Evaluation of Load-Bearing Capacity in Ceramic Bonded to Dentin Under Various Surface Treatment Protocols

Objectives: This study investigates the load-bearing capacity of lithium disilicate ceramic bonded to dentin, focusing on the effects of material thickness, surface treatments, and storage time.
Methods: Ninety-six lithium disilicate ceramic (IPS e.max CAD) specimens (7 mm diameter) were prepared with thicknesses of 0.8 mm and 1.5 mm. All specimens were bonded to flattened dentin using three different surface treatment protocols: no treatment (NT), Monobond Etch & Prime (MEP), and hydrofluoric acid followed by Monobond N (HFS). Adhesive cementation was performed using Single Bond Universal in self-etching mode, with a light-curing time of 10 seconds. The resin cement (Rely.X Ultimate) was then applied, with a total light-curing time of 100 seconds. Fracture load testing was conducted perpendicular to the ceramic surface using a universal testing machine after storage in artificial saliva for one week and one year. Statistical analyses were performed using linear mixed-effects models and Tukey’s multiple comparisons with a significance level of 0.05.
Results: Statistical analyses revealed that the load-bearing capacity was significantly influenced by material thickness, surface treatment, and storage time. Most specimens with a thickness of 1.5 mm exhibited a significantly higher load-bearing capacity than those with a thickness of 0.8 mm (p<0.05), with the exception of the MEP group at one week. The HFS group consistently outperformed the NT group in both thicknesses (p<0.05) and over storage time (p<0.05), while the performance of the MEP group was less consistent compared to the NT group. The HFS treatment was not significantly affected by storage time, while both the MEP and NT groups were influenced by storage time.
Conclusions: The load-bearing capacity of ceramic bonded to dentin was affected not only by ceramic thickness and storage time but also by the surface treatment used. The HFS treatment emerged as the most effective compared to MEP and NT.