In Vitro Study of Er,Cr:YSGG Laser Effects When Used for the Prevention of Dentin Demineralization

摘要

Erbium lasers can be used to prevent dental caries, which has a high prevalence in the worldwide population. However, effective irradiation parameters for root dentin have not yet been determined using the Er,Cr: YSGG laser. Objective: this study evaluated the chemical, morphological and optical effects of Er,Cr:YSGG laser on root dentin when aimed at preventing root caries. Methodology: 75 bovine root dentin slabs were randomly distributed in 5 groups: Gl-untreated; G2-treated with acidulated phosphate fluoride gel (APF-gel, [F~-] 1.23%); G3-Er,Cr: YSGG laser irradiation (2.78 μm, 60 μs, 6 J/cm~2, 8,67 mJ/pulse, 0.25 W); G4-Laser irradiation + APF-gel application; G5-APF-gel application + Laser irradiation. The chemical and morphological evaluations were performed using Fourier transformed infrared spectroscopy and scanning electron microscopy, respectively. Afterwards, the samples were submitted to an 8-day pH-cycling model and the optical attenuation coefficient was evaluated by optical coherence tomography. The statistical analysis was performed considering the level of significance of 5%. Laser irradiation alone does not alter the dentin composition, but the previous application of APF-gel followed by laser irradiation significantly decreased the content of v3v4 carbonate of dentin. This treatment also promoted greater morphological alterations, such as ablation of the surface, when compared to the treatments alone. After demineralization, this treatment also presented the highest optical attenuation coefficient value when compared to the other treatments, indicating less demineralization of the samples. Conclusion: Er,Cr: YSGG laser presents potential for use in prevention of root dentin demineralization, and is more efficient when preceded by the application of APF.