Prevention of Enamel Intrinsic Erosion Employing Nd:YAG Laser Irradiation

Objectives: The aim of this study was to evaluate the effect of  Nd:YAG laser  associated or not with topical acidulated phosphate fluoride gel preventing from enamel erosion caused by hydrochloric acid.

Methods: Enamel slabs (4mm x 4mm x 2mm) were cut from bovine incisors, ground flat, polished and based upon their Knoop microhardness values 40 specimens were selected. All the samples were isolated with nail varnish/wax except half of their outer surface (8mm2), and were randomly divided in 4 groups (n=10) according to the following treatments: G1 – no treatment (control) ; G2 – 1.23% acidulated fluoride gel; G3 – Nd:YAG (1W/10Hz, 100mJ, long pulse, 15s, contact mode, without cooling); G4 – fluoride gel + Nd:YAG (1W/10Hz, 100mJ, long pulse, 15s, contact mode, without cooling). After the treatments, specimens were cycled through acidic challenges in hydrochloric acid (HCl, 20s, 6x/d) and artificial saliva for 5 days to induce erosion-like lesions, simulating the gastric juice. Wear depth, roughness and enamel step were assessed using confocal laser microscopy (OLS 4000). Data were analysed by Kruskal-Wallis test (α=5%). 

Results: For the wear depth, enamel step and roughness G4 presented the lowest values and differed from G2 and G3 (p<0.05). For the roughness, G3 showed the highest values differing statistically from the other groups (p<0.05).

Conclusions: The findings suggest that the Nd:YAG laser irradiation associated with acidulated phosphate fluoride gel was capable to inhibit the erosive process of the enamel. Financial Support: Capes (grant # 23038.040859/ 2008-95). Acknowledgment: Arotec S/A Indústria e Comércio.