PERIOI

1. DR. MALTI GAUR
M.D.S. FIRST YEAR
PERIODONTOLOGY AND
ORAL IMPLANTOLOGY

2. • Introduction
• Definition
• Development
• Classification
• Anatomy
• Physiology
• Clinical Evaluation
• Clinical considerations
• Masticatory Muscle disorders
• Conclusion
• Refrence

3. • Muscle , is a contractile tissue found in animals,
the function of which is to produce movement.
• Movement, the intricate cooperation of muscle
and nerve fibres , is means by which an
organism interacts with its environment. The
innervation of muscle cells, or fibres , permits
an animal to carry out the normal activities of life.
• Muscle cells contains protein filaments of actin
and myosin that slide past one another,
producing a contraction that changes both the
length and the shape of the cell.

4. There are 3 types of muscles in the body:
• Skeletal muscles: responsible for moving
extremities and external areas of the body.
• Smooth muscles: muscle that is in the walls of
visceral organs, arteries and bowel.
• Cardiac muscles: heart muscle

5. The muscles of mastication are a group of
muscles responsible for the chewing movement
of the mandible at the Temporo-mandibular (TMJ)
joint, they enhance the process of eating, they
assist in grinding food, and also function to
approximate the teeth.
Muscle is defined as a soft tissue composed of
contractile cells or fibers that effect movement of
an organ or part of the body.

7. • MASTICATION:-It is defined as the process of chewing food in
preparation for swallowing and digestion.
It is the process of grinding and chewing food into smaller
pieces in the oral cavity turning it into a food bolus.

8. • PREPARATORY PHASE:-In this phase the ingested food
is positioned by the tongue towards the chewing side and
mandible moves to the same side.
• FOOD CONTACT:-There is momentary pause in
mastication-sensory receptors evaluate the viscosity of
food and probable load on masticatory apparatus.
• CRUSHING PHASE:-Food is crushed by equal activity
on both sides of arch. Crushing starts with the high
viscosity and then slows down

9. • ) TOOTH CONTACT:-Teeth come in contact and signifies
the end of crushing phase.
• 5) GUIDING PHASE:-Contact becomes unilateral and
there is transgression of mandibular molars across
maxillary counterparts.
• 6) CENTRIC OCCLUSSION:-Teeth come to a definite or
distinct stop.
• Maximal biting forces on a tooth usually range from
approximately 20–200 kg

11. • The muscular system develops from intra embryonic
mesoderm.
• Muscle tissues develop from embryonic cells called
myoblast.
• Embryologically, the muscles of mastication are derived
from the first pharyngeal arch that is the MANDIBULAR
ARCH.
• They are innervated by the nerve of first pharyngeal arch
which is the mandibular nerve.

12. Development

15. Muscles of mastication can be classified as:
Anatomical classification
Primary muscle
Accessory muscles
Functional classification
Jaw elevators
Jaw depressors

16. • PRIMARY MUSCLES OF MASTICATION
-MASSETER MUSCLE
-TEMPORALIS
-MEDIAL PTERYGOID
-LATERAL PTERYGOID
ACESSORY MUSCLES OF MASTICATION
• The four primary muscles are in turn supported by few
secondary or accessory muscles known as suprahyoid
muscles and Infrahyoid muscles
SUPRAHYOID MUSCLES
INFRAHYOID MUSCLES
BUCCINATORMUSCLES

17. SUPRAHYOID MUSCLES:
Mylohyoid
Geniohyoid
Stylohyoid
Digastric
Another important accessory muscle aiding in mastication is
Buccinator muscle.
INFRAHYOID MUSCLES
Sternothyroid
Omohyoid
Thyrohyoid
Sternohyoid

18. JAW ELEVATORS JAW
DEPRESSORS
a)MASSETER a)LATERAL
PTERYGOID
b)MEDIAL PTERYGOID b)DIGASTRIC
c)TEMPORALIS c)GENIOHYOID
d)MYLOHOID

19. • All are located in or around the infra-temporal fossa
• All are inserted into the ramus of the mandible
• All are innervated by the mandibular division of the
trigeminal nerve
• All are concerned with movements of the mandible on the
Temporo- mandibular joints
• All develop from mesoderm of the first pharyngeal arch

22. • NERVE SUPPLY By Massetric branch from the
Mandibular division of Trigeminal nerve.
VASCULAR SUPPLY By Maxillary artery
Venous drainage is through Massetric vein.

23. • Elevation of the mandible to occlude the teeth for forceful
bite
• Protrusion of mandible(when muscles on both sides act
together)
• Side-to-side movement(when muscles on both sides act
alternatively)

24. Palpate the origin of the masseter bilaterally along the zygomatic arch and
continues to palpate down the body of the mandible where the masseter is
attached.
The patient is asked to clench their teeth and by using both
hands , the practitioner palpates the masseter muscle on both
sides extra orally.

