Nanosecond pulsed fiber laser irradiation for enhanced zirconia crown adhesion: Morphological, chemical, thermal and mechanical analysis

The increasing demand for aesthetics, together with advancements in technology, have contributed to the rise in popularity of all-ceramic restorations. In the last two decades, the continuous progression in ceramic materials science for dental applications has permitted the fabrication of high-strength materials. Amongst these, zirconiabased ceramics have improved in terms of fracture resistance and long-term viability in comparison with other silica-based materials. Unfortunately, while bonding of resin cement-silica ceramics can be strengthened through creation of a porous surface by applying hydrofluoric acid (5%-9.5%) and a subsequent silane coupling agent, the glass-free polycrystalline microstructure of zirconia ceramics does not allow such a reaction. The aim of the present in vitro study was to observe the effect of 1070 nm fiber nanosecond pulse laser irradiation on zirconia samples through morphological analysis (profilometry, SEM), thermal recording with Fiber Bragg Gratings (FBGs), elemental composition analysis (EDX) and bond strength testing (mechanical tests) in order to evaluate the possible advantages of this kind of treatment on zirconia surfaces, as well as to show the potential side effects and changes in chemical composition. Despite laser irradiation with a 1070 nm wavelength fiber laser and correct process parameters demonstrating suitable outcomes in terms of improved surface roughness and minimal thermal damage, comparison between irradiated and unirradiated samples did not exhibit statistically significant differences in terms of bonding strength.