The effect of surface treatment with a fractional carbon dioxide laser on shear bond strength of resin cement to a lithium disilicate‑based ceramic

Background: This study investigated the impact of different surface treatments, including fractional carbon dioxide (CO2) laser on shear bond strength (SBS) of resin cement to lithium disilicate ceramic. Materials and Methods: In this in vitro study, 72 blocks of IPS e.max CAD ceramic were randomly divided into six groups in terms of treatment (n = 12). Group 1 underwent etching with 9.6% hydrofluoric (HF) acid, whereas group 2 was subjected to air abrasion with aluminum oxide particles. Groups 3 and 4 were treated with a fractional CO2 laser for 10 s using 10 W/14 mJ (group 3) or 20 W/10 mJ (group 4). In groups 5 and 6, the CO2 laser was applied similar to that in groups 3 and 4, respectively; then, the specimens were etched by HF acid. After silane application, luting cement was bonded to the specimens. The SBS was assessed with a universal testing machine, and the type of bond failure was determined. Data were analyzed by ANOVA, Duncan, and Fisher’s exact tests. Results: Surface conditioning with fractional CO2 laser alone resulted in significantly lower SBS than HF acid treatment (P < 0.05). Bond strengths of the specimens treated with a combination of laser irradiation and acid etching were significantly greater than all the other groups (P < 0.05). No significant difference was found in the distribution of failure modes among the groups (P = 0.337). Conclusion: The combination of fractional CO2 laser irradiation and HF acid etching could be recommended when extra retention is required for lithium disilicate‑based restorations, whereas laser treatment alone cannot produce sufficient SBS.