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SURGICAL ANATOMY OF PERIODONTAL STRUCTURES

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CONTENTS1) Introduction2) Anatomy of mandible3) Attachments and relations of mandible4) Age changes in mandible5) Anatomy of maxilla6) Age changes in maxilla7) Anatomic spaces8) Applied aspects of maxilla and mandible

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•INTRODUCTION

SURGICAL ANATOMY may be defined as

the presentation of anatomical facts

which have a local significance in relation

to injury, to particular diseases, or to the

surgical intervention which these may

entail. (Cunningham's Textbook)

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ANATOMY OF MANDIBLELargest and strongest bone of faceHorseshoe shaped bodyContains a pair of rami

Parts of mandible• Body• Ramus of mandible• Angle of mandible

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Right half of mandible seen from the lateral side

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Right half of the mandible seen from the medial side

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NERVE SUPPLY OF MANDIBLE

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VENOUS DRAINAGE OF MANDIBLE

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MUSCLES OF MANDIBLE – POSTERIOR GROUP

1) Masseter

Origin: Inferior 2/3 zygomatic

bone & medial surface of

zygomatic arch

Insertion :Lateral ramus and

angle of mandible

Innervation: Masseteric branch

of anterior division of mandibular

nerve (V)

Action: Elevate and protrude

mandible

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2) TEMPORALIS MUSCLE

Origin: Limits of temporal fossa

Insertion: Medial surface coronoid

process, anterior surface of ramus down

to occlusal plane

Innervation:Two deep temporal

branches of mandibular nerve (V),

sometimes reinforced by middle temporal

nerve

Action: Elevates mandible, posterior

fibres are the only muscle fibres to retract

the mandible

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3) MEDIAL PTERYGOID

Origin: Pterygoid fossa, mainly

medial surface of lateral pterygoid

process

Insertion :Medial surface of

ramus and angle of mandible

Innervation :Branch from main

trunk of mandibular nerve

Action: Pulls angle of mandible

superiorly, anteriorly and medially

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4) LATERAL PTERYGOID

MUSCLE

Origin: Upper head from

infratemporal surface of skull,

lower head from lateral

pterygoid plate

Insertion Upper head inserts

into TMJ capsule, lower head

into anterior surface of condylar

neck

Innervation Branch of anterior

division of mandibular nerve

Action Lateral movement,

protrusion, important in active

opening of the mouth

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MUSCLES OF MASTICATION

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Muscles of the mandible – Anterior group

Origin Insertion Innervation Action

Genioglossus

Upper genial tubercles

Dorsum of tongue Hypoglossal nerve (XII)

Depresses tongue, protrudes tongue

Geniohyoid Lower genial tubercles

Body of hyoid bone C1 through hypoglossal nerve (XII)

Pulls hyoid bone anterosuperiorly, shortens floor of mouth and widens pharynx

Mylohyoid Mylohyoid line of mandible

Raphe and body of hyoid bone

Mylohyoid nerve, a branch of inferior alveolar nerve (V3)

Elevates hyoid bone, floor of mouth and tongue during swallowing and speaking

Digastric Anterior: Digastric fossa of mandiblePosterior: Mastoid notch of temporal bone

Intermediate tendon to body and superior (greater) horn of hyoid bone

Anterior: Mylohyoid nerve (V3)Posterior: Facial nerve (VII)

Depresses mandible, raises hyoid bone and steadies it during swallowing and speaking

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ACTIONS OF MUSCLES

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OTHER MUSCLES1) Mentalis2) Platysma3) Depressor anguli oris4) Depressor labii

inferioris5) Buccinator

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AGE CHANGES IN MANDIBLEANATOMICAL LANDMARKS

AT BIRTH ADULT OLD AGE

Formation of mandible

Two halves of mandible fuse during first year of life

Alveolar ridge Alveolar and sub dental region of body are equal

Alveolar bone gets resorbed

Mental foramen

Opens below the two deciduous molars near the lower border

Opens mid way between upper and lower border

Close to alveolar border

Ramus Vertical in direction

Oblique in direction

Angle 140 degree More than 110 degree

More than 140 degree

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ANATOMY OF MAXILLA2nd largest bone of face2 maxillae forms whole of upper jawEach maxilla contributes in formation of –