25. • The masseter muscle can become enlarge in patients
who habitually clench or grind (with bruxism)their teeth
and even in those constantly chew gum.
• This masseteric hypertrophy is bilateral, asymptomatic
and soft; it is usually bilateral but can be unilateral
• This extra oral enlargement may be confused with parotid
salivary gland disease, dental infections or maxillofacial
neoplasm.
Even if the hypertrophy is
bilateral, asymmetry of face may
still occur due to unequal
enlargement of the muscles

26. It is formed due to action of masseter over buccinator
ON DENTURE BORDER :
• An active masseter muscle will create concavity in the
outline of the distobuccal border
• A less active masseter may result in convex border
• Moderate activity will create a straight line
• In this area the buccal flange must converge medially to
avoid displacement due to contraction of the masseter
mucle,because the muscle fibres in that area are vertical
and oblique to the action of masseter over buccinator

28. • The contour of distobuccal region of mandibular denture
is determined by action of masseter muscle.
• The fibers of buccinator muscles are at right angles to the
fibers of masseter muscle.
• When the masseter ativates it pushes inward against
buccinator muscle and produces a bulge into mouth.
• When properly moulded the distobuccal border of
impression must converge superiorly and medially
forming a groove called masseteric groove on model and
notch in patients

31. • There was a significant decrease in the thickness of the
masseter area of the face and the masseter muscles
during orthodontic treatment. The decrease in the
thickness of both larger in the extraction group than in
the nonextraction group. The decreases in the
thicknesses of MASSETER and MM were strongly
correlated to each other, and the change in the thickness
of Masseter and Fat Tissue were moderately correlated.
Extraction treatment and small Frankfort-mandibular
plane angle (FMA) significantly contributed to the
thickness decreases of both MAS and MM and
pretreatment thickness of fat tissue (FT) greatly
contributed to Masseter thickness change during the
orthodontic treatment.

32. • As the masseter became larger, the anterior maxillary
region tended to shift downwards relative to the cranial
base, whereas the posterior region tended to shift
upwards.

33. • studies in children and adoloscents have shown the
posterior cross bite has been asssociated with
assymetrical function of masticatory muscles
• Chewing side preference was defined by Christensen
and Radue14 (1985) as: "when mastication is performed
consistently or predominantly on the right or left side of
the dentition". Considering that masticatory function
during growth has a biological impact on the growing
structures, a unilateral mastication may lead to
asymmetric anatomical structures (bones,
temporomandibular joint, muscles, and teeth) on
completion of growth

35. • It is a thick quadrilateral muscle and consists of 2 heads:-
Superficial head
Deep head

37. • NERVE SUPPLY:-The medial pterygoid is supplied by a
nerve to medial pterygoid, a branch from the main trunk
of the mandibular nerve

38. • VASCULAR SUPPLY:-By pterygoid branch of 2nd part of
maxillary artery.

39. • Medial pterygoids of 2 sides elevate the mandible to help
in closing of mouth.
• Acting with lateral pterygoids, the medial pterygoids
protrude the mandible.
• When medial and lateral pterygoids of one side act
together, the corresponding side of the mandible is
rotated forwards and to the opposite side.
• Lateral and medial pterygoids of the 2 sides when
contract alternatively produce side-to-side movements,
which are used to grind the food

40. • Palpation is done mainly by the intraoral approach.
• The region of its attachment to inner aspect of angle of
mandible can be palpated by sliding finger lingually and
applying pressure at the insertion of muscle and placing
one hand extra orally below the border of mandible
On examination, functional manipulation is done when
muscle becomes fatigued and symptomatic:-
• The muscle contracts during clenching of teeth(if the
muscle is involved clenching of teeth will together
increase pain)
• During stretching of muscle when the mouth is wide
open, opening of mouth will cause pain if the muscle is
involved.

42. • It is one of the muscle that influences denture in region of
borders in retromylohyoid curtain .
• When patient closes his jaw medial pterygiod constrict
against the superir constrictor muscles which in turn
forms the posterolateral aspect of retromylohyoid curtain
which moulds the border of mandibular denture in
retromylohyoid fossa region

43. • Lingual flange should not be overextended as lingual
nerve is closely related to the lingual flange and even the
submandibular duct can be blocked

44. • The medial pterygoid muscle can sometimes be injured
during inferior alveolar nerve block due to its close
proximity to the nerve. The injury occurs if the anesthetic
needle is placed too medially and accidentally injects into
the muscle instead of the inferior alveolar nerve. This can
cause hemorrhage and the development of medial
pterygoid trismus hours to days after the procedure. This
manifests with inability to completely open the mouth and
significant medial pterygoid muscle pain when attempting
to open the mouth beyond the restriction.

