Influence of radiotherapy on the dentin properties and bond strength

The objective of this study was to evaluate the biomechanical properties of dentin and the microtensile bond strength (μTBS) performed before or after radiotherapy (RT). Dentin chemical composition (infrared spectroscopy—FTIR), SEM images, and mechanical properties (Vickers microhardness—VHN and elastic modulus—E) were evaluated comparing no irradiated and irradiate dentin (n = 5). RT was defined by application of 72 Gy (1.8 Gy daily, 5 days per week, during 8 weeks) with sample immersed in distilled water. μTBS evaluated three groups (n = 10): NI—no irradiated; IB—irradiation before restoration; and IA—irradiation after restoration. Resin-dentin sticks (1.0 mm2) were obtained and submitted to μTBS. Analysis of the bonding interface was made by confocal microscopy. After RT, percentage ratio of FTIR analysis showed increased absorption for all bands. SEM image showed a disorganized dentin structure. Two-way ANOVA showed increased VHN (p = 0.005) and decreased E (p