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.