Bonding of chitosan and nanochitosan modified universal adhesive to dentin

To evaluate Wettability, pH and Microtensile bond strength (immediate and after thermocycling) of a universal adhesive after incorporation of 0.5% and 1% bulk-chitosan or nanochitosan. All-bond universal adhesive was used to obtain five groups according to the type of additive; CONTROL, CHITOSAN (0.5), CHITOSAN (1%), NANOCHITOSAN (0.5%) and NANOCHITOSAN (1%). Contact angle and pH of the adhesives were tested with n = 7 for each test. for Microtensile bond strength testing, premolars teeth (N = 50) were used; twenty-five teeth for immediate bond strength and the other twenty-five were tested after thermocycling. CONTROL and CHITOSAN (0.5%) groups showed significantly higher contact angle measurements (30.78 ± 3.71 and 27.77 ± 4.63 respectively) compared to all other groups. CONTROL group showed significantly higher pH value (3.17 ± 0.05), followed by NANOCHITOSAN (0.5%) and NANOCHITOSAN (1%) and the least pH values were for 0.5% CHITOSAN group and CHITOSAN (1%). Bond strength results revealed that NANOCHITOSAN (0.5%) and NANOCHITOSAN (1%) had the highest bond strength (52.99 ± 16.14, 55.80 ± 16.11). CONTROL, CHITOSAN (0.5%) and CHITOSAN (1%) had no significant difference. After thermocycling, NANOCHITOSAN (0.5%) and NANOCHITOSAN (1%) had the highest bond strength values (38.58 ± 7.01 and 40.07 ± 11.40), followed by CHITOSAN (0.5%) and CHITOSAN (1%), and the least bond strength value was obtained by the control group. Hybrid layer micrographs showed that NANOCHITOSAN (1%) has intense resin infiltration before and after aging compared to all other groups. Incorporation of nanochitosan (0.5% and 1%) improved the universal adhesive microtensile bond strength and bond durability.