1. Face2. Nose3. Mouth 4. Orbit5. Infra temporal fossa6. Pterygopalatine fossa

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Each maxilla has –1. A body2. 4 processes – frontal zygomatic alveolar palatine

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1) BODY OF MAXILLA:•Shape – pyramidal• It has –

1. Base – directed medially at nasal surface2. Apex - directed laterally at zygomatic process3. Four surfaces

a) anterior / facialb) posterior / infratemporalc) medial / nasald) superior / orbital

Encloses a cavity – maxillary sinus

23A) ANTERIOR / FACIAL SURFACE

• Directs laterally• Incisive fossa – origin of depressor septi• Incisivus – arises from alveolar margin• Nasalis – superiolateral to the fossa, along nasal

notch

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•Canine fossa – levator anguli oris• Infraorbital foramen• levator labii superioris•Medially – the nasal notch - anterior nasal spine

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B) POSTERIOR / INFRATEMPORAL SURFACE• Concave• Directed – backward & laterally• Forms – anterior wall of infratemporal fossa• Separated from anterior surface by zygomatic process• Posteroinferiorly – maxillary tuberosity &gives origin laterally to

superficial head of medial pterygoid muscle• Above maxillary tuberosity -anterior wall of pterygopalatine fossa

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D) SUPERIOR / ORBITAL SURFACEi. Smooth, triangular & slightly concaveii. Forms – Greater Part Of Floor Of Orbitiii. Anterior border forms – part of inferior orbital margin

continues with lacrymal crest of frontal process

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iv) Posterior border –

smooth & rounded

inferior orbital fissure

In middle – infraorbital groove

v) Medial border –

• Anteriorly lacrymal notch, converted into nasolacrymal canal

• Behind the notch, articulation with lacrymal crest

vi) The superior surface presents –

• Infraorbital groove & canal

• Inferior oblique muscles

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PROCESSES OF MAXILLA

1.FRONTAL

2.ZYGOMATIC

3.ALVEOLAR

4.PALATINE

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FRONTAL PROCESS• Projects upward & backwards to articulate above – nasal margin of frontal bone infront – nasal bone behind – lacrymal bone• Lateral surface – divided by anterior lacrymal crest into

anterior smooth & posterior grooved• anterior lacrymal crest gives attachment to lacrymal fascia & medial palpebral ligament

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•Medial surface – forms lateral wall of nose from above downwards –

1. Uppermost roughened area for articulation with ethmoid

2. Ethmoidal crest – a horizontal ridge, articulates with middle nasal concha

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•ZYGOMATIC PROCESS•Pyramidal lateral projection•Anterior, posterior & superior surfaces converge here•Superiorly – rough, to articulate with zygomatic bone

32ALVEOLAR PROCESS•Forms half of alveolar arch•Bears socket for maxillary teeth• In adults = 8 sockets•Maxillay torus (occasionally)

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4)PALATINE PROCESSMedial border –• Thicker anteriorly• Groove between nasal crest of two maxilla receives lower border vomer

Anterior part of ridge – incisal crest & anterior nasal spine, Incisive canal

Posterior border articulates with horizontal plate of palatine bone

Lateral border is continuous with alvolar process• .

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•Superior surface –

concave from

side to side & forms floor of nasal cavity

•Various foramina & pits

•Posterolaterally –

greater palatine foremen

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AGE CHANGES IN MAXILLA

1) AT BIRTH –

• Transverse & anterioposterior diameter > vertical

diameter

• Well marked frontal process

• Tooth sockets – close to orbit

• Maxillary sinus is a mere furrow on the lateral wall

of nose

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2) IN ADULTS –

• Vertical Diameter Is more due to –developed alveolar

process and increased size of maxillary sinus

3) IN OLD –

• Infantile condition

• Resorption of alveolar bone

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ARTERIAL SUPPLY TO THE ORAL CAVITY

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NERVE SUPPLY TO ORAL CAVITY

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CONTENTS1) Introduction2) Anatomy of mandible3) Attachments and relations of mandible4) Age changes in mandible5) Anatomy of maxilla6) Age changes in maxilla7) Anatomic spaces8) Applied aspects of maxilla and mandible

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ANATOMICAL SPACES

• Anatomical spaces or compartments are

generally "potential spaces" that become

opened or expanded by invading infection

that intervenes between the structures

surrounding the space. Such spaces are of

particular significance in the head and

neck as they may serve as pathways for the

spread of infection from one region to

another.

