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8/13/2019 kuliah ppdgs - Mastikasi

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A dynamic biomechanical musculoskeletal system

The Masticatory Systemby Widyawati Sutedjo


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Maxilla

Mandible

Condyle

Ascending Ramus

Coronoid Process

Body of the mandible

Temporal bone

Skeletal Anatomy:Masticatory System


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Mastication

Mastication:

Processes involved in food preparation,

including moving unchewed food onto thegrinding surface of the teeth, chewing, it, and

mixing it with saliva in preparation for

swallowing


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Loss of Teeth CausesOcclusal Disharmony

Early loss of deciduous teeth withoutspace retaining appliances

Loss of mandibular first molar

l ingual and mesial tipping of mandibular 2nd and 3rd

molar

Loss vertical dimension Changing in masticatory habit and muscle tonicity


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Signs of occlusal disorders

Repeated fracture of teeth or restorations.

Repeated lossofcementationof indirect restorations whereretention and resistance in the preparation appear adequate.

Driftingor progressively increasingmobilityof a tooth orgroups of teeth.

Wearofthe functionalsurfacesof the teeth, which is out ofproportion to the patients age.

Signand symptomsfrom TMDor their associated muscles.


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OCCLUSAL THERAPY

The purpose of occlusal therapy is to establishstable functional relationships favorable to theoral health of the patient, including the

periodontium

Occlusal Adjustment

Occlusal adjustment, or coronoplasty, is the selectivereshaping of occlusal surfaces with the goal ofestablishing a stable, nontraumatic occlusion

have been used extensively in the past for treating avariety of problems including occlusal trauma, TMD

symptoms, bruxism, and headache


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Kriteria fungsi oklusi yang baik

Pengunyahan bilateral yang seimbang dan bergantian. Kontak ringan pada posisi interkuspa ketika menelan Gerak mengunyah kedalam dan keluar, yang bebas dari

kontak defleksi pada sisi kerja maupun non-kerja Tidak ada gerak adaptasi dagu atau bibir pada saat

menelan Tidak ada gerak mengerot (clenching) dan bruxism Tidak ada bunyi sendi pada saat mastikasi maupun

membuka mulut lebar-lebar

Tidak ada deviasi mandibula waktu mulut dibuka lebar Tidak ada kontak gigi pada saat berbicara atau

melakukan ekspresi wajah


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Centric Relation

Centric Relation is anorthopedically stable muscularposition where the condyle rests

in a superior anterior positionagainst the posterior wall of thearticular eminence with thearticular disk interposed.

A purely rotational movementcan occur for the first 20-25 mm

of jaw opening.


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Centric Occlusion vs.Maximum Intercuspation

Centric Occlusion is thetooth position when theTMJ is in CR and the

teeth first touch onclosing. Maximum intercuspation

is the position of theteeth when there ismaximum contact ofteeth in occlusion.


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Mandibular Movement

Mandibular movements occurs as acomplex series of interrelated three-dimensional rotational and translationalactivities.

It is determined by the combined andsimultaneous activities of

temporomandibular joints (TMJs). There are two types of movement occurs

in the TMJ: rotational and translational.


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Types of Mandibular Movement Rotational movement

Horizontal axis of rotationFrontal (vertical) axis of

rotationSagittal axis of rotation

Translational movement


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Rotational Movement Around the horizontal axis (hinge

axis)


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Rotational Movement Around the frontal

(vertical axis

Occurs when onecondyle movesanteriorly out of theterminal hinge position

with the vertical axisof the oppositecondyle remaining inthe terminal hinge

position


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Rotational Movement Around the

sagittal axis

Occurs whenone condylemoves inferiorlywhile the other

remains in theterminal hingeposition.


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Translational movement Can be defined

as a movement

in which everypoint of themoving objecthas

simultaneouslythe samevelocity anddirection.


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Anatomical Planes ofMandibular Movement

Frontal view Front view of

the jaws

Sagittal view Lateral view of

the jaws

Horizontal view Superior view

of the jaws


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Border Movements

Mandibular movement islimited by the ligaments,muscles of the TMJ,

articular surfaces andmorphology andalignment of teeth.

The outer limitsof themandibles range ofmotion are called bordermovements.

Gothic Arch Tracing


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BORDER AND FUNCTIONALMOVEMENTS (SAGITTAL PLANE)

**Movement is limited by ligaments

1

2

3

4


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BORDER MOVEMENTSSAGITTAL PLANE (Gothic Arch Tracing)

Posterior opening stage one - early rotational

movement around the horizontal axis.

Rotationalmovement of themandibular withthe condyles inthe terminal hingeposition.

This purerotational openingcan occur until theanterior teeth are20-25 mm apart.


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Second stage of rotationalmovement during opening.

The condyle is translateddown the articulareminence while the mouthrotates open to itsmaximum limit.

Maximum opening isreached when the capsularligament prevent furthermovement of the condyles.

Posterior opening stage two-

translational down theeminence.


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With the mandiblemaximally opened,closureaccompanied bycontraction of theinferior lateralpterygoids will

generate theanterior openingbordermovements.

Anterior opening in

sagittal plane


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BORDER MOVEMENTSSAGITTAL PLANE

Common relationship of theteeth when the condyles

are in the centric relation

(CR) position.

Force applied to the teethwhen the condyles are incentric relation (CR) willcreate a superoanteriorshift of the mandible tothe intercuspal position

(ICP).


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When mandibular movements are viewed inthe horizontal plane, a rhomboid-shapedpattern can be seen, as well as 4 distinctmovement components.

1. Left lateral2. Continued left lateral

with protrusion3. Right lateral4. Continued Right lateral

with protrusion


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BORDER MOVEMENTSHORIZONTAL PLANE


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FRONTAL PLANE BORDERMOVEMENTS

(Shield Shape)

** Note:Thered Dot=Postural Position

= Rest Position


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TMJ Ligaments


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Ligaments

Temporomandibular

ligament

extend from base of zygomatic

process of the temporal bone

downward and oblique to the

neck of the condyle


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Ligaments

Stylomandibular

ligament

From styloid process and

runs downward and

forward to attach broadly

on the inner aspect of theangle of mandible


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Ligaments

Sphenomandibular

ligament

arising from the angular

spine of sphenoid bone and

petrotympanic fissure,

ending at lingula ofmandible


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Functions of Ligaments

Accessory ligaments may limit

border movements of the

mandible

Fibrous capsule and TM ligament

may limit of extreme lateralmovements in wide opening of

mandible


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