Department of Dental Materials and Prosthodontics, Araçatuba School of Dentistry, São Paulo State University - UNESP, Araçatuba, SP, Brazil; Department of Prosthodontics and Periodontology, Bauru School of Dentistry, University of São Paulo - USP, Bauru, SP, Brazil.
Department of Preventive and Restorative Dentistry, Discipline of Endodontics, Araçatuba School of Dentistry, São Paulo State University - UNESP, Araçatuba, SP, Brazil.
J Photochem Photobiol B. 2024 Apr;253:112878. doi: 10.1016/j.jphotobiol.2024.112878. Epub 2024 Mar 1.
To investigate the influence of methylene blue (MB)-mediated antimicrobial photodynamic therapy (aPDT) and calcium hydroxide (CH) medication on the mechanical characteristics, degree of conversion (DC), quantification, and volume of gaps at the adhesive interface of glass fiber posts (GFPs) luted to distinct thirds of root canal dentin. Additionally, the microhardness (MH), elastic modulus (Eit), morphology, and chemical structure of the intraradicular dentin were assessed.
6 experimental groups were formed by sorting 102 bovine incisors. Canals receiving deionized water irrigation as a negative control; canals receiving deionized water irrigation and filled with CH as a positive control; groups treated with CH + MB at 50 and 100 mg/L without irradiation; and groups treated with CH + MB at 50 and 100 mg/L irradiated by red laser for 60 s (660 nm; 100 mW; 6.5 J; 72 J/cm). MH, Eit, and DC properties were evaluated for both the resin cement layer and root dentin substrate (n = 8). Volume and quantification of gaps at the bonding interface (n = 6), and dentin morphology and chemical content were investigated (n = 3). Data were analyzed using a repeated-measures 2-way ANOVA followed by Tukey post hoc analysis (α = 0.05).
The distinct intraradicular thirds and treatment with MB-mediated aPDT, whether activated or not, in combination with CH, had a significant impact on the mechanical characteristics of the root dentin. This effect was also observed in the MH, Eit, DC, quantification, and volume of gaps at the luting interface (P < .05). In general, a higher concentration of MB, whether activated by a red laser or not, led to lower values in the mechanical properties of the root dentin, as well as in MH, Eit, and DC at the adhesive interface (P < .05). Additionally, these groups exhibited higher values for quantification and volume of gaps at the luting substrate (P < .05). Scanning electron micrographs and energy dispersive X-ray spectra showed qualitative similarity among all groups, except for the negative experimental control group.
MB-mediated aPDT at 50 mg/L, in combination with CH, demonstrated favorable physico-chemical and mechanical characteristics in intraradicular dentin, along with satisfactory mechanical features and the adhesive interface integrity for GFPs at all intraradicular depths.
MB-mediated aPDT at a concentration of 50 mg/L combined to CH medication represents a suitable choice for photosensitization in the context of intracanal disinfection following the biomechanical procedure and prior to luting of intraradicular restorations.
研究亚甲蓝（MB）介导的光动力抗菌疗法（aPDT）和氢氧化钙（CH）药物对玻璃纤维桩（GFPs）黏接界面黏接剂的机械特性、转化率（DC）、定量和间隙体积的影响，以及根管内牙本质的显微硬度（MH）、弹性模量（Eit）、形态和化学结构。
将 102 颗牛切牙分为 6 个实验组。去离子水冲洗组为阴性对照；去离子水冲洗并填充 CH 的组为阳性对照；50mg/L 和 100mg/L 的 CH+MB 无光照组；50mg/L 和 100mg/L 的 CH+MB 用红色激光照射 60s（660nm；100mW；6.5J；72J/cm）组。对树脂水门汀层和根牙本质基质（n=8）分别评估 MH、Eit 和 DC 特性。黏接界面的间隙体积和定量（n=6），牙本质形态和化学含量（n=3）。采用重复测量 2 因素方差分析（ANOVA），然后进行 Tukey 事后检验（α=0.05）。
不同根管内三分之一和 MB 介导的 aPDT，无论是否激活，与 CH 联合使用，对根管内牙本质的机械特性有显著影响。MH、Eit、DC、黏接界面的定量和间隙体积也有类似的结果（P<0.05）。一般来说，较高浓度的 MB，无论是否被红色激光激活，都会导致根管内牙本质的机械性能降低，以及黏接界面的 MH、Eit 和 DC 降低（P<0.05）。此外，这些组在黏接基质的定量和间隙体积方面表现出更高的值（P<0.05）。扫描电子显微镜和能谱分析显示，除了阴性实验组外，所有组之间的定性相似。
50mg/L 的 MB 介导的 aPDT 与 CH 联合使用，在根管内牙本质中表现出良好的理化和机械特性，在所有根管内深度下，GFPs 均具有满意的机械性能和黏接界面完整性。
浓度为 50mg/L 的 MB 介导的 aPDT 结合 CH 药物治疗，在根管内消毒后进行生物力学处理并黏接根管内修复体之前，是一种合适的光动力疗法选择。
