the principles of cavity preparation

8/15/2019 The Principles of Cavity Preparation

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The principles of cavityThe principles of cavity

preparationpreparation

Are some fundamental principles which mustAre some fundamental principles which must

be realized in preparing cavities and must bebe realized in preparing cavities and must beintelligently applied and adhered to in all casesintelligently applied and adhered to in all casessince failure of whole procedure might occursince failure of whole procedure might occur

of one or any one is violated .of one or any one is violated .


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I-Biological principlesI-Biological principles

Concerned with Health and integrity ofConcerned with Health and integrity of

remaining tooth structureremaining tooth structure


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A-Pulp protection:A-Pulp protection:

1-Mechanical irritation

1.1. Cutting across recessional linesCutting across recessional lines

2.2. ver widthver width

!.!. ver depthver depth

".".

#$cessive pressure#$cessive pressure


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2-Thermal irritationMinimizing frictional heat .Minimizing frictional heat . Decrease pressure Decrease pressure Sharp tools Sharp tools

Use oolant Use oolant opious ! opious ! multi"irectionalmulti"irectional

same temperature same temperature


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#-hemical irritation$avity sterilizers an" con"itionersavity sterilizers an" con"itioners

%-Bacterial irritation$

Sterilization of instrumentSterilization of instrument

&iel" isolation&iel" isolation


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B-ontrol of caries$B-ontrol of caries$

1-'emoval of all caries1-'emoval of all caries

2-()ten" to all "efective areas *pit!2-()ten" to all "efective areas *pit!fissure an" angular groove+.fissure an" angular groove+.

#-'emoval of ,ea an" un"ermine"#-'emoval of ,ea an" un"ermine"enamelenamel

%-ppropriate S.%-ppropriate S.


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-/rotection of investing tissue an"-/rotection of investing tissue an"a"0acent tooth.a"0acent tooth.

'oun"ation an" smoothing of ragge"'oun"ation an" smoothing of ragge"margins especially those near themargins especially those near thegingivalgingival

voi" un in0u"icious sugingivalvoi" un in0u"icious sugingivale)tensione)tension

/rotect a"0acent tooth/rotect a"0acent tooth/roper guar" an" support/roper guar" an" support


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II-Mechanical principlesII-Mechanical principles

1- /reservation of structural integrity of1- /reservation of structural integrity ofoth tooth an" restorationoth tooth an" restoration

*/rovision of correct resistance form+.*/rovision of correct resistance form+.

2-'etaining the restoration insi"e the cavity2-'etaining the restoration insi"e the cavity

*/rovision of correct retention form+.*/rovision of correct retention form+.


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II-(sthetic principles$II-(sthetic principles$

1.1. /rovision of symmetrical outlines in/rovision of symmetrical outlines in

smooth s,eeping curves.smooth s,eeping curves.2.2. imiting restoration "isplayimiting restoration "isplay

#.#. (limination of "iscolore" tooth(limination of "iscolore" tooth

structurestructure


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Steps of cavity preparationSteps of cavity preparationas suggeste" y Dr. Blac are$as suggeste" y Dr. Blac are$1. 3tain the re4uire" outline form.1. 3tain the re4uire" outline form.

2. 3tain the re4uire" resistance form.2. 3tain the re4uire" resistance form.

#. 3tain the re4uire" retention form.#. 3tain the re4uire" retention form.%. 3tain the re4uire" convenience%. 3tain the re4uire" convenienceform.form.

5. 'emove any remaining carious "entin.5. 'emove any remaining carious "entin.

6. &inish the enamel ,all.6. &inish the enamel ,all.

7. /erforming toilet of the cavity.7. /erforming toilet of the cavity.


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11..3tain the re4uire" outline3tain the re4uire" outlineformform..

#$tent of caries %efective & non remeneralizable and retentive

enamel.

#nameloplasty'ea( undermined enamel)ear cavities Pro$imal outlines *straight line + uniform curve

+ reverse curve,Affected by Caries& size and location ofcontact occlusal forces

Cervical outlines


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22..3tain the re4uire"3tain the re4uire"resistance formresistance form..

