Influence of Er,Cr:YSGG laser on root dentin submitted to erosive and/or abrasive challenges

Abstract This study evaluated how Er,Cr:YSGG laser, associated or not with 5% fluoride varnish, influences the surface roughness and volume loss of bovine root dentin submitted to erosive and/or abrasive wear. One hundred and twenty dentin specimens were divided into the groups: without preventive treatment (WPT), 5% fluoride varnish (FV); Er,Cr:YSGG laser irradiation (L), and varnish combined with laser (FV + L). The specimens (n = 10) were subdivided into: 1 = erosion (E); 2 = abrasion (A); and 3 = erosion followed by abrasion (E + A). The erosive solution used was a soft-drink (pH = 2.42 at 4ºC) applied in 5-min cycles twice a day for 10d. Abrasive wear involved brushing for 60s with an electric brush (1,600-oscillations/s) at a load of 2.0N. Surface roughness and volume loss were evaluated using a laser scanning confocal microscope. Roughness data were submitted to one-way ANOVA and Tukey post-hoc test. For volume loss, the Kruskal-Wallis and Dunn’s post-hoc tests were used (α = 5%). The lowest values of roughness were found in the control areas of all subgroups (p > 0.05). In the experimental area, the [(WPT) + (E+A)] subgroup had a significantly higher roughness (5.712 ± 0.163 μm 2 ) than the other subgroups (p < 0.05). The L and (FV + L) groups had statistically similar roughness, regardless of the type of wear. The (FV + L) group had the lowest volume loss, regardless of the type of wear performed: [(FV + L) + (E)] = 7.5%, [(FV + L) + (A) = 7.3%, and [(FV + L) + (E + A)] = 8.1%. The subgroup [(WPT) + (E + A)] had the highest volume loss (52.3%). The proposed treatments were effective in controlling dentin roughness. Laser irradiation can be an effective method to increase root dentin resistance after challenges and limit problems related to non-carious lesions.

摘要 本研究探讨了Er,Cr:YSGG激光（Er,Cr:YSGG laser）联合或不联合5%氟涂膜（5% fluoride varnish）对经受侵蚀性磨损和/或磨耗性磨损的牛根面牙本质的表面粗糙度及体积损失的影响。将120个牙本质标本分为4组：无预防性处理组（without preventive treatment, WPT）、5%氟涂膜组（5% fluoride varnish, FV）、Er,Cr:YSGG激光照射组（Er,Cr:YSGG laser irradiation, L）以及激光联合氟涂膜组（FV + L）。每组的10个标本再细分为3个亚组：1. 侵蚀磨损组（E）、2. 磨耗磨损组（A）、3. 先侵蚀后磨耗组（E+A）。本研究采用的侵蚀液为碳酸饮料（4℃下pH值为2.42），以每5分钟为一个周期，每日施加2次，持续10天。磨耗磨损试验采用负载为2.0N的电动牙刷（振荡频率1600次/秒）刷洗标本60秒完成。采用激光扫描共聚焦显微镜对标本的表面粗糙度及体积损失进行检测。粗糙度数据采用单因素方差分析（one-way ANOVA）及Tukey事后检验（Tukey post-hoc test）进行统计分析；体积损失数据则采用Kruskal-Wallis检验（Kruskal-Wallis test）及Dunn事后检验（Dunn’s post-hoc test），检验水准α=5%。所有亚组的对照区域均表现出最低的粗糙度值（p>0.05）。在实验组区域中，[无预防性处理+先侵蚀后磨耗]亚组的粗糙度值（5.712±0.163 μm²）显著高于其余亚组（p<0.05）。无论磨损类型如何，激光照射组与激光联合氟涂膜组的粗糙度值均无统计学差异。无论采用何种磨损方式，激光联合氟涂膜组的体积损失均最低：[激光联合氟涂膜+侵蚀磨损]亚组为7.5%，[激光联合氟涂膜+磨耗磨损]亚组为7.3%，[激光联合氟涂膜+先侵蚀后磨耗]亚组为8.1%。[无预防性处理+先侵蚀后磨耗]亚组的体积损失最高，达52.3%。本研究所采用的干预措施均可有效控制牙本质表面粗糙度。激光照射可作为一种有效手段，提升根面牙本质在外界刺激后的抵抗能力，进而限制非龋性牙体损伤相关问题的发生。