Marginal adaptation and microleakage of resin‐based composite provisional crowns fabricated by different techniques and materials

The aim of this study was to evaluate the marginal adaptation and microleakage of resin-based composite provisional crowns fabricated using different techniques and materials and cemented with different temporary cements. One hundred twenty extracted molars prepared for zirconia crowns were allocated to three fabrication groups (n = 40): conventionally produced (CONV), computer-aided design and computer-aided manufacturing-milled (MILL), and three-dimensional-printed (PRNT). Each group was subdivided according to temporary cement type (n = 20): zinc oxide non-eugenol (ZONE) or dual-cure resin-based (DCRB) cement. Specimens underwent thermocycling for 500 (T1) (n = 10) or 5000 cycles (T2) (n = 10). Marginal adaptation was evaluated using scanning electron microscopy (n = 5), whereas microleakage was assessed by methylene blue dye penetration (n = 5). Statistical analysis included two-way analysis of variance with Tukey post hoc test for marginal adaptation and Kruskal-Wallis with Dunn's test for microleakage. PRNT and MILL crowns demonstrated smaller marginal gaps and lower microleakage scores than CONV crowns at both aging stages. DCRB cement produced smaller gaps and equal or lower leakage than ZONE across different material groups. All groups exhibited marginal discrepancies below the clinically acceptable limit of 120 µm. PRNT crowns cemented with DCRB demonstrated the most favorable marginal adaptation and sealing ability.