ENAMEL AXIOM #3 -ALMOST ALWAYS A BEVEL
To implement enamel axioms #1 and #2, almost all enamel margins will require a deliberate bevel
In this Handbook, a bevel is defined as an oblique trans-section of enamel rods beginning at the the DEJ and progressing continuously outwards to the cavosurface. It is not a butt margin with a bevel applied as an afterthought somewhere near the cavosurface.
The result of this protocol is that the origin of every enamel rod is tied to underlying dentin while rod ends cut obliquely are available for bonding at the cavosurface. Bevels in this Handbook vary from 6 degrees to 60 degrees, depending on
- the need for contraction resistance, which follows from the volume of contiguous resin and the contraction qualities of the resin being used
- The desire for blending of the resin to the adjacent tooth structure, which again follows from the opacity/ metamerism of the resin being used.
- See Cusp Shoes and Bevels for further explanation.
EXCEPTIONS FOR BEVEL PLACEMENT:
- The occlusal margins of posterior teeth do not require a bevel, because the surface is already inclined relative to the vertical insertion of a bur, and thus a bevel is inherent in the opening of the cavosurface.
- The inner surface of an Incisal Attrition preparation exposes rod ends for the incisal half of the preparation. Thus no additional bevel is required to meet axioms #1 and #2 – rod ends are fresh cut and exposed. A bevel would only rob healthy tooth structure for no gain in retention.
INSTRUMENTATION FOR BEVELS:
The design, inclination and instrumentation for bevels is covered for each preparation in the Handbook for Composite Excellence . See the preparation desired…