Orthodontic research center, school of dentistry, shiraz university of medical sciences, Shiraz, Iran.
Orthodontic research center, school of dentistry, shiraz university of medical sciences, Shiraz, Iran.
Int Orthod. 2021 Mar;19(1):123-129. doi: 10.1016/j.ortho.2020.10.002. Epub 2020 Nov 25.
White spot lesion (WSL) is one of the most important complications of fixed orthodontic treatment. Many methods have been studied to prevent this problem. This study is aimed to investigate the effect of high concentration nano-hydroxyapatite (nHAP) on shear bond strength (SBS) of metal brackets and Adhesive Remnant Index (ARI) score in different preparation methods.
Sixty human premolars, which were extracted for orthodontic reasons were included in this in vitro study. The teeth were randomly divided into 4 groups of 15 each: one control group and three nHAP groups. After applying nHAP for 2 to 3 minutes daily for 10 days, the groups 2 to 4 underwent sandblasting using 50μm aluminium oxide and 30 seconds etching, 60 and 30 seconds etching, respectively, and the brackets were then bonded to the teeth. After debonding, SBS and ARI scores were recorded. Data were analysed using the ANOVA test and posthoc test for pairwise comparisons.
No significant difference was observed in SBS between the control group and the nHAP groups. The sandblasted teeth showed significantly higher SBS than the 30 seconds etching after nHAP application (P=0.02). The teeth etched for 60 seconds showed a significantly higher ARI score than the 30 seconds etched teeth with (P=0.003) or without (P<0.001) nHAP application.
The use of nHAP before bracket bonding can be considered as a caries preventive method since it did not compromise the SBS. Sixty seconds etching is recommended for less likely damage to the enamel after debonding.
白色斑点病变（WSL）是固定正畸治疗中最重要的并发症之一。已经研究了许多方法来预防这个问题。本研究旨在探讨高浓度纳米羟基磷灰石（nHAP）对不同预备方法中金属托槽的剪切粘结强度（SBS）和粘着残留指数（ARI）评分的影响。
本体外研究纳入了 60 个人类前磨牙，这些牙齿因正畸原因而被拔出。牙齿被随机分为 4 组，每组 15 颗：一组对照组和三组 nHAP 组。在每天应用 nHAP 2-3 分钟 10 天后，组 2-4 分别用 50μm 氧化铝喷砂和 30 秒酸蚀、60 秒酸蚀和 30 秒酸蚀进行预处理，然后将托槽粘结到牙齿上。脱落后，记录 SBS 和 ARI 评分。使用 ANOVA 检验和两两比较的事后检验对数据进行分析。
对照组和 nHAP 组之间的 SBS 无显著差异。经过 nHAP 处理后喷砂处理的牙齿的 SBS 明显高于 30 秒酸蚀组（P=0.02）。经过 60 秒酸蚀处理的牙齿的 ARI 评分明显高于经过 30 秒酸蚀处理的牙齿（P=0.003）或未经 nHAP 处理的牙齿（P<0.001）。
在粘结托槽之前使用 nHAP 可以被认为是一种预防龋齿的方法，因为它不会影响 SBS。推荐使用 60 秒酸蚀，因为脱落后对牙釉质的损伤较小。
