Abstract
BACKGROUND: Treatment of acid-resistance high-translucent zirconia prior to luting procedures is usually carried out with sandblasting. Considering that this process could lead to the formation of cracks on the zirconia surface, laser irradiation became an alternative to sandblasting. The effect of diode laser, however, was never investigated under this context. Therefore, this study aimed to evaluate the effect diode laser irradiation on the bond strength between zirconia and two resin cements after 48-hour and 12-month water aging. MATERIAL AND METHODS: Slabs of high-translucent zirconia were sandblasted with 50-µm Al2O3 particles (SB), irradiated with diode laser (DL), or SB+DL. All slabs were etched with 10% hydrofluoric acid and layered with a universal adhesive. Plastic tubes with 0.8-mm internal diameter positioned on treated zirconia surfaces were used as matrices to insert a dual- (DUAL) or a light-cure (LC) resin cement. All specimens were light-cured for 40 seconds at 1000 mW/cm2 and submitted to the µSBS test after 48-hour or 12-month water storage. Data were statistically analyzed with a three-way analysis of variance (p<0.05). RESULTS: The µSBS of DUAL was higher than LC only after 12 months for SB or SB+DL-treated zirconia (p<0.05); in addition, SB+DL resulted in higher µSBS than DL only for DUAL resin cement (p<0.05). The 12-month aging resulted in higher µSBS for DUAL resin cement luted on SB or SB+DL-treated zirconia, as well as for LC luted on DL-treated zirconia (p<0.05). Most of the DUAL specimens presented adhesive failures after 48 hours. After 12 months, the majority of DUAL specimens luted on DL or SB+DL-treated zirconia presented adhesive failures. CONCLUSIONS: The use of dual-cure resin cement on sandblasted or sandblasted and diode laser-irradiated zirconia exhibited superior bond strength after aging. Key words:Microshear bond strength, Resin cement, Diode laser, Zirconia, Sandblasting.