The effect of different cavity disinfectant and adhesive applications on dentin bonding strength after radiotherapy

The aim of this study was to compare the bond strength of teeth treated with radiotherapy with two different adhesive systems after cavity disinfectants were applied (CHX, chitosan-containing agent). Twenty-four newly extracted, non-carious human molar teeth were used. A total dose of 70.2 Gy was divided into 39 days of administration of 1.8 Gy using a linear radiation accelerator. The enamel tissue on the occlusal surface of the teeth was removed with a low-speed rotating water-cooled cutting instrument (Isomer 1000, Buehler) to expose the dentin tissue to evaluate bond strength. The teeth were randomly divided into two main groups (n=12) as radiotherapy treated and non-radiated, and three subgroups (n=4) for disinfectant agent application (CHX, chitosan, control). The study was carried out as 12 subgroups (n=2) with a two-stage self-etch adhesive system (Clearfil SE Bond) or universal adhesive system (Clearfil Universal Bond Quick) application to each subgroup. Teeth were restored with composite resin after adhesive application. One hundred forty-four rod-shaped specimens with a cross-sectional area of 1x1 mm² were obtained with the cutting device from the teeth embedded in the acrylic blocks. A bond strength test was applied to the composite-dentin rods in a universal testing device (Micro Tensile Tester, BISCO). The data were analyzed with ANOVA at a significance level of p <0.05. Among all groups, Group Clerafil SE Bond with no radiotherapy application and the chitosan-containing disinfectant agent was showed the highest bond strength (49.12 ± 9.54), while Group Clearfil Universal Bond Quick with radiotherapy and disinfectant-free showed the lowest bond strength value (28.28 ± 5.03). The highest bond strength values were obtained after the application of the chitosan-containing agent in all groups. Within the limitations of this study, it was determined that radiotherapy application had a negative effect, and the use of disinfectant agents had a positive effect on the bond strength. These results need to be supported by clinical studies in patients received radiotherapy to the head and neck region.