Department of Orthodontics, Case Western Reserve University, Cleveland, OH, United States.
Department of Preventive and Restorative Dentistry, São Paulo State University, Araçatuba, São Paulo, Brazil.
J Mech Behav Biomed Mater. 2024 Apr;152:106390. doi: 10.1016/j.jmbbm.2024.106390. Epub 2024 Jan 14.
The primary objective of this in vitro study was to investigate the erosive potential of enamel under the use of clear aligners (CA), by simulating in vivo conditions experienced by patients who do not remove their CA during the consumption of acidic beverages. In addition, the difference in erosion protection conferred by artificial and human saliva was also evaluated. Sound-extracted human premolars (n = 20) had half of their surfaces protected with acid-resistant nail polish and were randomly distributed into two experimental groups (n = 10): teeth immersed in human saliva or artificial saliva. All teeth had half of their lingual surfaces enclosed by a CA device. The erosive challenges consisted of individual immersion of each sample in citrus acid three times a day, intermediated by immersion in human saliva or artificial saliva for 2 h, during ten days of the erosive protocol. The enamel mineral content was analyzed by high-resolution microtomography. The differential mineral concentration profiles were obtained by subtracting the profile of the mineral concentration of the exposed area and enamel under the CA area from the respective sound area (control). In addition, enamel wear and enamel volume loss were measured. Scanning electron microscopy (SEM) was also performed to analyze the enamel surface. Data were analyzed by two-way ANOVA, followed by the Student-Newman-Keuls test. The enamel wear was higher in teeth immersed in artificial saliva, when compared to human saliva (p < 0.001). The volume loss of the exposed enamel area was lower for tooth immersed in human saliva than in artificial saliva (p < 0.001), during the acid challenge protocol. The use of CA during acid challenges promoted wear and mineral loss of dental enamel, being these changes more pronounced on the enamel surface under the CA. These results open a new path for the development of further studies adopting clinical protocols that promote more accurate responses in the clinical practice during orthodontic treatment.
本体外研究的主要目的是模拟患者在佩戴透明矫正器（CA）期间不饮用酸性饮料时的体内情况，从而研究釉质的腐蚀性。此外，还评估了人工唾液和天然唾液在保护釉质免受腐蚀方面的差异。从健康的人上颌前磨牙上提取牙体（n=20），其一半表面用耐酸指甲油保护，然后随机分为两个实验组（n=10）：浸泡在人工唾液或天然唾液中的牙体。所有牙体的舌侧表面都用 CA 设备包裹一半。腐蚀性挑战包括将每个样本单独浸入柠檬酸中，每天三次，每次浸泡后将样本浸入人工唾液或天然唾液中 2 小时，持续十天。通过高分辨率微断层扫描分析釉质矿物质含量。通过从相应的完整区域（对照）中减去暴露区域和 CA 区域下的釉质的矿物质浓度分布，获得差异矿物质浓度分布。此外，还测量了釉质磨损和釉质体积损失。还进行了扫描电子显微镜（SEM）分析来研究釉质表面。数据采用双因素方差分析，然后进行 Student-Newman-Keuls 检验。与浸泡在人工唾液中的牙体相比，浸泡在天然唾液中的牙体的釉质磨损更高（p<0.001）。在酸蚀挑战期间，浸泡在天然唾液中的牙体的暴露釉质区域的体积损失低于浸泡在人工唾液中的牙体（p<0.001）。在酸蚀挑战期间使用 CA 会导致牙釉质磨损和矿物质损失，而 CA 下的釉质表面的这些变化更为明显。这些结果为采用临床方案的进一步研究开辟了新途径，这些方案在正畸治疗过程中更能准确反映临床实践。
