anatomical landmarks mandible

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ANATOMICAL LANDMARKS ANATOMICAL LANDMARKS MANDIBLE MANDIBLE

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Page 1: Anatomical Landmarks Mandible

ANATOMICAL ANATOMICAL LANDMARKS MANDIBLELANDMARKS MANDIBLE

Page 2: Anatomical Landmarks Mandible

Mandible is the movable member of the Mandible is the movable member of the stomatognathic system. The total area of stomatognathic system. The total area of support from the mandible is less than from the support from the mandible is less than from the maxilla. maxilla. Available denture bearing area is 14sqmm. The Available denture bearing area is 14sqmm. The bony foundation for the mandibular denture bony foundation for the mandibular denture become shorter vertically and narrower become shorter vertically and narrower buccolingualybuccolingualyLess bony supportLess bony supportBony crest narrower and sharperBony crest narrower and sharper

Page 3: Anatomical Landmarks Mandible

Supporting structuresSupporting structures

Crest of the residual ridgeCrest of the residual ridge

Buccal flange areaBuccal flange area

External oblique ridgeExternal oblique ridge

Mylohyoid lineMylohyoid line

Mental foramen areaMental foramen area

Torus mandibularisTorus mandibularis

Page 4: Anatomical Landmarks Mandible

Crest of the residual ridgeCrest of the residual ridge

Is covered by fibrous connective tissueIs covered by fibrous connective tissue

But underlying bone is thin and cancellous But underlying bone is thin and cancellous containing nutrient canals so is a releif containing nutrient canals so is a releif areaarea

It has spongy bone in the molar regionIt has spongy bone in the molar region

Page 5: Anatomical Landmarks Mandible

Buccal flange and buccal shelfBuccal flange and buccal shelf

Is a primary stress Is a primary stress bearing areabearing areaIs an area between the Is an area between the buccal frenum and edge buccal frenum and edge of masseterof masseterBoundariesBoundariesMedially- crest of the Medially- crest of the ridgeridgeAnt-buccal frenumAnt-buccal frenumLat- external oblique lineLat- external oblique lineDistal – retro molar padDistal – retro molar pad

Page 6: Anatomical Landmarks Mandible

It is a wide area and at right angles to vertical It is a wide area and at right angles to vertical forces and is covered with smooth cortical bone.forces and is covered with smooth cortical bone.

Inferior part of the buccinator is attached in the Inferior part of the buccinator is attached in the buccal shelf thus contraction does not lift the buccal shelf thus contraction does not lift the lower denture. lower denture.

Muscle fibers run antero posteriorly paralleling Muscle fibers run antero posteriorly paralleling the bone. The tray come to direct contact with the bone. The tray come to direct contact with mucosa of buccal shelf and soft tissue is slightly mucosa of buccal shelf and soft tissue is slightly displaced as the final impression is madedisplaced as the final impression is made

Page 7: Anatomical Landmarks Mandible

The external oblique line-The external oblique line-

is a ridge of dense bone extending from is a ridge of dense bone extending from the mental foramen and become the mental foramen and become continuous with the anterior border of the continuous with the anterior border of the ramus of the mandible. In most individuals ramus of the mandible. In most individuals it is the anatomic guide for the lateral it is the anatomic guide for the lateral termination of the buccal flange of the termination of the buccal flange of the lower denturelower denture

Page 8: Anatomical Landmarks Mandible

The mental foramenThe mental foramen

Is located on the lateral surface of the Is located on the lateral surface of the body of the mandible between the first and body of the mandible between the first and second premolars, about half way from the second premolars, about half way from the alveolar crest and the lower border. If the alveolar crest and the lower border. If the resorption is greater it occupies a superior resorption is greater it occupies a superior position and the denture base must be position and the denture base must be relived over the foramenrelived over the foramen

Page 9: Anatomical Landmarks Mandible

The mylohyoid lineThe mylohyoid line

Is an irregular rough bony Is an irregular rough bony crest extending from the crest extending from the third molar region to the third molar region to the lower border of the lower border of the mandible in the region of mandible in the region of the chin. It is more the chin. It is more prominent in the third prominent in the third molar region to the 2molar region to the 2ndnd premolar region. The premolar region. The lingual flange must lingual flange must extend inferior to and not extend inferior to and not lateral to the mylohyoid lateral to the mylohyoid line line

Page 10: Anatomical Landmarks Mandible

The lingual tuberosityThe lingual tuberosity

Is an irregular bony prominence on the Is an irregular bony prominence on the distal end of the mylohyoid line distal end of the mylohyoid line

The mental spine is situated on the lingual The mental spine is situated on the lingual aspect of the mandibular bodyaspect of the mandibular body

Page 11: Anatomical Landmarks Mandible

Torus mandibularisTorus mandibularis

Is a bony prominence found near the I &II Is a bony prominence found near the I &II premolar between the soft tissue and the premolar between the soft tissue and the floor of the mouthfloor of the mouth

Covered by extremely thin mucous Covered by extremely thin mucous membrane may be irritated with slight membrane may be irritated with slight movement. movement.

