Randomized in situ study on the efficacy of CO 2 laser irradiation in increasing enamel erosion resistance

Abstract

Objectives

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.

Methods

Two hundred forty bovine enamel blocks were prepared for individual palatal appliances (n = 6 samples/appliance). The study had four phases of 5 days 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 0.3 J/cm² (5 μs/226 Hz/10.6 μm) and the fluoride gel contained AmF/NaF (12′500 ppm F⁻/pH = 4.8–6). For erosive demineralization, the appliances were immersed extra-orally in citric acid (0.05 M/20 min/pH = 2.3) twice daily. Analysis of enamel surface loss was done using a 3D-laser profilometer on 3 days. 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).

Results

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 ± 12.6 μm) were even significantly lower than all other groups (C 67.8 ± 15.4 μm; F 57.5 ± 20.3 μm; L 46.8 ± 14.5 μm). Significantly increased enamel fluoride uptake was observed for both fluoride-containing groups (p < 0.05) at day 1.

Conclusion

Compared to the control, the CO₂ laser irradiation with a specific set of laser parameters (0.3 J/cm²/5 μs/226 Hz) either alone or in combination with a fluoride gel (AmF/NaF) could significantly decrease enamel erosive loss up to 5 days in situ.

Clinical relevance

Combined CO₂ laser-fluoride treatment has a significant anti-erosive effect.

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