Optical Properties of Bovine Dentin When Irradiated by Nd:YAG and a Black Dentifrice Aimed at Treating Dentin Erosion

Dental erosion has been extensively studied as a risk factor for tooth loss or injure, and the early diagnosis of lesions is essential for avoiding greater damages. Optical Coherence Tomography (OCT) is a potential tool for early diagnosis of demineralization. In this study, this technique was used to analyze the optical changes of dentin samples irradiated with Nd:YAG laser using a black dentifrice as photoabsorber, then submitted to an erosive cycling. 75 slabs of bovine root dentin were randomized into 5 groups: G1—untreated; G2—treated with acidulated phosphate fluoride gel (APF-gel, [F^-] = 1.23%, pH = 3.3–3.9); G3—irradiated with Nd:YAG laser (100 µs, 1064 nm, 0.6 W, 10 Hz) without photoabsorber; G4—irradiated with Nd:YAG laser using a coal paste as photoabsorber; G5—irradiated with Nd:YAG laser using a black dentifrice as photoabsorber. All samples were submitted to a 3-day erosive demineralization (Citric acid 1%, pH = 3.6, 5 min, 2×/day) under agitation, and remineralization (artificial saliva, pH = 7, 120 min) cycling. The samples were evaluated by OCT before treatments (baseline), after treatments and after erosive cycling. Optical attenuation coefficient (µ) was calculated using a Matlab routine, and the statistical analysis was performed (α = 0.05). It was observed a significant decrease on µ values after all treatments. Also, the µ values decreased after erosive cycling, except for the groups G3 and G5. It was concluded that OCT technique is capable to distinguish among sound, treated and demineralized dentin. As well, the black paste was efficient to act as a photoabsorber, helping the Nd:YAG laser to decrease dentin erosion.