Micromeasurement of Cavity Lining, Using Ultraviolet and Reflected Light, and the Effect of the Liner on Marginal Penetration, Evaluated with Ca⁴⁵

¹ University of Minnesota School of Dentistry, Minneapolis, Minnesota

One cannot give unqualified clinical application from in vitro studies. However, such studies should point the way toward clinical evaluation and in vivo studies. There may be a definite and lasting role for cavity liners, at least until true adhesion is achieved in restorative materials.

In this study, three groups of extracted teeth showed a convincing trend toward reduction of marginal leakage by liners. The control group (no lining) was compared with groups having coverage of dentin only and coverage of the entire cavity with lining material.

Copalite may be an effective tubule sealer, as demonstrated by its presence in the tubules.

The character of the liner film was also investigated and measured. The liner was discovered to be noncontinuous, but this property did not eliminate entirely the usefulness of the material. The thickness of the film in section was 3 to 9 µ; however, the significance of this thickness was not apparent.

The theory of crystal diffusion as the primary process of uptake was discussed and the extent of dentinal diffusion questioned as a valid measure of the amount of marginal leakage, a theory here thought to be secondary to the theory of direct diffusion via the tubular lumens.