49. • NERVE SUPPLY:-lateral pterygoid is supplied by a
branch of anterior division of the mandibular nerve
-upper head, lateral part of lower head;-by buccal nerve
medial part of lower head:-by branch from the anterior
trunk

50. • VASCULAR SUPPLY:-pterygoid branches from the
maxillary artery.
• The ascending palatine branch of the facial artery.

51. • Lateral pterygoids of 2 sides depress the mandible(opens
the mouth)by pulling forward the condylar processes of
the mandible and the articular discs of the TMJ.
• Lateral and medial pterygoid muscles of 2 sides acting
together protrude the mandible.
• Lateral and medial pterygoid muscles of the 2 sides
contract alternatively to produce side-to-side movements
of the lower jaw as in chewing

52. To palpate, place the index finger inside the mouth. Apply
pressure in a cranial direction just underneath the
zygomatic arch.
Palpate by pressing in a superior, medial, and posterior
direction.
• Palpation is done by placing the forefinger, over the
buccal area of the maxillary 3rd molar region and
exerting pressure in a posterior, superior and medial
direction behind the maxillary tuberosity

53. • Long-term completely edentulous patients wearing dentures with
worn-out occlusal surfaces of the artificial teeth tend to position their
mandible in the forward and lateral position. The dentist may notice
different anteroposterior/lateral teeth contact positions during
subsequent appointments, which poses difficulty in fabricating a new
complete denture, particularly during the recording of the
maxillomandibular relations. There have been suggestions that this
variation in the position of the mandible during resting jaw posture is
a result of an attempt to attain a reasonable bite with worn-out
dentures. Some authors believe that the lateral pterygoid muscle's
lower and upper belly plays a significant role in maintaining the
mandible at this new anterior position. The variations in the activity
levels between the two bellies on each side determine the lateral and
anteroposterior positioning of the jaw.[2]
• The origin of both the bellies of the lateral pterygoid muscle is medial
to their insertions. Thus, the wide opening of the mandible may
temporarily result in the mandible undergoing distortion in the
transverse plane. Therefore, during impression making of the lower
arch, if the mouth is widely open, it may result in an impression that
is not accurate in the transverse dimension due to mandibular

54. • The spasm of the lateral pterygoid muscle can be painful and
result in trismus (locked jaw),During temporomandibular
disorders, this muscle plays an important role. This
involvement due to the absence of coordination between the
muscle's superior and inferior bellies. This lack of coordination
leads to disturbance in the horizontal positioning of the intra-
articular disc relative to the condyle.
Clinical examination of patients with such disorders reveals
pain in this muscle region during jaw movements and with
palpation behind the tuberosity region.[2] In the internal
derangement of the temporomandibular joint, there are
implications that the superior belly of the lateral pterygoid muscle
plays a role in causing anterior dislocation of the disk.[13] The
prolonged contraction of the muscle places forward traction on
the disk, resulting in anterior displacement of the dis

55. • is responsible for lateral and protrusive movement .It is
the most commonly involved muscle in Myofacial Pain
Dysfunction Syndrome.
• Unilateral failure of lateral pterygoid muscle to contract
results in deviation of the mandible toward the affected
side on opening.
• Bilateral failure results in limited opening, loss of
protrusion and loss of full lateral deviation.
• Lateral pterygoid muscle are for making an eccentric
interocclusal record or pantographic tracing when
adjusting the horizontal condylar guidance and lateral
condylar guidance

56. It is a broad fan shaped muscle on each side of the head located in the
temporal fossa.
It is covered by the tough temporal fascia which is attached above to the
temporal line and below to the zygomatic arch.

57. • Origin
• a)Whole of the floor of temporal fossa except the part
formed by the zygomatic bone
• b)Deep surface of the temporal fascia
Insertion Apex and medial surface of coronoid process
of
mandibleb)The anterior border of ramus of mandible
,almost upto the last molar tooth.

58. • Anterior fibres: Elevates mandible
• Posterior part: Retracts mandible And side to side
movement of jaw

59. • The temporalis muscle is the most powerful muscle of the
temporomandibular joint. The temporalis muscle can be
divided into two functional parts; anterior and posterior. The
anterior portion runs vertically and its contraction results in
elevation of the mandible (closing the mouth). The posterior
portion has fibers which run horizontally and contraction of
this portion results in retrusion of the mandible. The middle
portion which fibers run in an oblique direction towards
inferior and anterior are used for both elevation and retraction
of the mandible and in a unilateral contraction provoke lateral
movement of the mandible.

