Department of Pediatric and Orthodontic Sciences, College of Dentistry, King Khalid University, Abha, Saudi Arabia.
Department of Restorative Dental Sciences (Operative Dentistry), College of Dentistry, King Khalid University, Abha, Saudi Arabia.
Photodiagnosis Photodyn Ther. 2021 Jun;34:102232. doi: 10.1016/j.pdpdt.2021.102232. Epub 2021 Feb 22.
The aim of this laboratory study was to investigate the amount of bacterial destruction through riboflavin mediated photodynamic therapy (PDT) around fixed orthodontic devices by using the two strains of bacteria Streptococcus mutans and Streptococcus sanguinis.
A total of 80 metallic brackets were divided into four groups consisting of 20 brackets each. Group-I: riboflavin + LED irradiation; Group-II: riboflavin alone; Group-III: immersion in 0.2 % chlorhexidine gluconate solution and Group-IV: not submitted to any treatment. All metallic brackets were immersed in the standard bacterial solutions and incubated at 48 h. All samples were subjected to MTT assay for microbial cell viability testing after treatment. After 24 h of incubation, biofilms adhered on the mesh of metallic brackets after treatment were assessed by confocal laser microscopy. The total CFU/mL was estimated, and the results were log-transformed (log) and analyzed using one-way analysis of variance and Tukey-Kramer test. P-value was set to <0.05 that indicated statistical significance.
The samples from group-IV showed the highest amount of relative biofilm viability compared to any other group while group-I (PDT) showed the least viability of the two bacterial strains studied (p < 0.05). Group-I showed no significant difference when compared with group-III (chlorhexidine) (p > 0.05). The biofilms on the samples from group-II and group-IV were largely viable indicating thick green staining across the mesh of the brackets. Among the group-III samples, there were predominantly dead cells as compared to the live cell staining. A considerable amount of red staining was observed with noticeable less green staining in group-I samples.
This laboratory investigation revealed that riboflavin mediated PDT significantly reduced the amounts of S. mutans and S. sanguinis around the orthodontic brackets.
本实验室研究的目的是通过使用两种细菌变异链球菌和血链球菌来研究固定正畸装置周围核黄素介导的光动力疗法（PDT）对细菌破坏的程度。
将 80 个金属托槽分为四组，每组 20 个。组 I：核黄素+LED 照射；组 II：核黄素单独处理；组 III：浸入 0.2%葡萄糖酸氯己定溶液中；组 IV：不做任何处理。所有金属托槽均浸入标准细菌溶液中，48 小时孵育。所有样本均进行 MTT 测定以检测微生物细胞活力。处理后 24 小时，通过共聚焦激光显微镜评估处理后附着在金属托槽网眼上的生物膜。估计总 CFU/mL，并对数转换（log），使用单因素方差分析和 Tukey-Kramer 检验进行分析。P 值设为<0.05 表示有统计学意义。
与其他组相比，组 IV 的样本显示出最高的相对生物膜活力，而组 I（PDT）显示出研究的两种细菌中最低的活力（p<0.05）。与组 III（洗必泰）相比，组 I 没有显著差异（p>0.05）。组 II 和组 IV 的样本生物膜大部分存活，表明支架网眼上有大量绿色染色。与活细胞染色相比，组 III 的样本中主要是死细胞。组 I 样本中观察到相当数量的红色染色，绿色染色明显减少。
本实验室研究表明，核黄素介导的 PDT 可显著减少正畸托槽周围变异链球菌和血链球菌的数量。
