A new era in provisional restorations: evaluating marginal accuracy and fracture strength in additive, substractive...

The aim of this study was to compare the marginal gaps and fracture resistance of fixed provisional restorations fabricated using conventional, subtractive (Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM)), and additive (3D printing) techniques.

In this study, fixed provisional restorations were fabricated on 60 epoxy resin dies using conventional, subtractive, and additive methods. The marginal gaps of the restorations cemented onto epoxy resin dies with temporary cement were measured using a stereomicroscope. Half of the samples from each group were stored in artificial saliva at 37 °C, while the other half underwent 5000 thermal cycles for aging. After the aging process, marginal gap measurements were repeated using a stereomicroscope. Scanning Electron Microscope (SEM) images were obtained for one sample from each group prepared using different techniques, with and without the aging process. Fracture resistance was evaluated using an Instron Universal Testing Machine. The data were analyzed using the Jamovi statistical software (version 2.3.28) with two-way analysis of variance and Tukey's post hoc test.

Variance analysis revealed that the fabrication method and aging process significantly affected the results (p < 0.05). There was no significant difference in the marginal gaps of restorations fabricated using subtractive and additive techniques (p > 0.05). However, restorations fabricated using subtractive and additive methods exhibited significantly smaller marginal gaps compared to those fabricated using the conventional method (p < 0.001). In terms of fracture resistance, there was no significant difference between restorations fabricated using the additive and conventional methods (p > 0.05). However, both showed significantly lower fracture resistance compared to restorations fabricated using the subtractive method (p < 0.001).

This study determined that the highest fracture resistance was observed in restorations fabricated using the subtractive method, while the lowest was found in those fabricated using the additive method. For long-term use of fixed provisional restorations, the subtractive method (CAD/CAM) may be considered.