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

Abstract

Background: This study investigated the impact of different surface treatments, including fractionalcarbon 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 randomlydivided 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) or20 W/10 mJ (group 4). In groups 5 and 6, the CO2 laser was applied similar to that in groups 3 and4, respectively; then, the specimens were etched by HF acid. After silane application, luting cementwas bonded to the specimens. The SBS was assessed with a universal testing machine, and the typeof 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 SBSthan HF acid treatment (P < 0.05). Bond strengths of the specimens treated with a combination oflaser irradiation and acid etching were significantly greater than all the other groups (P < 0.05). Nosignificant 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 berecommended when extra retention is required for lithium disilicate‑based restorations, whereaslaser treatment alone cannot produce sufficient SBS.Key Words: Bond strength, carbon dioxide laser, ceramics, laser treatment, lithium disilicate