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TYPES OF SPACESPrimary maxillary- canine, buccal.

• Primary mandibular- submental, sublingual, buccal,

submandibular.

• Secondary spaces- masseteric, pterygomandibular,

superficial & deep temporal, lateral pharyngeal,

retropharyngeal, parotid, prevertebral

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1) CANINE SPACEIt is the region between anterior surface of maxilla and

overlying levator muscles of upper lip.Contains angular artery & vein, infraorbital nerve. Etiology-Maxillary canine & 1st premolar infection &

sometimes mesiobuccal root of first molars.

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Boundaries-

•Superiorly: levator superioris

alaque nasi and levator labii

superioris

•Inferiorly: caninus muscle

•Medially: anterolateral surface of

maxilla

•Posteriorly: buccinator mucsle.

•Anteriorly: orbicularis oris

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Clinical Features-

• Swelling of cheek, lower eyelid & upper lip.

• Drooping of angle of mouth.

• Nasolabial fold obliterated.

• Odema of lower eyelid

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2) BUCCAL SPACEBoundaries-

• Superiorly: zygomatic arch.

• Inferior: inferior border of mandible.

• Laterally: skin & subcutaneous tissue.

• Medially: buccinator muscle ,buccopharyngeal fascia.

• Posteriorly: anterior edge of masseter muscle.

• Anteriorly: posterior border of zygomaticus major &

depressor anguli oris.

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Contents-

Buccal fat pad.

Stenson’s duct.

Facial artery

Etiology-

Infected mandibular & maxillary premolars & molars.

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Clinical Features-• Obliteration of nasolabial fold.• Angle of mouth shifted to opposite side.• Swelling in cheek extending to corner of mouth to

zygomatic arch.

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4) SUBMENTAL SPACEBoundaries-• Roof: mylohyoid muscle.• Inferior: deep cervical fascia, platysma, superficial

fascia & skin.• Laterally: anterior belly of digastric.• Posteriorly: submandibular space.Contents-Lymph nodes, anterior jugular vein.

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Etiology-• Infected mandibular incisors.• Anterior extension of submandibular space.Clinical Features-• Chin appears glossy & swollen.• Pain & discomfort on swallowing.

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5) SUB LINGUAL SPACEBoundaries-• Superiorly: mucosa of floor of mouth.• Inferior: mylohyoid muscle. • Posteriorly: body of hyoid bone.• Anteriorly & laterally: inner aspect of mandibular

body.• Medially: geniohyoid,styloglossus,genioglossus

muscle..

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Contents-• Deep part of Submandibular gland.• Wharton’s duct.• Sublingual gland.• Lingual & hypoglossal nerves.• Terminal branches of lingual artery

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Etiology-Infected mandibular premolar & 1st molar.Clinical Features-• Swelling of floor of mouth.• Elevated tongue.• Pain & discomfort on swallowing

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6) SUB MANDIBULAR SPACEBoundaries-• Superiorly: mylohyoid muscle• Inferior: anterior & posterior belly of digastric.• Laterally: deep cervical fascia, platysma, superficial

fascia & skin.• Medially: hyoglossus,styloglossus,• mylohyoid muscle.• Posteriorly: to hyoid bone.• Anteriorly:: submental space.

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Contents-• Submandibular salivary gland.• Proximal portion of Wharton’s duct.• Lingual & hypoglossal nerves.• Branches of facial artery-

palatine,tonsillar,glandular,submental

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•Etiology-• Infected mandibular 2nd & 3rd molars.• From submental,sublingual spaces.

Clinical Features-• Indurated swelling in submandibular region.• Usually bulges over lower border of mandible.

Spread of Infection-• Across midline to contralateral space.• To contiguous pharyngeal spaces.

