Abstract
Background: Zirconia crowns bonded to prefabricated titanium (Ti) bases represent a popular and innovative approach in modern restorative dentistry for implant-supported restorations. This combination leverages the superior aesthetics and strength of zirconia with the convenience and reliable stability of prefabricated titanium bases, providing patients with durable and aesthetically pleasing dental prostheses. There is limited research on the bonding between zirconia crowns and Ti bases. Therefore, this study aims to investigate the retention force between zirconia crowns and Ti bases using different surface treatments.
Materials & methods: One hundred and sixty 5Y-PSZ crowns (Lava™ Esthetic, 3M™) were fabricated according to a standardised maxillary central incisor shape to fit Ti bases (Straumann Variobase™, Institute Straumann AG). These were divided into two groups based on the Ti base design (Standard: n = 80; Angled Solution: n = 80). The crowns were cemented to the Ti bases following one of four treatment protocols (n = 20 per group): no treatment, sandblasting only, new generation bonding agent application only, and sandblasting and new generation bonding agent application. The crowns were bonded to the Ti-bases using a resin cement (RelyX™ Universal Resin Cement, 3M™). Half of each surface group (n = 10 per group) was subjected to artificial ageing (10,000 cycles, 5°C/55°C) using a thermocycler (Proto-tech, Dental Research Instruments, USA). Each sample was connected to an implant analogue mounted on a metal jig. The retention forces between the crowns and Ti bases were measured with a pull‐off test. The treatment protocols were compared using one-way analysis of variance (ANOVA), followed by Tukey post hoc tests (p < 0.05). Some samples were further analysed under the scanning electron microscope (SEM) to assess the mode of failure.
Results: Retentive forces for standard Ti bases (474.6 ± 91.9 N) were significantly greater than Angled Solution Ti bases (280.2 ± 70.4 N) (p < 0.001). No significant differences were found between different surface treatment groups of the same Ti base designs.
Conclusions: Standard Ti bases showed greater retention with zirconia than Angled Solution Ti bases. Within the limitations of this study, the different surface treatments used and thermocycling did not have an impact on the retentive forces.