INFLUENCE OF RADIATION DOSE IN COLLAGEN IV AND MMP20 IMMUNOEXPRESSION AND THE TOOTH IMMEDIATE ADHESIVE PROPERTIES

Objectives Radiation-related caries is an important collateral effect in patients with head and neck cancer subjected to radiotherapy, with rapidly progressive, asymptomatic and ample lesions, associated to direct and indirect effects of radiation. The present study has the aim of determine the alterations of the immunoexpression of collagen IV and MMP20 in the amelodentin junction and its relationships with odontoblasts according to the radiation dose (0, 20, 40, and 70Gy) and its influence on the immediate adhesive properties (μTBS and μSBS) of enamel and dentin. The immunoexpression was performed with immunofluorescence confocal microscopic analysis. Forty caries-free extracted third molars were divided into eight groups according to the factors: radiation dose (0, 20, 40, and 70Gy) for the experiments. Data from immunofluorescence was analyzed descriptively and adhesive properties were analyzed using two-way ANOVA and Tukeys test. Findings The alterations in the immunoexpresion of collagen IV and MMP20 is directly associated with the dose of radiation, showing increasing levels of MMP20 and decreasing levels of collagen IV in the most irradiated teeth.When radiation doses were applied between 40 to 70 Gy, the adhesive values were significantly lower for both strategies in the two tests performed. Conclusion High doses of radiation above 40 Gy affect the expression of collagenIV, MMP20 and immediate adhesive proprieties on dentin and enamel. The information obtained about the altered expression of collagen IV and MMP20, and the adhesive properties in dental irradiated tissue is crucial to understand the process of radiation-related caries and the restorative treatment of these patients.