Influence Of Self-etching Adhesive Containing Silanized Nano-ACP On Short And Long Dentin Micro-tensile Bond Strength

Object:The study investigated the influence of a mild self-etching adhesive mixed with different weight nano-particles of amorphous calcium phosphate (nACP) on the short-and long-term dentin micro-tensile bond strengths (MTBS).Methods:The silanized particles (nACP) were incoporated into self-etching adhesive Clearfil S3Bond (Kuraray Co.) in weight ratio of0%,5%,10%,20%,30%. The mid-coronal dentin was exposed for twenty freshly extracted third molars. The dentin surfaces (2each subgroup) were applied with the self-etching adhesive Clearfil S3Bond containing0%(serving as control),5%,10%,20%, or30%wt nACP in accordance with the manufacturer’s recommendations. Afterwards, the resin-composite Clearfil Majesty (Kuraray Co.) was placed over the adhesive-treated dentin surfaces were in four1-mm increments and light-cured. After24-h water storage, the bonded specimens were sectioned vertically through the resin-dentin interfaces into multiple beams, each with a cross-sectional area of about1mm2. After the beams were stored in water for1yr or24h, the MTBS tests were performed with a micro-tensile tester (Bisco) at a cross-head speed of lmm/min until failure. The MTBS was calculated in megapascals (MPa). The MTBS data were analyzed with two-way repeated measures ANOVA followed by Tukey test. Results:After storing in the water for24h, the control group yielded the highest bond strength of39.24±8.57MPa (p<0.01). There were the significant differences among the experimental groups (p<0.05). Among the four experimental groups, the dentin MTBS of5%wt nACP (32.59±8.33MPa),10%wt nACP (27.33±4.21MPa),20%wt nACP (29.02±7.28MPa) were significantly higher than those of30%nACP (12.83±3.83MPa)(p<0.05). The dentin MTBS of5%nACP were higher than those of10%nACP (p<0.05). The dentin MTBS of20%nACP were not significantly different from those of5%nACP and10%nACP (p>0.05). After storing in the water for1year, the dentin MTBS of control group decreased to33.48±4.83MPa (p<0.05), while those of the experimental groups significantly increased (5%wt nACP (36.02±5.92MPa),10%wt nACP (33.59±6.51MPa),20%wt nACP (34.17±5.31MPa) and30%nACP (18.60±6.27MPa)). The former three (5%wt-20%wt nACP) were not significantly different among themselves (P>0.05), but significantly higher than the latter (30%wt nACP)(p<0.05).Conclusion:The incoporation of silanized nACP into the self-etching adhesive Clearfil S3Bond significantly decreased the short-term dentin MTBS with the increased amount of nACP, but significantly increased long-term dentin MTBS.