Class V Cavity Preparation
The Class V outline form follows decalcification, erosion, abrasion, ablation, and/or caries along the gingival third of the tooth crown and adjacent root surface.
In this cross-section, note the axial wall is convex following the curvature of the DEJ and external surface of the tooth. The mesial and distal walls diverge from one another to preserve resistance form of tooth structure while providing proper resistance form for the amalgam restorative material.  The bur is angulated to insure these features. The axial depth is a minimum of 0.75 mm for resistance form of amalgam, but must be 0.5mm inside the DEJ for placement of proper retention form.
OUTLINE FORM
RESISTANCE FORM
Class V, page 2
Divergent mesial and distal walls do NOT provide retention form
Incipient lesions may also be treated by remineralization, smoothing, polishing, & fluoride treatment