Introduction: The aim of this study was to clinically evaluate Streptococcus mutans adhesion on titanium dioxide–coated stainless steel orthodontic wires to decrease white-spot formation.
Methods: In this study, four groups of 17 patients each (n=68) aged 12– 25 years participated. A titanium dioxide coating layer was deposited on 0.4572 mm stainless steel orthodontic wires using physical vapor deposition. The coated wires were randomly assigned to one jaw, and the opposite jaw received an uncoated wire as control. Patients were divided into groups according to the duration that wires were in their mouths: A) 1 week, B) 2 weeks, C) 3 weeks, and D) 4 weeks. Block randomization was used to assign patients to each group. At the end of the experiment, 20 mm of each wire (canine-to-canine area) was cut and cultured in S. mutans–specific medium. The culture plates were placed in an incubator containing 5% CO₂ for 72 hours at 37°C, and then colonies were counted. MTT was used to test the biocompatibility of the coated and uncoated wires. To evaluate the stability of the coated titanium dioxide layer on the wires, titanium concentration on the saliva was determined using inductively coupled plasma mass spectroscopy.
Results: The Kruskal–Wallis test showed that there was no significant difference in colony counts among the coated wires during 1– 4 weeks (p< 0.48). In the uncoated-wire groups, colonys count at week 1 were higher than weeks 24 –(p< 0.022). Wilcoxon’s test showed that the number of colonies was significantly different in groups A and C, but there was no significant difference in groups B or D. MTT-assay results showed that there was not a significant difference between cell viability in the coated-wire group and the control. The Kruskal–Wallis test showed that there was no significant difference in titanium concentration in the studied groups (p< 0.834).
Conclusion: Application of titanium dioxide coating is effective in reducing bacterial adhesion at wire insertion.

Keywords: orthodontic wire, titanium dioxide, Streptococcus mutans, bacterial adhesion


中文翻译：

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二氧化钛涂层不锈钢正畸丝对变形链球菌的影响：一项临床研究

简介：本研究的目的是临床评估变形链球菌在二氧化钛涂层不锈钢正畸丝上的粘附，以减少白斑形成。
方法：在这项研究中，四组 17 名 12 至 25 岁的患者（n = 68）参加。使用物理气相沉积将二氧化钛涂层沉积在 0.4572 mm 不锈钢正牙线上。有涂层的金属丝被随机分配到一个钳口，而另一只钳口则接受一根未涂层的金属丝作为对照。患者根据线在嘴里的持续时间分为：A) 1 周，B) 2 周，C) 3 周和 D) 4 周。使用区组随机化将患者分配到每组。在实验结束时，每根金属丝（犬对犬的区域）长 20 mm 被切割并在S. mutans特异性培养基中培养。将培养板置于含 5% CO _{2的培养箱中}在 37°C 下放置 72 小时，然后计数菌落。MTT 用于测试有涂层和无涂层电线的生物相容性。为了评估导线上涂覆的二氧化钛层的稳定性，使用电感耦合等离子体质谱法测定唾液上的钛浓度。
结果： Kruskal-Wallis 检验表明，在 1-4 周内，涂层导线之间的菌落计数没有显着差异（p < 0.48）。在未涂层导线组中，第 1 周的菌落计数高于第 24 周 -( p< 0.022)。Wilcoxon检验表明A组和C组菌落数有显着差异，但B组和D组无显着差异。MTT-assay结果显示包覆线组细胞活力无显着差异和控制。Kruskal-Wallis 检验表明，研究组中钛浓度没有显着差异（p < 0.834）。
结论：二氧化钛涂层的应用可有效减少导线插入时的细菌粘附。

关键词：正畸丝，二氧化钛，变形链球菌，细菌粘附