Photocatalytic antimicrobial effect of titanium dioxide coated clear-aligners on Streptococcus mutans and evaluation the physico-mechanical characteristics

IF 2.6 3区医学 Q2 ONCOLOGY

Photodiagnosis and Photodynamic Therapy Pub Date : 2025-09-25 DOI:10.1016/j.pdpdt.2025.105235

Maryam Pourhajibagher , Rashin Bahrami , Mohammadreza Moeininejad , Roghayeh Ghorbanzadeh , Abbas Bahador

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Abstract

Background

This study evaluated the photocatalytic antimicrobial effect of titanium dioxide (TiO₂)-coated clear aligners against Streptococcus mutans and assessed the impact of TiO₂ coating on surface microhardness and optical transparency.

Materials and methods

Clear aligner samples (10 × 10 × 2 mm) were coated with different concentrations of TiO₂ (1 %, 2 %, and 4 %) via submerging. Uniformity of particle distribution and surface microhardness were measured using scanning electron microscope (SEM) and Vickers hardness testing, respectively. Optical transparency was assessed via ultraviolet-visible spectrophotometry. After incubation in artificial saliva, samples were exposed to ultraviolet A (UVA) at 320 nm for 1 min with an energy density of 18.75 J/cm²). Biofilm inhibition was evaluated by crystal violet colorimetric assay, measuring optical density at 595 nm. Expression of gtfB gene was analyzed via quantitative real-time polymerase chain reaction.

Results

SEM images confirmed uniform nanoparticle distribution with no surface damage. The combination of TiO₂ coating and UVA exposure significantly reduced biofilm formation, with the 4 % TiO₂ group demonstrating the highest inhibitory effect compared to the control group (P < 0.001). Additionally, expression of the gtfB gene was significantly downregulated in this group (–6.35 ± 0.30). Surface microhardness showed a non-significant increase with higher TiO₂ concentrations, suggesting enhanced wear resistance without compromising material properties. However, the 4 % TiO₂ coating resulted in a significant reduction in optical transparency compared to other groups (P < 0.01).

Conclusion

While 4 % TiO₂ coating with UVA activation achieved the strongest antibiofilm effect, it compromised optical transparency. The 2 % TiO₂ coating preserved aesthetics and still provided substantial antimicrobial activity, making it the more practical clinical option.

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二氧化钛包覆透明对准剂对变形链球菌的光催化抑菌作用及其物理力学特性评价。

背景：本研究评估了二氧化钛（TiO2）涂层透明对准剂对变形链球菌的光催化抗菌效果，并评估了TiO2涂层对表面显微硬度和光学透明度的影响。材料和方法：将10 × 10 × 2mm的透明对准剂样品浸泡在不同浓度的TiO2（1%、2%和4%）上。采用扫描电镜（SEM）和维氏硬度测试分别测定了颗粒分布均匀性和表面显微硬度。通过紫外可见分光光度法测定其光学透明度。在人工唾液中孵育后，将样品暴露在320 nm紫外线下1分钟，能量密度为18.75 J/cm²。采用结晶紫比色法测定595 nm光密度，评价生物膜的抑制作用。通过实时定量聚合酶链反应分析gtfB基因的表达。结果：SEM图像证实纳米颗粒分布均匀，表面无损伤。TiO2涂层和UVA暴露的组合显著减少了生物膜的形成，与对照组相比，4% TiO2组表现出最高的抑制效果（P < 0.001）。此外，gtfB基因表达显著下调（-6.35±0.30）。随着TiO2浓度的增加，表面显微硬度的增加不显著，表明在不影响材料性能的情况下增强了耐磨性。然而，与其他组相比，4% TiO2涂层导致光学透明度显著降低（P < 0.01）。结论：UVA活化的4% TiO2涂层具有最强的抗菌膜效果，但降低了其光学透明度。2%的二氧化钛涂层保留了美观性，仍然提供了大量的抗菌活性，使其成为更实用的临床选择。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Photodiagnosis and Photodynamic Therapy ONCOLOGY-

CiteScore

5.80

自引率

24.20%

发文量

509

审稿时长

50 days

期刊介绍： Photodiagnosis and Photodynamic Therapy is an international journal for the dissemination of scientific knowledge and clinical developments of Photodiagnosis and Photodynamic Therapy in all medical specialties. The journal publishes original articles, review articles, case presentations, "how-to-do-it" articles, Letters to the Editor, short communications and relevant images with short descriptions. All submitted material is subject to a strict peer-review process.