It may be removed surgically without It may be removed surgically without breaking the border sealbreaking the border seal

Page 12: Anatomical Landmarks Mandible

Limiting structuresLimiting structures

Labial frenumLabial frenumLabial vestibuleLabial vestibuleBuccal frenumBuccal frenumBuccal vestibuleBuccal vestibuleMasseter muscle regionMasseter muscle regionDistal extension of mandibular impressionDistal extension of mandibular impressionRetromolar regionRetromolar regionMylohyoid muscles and ridgeMylohyoid muscles and ridgesublingual gland regionsublingual gland regionLingual frenum and lingual notchLingual frenum and lingual notchLingual vestibuleLingual vestibule

Page 13: Anatomical Landmarks Mandible

Labial frenumLabial frenum

Contains a band of fibrous connective Contains a band of fibrous connective tissue that is attached to the orbicularis tissue that is attached to the orbicularis orisoris

Sensitive and activeSensitive and active

It is accommodated by a groove on the It is accommodated by a groove on the mandibular denturemandibular denture

Page 14: Anatomical Landmarks Mandible

Labial vestibuleLabial vestibule

Is the area extending from the labial Is the area extending from the labial frenum to the buccal frenum.frenum to the buccal frenum.The denture should not be extended The denture should not be extended beyond the mucolabial fold as it is limited beyond the mucolabial fold as it is limited by the fibers of the orbicularis oris and the by the fibers of the orbicularis oris and the incivious labi inferioris which is fairly close incivious labi inferioris which is fairly close to the ridgeto the ridgeTone of the lip depends on the thickness Tone of the lip depends on the thickness of the flange and position of teethof the flange and position of teeth

Page 15: Anatomical Landmarks Mandible

Recording labial and buccal flangesRecording labial and buccal flanges

The labial frenum is molded by moving the The labial frenum is molded by moving the lip outward, upward and inward.lip outward, upward and inward.

Page 16: Anatomical Landmarks Mandible

Buccal frenumBuccal frenum

Overlies the depressor anguli orisOverlies the depressor anguli oris

Connected to the buccal frenum in maxilla as a Connected to the buccal frenum in maxilla as a continuous band through the modiolus at the continuous band through the modiolus at the corner of the mouthcorner of the mouth

Clearance must be achieved in the denture base Clearance must be achieved in the denture base to avoid displacement of the dentureto avoid displacement of the denture

The fibrous and muscular tissues pull actively The fibrous and muscular tissues pull actively across the denture bordersacross the denture borders

Denture must be extended less in this regionDenture must be extended less in this region

Page 17: Anatomical Landmarks Mandible

Buccal vestibuleBuccal vestibule

Extends from the buccal frenum posteriorly to Extends from the buccal frenum posteriorly to the outside back corner of the retromolar pad the outside back corner of the retromolar pad and from the crest of the ridgeand from the crest of the ridge

Overlies buccal shelf and ex oblique lineOverlies buccal shelf and ex oblique line

Buccinator attached to oblique ridgeBuccinator attached to oblique ridge

Buccinators action occurs in horizontal direction Buccinators action occurs in horizontal direction so it cannot lift the dentureso it cannot lift the denture

Buccinator extends from modiolus to the Buccinator extends from modiolus to the pterygomandibular raphaepterygomandibular raphae

Page 18: Anatomical Landmarks Mandible

Recording the buccal frenumRecording the buccal frenum

The buccal frenum is recorded by moving The buccal frenum is recorded by moving cheek outward, upward backward and cheek outward, upward backward and forward. forward.

To record the disto buccal sulcus the To record the disto buccal sulcus the cheek should be well retracted and moved cheek should be well retracted and moved upward and inward.upward and inward.

