The effect of nanocoatings of SiO2, TiO2, and ZrO2 on titanium-porcelain bonding

Abstract

Statement of problem: Durable titanium-porcelain bonding is challenging because of the formation of a thick oxide layer on the surface during porcelain firing.

Purpose: The purpose of this in vitro study was to evaluate how atomic layer deposition (ALD) of different oxide coatings affected titanium-porcelain bonding and failure types.

Material and methods: Forty-four airborne-particle abraded Type-2 titanium specimens were coated by ALD with either SiO₂, TiO₂, or ZrO₂ (n=11) at a thickness of 30 nm, whereas control specimens were left uncoated (n=11) (airborne-particle abraded only). The surface roughness of the specimens was analyzed with a profilometer before applying porcelain (Vita Titankeramic). Titanium-porcelain bonding was analyzed by using a 3-point bend test. Surface properties and titanium-porcelain interfaces were examined under scanning electron microscopy combined with energy-dispersive spectroscopy, and failure types were evaluated by using a stereomicroscope. Surface roughness and bond strength data were analyzed by 1-way ANOVA and Tukey HSD tests. Failure type data were analyzed by the Fisher-Freeman-Halton exact test (α=.05).

Results: All nanocoatings increased surface roughness values, but only TiO₂ and ZrO₂ coatings showed statistically significant higher roughness than the control surfaces (P<.001). Specimens coated with SiO₂ (28.59 ±4.37 MPa) and TiO₂ (26.86 ±3.66 MPa) presented significantly higher bonding strength than control (22.04 ±4.59 MPa) specimens (P<.01). Fracture types of different groups were not statistically different (P>.05).

Conclusions: Nanocoating titanium surfaces with SiO₂ and TiO₂ by using the ALD technique significantly improved titanium-porcelain bonding.