Farzaneh Ahrari
Alireza Boruziniat
Hamideh Sadat Mohammadipour
Mehrnoosh Alirezaei

Abstract Introduction: This study investigated the effect of fractional CO۲ laser on shear bond strength (SBS) of resin cement to feldspathic porcelain.Methods: Sixty blocks of unglazed feldspathic porcelain were randomly divided into ۵ groups of ۱۲ by treatment. Group ۱ and ۲ underwent etching with ۹.۶% hydrofluoric acid (HF) and air abrasion with alumina particles, respectively. In groups ۳ and ۴, a fractional CO۲ laser was applied for ۱۰ seconds using ۲۰ W/۱۰ mJ (group ۳) or ۱۵ W/۲۰ mJ (group ۴). The specimens in group ۵ were first treated by fractional CO۲ laser (۱۵ W/۲۰ mJ) and then etched by HF acid. After silane application, a resin cement (Clearfil SA) was poured into plastic molds over the porcelain surface and light cured. SBS was assessed by a universal testing machine and the type of bond failure was determined.Results: Analysis of variance (ANOVA) indicated a significant difference in SBS among the study groups (P < ۰.۰۰۱). Pairwise comparison demonstrated that the application of fractional CO۲ laser followed by HF acid yielded SBS that was significantly greater than that of the other groups (P < ۰.۰۵). The SBS of both laser groups (groups ۳ and ۴) were comparable to each other and significantly lower than the other groups (P < ۰.۰۵). No significant difference was found in the distribution of failure modes among the groups (P = ۰.۵۲۲)Conclusion: The application of fractional CO۲ laser followed by HF acid treatment can improve SBS of resin cement to feldspathic porcelain and could be recommended when demanding extra retention. Keywords: Acid etching Air abrasion Bond strength CO۲ laser Feldspathic porcelain.