RESUMO
The effectiveness of mouthwash protocols in preventing gamma irradiation therapy damage to the ultimate tensile strength (UTS) of enamel and dentin is unknown. It was hypothesized that the use of chlorhexidine and fluoride mouthwash would maintain the UTS of dental structures. One hundred and twenty teeth were divided into 2 groups: irradiated (subjected to 60 Gy of gamma irradiation in daily increments of 2 Gy) and non-irradiated. They were then subdivided into 2 mouthwash protocols used 3 times per day: 0.12% chlorhexidine, 0.05% sodium fluoride, and control group (n = 10). The specimens were evaluated by microtensile testing. The results of the Tukey test (p < 0.05) indicated that the gamma irradiation therapy significantly reduced the UTS of the enamel, crown, and root dentin. Macromolecular alterations were suggested by optical retardation data in dentin. Structural alterations, in both substrates, were detected by scanning electron microscopy analysis. Mouthwash with 0.12% chlorhexidine partially prevented the damage to the mechanical properties of the irradiated crown dentin, whereas the 0.05% sodium-fluoride-irradiated enamel showed UTS similar to that of non-irradiated enamel.
Assuntos
Clorexidina/farmacologia , Esmalte Dentário/efeitos da radiação , Dentina/efeitos da radiação , Raios gama/efeitos adversos , Antissépticos Bucais/farmacologia , Protetores contra Radiação/farmacologia , Fluoreto de Sódio/farmacologia , Adolescente , Análise de Variância , Esmalte Dentário/química , Análise do Estresse Dentário , Dentina/química , Humanos , Microscopia Eletrônica de Varredura , Estrutura Molecular , Estatísticas não Paramétricas , Resistência à Tração/efeitos dos fármacos , Resistência à Tração/efeitos da radiação , Coroa do Dente/efeitos da radiação , Raiz Dentária/efeitos da radiação , Adulto JovemRESUMO
The effect of gamma irradiation therapy on the ultimate tensile strength (UTS) of enamel and dentin in relation to prism orientation, dentin tubule orientation, and location is unknown. It was hypothesized that tubule and prism orientation, location, and irradiation have an effect on the UTS of dental structures. Forty human third molars were used, half of which were subjected to 60 Gy of gamma irradiation, in daily increments of 2 Gy. The specimens were evaluated by microtensile testing. Results showed that irradiation treatment significantly decreased the UTS of coronal and radicular dentin and of enamel, regardless of tubule or prism orientation. With or without irradiation, enamel was significantly stronger when tested parallel to its prismatic orientation. Coronal and radicular dentin of non-irradiated specimens presented significantly higher UTS when tested perpendicularly to tubule orientation. However, when the teeth were irradiated, the influence of tubule orientation disappeared, demonstrating that irradiation is more harmful to organic components.
