BACKGROUND The antimicrobial properties of orthodontic wire and brackets with nitrogen-doped titanium dioxide (N-doped TiO2) coating have been studied in the past. However, the evaluation period had been short and limited to 30 days. The aim of the present study was to extend the evaluation period (up to 90 days) of assessing the long-term antimicrobial effects of stainless steel orthodontic brackets coated with nitrogen-doped titanium dioxide (N-doped TiO2). METHODS A total of 40 stainless steel pre-adjusted premolar brackets were equally divided into two groups; namely the control group (n=20, uncoated brackets) and the experimental group (n=20, coated brackets). RF magnetron sputtering was used to apply a thin film of TiO2 on the bracket surface. The crystalline structure of the thin film was assessed using X-ray diffraction. The antimicrobial property of the brackets against Streptococcus mutans (S. mutans) was evaluated using the survival rate by colony-forming units (CFU) at four intervals: 24 hours (T0), 30 days (T1), 60 days (T2), and 90 days (T3). 2-way ANOVA Repeated Measures was used to compare the effects between the groups over the time. RESULTS There was no significant interaction between group and time (p = 0.568). The orthodontic brackets coated with the N-doped TiO2 thin film showed a significant CFU reduction (37.71 ± 5.21, 37.81 ± 5.03, 37.98 ± 5.37, and 37.74 ± 5.21 at T0, T1, T2, and T3, respectively) compared to the uncoated brackets (400.91 ± 14.67, 401.58 ± 14.01, 400.31 ± 14.68, and 402.04 ± 13.98 at T0, T1, T2, and T3, respectively) through visible light (p < 0.001). CONCLUSION N-doped TiO2 coated orthodontic brackets showed strong antimicrobial property against S. mutans over a period of 90 days, which is effective in preventing enamel decalcification during orthodontic therapy.

中文翻译：

---

长期涂有氮掺杂二氧化钛的正畸托槽对变形链球菌的长期抗菌评估。

背景技术过去已经研究了具有氮掺杂的二氧化钛（N掺杂的TiO 2）涂层的正牙线和托槽的抗菌性能。但是，评估期很短，限制为30天。本研究的目的是延长评估涂有氮掺杂二氧化钛（N掺杂TiO2）的不锈钢正畸托槽的长期抗菌作用的评估时间（最多90天）。方法将总共40个不锈钢预调节前磨牙支架平均分为两组。即对照组（n = 20，无涂层括号）和实验组（n = 20，无涂层括号）。使用射频磁控溅射在支架表面上涂覆TiO2薄膜。使用X射线衍射评估薄膜的晶体结构。使用菌落形成单位（CFU）的存活率，按以下四个时间间隔评估菌落对变形链球菌（S. mutans）的抗菌性能：24小时（T0），30天（T1），60天（T2），和90天（T3）。使用2向ANOVA重复测量法比较一段时间内各组之间的影响。结果组与时间之间没有显着的相互作用（p = 0.568）。与未涂层相比，涂有N掺杂TiO2薄膜的正畸托槽显示出显着的CFU降低（分别在T0，T1，T2和T3处，分别降低了37.71±5.21、37.81±5.03、37.98±5.37和37.74±5.21）。支架（分别在T0，T1，T2和T3处分别为400.91±14.67、401.58±14.01、400.31±14.68和402.04±13.98）通过可见光（p <0.001）。