Progression Of Erosive Lesions Research Articles

Using Optical Attenuation Coefficient to Monitor the Efficacy of Fluoride and Nd:YAG Laser to Control Dentine Erosion

The present study evaluated the protective effects that are induced by fluoride and Nd:YAG laser irradiation to control dentine erosion. One hundred and twenty bovine dentine slabs were eroded with citric acid twice a day for a total period of 15 days. At day 10, the samples were randomly assigned into eight groups: C (Control); F (Fluoride); L1 (Nd:YAG laser, 1 W, 100 mJ, 79.5 J·cm−2); L2 (Nd:YAG laser, 0.7 W, 70 mJ, 55.7 J·cm−2); L3 (Nd:YAG laser, 0.5 W, 50 mJ, 39.7 J·cm−2); F + L1; F + L2; and, F + L3. Optical Coherence Tomography images were collected from the surface of the samples in order to monitor the alterations that were induced by erosion and the effectiveness of each treatment using the Optical Attenuation Coefficient (OAC). OAC values that were calculated for samples from groups C, F, L1, L3, FL1, and FL3 indicated no protective effects against the progression of erosive lesions. Samples from L2 and FL2 groups presented OAC values, indicating that laser irradiation under this condition did not induce the formation of craters on dentine tissue and promoted sufficient chemical and morphological changes to avoid the progression of dentine erosion.

Progression of erosive lesions after Nd:YAG laser and fluoride using optical coherence tomography.

This study aimed to use optical coherence tomography (OCT) to assess the progression of erosive lesions after irradiation with Nd:YAG laser and application of topical fluoride. One-hundred and twenty dentin samples (4 × 4 × 2mm) obtained from bovine incisors were used. Samples were protected with acid-resistant nail varnish, with exception of a central circular area 2mm in diameter. All samples were submitted to erosive cycles with citric acid solution 0.05M (citric acid monohydrate-C6H8O7·H2O); M = 210.14g/mol) pH 2.3, at room temperature, for 20min, 2×/day, throughout 20days. After 10days of acid challenges, lesions became visible, and each group received a different treatment (n = 15): control (without treatment), topical application of sodium fluoride 2% for 4min; Nd:YAG laser with different irradiation parameters (1, 0.7, and 0.5W); and the association of fluoride with the laser parameters. OCT readouts were performed on day 01 (before the first acid challenge-OCT1), on day 05 (OCT2), day 10 (OCT3-after treatment), day 15 (OCT4), day 17 (OCT5), and day 20 (OCT6). The OCT images generated made it possible to measure the amount of tooth tissue loss over the 20days of erosive cycle, before and after treatments, and to monitor early dentin demineralization progression. After statistical analysis, the fluoride group was observed to be the one that showed smaller loss of tissue over time. The OCT technique is promising for diagnosing and monitoring erosive lesion damage; however, further in vitro and in vivo research is needed to improve its use.