60. • NERVE SUPPLY:-The temporalis is supplied by the
anterior and posterior deep temporal nerves, the
branches of the anterior division of the mandibular nerve

61. • Blood supply
• The muscle receives its blood supply from the deep
temporal arteries which anastomose with the middle
temporal artery.

62. • As the muscle is divided into 3 functional areas, therefore
each area is independently palpated
• To locate or to examine the muscle, ask the patient to
clench his/her teeth
• The anterior region is palpated above the zygomatic arch
and anterior to TMJ
• The middle region is palpated directly above the TMJ and
superior to the zygomatic arch
• The posterior region is palpated above and behind the
ear

64. • Sudden contraction of the temporalis muscle will result
in coronoid fracture and condylar fractures.
JAW JERK REFLEX:-It is a brisk,partial,upward jerk of
the jaw caused sudden contraction of the temporalis and
masseter muscle in response to striking the chin when
mouth is open. In a positive response sudden stretching
of the muscle causes contraction ,moving the jaw briskly
upwards.
The temporalis is likely to be involved in jaw pain
and headaches
BRUXISM,the habitual grinding of the teeth
typically while sleeping and clenching of the jaw
while stressed can lead to overwork of the
temporalis and results in pain.

65. • ROLE:-independently has no significant role, but
associated with retromolar pad, is important for obtaining
support and peripheral seal
• it helps in obtaining pterygomandibular seal
• When lower dentures are fitted ,they should not extend
into the retromolar fossa to prevent trauma of the mucosa
due to the contraction of the temporalis muscle

69. • Origin Anterior belly: digastric fossa of mandible
• Posterior belly: mastoid notch of temporal bone
• Insertion Body of hyoid bone (via intermediate tendon and
its fibrous sling)
• Action Depresses mandible
• Elevates hyoid bone during chewing, swallowing
• Innervation Anterior belly: mylohyoid nerve (of inferior
alveolar nerve) (CN V3)
• Posterior belly: digastric branch of facial nerve (CN VII)
• Blood supply Anterior belly: facial artery
• Posterior belly: occipital artery

70. It is a slender muscle that lies along the upper border of the
posterior belly of the digastric muscle
• ORIGIN
• It arises from the posterior surface of the styloid process
• INSERTION
• It is inserted into the hyoid bone at the junction
between the body and the greater cornu. At insertion, its
tendon splits into 2 slips that pass one on either side of
the intermediate tendon of the digastric muscle.

71. • NERVE SUPPLY:-
The stylohyoid muscle develops from the 2nd arch and
therefore, it is supplied by the facial nerve.

72. MYLOHYOID MUSCLE:-It is a flat, triangular muscle lying deep to the
anterior belly of the digastric muscle. The right and left mylohyoid muscle
join in the median fibrous raphe to form the gutter-shaped floor of the
mouth; over which lies the tongue, hence the floor of the mouth is also
called diaphragma oris

73. ORIGIN
• It arises from the mylohyoid line of the mandible.
INSERTION
The fibres run downwards and medially. The posterior
fibres are inserted into the body of the hyoid bone. The
middle and anterior fibres are inserted into median raphe
from symphysis menti to hyoid bone.

74. ACTIONS:-a)It elevates the floor of the mouth and hence the tongue
during the first stage of the deglutition.
b)It also helps in depression of the mandible against resistance.
c)It fixes or elevates hyoid bone
NERVE SUPPLY:-
The mylohyoid muscle develops from the 1st pharyngeal arch,
therefore it is supplied by mylohyoid nerve, a branch of inferior
alveolar nerve from mandibular nerve.
CLINICAL IMPORTANCE:-
ON DENTURE BORDERS=MYLOHYOID AREA-
• The patient is instructed to place the tip of his tongue into the
upper and lower vestibules on the right and left sides
• The area to be molded is reheated and the patient is instructed to
swallow 2 or 3 times in rapid succession
• The tongue movements raise the floor of the mouth through
contraction of the mylohyoid muscle

75. • ORIGIN Arises from the inferior genial tubercle of the
mandible
• INSERTION The fibres run backwards and downwards to
be inserted into the anterior surface(front)of the body of
the hyoid bone, above the medial part of the mylohyoid
muscle.

76. • NERVE SUPPLY:-
• By C1 fibers through hypoglossal nerve.
• CLINICAL IMPORTANCE:-
• FOR MANDIBULAR IMPRESSIONS:-
• On recording labial flange and labial frenum.
• The lip is massaged from side to side to mold the
compound to desired functional extension.

