STATEMENT OF PROBLEM

The triple-scan method for assessing the 3D adaptation of dental restorations has been introduced and reported to be reliable. However, the suitability of using a dental laboratory scanner in the triple-scan method has not been evaluated.

PURPOSE

The purpose of this in vitro study was to evaluate the suitability of the triple-scan method using a dental laboratory scanner to assess the 3D adaptation zirconia crowns.

MATERIAL AND METHODS

A zirconia abutment and a zirconia crown were fabricated, and the abutment was fixed in a custom-made base. The crown was seated onto the abutment with the interposition of light-body silicone impression material between them. The triple-scan method was performed by using a dental laboratory scanner, and the mean cement-gap thickness was calculated. The seating and digitalization process was repeated 10 times, and after each digitalization, the light-body silicone layer was stabilized by applying heavy-body silicone impression material over it. Cement-gap thickness was measured on cross-sections of the aligned scan data sets and of the physical silicone replica. The results were assessed by using the paired t test and the Bland-Altman method (α=.05).

RESULTS

Mean 3D cement-gap thickness assessed by the triple-scan method reported small dispersion with a coefficient of variation of 5.6% for the occlusal area, 1.9% for the axial area, and 6.4% for the margin area. Cement gap thickness measured at corresponding locations in the aligned scan data sets and in the physical silicone replica reported no significant difference (P=.326) and good agreement.

CONCLUSIONS

The cement gap was accurately duplicated in scan data sets. The triple-scan method by using a dental laboratory scanner is suitable for assessing the 3D adaptation of zirconia crowns.