Gomes-Silva Wagner, Prado Ribeiro Ana Carolina, de Castro Junior Gilberto, Salvajoli João Victor, Rangel Palmier Natalia, Lopes Marcio Ajudarte, Rocha Marcelo Marques, de Goes Mario Fernando, Brandão Thais Bianca, Santos-Silva Alan Roger
Oral Diagnosis Department, Piracicaba Dental School, University of Campinas, Piracicaba, Sao Paulo, Brazil; Dental Oncology Service, Instituto do Câncer do Estado de São Paulo, Faculdade de Medicina da Universidade de São Paulo, Sao Paulo, Brazil.
Clinical Oncology Department, Instituto do Câncer do Estado de São Paulo, Faculdade de Medicina da Universidade de São Paulo, Sao Paulo, Brazil.
Oral Surg Oral Med Oral Pathol Oral Radiol. 2017 Aug;124(2):175-182. doi: 10.1016/j.oooo.2017.04.009. Epub 2017 Apr 25.
Recent studies suggested that head and neck radiotherapy increases active forms of matrix metalloproteinases (MMPs) in the dentin-enamel junction (DEJ), leading to enamel delamination and radiation-related caries. This study aimed to assess the expression and activity of the gelatinases MMP-2 and MMP-9 in the DEJ and dentin-pulp complex tissues of teeth irradiated in vivo.
Thirty-six teeth were studied, including 19 irradiated and 17 non-irradiated controls. In situ zymography was used to investigate the gelatinolytic activity in the micromorphologic components of enamel, DEJ, dentin-pulp complex, and caries. Immunohistochemical analysis was conducted on the demineralized samples to assess MMP-2 and MMP-9 expression levels in the DEJ, dentin-pulp complex components, and caries.
No statistically significant differences were detected between groups in gelatinolytic activity or in MMP-2 expression levels (P > .05). Odontoblast MMP-9 expression was reduced in the irradiated group (P = .02).
The study rejected the hypothesis that MMP-2 and MMP-9 would be overexpressed or more activated in the DEJ and dentin-pulp complex of irradiated teeth. Direct effects of radiation should not be regarded as an independent factor for explaining radiation-related caries onset and progression.
近期研究表明，头颈部放疗会增加牙本质-釉质交界（DEJ）处基质金属蛋白酶（MMPs）的活性形式，导致釉质分层和放射性龋齿。本研究旨在评估体内照射牙齿的DEJ和牙髓复合体组织中明胶酶MMP-2和MMP-9的表达及活性。
对36颗牙齿进行研究，包括19颗照射牙齿和17颗未照射的对照牙齿。采用原位酶谱法研究釉质、DEJ、牙髓复合体和龋齿微观形态成分中的明胶水解活性。对脱矿样品进行免疫组织化学分析，以评估DEJ、牙髓复合体成分和龋齿中MMP-2和MMP-9的表达水平。
两组在明胶水解活性或MMP-2表达水平上均未检测到统计学显著差异（P>.05）。照射组成牙本质细胞MMP-9表达降低（P =.02）。
该研究否定了MMP-2和MMP-9在照射牙齿的DEJ和牙髓复合体中会过度表达或更活化的假设。不应将辐射的直接影响视为解释放射性龋齿发生和进展的独立因素。
