Enamel and dentin irradiation with 9.6 μm CO₂ and 2.94 μm Er:YAG lasers: bond strength evaluation

Background and objective: The objective of this study was to evaluate the bond strength between a composite resin and dental hard tissues, which have been previously irradiated with an Er:YAG (2.94 μm) or CO₂ (9.6 μm) laser. Materials and methods: A total of 156 bovine teeth were divided into 6 groups: Group 1 – Enamel control: acid etched enamel (Single Bond); Group 2 – Dentin control: acid etched dentin (Single Bond); Group 3 – Irradiated enamel (CO₂ laser – 3 W) followed by acid etching; Group 4 – Irradiated dentin (CO₂ laser – 3 W) followed by acid etching; Group 5 – Irradiated enamel (Er:YAG laser – 0.16 W) followed by acid etching; Group 6 – Irradiated dentin (Er:YAG laser – 0.16 W) followed by acid etching. Results: Treatment only with acid etching and also the Er:YAG laser irradiation followed by acid etching showed the highest bond strength value while the CO₂ laser irradiation followed by acid etching treatment produces the lowest bond strength values in both tissues. Conclusion: Acid etching of non-irradiated and Erbium YAG laser irradiated tissues produces better adhesion than acid etching of CO₂ laser irradiated surfaces.