77. • BUCCINATOR MUSCLE
Bugler’s muscle/trumpeter’s muscle-it is a muscle of
cheek
It is an accessory muscle of mastication, occupying the
gap between mandible and maxilla forming important part
of cheek

78. • Arises from the following sites:-
a)Outer surface of the alveolar process opposite 3 molar
teeth(maxilla)
b)Fibrous band that extends from pterygoid hamulus to maxillary
tuberosity
c)Pterymandibular raphe, which extends from pterygoid hamulus
to the mandible behind the 3rd molar tooth
• d)From the outer surface of the alveolar process of mandible

79. • After origin,fibres run towards the mouth and fill the gap
between the upper and lower jaws. The fibres are arranged
into upper, intermediate and lower groups
Muscle inserted into upper and lower lips in following manner:-
on reaching near the angle of mouth:-
• a)Upper fibres pass into upper lip
• b)Lower fibres pass into the lower lip
• c)Intermediate fibres decussate and as a result upper fibres
pass into lower lip and lower fibres pass into upper lip

80. • ACTION:-a)It flattens the cheek against gums and teeth,
and thus prevents accumulation of food in the vestibule of
mouth during mastication
b)It is responsible for blowing cheek(PUFFING OUT
CHEEKS) and expelling the air between the lips from
inflated vestibule as in blowing trumpet.
C)it draws the corner of the mouth laterally pulling the lips
against the teeth and flattening the cheek and keeps the
teeth in close contact with cheek to avoid pocketing of food
between teeth and cheek

81. • NERVE SUPPLY:-
• By buccal branch of facial nerve.
• CLINICAL SIGNIFICANCE:-
• PARALYSIS OF BUCCINATOR MUSCLE:-If the
buccinator muscle is paralyzed, as it occurs in facial
palsy, the food accumulates in the vestibule of mouth
during mastication and the person cannot blow his cheek.
• In paralysis of bucccinator muscle,there is loss of
resistance when one presses the cheek with inflated
vestibule and air leaks out from between the lips.
• It is one of the first muscles in an infant to get activated
during sucking.

83. • It is a continuous muscle band that encircles the dentition
and is anchored at the pharyngeal tubercle.
• COMPONENTS:-a)Orbicularis oris
• b)Buccinator
• c)Pterygomandibular raphe
• d)Superior constrictor of pharynx
• Opposing the buccinator mechanism there is a very
powerful muscle-Tongue
•

85. • It forms the functional unit which is essential for the
orofacial functions such as
swallowing,mastcation,blowing and sucking. In the oral
cavity inward forces by the orbicularis and the buccinator
muscle get balance by the outward forces of the tongue

86. • CLINICAL SIGNIFICANCE:-
• Hyperactivity of the muscle can cause excessive
pressure on the underlying hard tissues resulting in
narrow arches and malocclusion
• In class II div I-the tongue occupies a lower posture
thereby failing to counteract the buccinator activity-the
unrestrained activity results in the narrowing of upper
arch at premolar and canine region producing V-shaped
• Abnormal attachment of the muscle may interfere with
proper prosthodontic management and in maintaining
oral hygiene. It will also restrict the movement of the lips
and cheek leading to difficulty In mastication and
phonation.

87. • Prosthodontic implication of buccinator is that, it plays
role in stabilizing the denture by gripping the polished
surface of denture.
Longitudinal fibres hold the bolus of food between the
teeth during mastication.
The maxillary bundles of this muscle tends to raise the
upper denture, whereas the mandibular bundle of this
muscle depresses the lower denture, thus aiding in
denture stability and retention

88. • IMPORTANT FACTS ABOUT MASTICATION
-There are about 15 chews in a series from the time of
food entry until swallowing.
-Average jaw opening during chewing is between 16-
20mm
MASTICATORY FORCES:-
The average sustainable biting force is 756N(170pounds)
BITING FORCE ON:- a)Molar region=400-890N
b)Premolar region=222-445N
c)Canine region=133-334N
d)Incisor region=89-111N
Average lateral displacement on chewing is between 3-5mm
-Duration of masticatory cycle varies between 0.6-1 second
-Men chew faster and have a shorter occlusal phase than women, it
also depends upon type of food

90. • Masticatory space is formed by splitting of investing
fascia into superficial and deep layers; which define the
lateral and medial extent of space
• MASTICATORY SPACES COMPRISE OF THE
FOLLOWING SPACES:-
• a)Submasseteric space
• b)Pterygomandibular space
• c)Temporal-superficial temporal space
• d)Deep temporal or subtemporal spaces

92. • SUBMASSETRIC SPACE:-masseter consists of 3 layers,
which are fused anteriorly, but can be easily separated
posteriorly. There is a potential space in the substance of
muscle between middle and deep head, in which there can be
easily pus accumulated at this site.
• When pus accumulates between the ramus of the mandible
and the masseter muscle, it produces a submasseteric space
abscess.
• Infection originates from the lower 3rd molars, either resulting
from-pericoronitis(vertical or distoangular 3rd molars) or
periapical abscess
• The extension of abscess inferiorly is limited by the firm
attachment of masseter to lower border of ramus of mandible
• Forward spread is restricted by anterior tail of tendon of
temporalis.

