Method: Fifty-six bovine incisors enamel slabs (5x3x2.5 mm) had ¼ of the surface covered with resin composite (control area). To create erosive lesion, specimens were immersed in 1% citric acid (pH=2.3; 5 min), 2x/day, for 2 d. Specimens with pre-formed lesions were divided into two groups: CO2laser irradiated (λ=10.6µm; 0.5W, ultrapulse) and non-irradiated. Fourteen volunteers (n=14) wore a palatal device containing two irradiated and two non-irradiated specimen. Volunteers immersed their appliances extraorally in citric acid 3x/day (8a.m, noon, 4p.m) for 5 d. One hour after each erosive challenge, one irradiated specimen and one non-irradiated were brushed using an electrical toothbrush. Enamel wear was determined using an optical profilometer.
Result: Two-way ANOVA revealed that there was no significant interaction between erosive-abrasive challenges and CO2 laser irradiation (p=0.614). Laser irradiation did not influence enamel wear (p=0.742). Enamel wear of the specimens subjected to erosion plus abrasion was not different from that verified when erosion only was performed (p=0.626), regardless whether CO2laser was or was not applied.
Conclusion: Under the parameters used, CO2 laser irradiation was not able to control the progression of erosive/abrasive lesions.