Evaluating the marginal fit of zirconia copings with iTero digital impressions

Abstract

Digital impression systems have been developed to overcome the disadvantages associated with conventional impression methods. The purpose of this study was to compare the marginal fit of zirconia copings designed with the use of an iTero digital scanner with those designed by the conventional impression technique. Thirty identical cast base metal dies from one maxillary central incisor prepared for an all-ceramic crown restoration were fabricated. For group 1, base metal dies (n = 10) were duplicated into stone dies by means of a conventional impression technique with polyvinyl siloxane material. For group 2, base metal dies (n = 10) were duplicated into polyurethane dies using the iTero digital impression system. For group 3, base metal dies (n = 10) were scanned with the iTero digital impression system, but no dies were fabricated. For each group, ten zirconia copings were fabricated based on stone dies (group 1), polyurethane dies (group 2), or stereolithography (STL) files (group 3). The marginal gap of each specimen was measured. One-way analysis of variance (ANOVA) and the Tukey’s honestly significant difference (HSD) test were used for statistical analysis. Statistically significant differences were found between groups 1 and 2 (p < .05) and between groups 1 and 3 (p < .05).Within the limitations of this in vitro study, the following conclusion could be drawn: the marginal gap between the restoration and master cast base metal die was greater in the groups that used the digital impression method compared to the group that used the conventional impression method. However, the marginal discrepancies of all of the groups were clinically acceptable.