends
from the symphysis to the last molar.

53.  This muscle is an important anatomic barrier
separating the sublingual and submandibular
spaces.The submandibular fossa is below the
mylohyoid muscle, and the sublingual fossa is
superior to the muscle.

54.  GenialTubercles (genioglossus and
geniohyoid muscles)
 The genial tubercles are small, bony
elevations located on the lingual surface of
the mandible.
 They are found on either side of the midline
close to the inferior border of the mandible .

55.  There are two superior and two inferior
tubercles.
 The genioglossus originates from the
superior genial tubercles.
 And the geniohyoid originates from the
inferior genial tubercles.

56.  Depressor Anguli Oris and Depressor Labii
Inferiorus
 TheseTwo muscles that overlie the mental
foramen need to be displaced when exposing
the roof of the foramen.

57.  Once the flap is elevated past the
mucogingival junction, these muscles can be
released by using wet gauze to push back the
flap.The wet gauze is used to protect the
mental nerve.

58.  Buccinator and Orbicularis Oris Muscles
 The submucosa is strongly attached to the
buccinator muscle in the cheek region and
the orbicularis oris in the lip area.

59.  Masseter Muscle
 The masseter muscle consists of two
portions: superficial and deep
 When the mandibular ramus area is used as a
donor site for bone grafting(i.e., block graft),
part of the masseter muscle is released from
the ramus when the periosteum is elevated in
this region.

60.  Familiarity with the anatomic structures
pertaining to dental implantology is critically
important.
 Preplanning and review of anatomy before
surgical procedures can help to avoid
problems.