Evaluation of the Milled and Three-Dimensional Digital Manufacturing, 10-Degree and 20-Degree Preparation Taper, Groove and Box Auxiliary Retentive Features, and Conventional and Resin-Based Provisional Cement Type on the Adhesive Failure Stress of 3 mm Short Provisional Crowns

BACKGROUND This study evaluated the effects of milling (CADCAM), 3D printing, preparation taper angles (10-degree and 20-degree), auxiliary retentive features (groove and box), and provisional cement types (conventional and resin-based) on the adhesive failure stress of 3-mm short provisional crowns (PC). The research was motivated by the need to understand how digital dentistry technologies impact the retention and durability of provisional crowns. MATERIAL AND METHODS A total of 160 working models (3D-printed) and PCs [80 milled (CopraTemp)/80 printed (Asiga)] were fabricated from two 10- and 20-degree typodont master models and two 20-degree 3D-printed master models (groove and box), simulating a 3 mm high all-ceramic short PC. After provisional cementation with conventional (Kerr TempBond) and resin-based (ProviTemp) cements, 16 subgroups (n=10 each) underwent thermocycling (10 000 cycles; 5-55°C) and pull-off tests on a universal testing machine. Statistical analysis was performed using one-way ANOVA and post hoc Tukey test. RESULTS Conventional cement failed at lower stress for milled (47.68 to 73.54) and printed (48.40 to 77.91) as compared to resin cement for milled (104.2 to 137.27) and printed (184.85 to 328.84), respectively, with significant differences. Increased taper and groove decreased failure load except for the printed PC/resin cement combination. Use of proximal box preparation increased retention significantly. Except for 20-degree taper cemented with conventional cement, the differences in auxiliary retentive features for milled and printed provisional crowns were statistically significant at P≤0.05. CONCLUSIONS 3D-printed PC, resin-based cement, 10-degree taper, and proximal box preparation were associated with higher retention than milled, conventional cements, 20-degree taper, and vertical groove.