Effect of ionizing radiation on the chemical structure of sound and caries-affected root dentine and on the bond strength to glass ionomer cements and adhesives systems
Ionizing Radiation, Microshear Bond Strength, Root Dentin
Objective: to evaluate the impact of ionizing radiation on the sound and carious root dentine chemical composition and microshear bond strength of different glass ionomer cements and different adhesive systems. Methods and Materials: Non-carious human third molars were divided according to radiation (irradiated and non-irradiated). These groups were then divided into sound dentin and artificial carious dentin, and restored with either conventional glass ionomer cement (GIC) or resin-modified glass ionomer cement (RMGIC) and either three-step etch-and-rinse adhesive (Optibond FL) or two-step self-etch adhesive (Clearfil SE). Elemental analysis of root dentin was performed using an EDS, the bond strength of adhesive system to dentin was assessed by microshear bond testing, and the failure modes were evaluated using scanning electron microscopy (SEM). The bond strength of glass ionomer cements and adhesive system to dentin was assessed by microshear bond testing, and the failure modes were evaluated using scanning electron microscopy (SEM). Non-parametric statistical tests were used to assess possible statistical differences between the control and experimental groups. Results: ionizing radiation and artificial carious process affected the chemical composition dental structure. Irradiated dentin (sound and carious) had the lowest bond strength values when GICs were used. Irradiated dentin carious had the lowest bond strength when the RMGIC was used. Irradiated dentin (sound and carious) had the lowest bond strength values for both adhesive systems. Conclusions: Ionizing radiation affects the chemical composition of root dentin and subsequently the bond strength of adhesive systems and Glass ionomer cements in root dentin.