94. • CLINICAL FEATURES:-
• -external facial swelling in moderate size and is confined
to the outline of masseter muscle(swelling is seen
extending from lower border of mandible to the zygomatic
arch; anteriorly to the anterior border of masseter and
posteriorly to the posterior border of the mandible.
• -tenderness over angle of the mandible.
• -almost complete limitation of mouth opening.

96. • INVOLVEMENT:-a)Pericoronitis related to the mandibular 3rd
molar.
• b)Infection can be produced by a contaminated needle used
for an inferior alveolar nerve block.
• c)Infection, at times can also originate from a maxillary 3rd
molar, following a posterior superior alveolar nerve block
injection.
• CLINICAL FEATURES:-
• -Does not cause much swelling of face over the
submandibular region.
• -There is a severe degree of limitation of mouth opening.
• -Tenderness over the swollen soft tissue medial to anterior
border of ramus of the mandible.
• -Dysphasia is present
• -Medial displacement of the lateral wall of the pharnyx,redness
and edema of the area around 3rd molar
• -Difficulty in breathing.

97. • BUCCAL SPACE:-It is the potential space between
buccinator and masseter muscle.
It contains buccal pad of fat,stenson‘s duct, facial vein
and artery.
The location of the root tip of the premolars and
molars to the level of origin of buccinator muscle
determines the spread of infection either intraorally
into vestibule or deep into buccal space.
CLINICAL FEATURES:-when pus accumulates on
oral side of the muscle-GUM BOIL is seen in the
vestibule.
If pus accumulates lateral to the muscle,extraoral
swelling is seen extending from the lower border of
mandible to infraorbital margin

98. INVOLVEMENT:-
• -Infection from the infratemporal space arise from the
infection of the buccal roots of maxillary 2nd and 3rd
molars, particularly from unerupted molars.
• -local anesthetic injections with contaminated
needles in the area of tuberosity

99. • CLINICAL FEATURES:-A)EXTRAORAL:-
TRISMUS=marked limitation of oral opening.
• Bulging of temporalis muscle
• Marked swelling of face on affected side in front of ear,
overlying area of TMJ
• B)INTRAORAL=swelling in tuberosity area, elevation of
body temperature up to 104 degree F.
• Pus may extend upwards to involve temporal space or
inferiorly may perforate lateral pterygoid muscle to
involve pterygomandibular space.

100. MASTICATORY MUSCLE
DISORDERS

101. • 1)Muscle Pain
• a)Myalgia
• -Local myalgia
• -Myo fascial pain
• -Myo fascial pain with referral
• 2)Contracture
• 3)Hypertrophy
• 4)Neoplasms
• 5)Movement disorders
• -Oro fascial dyskinesia
• -Oro mandibular dystonia
• 6)Masticatory muscle pain attributed to systemic/central pain
disorders
• 7)Trismus , bruxism,myaesthenia gravis and temporal
tendonitis

102. • MPDS is a pain disorder, in which unilateral pain is referred
from the trigger points in myofascial structures to the muscles
of the head and neck.
• Pain is constant, dull in nature, in contrast to the sudden
sharp, shooting, intermittent pain of neuralgias. But pain may
range from mild to intolerable.
• TRIGGER POINTS:-Trigger points exist as a localized tender
area within taut bands of skeletal muscles and when
stimulated by macro and microtraumatic episodes, they refer a
characteristic pain pattern to a distinct group of muscles, i.e.
zone of reference.
• Palpation of trigger points will give rise to a positive “jump
sign”
• TREATMENT:-
• a)counselling of the patient and modification of diet with
advising home exercises to be followed.
• b)Heat application,cryotherapy
• c)NSAIDS and muscle relaxants
• d)Occlusal splints

103. • It is a disorder of the fibrous insertion of the temporalis
muscle tendons on the coronoid process of the mandible
which is characterized by both inflammation and
degeneration
• This can cause sharp headache in the temples, just to
the sides of the eye.
• It may feel like a migraine headache and so is also called
as the “migraine mimic”.

