In situ Effect of CO₂ Laser (9.3 μm) Irradiation Combined with AmF/NaF/SnCl₂ Solution in Prevention and Control of Erosive Tooth Wear in Human Enamel

Objectives: This single-blind, controlled crossover in situ study aimed to evaluate the effect of CO₂ laser (9.3 µm) irradiation combined with AmF/NaF/SnCl₂ solution on prevention and control of erosive tooth wear (ETW) in human enamel. Materials and Methods: Two trial conditions were analyzed, condition 1 as ETW prevention (sound tooth surface) and condition 2 as ETW control (in vitro initial erosive lesion). The experiment was conducted in 2 phases, one with and one without exposure to AmF/NaF/SnCl₂ solution. Hundred and ninety-two samples of human enamel (3 × 3 × 1 mm) were randomly divided into 4 experimental groups for each condition: C, without treatment (negative control); F, AmF/NaF/SnCl₂ solution (positive control); L, CO₂ laser irradiation; and L + F, CO₂ laser + AmF/NaF/SnCl₂ solution. Twelve volunteers used a removable device, each containing 8 samples per phase. Ex vivo erosive challenges (4 × 5 min/day) and rinsing protocol (1 × 30 s/day) were performed. The surface loss was determined using optical profilometer (n = 12 per group), and the surface morphology was observed with scanning electron microscopy (n = 3). Results: In condition 1, data were analyzed by one-way ANOVA and condition 2 by two-way repeated-measures ANOVA, both with Tukey post hoc tests (α = 5%). In condition 1, groups L (4.59 ± 2.95 µm) and L + F (1.58 ± 1.24 µm) showed significantly less surface loss in preventing ETW than groups C and F. In condition 2, in controlling the progression of ETW, L + F was the only group with no significant surface loss between initial erosive lesion (3.65 ± 0.16 µm) and after erosive challenge (4.99 ± 1.17 µm). Conclusions: CO₂ 9.3-µm laser application prevented and controlled ETW progression in human enamel, with greater efficiency when combined with AmF/NaF/SnCl₂ solution application.