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7) PTERYGOMANDIBULAR SPACEBoundaries-• Superiorly: lower head of lateral pterygoid muscle.• Laterally: medial surface of ramus.• Medially: medial pterygoid muscle.• Posteriorly: deep part of parotid.• Anteriorly: pterygomandibular raphe.

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Contents-

• Inferior alveolar neurovascular bundle.

• Lingual & auriculotemporal nerves.

• Mylohyoid nerve & vessels

Etiology-

• Infected mandibular 3rd

molars(mesioangular/horizontal)

• Pericoronitis.

• Infected needles or contaminated LA solution

.

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.Clinical Features-• Absence of extra-oral swelling.• Severe trismus.• Difficulty in swallowing.• Anterior bulging of half of soft palate & tonsillar

pillars with deviation of uvula to unaffected side.Spread of Infection-• Superiorly to infratemporal space.• Medially to lateral pharyngeal space.• To submandibular space

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8) MASSETERIC SPACEBoundaries-• Superiorly: zygomatic arch.• Inferiorly: inferior border of mandible.• Laterally: masseter muscle.• Medially: ramus of mandible.• Posteriorly: parotid gland & its fascia.• Anteriorly: buccal space & buccopharyngeal fascia.

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Contents-

Masseteric artery & vein.

Etiology-

Mandibular 3rd molars(pericoronitis).

Clinical Features-

1) Swelling limited to masseter muscle.

2) Severe trismus & throbbing pain.

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SURGICAL ANATOMYMANDIBLE1) Anterior facial region2) Anterior lingual region3) Posterior facial region4) Posterior lingual region

MAXILLA5) Anterior facial region6) Posterior facial region7) PalateRETROMOLAR REGIONS AND MAXILLARY

TUBEROSITY

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MANDIBLE 1) Anterior F a c i a l Region:The main concerns are•the location of the muscle attachments

and •the thinness or absence of radicular bone

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MENTALIS MUSCLES

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•The plate of bone overlying the facial and

lingual root surfaces of the anterior teeth

is usually quite thin.

•A prominent mental tuberosity may also

limit the depth of the vestibule by forming

a flat projection in the midline of the

mandible

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2) An terior Lingual Region:

•presence of an unusually large or high

genial tubercle upon which several

muscles attach.

•The tubercles could approximate deep

osseous defects in the area and prevent

lingual osseous recontouring during

periodontal surgery.

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3)Posterior Facial Region.

• the presence of a

prominent external

oblique ridge.

• If the periodontal osseous

defects extend below the

level of the ridge, osseous

recontouring in an

attempt to eliminate

these defects would

require extensive and

unwanted removal of

large amounts of bone.

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• Anterior border of the ramus

of the mandible often sharply

approximate the last

mandibular molar

• In such situations loose

aerolar mucosa is often found

attached by a narrow ring of

gingiva to the distal surface of

the last molar.

• Surgical correction of distal

defects in these areas which

attempt to widen the band of

attached tissue are hampered

by the vertical bony

prominence of the ramus.

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• The thin attachment of the

buccinator muscle to the

mandible along the molar

teeth may also limit any

necessary extension of the

vestibule.

• The buccinator muscle forms

a portion of the medial wall of

the buccal space. If the

buccinator muscle were

perforated while elevating a

buccal flap, the buccal space

would be entered, producing

the possibility of an infection

in the space.

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Inferior alveolar artery

normally continues its

course deep within the

cheek and is not disturbed

while elevating mucosal

flaps from the mandible.

• Danger exists when

surgeon's knife could

accidentally penetrate to

the depth of the inferior

border of the mandible

and possibly sever the

artery.

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MENTALFORAMEN

Traumatizing or severing the

mental nerve could result in

temporary to permanent

paresthesia of the lip and

gingiva.

• Severing the mental artery is

less significant as adequate

collateral circulation exists

for the area supplied by the

vessel; the immediate

problem of hemorrhage

control should be achieved.

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4) POSTERIOR LINGUAL REGION

• Avoid incising the

superficial structures

which lie just under the

thin mucosa which forms

the floor of the mouth.

