Randomized in situ study on the efficacy of CO2 laser irradiation in increasing enamel erosion resistance.

Abstract

The aim of this double-blind, randomized in situ study was to evaluate the erosion-preventive effect of a specific set of CO2 laser parameters, associated or not with fluoride. Two hundred forty bovine enamel blocks were prepared for individual palatal appliances (n = 6 samples/appliance). The study had four phases of 5days each, with ten volunteers and the following treatments: CO2 laser irradiation (L), fluoride treatment (F), combined fluoride and laser treatment (FL), and no treatment, control (C). Laser irradiation was performed at 0.3J/cm2 (5μs/226Hz/10.6μm) and the fluoride gel contained AmF/NaF (12'500ppmF-/pH = 4.8-6). For erosive demineralization, the appliances were immersed extra-orally in citric acid (0.05M/20min/pH = 2.3) twice daily. Analysis of enamel surface loss was done using a 3D-laser profilometer on 3days. Additionally, fluoride uptake was quantified and scanning electron microscopies were done. Data were analyzed with repeated measures ANOVA and post hoc pairwise comparisons (α = 0.05). At all analyzing days, both laser groups caused the lowest means of enamel loss, which were also statistically significant lower than C (p < 0.05). At day 5, FL means ± SD (33.6 ± 12.6μm) were even significantly lower than all other groups (C 67.8 ± 15.4μm; F 57.5 ± 20.3μm; L 46.8 ± 14.5μm). Significantly increased enamel fluoride uptake was observed for both fluoride-containing groups (p < 0.05) at day 1. Compared to the control, the CO2 laser irradiation with a specific set of laser parameters (0.3J/cm2/5μs/226Hz) either alone or in combination with a fluoride gel (AmF/NaF) could significantly decrease enamel erosive loss up to 5days in situ. Combined CO2 laser-fluoride treatment has a significant anti-erosive effect.