Diniz Ivana Márcia Alves, Teixeira Karina Imaculada Rosa, Araújo Patrícia Valente, Araújo Márcio Sobreira Silva, Marques Márcia Martins, Poletto Luiz Thadeu de Abreu, Cortés Maria Esperanza
Restorative Dentistry Departament, Universidade Federal de Minas Gerais (UFMG), Avenida Antônio Carlos 6627, CEP 31270-901 Belo Horizonte, Brazil.
Centro de Pesquisas René Rachou, Fundação Osvaldo Cruz, Avenida Augusto de Lima 1715, CEP 30190-002 Belo Horizonte, Brazil.
Photodiagnosis Photodyn Ther. 2014 Sep;11(3):300-6. doi: 10.1016/j.pdpdt.2014.03.010. Epub 2014 Apr 13.
The antibacterial photodynamic therapy (aPDT) has been used in dentistry against oral microorganisms because of its excellent biocide effect. However, for carious lesions applications, there is little evidence that this therapy is safe for the pulp tissue.
This study evaluates the effects of an aPDT protocol on human pulp cells in vitro.
Pulp cells isolated from dental pulp were exposed to an aPDT protocol associating methylene blue (MB) at concentrations of 0.0125, 0.025 and 0.050mg/ml and red laser irradiation using a continuous-wave indium-gallium-aluminum-phosphide (InGaAlP) diode laser (λ=660nm, 40mW, 2.4J, 60J/cm(2) for 1min). Pre-irradiation time was 5min for each MB concentration. Cell viability was determined by MTT assay and activity of alkaline phosphatase was assessed by BCIP-NBT assay. Type of aPDT-induced cell death was assessed by flow cytometry. Data was statistically compared (ANOVA followed by Tukey' or Bonferroni's post hoc tests).
aPDT was able to kill pulp cells in a dye concentration-dependent manner. The cellular viability was significantly reduced when used MB at 0.025 or 0.050mg/ml concentrations (p<0.0001). At these concentrations, aPDT-induced cell death occurred mostly by necrosis. Alkaline phosphatase activity was significantly reduced in all experimental groups (p<0.001). Pulp cells showed suitable viability when MB at 0.0125mg/ml was exposed to laser irradiation.
aPDT with MB at 0.0125mg/ml may represent a low-risk therapy for restorative dentistry applications. aPDT protocol using concentrations above 0.025mg/ml of MB associating red laser irradiation may be harmful for dental pulp cells.
抗菌光动力疗法（aPDT）因其出色的杀菌效果已被应用于牙科治疗口腔微生物。然而，对于龋损应用，几乎没有证据表明该疗法对牙髓组织是安全的。
本研究评估一种aPDT方案对人牙髓细胞的体外作用。
从牙髓分离的牙髓细胞暴露于一种aPDT方案，该方案联合使用浓度为0.0125、0.025和0.050mg/ml的亚甲蓝（MB）以及使用连续波铟镓铝磷化物（InGaAlP）二极管激光器（λ = 660nm，40mW，2.4J，60J/cm²，照射1分钟）进行红色激光照射。每种MB浓度的预照射时间为5分钟。通过MTT法测定细胞活力，通过BCIP - NBT法评估碱性磷酸酶活性。通过流式细胞术评估aPDT诱导的细胞死亡类型。数据进行统计学比较（方差分析，随后进行Tukey或Bonferroni事后检验）。
aPDT能够以染料浓度依赖性方式杀死牙髓细胞。当使用浓度为0.025或0.050mg/ml的MB时，细胞活力显著降低（p < 0.0001）。在这些浓度下，aPDT诱导的细胞死亡主要通过坏死发生。所有实验组的碱性磷酸酶活性均显著降低（p < 0.001）。当0.0125mg/ml的MB暴露于激光照射时，牙髓细胞显示出合适的活力。
0.0125mg/ml的MB进行aPDT可能代表一种用于修复牙科应用的低风险疗法。使用浓度高于0.025mg/ml的MB联合红色激光照射的aPDT方案可能对牙髓细胞有害。
