SHELLS FOR TEMPORARY AND PROVISIONAL CROWNS WITH AN HOURGLASS-SHAPED OCCLUSAL PROFILE

摘要

A set of fiber-polycarbonate shells for making bicuspid and molar crowns are formed with hourglass shaped occlusal profiles. Mesio-distal sidewalls of the shells have a concave shape matching the concavity of the occlusal profile. The shells are sized to fit loosely between adjacent teeth and relative to opposed teeth. The concavity of the mesio-distal sides and the occlusal surface of each shell allows a good fit between the shell and the convex sides of adjacent teeth. A good fit provides a substantially uniform-width proximal gap between mesio-distal sidewalls of the shell and the adjacent teeth. Each shell further has small mesio-distal windows in the mesio-distal sidewalls. The uniform-width gap and the mesio-distal windows control mesio-distal resin flow to adjacent teeth. A new method of forming crowns using such shells provides a good fit to a prepared tooth and relative to adjacent and opposed teeth by filling the shell with a glass-filled acrylic resin filler and then positioning the shell gingivally and occlusally. Resin extrudes through the window to form good proximal contacts, with the shell rocking about the facial gingival margin to a comfortable fit with an opposed tooth. The excess resin and shell are shaped to form the final crown. The crown, formed by Ti particle reinforced resin, is durable enough for long-term wear.