Microradiographic and microscopic studies on in situ induced initial caries in irradiated and nonirradiated dental enamel.

The objective of this study was to evaluate the onset of initial demineralization in irradiated and nonirradiated human enamel. Enamel specimens were prepared from the lingual and buccal surfaces of 48 freshly extracted, caries-free third molars. Either the lingual or the buccal enamel specimen of each tooth was irradiated with 60 Gy. The remaining enamel sample was not irradiated. Two irradiated and two nonirradiated enamel specimens were inserted into both buccal aspects of each 12 intraoral mandibular appliances. The appliances were worn by 12 persons for 6 weeks throughout day and night. One side was brushed daily with a fluoride-free toothpaste. On the other side plaque was allowed to grow. Individual oral hygiene techniques were performed without any fluorides. During meals, the appliance was stored in 10% sucrose solution. The enamel specimens were cut perpendicular to the enamel surface. Subsequently, the slabs were ground to a thickness of 90 microm, and studied by means of TMR and microscopic techniques. Evaluated data did not show any differences between irradiated and nonirradiated enamel lesions (ANOVA). The onset of caries in irradiated enamel can be hampered by regularly performed oral hygiene techniques.