Class 3 Restoration

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Cards (41)

  • How many line angles and point angles there in Class III preparation?
    6 line angles and 3 point angles
  • what are the line angles in class III preparations?
    ● Faciogingival
    ● Linguogingival
    ● Axiogingival
    ● Axiolingual
    ● Axioincisal
    ● Axiofacial
  • what are the point angles of class III preparation?
    ● Axiofaciogingival point angle
    ● Axiolinguogingival point angle
    ● Axioincisal point angle
  • how many line angles and point angles in class IV preparation?
    11 line angles and 6 point angles
  • what are the line angles of the class IV preparation?
    ● Faciogingival
    ● Linguogingival
    ● Mesiofacial
    ● Mesiolingual
    ● Mesiopulpal
    ● Faciopulpal
    ● Linguopulpal
    ● Axiogingival
    ● Axiolingual
    ● Axiofacial
    ● Axiopulpal
  • what are the point angles of class IV preparation?
    ● Axiofaciopulpal point angle
    ● Axiolinguopulpal point angle
    ● Axiofaciogingival point angle
    ● Axiolinguogingival point angle
    ● Distofaciopulpal point angle
    ● Distolinguopulpal point angle
  • In tooth preparation for COMPOSITE RESTORATION, Retention comes primarily from micromechanical mode of retention (bonding to enamel and dentin)
  • For tooth preparation for COMPOSITE RESTORATION: Flat pulpal floor, or wall surfaces not as critical as for amalgam restoration
  • In tooth preparation for COMPOSITE RESTORATION: Retention grooves not necessary unless margin is on root surface or preparation is very large
  • In tooth preparation for COMPOSITE RESTORATION: 90 degree or greater (beveled) cavosurface margins
  • In tooth preparation for COMPOSITE RESTORATION: Isolation is extremely important. Use rubber dam especially when restoring
  • Class III preparations are present on proximal surface of anterior teeth and not involving the incisal angles.
  • In class III, For gaining entry into the lesion, bur is entered from palatal side.
  • Advantages of palatal access?
    ● Preservation of esthetics
    ● Color matching not critical
    ● Unsupported facial enamel
    can be preserved for bonding with composite resin
  • Indications for labial approach?
    ● Involvement of labial approach
    ● Rotated teeth where lingual approach is difficult
    ● Malaligned teeth
  • Conventional Class III tooth preparation INDICATION?
    ● Lesion present on the root surface
    ● Tooth preparation on
    ○ root is done in conventinal method whereas on the
    ○ crown, it is prepared in beveled conventional or modified type
  • Conventional class III Tooth preparation OUTLINE FORM steps:
    1. Outline form depends on the extent of caries and convenience form
    2. Approach carious area palataly with no. 1⁄2, 1 or 2 round bur and move the bur in incisogingival direction (fig. 9.30). Initial depth of axial wall should be 0.75 mm deep gingivally and 1.25 mm deep incisally. This results in the axial wall depth of 0.5 mm into the dentin
  • Class III Primary Resistance and Retention Form
    1. Conventional preparation is done with 90 degrees cavosurface margins (fig 9.31)
    2. If required, prepared retentive grooves and coves along gingivoaxial line angle and incisoaxial line angle, respectively, with the help of no. 1⁄4 or 1⁄2 round burs. Depth of these grooves should be 0.2-0.5 mm into the dentin
  • Retention in conventional tooth:
    1. Roughening of the preparation surface
    2. Parallelism or convergence of opposing external walls
    3. Giving retention grooves and coves
    4. Grooves should be located at least 1 mm from tooth surface and at least 0.5 mm deep into dentin.
  • Beveled Conventional Class III Tooth preparation, INDICATIONs?
    ● For replacing an existing defective restoration on crown portion of an anterior tooth
    ● For restoration of large preparations.
  • Steps in Beveled Conventional Class III Tooth preparation

    1. Approach carious area lingually with a no. 1⁄2,1or2roundburandmovetheburin incisogingival direction
    2. Shape of the tooth preparation should be identical to the shape of existing carious lesion
    3. Initial depth of axial wall should be 0.75 mm deep gingivally and 1.25 mm deep incisally. This results in the axial wall depth of 0.2–0.5 mm into the dentin. Axial wall should follow the contour of tooth, i.e. shape of axial wall should be convex outwardly
    4. In final tooth preparation, remove all remaining infected dentin or defective restoration using spoon excavator or slow-speed round bur
    5. Keep external walls of tooth preparation perpendicular to the enamel surface with all enamel margins beveled. Prepare bevels using flat end tapering fissure diamond bur at cavosurface margins. Bevel should be 0.2–0.5 mm wide at an angle of 45 degree to external tooth surface (Fig. 9.32)
    6. Bevels are not given in areas bearing heavy occlusal forces or on cemental cavosurface margins
    7. If required, prepare retentive grooves and coves along gingivoaxial line angle and incisoaxial line angle, respectively, with the help of no. 1/4 or 1/2 round burs. Depth of these grooves should be 0.2 mm into the dentin
  • It is the most conservative type of tooth preparation used for composites?
    Modified (Conservative) Class III tooth Preparation
  • Modified (Conservative) Class III Tooth Preparation Indications?
    1. to moderate class III lesion
    2. In this tooth preparation, basically infected
    carious area is removed as conservatively as possible by “scooping” out. This results in ‘scooped-out’ or ‘concave’ appearance of the preparation (Fig. 9.33).
  • Steps in Modified (Conservative) Class III Tooth Preparation:
    1. Make initial entry through palatal surface with a round bur
    2. Design and extent of preparation is determined by extent of carious lesion
    3. Modified preparation does not have definite axial wall depth and walls diverge externally from axial depth in a scoop shape
    4. Finally check the preparation after cleaning and provide pulp protection.
  • Class III Resin Composite Preparation: Determine the measurements of the Outline Form?
    Incisal Floor width- 1.25mm-1.5mm
    Gingival floor width- 1.25-1.5mm
    Inciso-gingival length- 2.25mm, no greater than 3mm

    Determine the measurements
  • Checklist of Class III preparation:

    Axial wall: flat or. Slightly convex
    Facial wall: at least 90 degrees relative to the axial wall
    Facial. Depth: depends on the facio-lingual depth of the contact area
    Preserve the facial Contact
    Gingival floor width: 1-1.25mm
    Incisal floor width: 1.25-1.5mm
    Inciso-gingival length: 2.25mm, no greater than 3mm (depends on length of contact area)
    Preserve the incisal contact
    Gingival contacts broken by: 0.25mm
  • If caries is at the labial, you access the labial area
  • Preserve the labial for esthetics
  • if no adjacent tooth, access the proximal area
  • If there is an adjacent tooth, access the labial or lingual area
  • Ideal outline in proximal access:
    Below the contact area- towards the gingival (not cleanse by bristles)
    Above the contact area- towards the incisal
  • All concavities are prone to caries
  • ideal class III preparation shape?
    Triangular shape in proximal access
  • In class III, retention is placed on incisal point angle
  • Mechanical undercuts in class III?
    Axiogingival and incisoaxial
  • It is a tooth conditioner?
    etchant
  • What composite depends on etch or microundercuts?
    Light Curing composite
  • What etchant diffuse and is quick to etch?
    Liquid etchant
  • what etchant targets only one area?
    thixotropic etchant
  • In self curing composite, the cavosurface should be at 90 degrees