Tuesday 22 May 2012

PRIMARY RESISTANCE FORM


    This is that shape and placement of cavity walls that best enables both the restoration and tooth to withstand without fracture the masticatory forces delivered principally along the long axis of the tooth.

    FEATURES 
     ¨Relatively flat floors.
     ¨Box shape.
     ¨Inclusion of weakened tooth structure.
     ¨Preservation of cusps and marginal ridges.
     ¨Rounded internal line angles.
     ¨Adequate thickness of restorative material.
    ¨Reduction of cusps for capping when indicated.
     ¨Butt joint between tooth and restoration.
     ¨90˚ cavosurface angle.
     ¨Adequate depth and width of the cavity.
     ¨ Gingival cavosurface bevel is given in case of permanent teeth.  
     ¨ Width of cavity should not be more than 1/4th -1/5th  the intercuspal distance.
     ¨ Cavity wall should be occlusally divergent at the marginal ridges areas.
     ¨ Removal of unsupported enamel.



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