104. • In this condition a painful area develops in muscle or soft
tissue following blow to the area, a muscle tear or repeated
minor trauma.
• The painful area gradually develops masses of cartilaginous
consistence and within 4-7 weeks a solid mass of bone can be
felt.
• Among the facial muscles masseter and temporalis muscles
occurs usually following a single acute traumatic injury.
• Growth of calcified lesions is rapid and when the maximum
size is obtained, the lesion remains static or diminishes in size
• Some difficulty in opening the mouth maybe experienced by
the patients with myositis ossificans of the masseter muscle.
• TREATMENT:-
• Surgical excision

105. • It is an initial response to altered sensory or proprioception or injury.
• In presence of altered sensory input or pain, antagonistic muscle
groups are seen to fire during movement in attempt to protect injured
parts,
• therefore, pain felt in masticatory system can produce protective
contracture of masticatory muscles.
• There is increased activity of jaw opening muscles during closing of
mouth as well as closing muscle activity during mouth opening.
• It is not a pathological condition but a normal physiologic response of
musculoskeletal system.
• ETIOLOGY:-1)altered sensory input
• 2)presence of constant deep pain
• 3)increased emotional stress
• TREATMENT:-1)stress management
• 2)supportive therapy=in case of tissue injury instruct
the patient to restrict the use of mandible within painless limits
• 3)soft diet
• 4)NSAIDS

106. •
• It is a neurological disorder that affects the muscles and is
characterized by repetitive or sustained involuntary prolonged
spastic movements of tongue, facial muscles and masticatory
muscles.
• Clinical presentation depends upon affected muscles
• Dysfunction includes:-
• -impaired mastication
• - dysphagia
• - speech alteration
• - unconscious opening and closing of mandible, pulling and
twisting of mandible forward and laterally
• Injection of botulinum toxin has been used to treat dystonia.

107. • Hypertrophy of muscle refers to an increase in size of
individual muscle fibers.
• It can affect all the muscles of mastication, several muscles or
just one muscle.
• It can occur either bilaterally or unilaterally and most
commonly masseter muscle alone is affected.
• Masseter muscle hypertrophy is characterized by increased in
volume of muscle mass.
• Patient may present with complaint of unaesthetic appearance
due to facial asymmetry or square face appearance.
• Some complaints of pain,headache,muscle stress or trismus
• TREATMENT:-a long acting more reliable method of obtaining
masticatory muscle relaxation can be achieved by injecting
measured doses of botulinum toxin(BTX)into specific sites in
major muscles of mastication.

108. • Whenever there is restriction of normal oral opening or inability
to open the mouth fully, the term trismus is used.
• Trismus is brought about by extra-articular causes and it is
also labeled as false ankylosis.
• It is also defined as a condition in which muscle spasm or
contracture prevents opening of the mouth(due to infection or
other conditions which alter muscle structure).
• CAUSES OF TRISMUS
• a)Due to infection:- orofacial infections around joint area can
bring about trismus or limitation of oral opening.
• b)Trauma:- Fracture of the zygomatic arch may impinge on
coronoid process and restrict the mouth opening.
• Fracture of mandible can bring about trismus because of pain
and tenderness or muscle spasm.

109. • c)Inflammation:- myositis or muscular atrophy can bring about
trismus.
• d)Myositis ossificans:- following trauma, a hematoma can be
formed within the fibres of the masticatory group of muscles,
specially masseter, which can progress into ossification and
the muscle stiffness.
• e)Tetany:- typical carpopedal spasm along with trismus can be
seen due to hypocalcaemia.
• f)Tetanus:- following acute infection by clostridium tetani, the
typical lockjaw symptoms can be seen because of persistent
tonic muscle spasm.
• A classical clinical example of trismus is seen occasionally
following the injection of the Inferior Nerve Block with local
anesthetic agent. Bleeding created by the needle puncture in
the medial pterygoid muscle produces a hematoma followed
by fibrosis and subsequent trismus.

110. • NSAIDS
• Heat therapy
• Passive muscle stretching exercises
• In most cases hematoma is spontaneously resolved and
normal jaw function returns within a week or two. In some
cases, under sedation or GA, manipulation of jaw with
jaw stretcher maybe required to break up the adhesions
and restore function.

111. • It is the habitual grinding or clenching of the teeth, either
during sleep or as an unconscious habit during waking hours.
• ETIOLOGY :
• a)Local factors:- associated with some form of mild occlusal
disturbances which produces mild discomfort.
• b)Systemic factors:- gastrointestinal disturbances, nutritional
deficiencies and allergy.
• c)Psychologic factors:- most common cause of bruxism,
associated with high levels anxiety, stress and emotional
tension.
• d)Occupational factors:-Voluntary bruxism is recognized in
persons who habitually chew gum, tobacco or subjects such
as toothpicks or pencils. Although voluntary this is too a
nervous reaction and may lead eventually to involuntary or
subconscious bruxism

112. • CLINICAL FEATURES:-the symptomatic effects of this habit
are divided into 6 major categories:-
• 1)Effects on dentition
• 2)Effects on periodontium
• 3)Effects on the masticatory muscle
• 4)Effects on TMJ
• 5)Head ache
• 6)Psychologic and behavioral effects
• When habit is firmly established severe wearing or attrition
occurs along with occlusal wear and interproximal wear which
produces sensitivity.
• On both surfaces actual facets may be worn in the teeth.
• As the bruxism continues, there maybe loss of integrity of
periodontal structures resulting in loosening or drifting of teeth.
• Hypertrophy of masticatory muscles, particularly the masseter
muscle , may interfere with maintenance of the rest position
and the opening and closing of the jaws.