• The lingual nerve is most

easily damaged as it lies

very close to the mucosal

surface in the region of

the second and third

molars

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• Whenever the attached

gingiva is elevated from the

lingual aspect of a

mandible, or when the

mucosal lining of the floor

of the mouth is perforated,

the sublingual space may be

entered.

• Infection within the space

may spread to the opposite

side and into the body of

the tongue resulting in an

elevation of the tongue and

respiratory difficulty.

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MAXILLA1) ANTERIOR FACIAL REGION

• Severe bone loss in this

region could result in the

base of the periodontal

pocket approximating both

zygomatic process of the

maxilla and the attachment of

the buccinator muscle.

• Each could complicate and

surgical attempt to deepen

the vestibule or increase the

zone of attached gingiva.

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• Perforation of the buccinator muscle would

establish entry into the buccal space and

possible postoperative infection.

• As in the anterior facial region of the maxilla, a

surgical technique may be employed which

prevents exposure of the bone and possible

postoperative recession.

• The maxillary sinus closely approximates the

roots of the maxillary first and second molars

and may extend as far forward and posteriorly

as the canine and third molar respectively

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• Deep infrabony pockets

approach the floor of the

sinus and when the

thickness of supporting

bone becomes very thin or

nonexistent

• In these situations,

ostectomy to gain more

desirabl postoperative

contours must be limited

in order to prevent sinus

perforation.

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•The sinus may also be a factor to consider

when performing osseous ramping of

edentulous ridges.

•Osseous ridge thinning performed to gain

more favorable contours in preparation

for prosthetic replacement may often be

contraindicated by the expansion of the

sinus in an edentulous area.

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Greater palatine foramen and its contents:

• Severance of the greater

palatine artery must be

avoided as it is very difficult

to stop the hemorrhage by

local clamping or by

tamponade. In certain

instances stoppage has only

been accomplished by ligation

of external carotid artery.

• Vertical incisions in the

posterior portion of the palate

are hazardous since the

possibility of severing a large

vessel or nerve is likely.

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NASOPALATINE NERVES

The nasopalatine nerve

emanates from the incisive

foramen to supply the sensory

innervation for the palatal

mucosa from canine to canine.

• Surgery to eliminate

periodontal pockets in this

region of requires removing or

undermining the incisive

papilla, which could result in

servering the nasopalatine

nerve and a temporary

paresthesia of the area

supplied.

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OSSEOUS CONSIDERATIONS

IN THE PALATE

• Prominent exostoses or a flat,

shallow palatal roof make

osseous interproximal ramping

either impossible or difficult to

accomplish.

• In Gingivectomy procedures on

the palate, if the alveolar

process is very short due to a

shallow palatal vault, it would

be very difficult to achieve a

properly beveled result without

making an extremely wide

incision with its probable

postoperative discomfort.

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RETROMOLAR REGIONS

• If a mucosal incision were

carried through and distal

to the retromolar pad and

medial to the anterior

border of the ramus, the

buccinator of superior

pharyngeal constrictor

muscles could be

perforated or the

pterygomandibular raphe

divided.

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• Such an overextended incision

would create entry to the

pterygomandibular space

housing the lingual and

inferior alveolar nerves and

the inferior alveolar vessels.

the free communication of the

pterygomandibular space with

the retromandibular space

(containing the parotid gland)

and the parapharyngeal space.

• An infection of the

pterymandibular space could

potentially spread into deeper

structures

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• The mucosa behind the

maxillary tuberosity also

covers a mass of areolar-

glandular tissue.

• An incision carried through

and behind this mass would

perforate the superior

pharyngeal constrictor muscle

and establish entry into the

parapharyngeal space (if

perforation is medial to the

internal pterygoid muscle) or

into the pterygomandibular

space (if perforation is lateral

to the muscle)

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SUMMARY

Eloquent advice to the periodontal surgeon

(a) constantly revise your knowledge of

anatomy;

(b) constantly think of the local anatomy in

relation to injury and disease;

(c) never take a knife in your hand without

picturing in your mind's eye the structures in

and adjacent to your operative field,

however small that field may be."

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REFERENCES

• B.D. Chaurasia- human anatomy• Anatomical considerations in periodontal surgery

by michael a . clarke, d.d.s., m.s. j.p 1977Oral anatomy- sicher