Page 19: Anatomical Landmarks Mandible

Masseter muscle regionMasseter muscle region

The distobuccal border of the mandibular The distobuccal border of the mandibular denture must converge rapidly to avoid denture must converge rapidly to avoid displacement by the contracting pressure of the displacement by the contracting pressure of the masseter muscle.masseter muscle.Masseter muscle runs at right angles to the Masseter muscle runs at right angles to the buccinatorbuccinatorWhen masseter contracts it pushes the When masseter contracts it pushes the buccinator and tissues inward against the buccinator and tissues inward against the denture and alters the size and shape of the denture and alters the size and shape of the distobuccal end of the lower buccal vestibule distobuccal end of the lower buccal vestibule reducing the space in that region (dislodging reducing the space in that region (dislodging forceforce

Page 20: Anatomical Landmarks Mandible

Masseter muscle pushes the buccinator towards Masseter muscle pushes the buccinator towards the retromolar pad. The denture base must be the retromolar pad. The denture base must be contoured to accommodate this massetric notch.contoured to accommodate this massetric notch.One can register the masseter pull on the One can register the masseter pull on the impression by softening the compound with an impression by softening the compound with an alcohol flame along the disto buccal border alcohol flame along the disto buccal border tempering in warm watertempering in warm waterAfter seating in the impression in patients mouth After seating in the impression in patients mouth exert downward pressure by placing the index exert downward pressure by placing the index fingers on the impression in the 2fingers on the impression in the 2ndnd premolar premolar region and instructing the patient to exert a region and instructing the patient to exert a closing force. these opposing forces will cause the closing force. these opposing forces will cause the masseter to contract and trim the compound in masseter to contract and trim the compound in that area recording the masseteric notchthat area recording the masseteric notch

Page 21: Anatomical Landmarks Mandible

Distal extension of the mandibular Distal extension of the mandibular impressionimpression

Limited by the ramus of mandibleLimited by the ramus of mandible

By buccinator fibersBy buccinator fibers

By sharpness of bony boundaries of By sharpness of bony boundaries of retromolar fossaretromolar fossa

If the impression is extended on to ramus If the impression is extended on to ramus the buccinator will be compressed the buccinator will be compressed between the hard denture border and between the hard denture border and sharp external oblique ridgesharp external oblique ridge

Page 22: Anatomical Landmarks Mandible

Retromolar region and padRetromolar region and pad

Is a triangular pear Is a triangular pear shaped soft pad of tissue shaped soft pad of tissue in the distal end of the in the distal end of the mandibular ridgemandibular ridge

It must be covered by the It must be covered by the denture for the perfect denture for the perfect border seal. Aids in the border seal. Aids in the stability of the denture by stability of the denture by adding another plane to adding another plane to resist the movement of resist the movement of the basethe base

Page 23: Anatomical Landmarks Mandible

ContentsContentsSome glandular tissueSome glandular tissueFibers of temporalis tendonFibers of temporalis tendonFrom buccal side- buccinatorFrom buccal side- buccinatorFrom lingual side- superior pharyngeal From lingual side- superior pharyngeal constrictorconstrictorSupero posterior inside corner- Supero posterior inside corner- pterygomandibular raphepterygomandibular rapheThese structures prevent the placement of extra These structures prevent the placement of extra pressure during the impression procedurepressure during the impression procedure

Page 24: Anatomical Landmarks Mandible

Retromolar papillaRetromolar papilla

Is a small pear shaped area anterior to the Is a small pear shaped area anterior to the pad pad

Is a dense fibrous connective tissueIs a dense fibrous connective tissue

Retro molar pad should be registered in a Retro molar pad should be registered in a resting position in the final impressionresting position in the final impression

Page 25: Anatomical Landmarks Mandible

Recording the retromolar padRecording the retromolar pad

To record the distal end of the try the To record the distal end of the try the patient is asked to open the mouth wide. If patient is asked to open the mouth wide. If notch is produced in the posteromedial notch is produced in the posteromedial end of the try it indicates that the tray is end of the try it indicates that the tray is over extended up to the over extended up to the pterygomandibular raphepterygomandibular raphe

Page 26: Anatomical Landmarks Mandible

Sublingual gland regionSublingual gland region

Rest above the mylohyoid muscle. When Rest above the mylohyoid muscle. When the floor of the muscle is raised the gland the floor of the muscle is raised the gland come close to the crest of the ridge and come close to the crest of the ridge and reduces the vertical space available for the reduces the vertical space available for the flange extension in the anterior part of the flange extension in the anterior part of the mouthmouth

