X-ray microtomographic evaluation of the influence of two preparation types on marginal fit of CAD/CAM alumina copings: a pilot study.

This study evaluated the influence of two preparation types on the marginal fit of computer-aided design/computer-assisted manufacture (CAD/CAM) alumina copings. Two subgroups of four alumina copings each were fabricated using alumina master dies with either a chamfer or 90-degree shoulder preparation. Copings were scanned with an x-ray microtomographic scanner, and marginal fit was evaluated. The preparation types presented no statistically significant differences regarding marginal gap (P = .410) and absolute marginal discrepancy (P = .229). No correlation was found between marginal fit of CAD/CAM alumina copings and preparation type. Marginal fit could be considered within the limits of clinical acceptance.