113. • 1)Nervous factors must be corrected.
• 2)Removable splints to be worn at night to immobilize the
jaws.
• 3)BOTULINUM TOXIN(botox) successful in treating the
grinding and clenching.
• Botox when injected into the masseter muscle, weakens
the muscles enough to stop the grinding and clenching
but not so much to interfere with chewing or facial
expressions

114. • It is an acute potentially fatal infection of the nervous system
characterized by intense activity of motor neurons and results
in severe muscle spasms.
• It is caused by the exotoxin of the anaerobic, gram positive
bacillus clostridium tetani.
• CLINICAL FEATURES:-
• GENERALISED TETANUS:- It is characterized by lock-jaw or
trismus due to spasm of masseter, which is the initial
symptom,
• Dysphagia, stiffness or pain in the neck and shoulder.
• Marked rigidity interferes with the movement of chest and
impairs cough and swallowing reflexes.
• LOCALISED TETANUS:-It manifests as the spasm of muscles
near the wound.

115. • a)Sedation, airway and nutrition should be maintained.
• b)Antibiotics are given to eradicate vegetative organisms.
Penicillin metronidazole.
• Clindamycin or erythromycin is an alternative for
penicillin allergic patients.
• ANTITOXIN is injected to neutralize circulating toxin
unbound toxin. Human tetanus
immunoglobulin(TIG)3000-6000units IM individual doses
• An active immunization schedule requires 3 doses
triple vaccine in the first year of life with subsequent
doses or booster doses of TT at school entry and at 5-
10yr interval should be given.

116. • Myasthenia is an abnormal weakness and fatigue in muscle
following activity.
• Myasthenia gravis is an acquired autoimmune disorder
characterized clinically by weakness of skeletal muscles and
fatigability of striated muscles on exertion.
• The antibodies are directed towards the acetylcholine
receptor.
• CLINICAL FEATURES
• occurs in adults, common in women and is characterized by a
rapidly developing weakness in voluntary muscles following an
activity.
• The muscles of mastication and facial expressions are
involved by this disease. The patient’s chief complaint maybe
difficulty in mastication and in deglutition and dropping of the
jaw.
• TREATMENT :Physostigmine, an
anticholinestrase,administered IM improves the strength of the
affected muscle.

117. Electromyography (EMG) is a diagnostic procedure to assess the health
of muscles and the nerve cells that control them (motor neurons). EMG
results can reveal nerve dysfunction, muscle dysfunction or problems with
nerve-to-muscle signal transmission.
Motor neurons transmit electrical signals that cause muscles to contract.
An EMG uses tiny devices called electrodes to translate these signals into
graphs, sounds or numerical values that are then interpreted by a
specialist.
During a needle EMG, a needle electrode inserted directly into a muscle
records the electrical activity in that muscle.
A nerve conduction study, another part of an EMG, uses electrode
stickers applied to the skin (surface electrodes) to measure the speed
and strength of signals traveling between two or more points.

118. • Patient requires EMG if heshe may have signs or
symptoms that may indicate a nerve or muscle disorder.
Such symptoms may include:
• Tingling
• Numbness
• Muscle weakness
• Muscle pain or cramping
• Certain types of limb pain

119. • EMG results are often necessary to help diagnose or rule
out a number of conditions such as:
• Muscle disorders, such as muscular dystrophy or
polymyositis
• Diseases affecting the connection between the nerve and
the muscle, such as myasthenia gravis
• Disorders of nerves outside the spinal cord (peripheral
nerves), such as carpal tunnel syndrome or peripheral
neuropathies
• Disorders that affect the motor neurons in the brain or
spinal cord, such as amyotrophic lateral sclerosis or polio
• Disorders that affect the nerve root, such as a herniated
disk in the spine

120. • Disorders of masticatory muscles. De Rossi et al
• Charausia B.D. Human Anatomy. 6th edition
• Malik N.A. Textbook of Oral and Maxillofacial Surgery. 4th
edition.
• Wheeler’s Dental Anatomy, Physiology and Occlusion.
8th edition.
• Glick M. Burket’s Oral Medicine. 12th edition
• www.mayoclinic