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Cavity-Preparation-According-G.V.Black.09.May.2011

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					 Cavity preparation
according G.V.Black

     II. Black class


                       3.Year - FS
   G.V. Black’s Approach to
      Cavity Preparation


1. Outline form
2. Resistance form
3. Retention form
4. Convenience form
5. Removal of remaining caries
6. Finish enamel walls
7. Clean cavity preparation
             G.V. Black’s Approach to
                Cavity Preparation


1. Outline form

   Based primarily on the location and extent of the caries.

   Final outline form is not established until the carious
    dentin and, usually, its overlying enamel has been
    removed
             G.V. Black’s Approach to
                Cavity Preparation


    2. Resistance form

   Resistance to both fracture of the tooth and filling
    material must be built in so both will be resistant to
    fracture during function
            G.V. Black’s Approach to
               Cavity Preparation


    3. Retention form

   The tooth preparation must be shaped in such a
    way to retain the filling material, without
    weakening the remaining tooth structure
             G.V. Black’s Approach to
                Cavity Preparation


    4. Convenience form

   Allows adequate observation, accessibility, and ease of
    operation during the preparation and restoration of the
    tooth.
   Only the minimal amount of reduction that will provide
    the necessary convenience should be done
             G.V. Black’s Approach to
                Cavity Preparation


    5. Removal of the remaining caries

   Deeper caries not removed by the initial cavity
    preparation is now removed. Care must be
    exercised as the pulp may be in close proximity.
             G.V. Black’s Approach to
                Cavity Preparation


    6. Finish of enamel walls and margins

   Remove unsupported enamel, make the margins
    smooth and continuous to facilitate finishing of
     the restoration.
             G.V. Black’s Approach to
                Cavity Preparation


    7. Clean the cavity preparation

   Rinse away all debris and dry the cavity
    preparation.
Black class II. preparation
Black class II. preparation
     Features of the Class II preparation:



   open gingival, lingual, buccal contacts;
   dove tail; reverse “S”; convergent walls;
   even depth;
   smooth surfaces;
   no sharp angles.
      STANDARD PRINCIPLES


 Margins 90° (perpendicular) to tangent to
  carvosurface
 Proper clearance: 0.25mm – 0.5mm
 Occlusal, axial and gingival walls in dentin
Extension
    Provide vertical support for occlusal forces

   Avoid inclined planes
    Provide vertical support for occlusal forces

   Convert inclined planes to “steps”
            Preparation

Incorporate the reverse-S curve (all walls
approx. 90 degrees to cavosurface)




                                         Black II - MOD
Preparation




  Proximal box and
  rounded axiopulpal angle
  Preparation


Just open” buccal proximal
wall
Black II - contact point


                 Positive contact
Matrix retainer
           Matrix system


A matrix system provides and takes the place
of the proximal tooth surface that was removed
to restore the proximal contours and contact to
their normal shape and function.
         Posterior Matrix System
   Universal retainer
      Also referred to as the Tofflemire retainer. This
       device holds the matrix band in position. The
       retainer is positioned most commonly from the
       buccal surface of the tooth being restored.
Components of a Universal Retainer
       Posterior Matrix System
   Matrix bands
     Matrix bands are made of flexible stainless steel
      and are available in premolar, molar, and
      universal sizes and thicknesses.
        The larger circumference of the band is the
         occlusal edge and is always placed toward the
         occlusal surface.

         Thesmaller circumference of the band is the
         gingival edge and it is always placed toward
         the gingiva.
                  Wedges

   A wedge is either triangular or round and
    made of wood or plastic.

   The wedge is inserted into the lingual
    embrasure to position the matrix band firmly
    against the gingival margin of the
    preparation.
A wedge correctly positioned.
            Sectional Matrices


   A thin polished palodent-type band and a
    tension ring produce a tight anatomic contact
    for composite resin materials for class II
    restorations.
Sectional matrices.
Thank you for attention!

				
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