Influence of ceramic thickness and cementation strategy on long-term fracture load of glass-ceramics bonded to dentin

Abstract

Purpose: This study aimed to investigate the effect of light-curing on the fracture load of glass-ceramic discs bonded to dentin. Methods: IPS e.max CAD (lithium disilicate) and Celtra Duo (zirconia-reinforced lithium silicate) glass-ceramic discs, each 7 mm in diameter, were bonded to flattened dentin using three different cementation strategies. The discs varied in thickness, measuring 0.8 mm and 1.5 mm. The three strategies implemented were as follows: (1) SBU/ULT(AL): auto-cured adhesive and light-cured resin cement, (2) SBU/ULT(LL): light-cured adhesive and light-cured resin cement, and (3) resin composite, which served as the positive control. The fracture loads of eight specimens from each group were evaluated after storing the samples for one week and one year. Data were analyzed using linear mixed-effects models with a significance level of 0.05. Results: The thickness of the ceramic material and the cementation strategy significantly influenced the fracture load (P < 0.05). Ceramics bonded using SBU/ULT(LL) and composite cement, regardless of thickness, demonstrated significantly higher fracture loads than those bonded using SBU/ULT(AL) (P < 0.05). Ceramics with a thickness of 0.8 mm bonded with either SBU/ULT(LL) or composite cement exhibited fracture loads comparable to those of 1.5 mm thick ceramics bonded with SBU/ULT(AL) (P > 0.05). Conclusions: Light-curing the adhesive separately from the resin cement (SBU/ULT(LL)) and employing composite cement are recommended strategies for cementing glass ceramics with dentin to enhance fracture load resistance.