/rimary resistance form may e "efine" as/rimary resistance form may e "efine" as

that shape an" placement of thethat shape an" placement of thepreparation ,alls that est enale othpreparation ,alls that est enale oththe restoration an" the tooth tothe restoration an" the tooth to

,ithstan"! ,ith out fracture! masticatory,ithstan"! ,ith out fracture! masticatory

forces "elivere" principally in theforces "elivere" principally in the

long a)is of the toothlong a)is of the tooth


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& fl f h


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&actors influencing stress response of tooth&actors influencing stress response of toothan" restoration$an" restoration$

1-3cclusal loa"ing in terms of1-3cclusal loa"ing in terms of

Magnitu"e. Direction an" haracterMagnitu"e. Direction an" haracter2-avity "esign in terms of2-avity "esign in terms of

1.1. Direction of ,allsDirection of ,alls

2.2. Smoothness an" flatness ,allsSmoothness an" flatness ,alls#.#. line an" point anglesline an" point angles

%.%. SS

5.5. BulBul6.6. 'etention'etention

#-Strength characteristic of restorative#-Strength characteristic of restorative

materials.materials.


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#. 3tain the re4uire"'etention form.

Is that shape or form of the prepare"Is that shape or form of the prepare"cavity that resists "isplacement or removalcavity that resists "isplacement or removalof the restoration y the force ofof the restoration y the force of

mastication an" also against the pull ofmastication an" also against the pull ofsticy foo".sticy foo".


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'etention mechanisms'etention mechanisms::

1-hemical e). 8.I1-hemical e). 8.I

2-Mechanical2-Mechanical-Macro mechanical-Macro mechanical

B-Micro mechanicalB-Micro mechanical


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Types of retentions accor"ing toTypes of retentions accor"ing topossile "irections of "isplacementpossile "irections of "isplacement::

1-)ial 'etention$

Direct restorations 9 3cclusal convergenceDirect restorations 9 3cclusal convergence*un"ercuts+*un"ercuts+

In Direct restorations99../arallelism ofIn Direct restorations99../arallelism ofopposing cavity ,allsopposing cavity ,alls

Dentine le"gesDentine le"ges


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2-ateral 'etention

&eatures provi"e" to give retention to anyother "irection than the a)ial e.g.pro)imal! uccal an" lingual


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'etentive features:

1. &riction of restoration ,ith the parallelopposing ,alls

2. /ro)imo-a)ial groove *locs+

#. Buccal an" lingual e)tensions%. 'everse evel5. Dove tail loc6. Slots7. )ial coves:. Dentin pins


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&actors affecting selection ofretentive means:

1. Size of cavity an" remaining toothstructures

2. ;umer of missing ,alls

#. Site of cavity an" occlusal stresses

%. Type of restoration

5. /ulp vitality6. (sthetic re4uirements


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%. 3tain the re4uire"onvenience form

s that shape and form of the cavity thats that shape and form of the cavity thatma(e the cavity convenientlyma(e the cavity conveniently seenapproache" an" restore"

n other words slight increase in outlinen other words slight increase in outlineto improve the accessibility andto improve the accessibility andvisibility during operative andvisibility during operative and

restorative proceduresrestorative procedures1.1. utline e$tensionutline e$tension

2.2. Accentuation of point and line anglesAccentuation of point and line angles

!.!. weeping out line fromweeping out line from


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5-'emoval of remaining caries:

/and methodharp e$cavator from periphery toward the

center with light force parallel to recessional

lines of the pulp0otary methodse round bur with light pressure and

intermittent stro(es nfected and affected dentine pots in the floorA%


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6-&inishing of cavity ,alls:

30ectives$

1.1. 0emoval of undermined enamel0emoval of undermined enamel

2.2. btaining the suitable CA accordingbtaining the suitable CA accordingto the restorative materialto the restorative material

!.!. /aving correct cavity walls inclination/aving correct cavity walls inclination

".". moothening walls and margins formoothening walls and margins forbetter adaptationbetter adaptation

3.3. 0oundation of line and point angle0oundation of line and point angle


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&actors affecting S

1. 4ype of restoration

2. tress acting on cavity margin

!. 5ocation of the margin". Condition of enamel

3. Pulp vitality

6. #sthetic re7uirements


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Types of avo-Surface evels

Short evel

ong evel


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7-Toilet of the cavity

4oilet of the cavity is cleaning of thecavity from small chips of cutting toothstructure and carious lesion& using sharp

hand instrument to loosen it and washedwith air +water spray& cotton pelletsthen gentle dryness with oil free air.

the principles of cavity preparation

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