الفهرس 
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Abstract
Purpose: This study aimed to evaluate and compare the effect of incorporating different concentrations of chlorhexidine to polyacrylic acid conditioner on the bond strength of resin-modified glass ionomer cement (RMGIC) to caries-affected dentine. Moreover, the effect of direct treating of caries affected dentine with different percentages of chlorhexidine solution on the bond strength of RMGIC was evaluated after polyacrylic acid conditioning.
Materials and Methods: Dentine surfaces of 101 human third molars were used in this study, 80 specimens were used for micro-shear bond strength (µSBS) and 21 specimens were used to examine the conditioned dentine surface by using scanning electronic microscope (SEM). The 80 specimens were divided into eight groups (n=10); group A; sound dentine specimens (SD) and group B; caries affected dentine specimens (CAD), the specimens of group A & B were treated with polyacrylic acid conditioner with no additive before application of RMGI, group C; 30 CAD specimens were subdivided into C1, C2 & C3 (n=10) according to concentration of CHX powder (0.5%, 0.05% or 0.02%) respectively which was incorporated in polyacrylic acid conditioner (Ac/CHX), group D ; 30 CAD specimens were subdivided into D1, D2 & D3 (n=10) according to concentration of CHX solution (0.5 % , 0.05% or 0.02%) respectively which was used after conditioning with polyacrylic acid. Then, tygon tubing were placed over dentine surfaces, filled with RMGIC, and mixed as recommended by the manufacturer, light cured and stored in distilled water at 37° C, for 24 hours, then micro-shear bond strength and the type of bond failure (adhesive/cohesive/mixed) was evaluated and the data was statistically analysed. Results: The results in the current study showed statistically significant difference of sound dentine (group A) with all groups except group D3 (p=0.069). Mean shear stress was the highest in sound dentine (16.64 ±3.83) followed by group D3 (13.97±1.78) and the lowest shear bond was in group D1 (8.77 ± 1.36). group B, C1 & C2 mean shear stress was (9.78±2.87, 9.94± 1.47 & 9.92± 1.08, respectively). group C3 & D2 mean shear stress was (11.12 ±0.35 & 11.88± 3.37, respectively). Conclusion: The bond to caries-affected dentine was lower than that verified to sound dentine. Furthermore, 0.5%, and 0.05%, & 0.02% CHX application, either in an aqueous solution or associated with the acid conditioner caused no adverse effects on the immediate bond strength of the tested RMGIC to caries-affected dentine. The application of 0.02% CHX solution, after acid conditioning, caused improved immediate bond strength of the tested RMGIC to caries-affected dentine.