Page 27: Anatomical Landmarks Mandible

Lingual frenum& lingual notchLingual frenum& lingual notch

Extremely resistant and active and wideExtremely resistant and active and wide

Should be registered in functionShould be registered in function

In function it come close to the ridge In function it come close to the ridge

At rest it is much lowerAt rest it is much lower

Overlies the genioglossus muscleOverlies the genioglossus muscle

Page 28: Anatomical Landmarks Mandible

Lingual vestibuleLingual vestibule

Occupies the alveolingual sulcusOccupies the alveolingual sulcusDistal end extend to the retromylohyoid curtainDistal end extend to the retromylohyoid curtainAnteriorly influenced by mylohyoidAnteriorly influenced by mylohyoidFlange extend below the mylohyoid ridge to occupy the Flange extend below the mylohyoid ridge to occupy the alveolo lingual sulcus.alveolo lingual sulcus.Flange leaves the bony attachment at the mylohyoid Flange leaves the bony attachment at the mylohyoid ridge and slopes inward under the tongue to fill the ridge and slopes inward under the tongue to fill the alveololingual sulcusalveololingual sulcusThus there is a space between the flange and mucous Thus there is a space between the flange and mucous membrane when the muscle is relaxed and there is membrane when the muscle is relaxed and there is contact when the tongue is raised and thrust outcontact when the tongue is raised and thrust out

Page 29: Anatomical Landmarks Mandible

Recording the lingual frenumRecording the lingual frenum

The anterior lingual border is molded by The anterior lingual border is molded by asking the patient to protrude his tongue to asking the patient to protrude his tongue to touch the anterior part of palate.touch the anterior part of palate.

Protrusion records the length of lingual Protrusion records the length of lingual flangeflange

Touching the anterior part of hard palate Touching the anterior part of hard palate helps to establish the width of the flange.helps to establish the width of the flange.

Page 30: Anatomical Landmarks Mandible

Mylohyoid muscle & ridgeMylohyoid muscle & ridge

Mylohyoid muscle arise from the whole length of Mylohyoid muscle arise from the whole length of the mylohyoid line extending from about 1 cm the mylohyoid line extending from about 1 cm back of the distal end of the mylohyoid ridge to back of the distal end of the mylohyoid ridge to the lingual anterior portion of the mandible at the the lingual anterior portion of the mandible at the symphysissymphysis

This ridge is near the inferior border in the incisal This ridge is near the inferior border in the incisal region but become progressively higher on the region but become progressively higher on the posterior border, so posterior part affect the posterior border, so posterior part affect the lingual impression in swallowing and tongue lingual impression in swallowing and tongue movementsmovements

Page 31: Anatomical Landmarks Mandible
Page 32: Anatomical Landmarks Mandible

The lingual flange should extend inferior but The lingual flange should extend inferior but not lateral to the mylohyoid line.not lateral to the mylohyoid line.

The movement of tongue and displacability of The movement of tongue and displacability of the floor of the mouth will determine the the floor of the mouth will determine the length of the flange. If the flange is properly length of the flange. If the flange is properly shaped it will complete the lingual border seal shaped it will complete the lingual border seal in the retromylohyoid fossa and guide the in the retromylohyoid fossa and guide the tongue on top of the flangetongue on top of the flange

Page 33: Anatomical Landmarks Mandible

Recording the mylohyoidRecording the mylohyoid

Protrusion of the tongue record the Protrusion of the tongue record the movement of the mylohyoid muscle. This movement of the mylohyoid muscle. This raises the floor of the mouth. The lingual raises the floor of the mouth. The lingual flange recorded will be lingually sloping nd flange recorded will be lingually sloping nd parallel to the direction of the mylohyoid parallel to the direction of the mylohyoid muscle. Increse in the thicknes odf the muscle. Increse in the thicknes odf the posterior part otf the lingual flange can posterior part otf the lingual flange can interfere with the action of the mylohyoid interfere with the action of the mylohyoid muscle. muscle.

Page 34: Anatomical Landmarks Mandible

While border molding the distal end of the lingual While border molding the distal end of the lingual flange the action of the mylohyoid curtain should flange the action of the mylohyoid curtain should be recorded. The superior constrictor and the be recorded. The superior constrictor and the medial pterygoid determine the position of he medial pterygoid determine the position of he retromylohyoid curtainretromylohyoid curtain

Superior constrictor- by protruding the tongueSuperior constrictor- by protruding the tongue

Medial pterygoid- by asking the patient to Medial pterygoid- by asking the patient to forcefully close against resistanceforcefully close against resistance