1 Tooth Preparation

8/6/2019 1 Tooth Preparation

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FUNDAMENTALS OF TOOTH PREPARATION


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DEFINITIONTOOTH PREPARATION IS DEFINED AS MECHANICAL

ALTERATION OF A DEFECTIVE, INJURED OR

DISEASED TOOTH TO BEST RECEIVE A RESTORATIVEMATERIAL THAT WILL ESTABLISH A HEALTHY

STATE FOR TOOTH,INCLUDING ESTHETIC

RESTORATION WHERE INDICATED, ALONG WITHNORMAL FORM AND FINCTION.


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OBJECTIVESOBJECTIVES

Remove all defects and provide necessaryprotection to the pulp

Extend the restoration as conservatively aspossible

Form the tooth preparation so that underforce of mastication the tooth or therestoration or both will not fracture and therestoration will not be displaced

Allow for esthetic and functional placement of

restorative material


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NomenclaturesNomenclaturesCARIES

Can be described according to

Location

Extent

Rate


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LOCATIONLOCATION

Primary caries :

Original carious lesion of tooth.

Three morphological types1. In enamel pit and fissures

2.On enamel smooth tooth surfaces

3.On root surfaces


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PIT AND FISSURE CARIESPIT AND FISSURE CARIES

Pit and fissure caries can form inregions of pits and fissures usuallyresulting from imperfect coalescence

of the developmental enamel lobes


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SMOOTH SURFACE CARIESSMOOTH SURFACE CARIES

Begins in smooth area of enamel surface thatis habitually unclean and is usually covered by

plaque


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BACKWARD CARIESBACKWARD CARIES

When spread ofcaries along DEJexceeds thecaries in thecontiguousenamel, cariesextends into thisenamel fromjunction and istermed backwardcaries.


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FORWARD CARIESFORWARD CARIES

Forward caries is wherever the caries cone inenamel is larger or at least the same size as

that in dentin


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RESIDUAL CARIESRESIDUAL CARIES

Caries thatremains in acompleted toothpreparation,whether byoperatorsintention oraccident


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ROOT SURFACE CARIESROOT SURFACE CARIES

Root surface caries may occur on the toothroot that has not been exposed to the oralenvironment and habitually covered plaque.

Usually more rapid other forms of caries


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SECONDARY CARIESSECONDARY CARIES

Secondary caries occurs at the junction of arestoration and the tooth and may progress

under the restoration.


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EXTENT OF CARIESEXTENT OF CARIES

Incipient caries (reversible)

Cavitated caries (nonreversible)


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INCIPIENT CARIES/REVERSIBLEINCIPIENT CARIES/REVERSIBLE

First evidence of caries activity in mouth

Lesion appear opaque white when air dried and willseem to disappear if wetted.

Lesion can be remineralized if corrective measuresare taken


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CAVITATED CARIES /IRREVERSIBLECAVITATED CARIES /IRREVERSIBLE

In cavitated caries the enamel surface isbroken and usually the lesion is advanced indentin. Remineralization is not possible.


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RATE (SPEED) OF CARIESRATE (SPEED) OF CARIES

Acute (rampant caries )

Chronic (arrested caries )


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ACUTE (RAMPANT CARIES )ACUTE (RAMPANT CARIES )

Usually in form of many, soft, light coloredlesion in mouth and is infectious.


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ARRESTED CARIESARRESTED CARIES

Disease is episodic, slow rate is due todemineralization followed by mineralization

Color is brown black, hard and may be more caries

resistant


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TOOTH PREPARATION TERMINOLOGYTOOTH PREPARATION TERMINOLOGY

SIMPLE COMPOUND


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TOOTH PREPARATION WALLSTOOTH PREPARATION WALLS


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TOOTH PREPARATION ANGLESTOOTH PREPARATION ANGLES

Cavosurface angle


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Cavosurface angle and cavosurface margin

Cavosurface angle is the angle of tooth structureformed by the junction of a prepared (cut) wall andexternal surface of the tooth

The junction of both (external and internal ) surfacesis termed cavosurface margin.


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Line angle :a line angle is the junction of two planalsurfaces of different orientation along a line .

Internal line angle is a angle whose apex points intothe tooth.

External line angle is a line angle whose apex pointsaway from tooth.

Point angle :a point angle is the junction of threeplanal surfaces of different orientation


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TOOTH PREPARATION TERMINOLOGYTOOTH PREPARATION TERMINOLOGY

Class I preparation: All pit and fissurerestorations are class I.

Restorations on occlusal surface of premolarsand molars

Restorations on occlusal two third of facial and

lingual surfaces of molars Restorations on lingual surfaces of maxillary

incisor


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Class I tooth preparation


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Class IIrestoration

Restorations

on proximalsurfaces ofposteriorteeth are

class II.


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Class IIIrestoration

Restorations onproximalsurfaces ofanterior teeththat does notinvolve incisaledge are classIII.


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Class IV

restoration:Restorationon proximalsurfaces of

anteriorteeth thatinvolve incisaledge areclass IV


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Class VrestorationRestorationson the gingivalthird of facialor lingualsurfaces of allteeth.


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Schematic representation of walls, line angle and point angle for class Icavity


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Schematic representation of walls ,lineangles ,point angles for class II cavity


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Schematic representation of walls line angles,point angles for class III cavity


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Schematic representation of walls line anglesand point angle for class IV cavity


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Schematic representation of walls .line anglesand point angles for class V cavity

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