[Effects of carboidiimide with different bonding techniques on the property of dentin bonding].

PURPOSE: To explore the effects of carbodiimide combined with different bonding techniques on the property of dentin bonding. METHODS: 64 third molars in vitro were randomly divided into 8 groups(n=8), including EWB and EWBa (no pretreatment+ethanol-wet bonding), E-EWB and E-EWBa (0.5 mol/L EDC+ethanol-wet bonding), E-WB and E-WBa (0.5 mol/L EDC+water-wet bonding), E-DB and E-Dba (0.5 mol/L EDC+dry bonding). Group EWB, E-EWB, E-WB and E-DB were immediate groups, while group EWBa, E-EWBa, E-WBa and E-DBa were aging groups. Six specimens in each group were randomly chosen to test shear bonding strength and then observe failure patterns. The remaining specimens were used to observe bonding interface under SEM. SPSS 20.0 software package was used for statistical analysis of the data. RESULTS: There was no significant difference in shear bonding strength between group EWB and E-EWB, group E-EWB and E-WB(P＞0.05), while shear bounding strength in group E-EWB and E-WB were significantly greater than group E-DB(P＜0.05). The shear bonding strength of group E-EWBa was significantly greater than group EWBa (P＜0.05). The shear bonding strength of group E-EWBa, E-WBa and E-DBa was gradually decreased, and their differences were significant (P＜0.05). The factors of EDC, bonding techniques and aging played a significant role in shear bonding strength (P＜0.05). Interactions between EDC and aging was significant (P＜0.05), and that between bonding techniques and aging was also significant (P＜0.05). The main failure modes of the water-wet bonding and the ethanol-wet bonding were resin failure, adhesive interface failure and mixed failure. The main failure of dry bonding was adhesive interface failure. The thickest and densest hybrid layer were found in group E-EWB. Some tiny cracks were presented between the hybrid layer and adhesives layer in group EWBa and E-EWBa. Partially uneven cracks existed in the hybrid layer in group E-WBa, and that was more obvious in group E-DBa. CONCLUSIONS: EDC pretreatment combined with ethanol-wet adhesive technique acquires the optimal shear bonding strength and the durability of dentin bonding.

[The influence of carbodiimide in different solvents on bonding performance of acetone-based etch-and-rinsing adhesive system].

PURPOSE: To investigate the influence of carbodiimide (EDC) in water, ethanol and acetone on bonding performance of acetone-based etch-and-rinsing adhesive system. METHODS: Sixty-four third molars in vitro were randomly divided into 8 groups according to the types of pretreatment agents, with or without aging(n=8), group S0 and S0a: deionized water; group S and Sa: EDC in water; group E and Ea: EDC in ethanol; group B and Ba: EDC in acetone. After pretreatment, the adhesive specimens were prepared by Prime Bond NT. S0, S, E and B were immediate groups, and S0a, Sa, Ea and Ba groups were subjected to aging test for 5 000 times. Six specimens were randomly selected from each group to test the shear bond strength and observe the fracture mode. The remaining 2 specimens were used to observe the microstructure of bonding interface by scanning electron microscopy. The shear bond strength was statistically analyzed with SPSS 20.0 software package. RESULTS: It was found that the shear bond strength of group S was significantly higher than that of group S0, and the shear bond strength of group Sa was significantly higher than that of group S0a(P<0.05). There was no significant difference between groups S, E and B(P>0.05). The shear bond strength of Sa, Ea and Ba increased successively, and the difference was statistically significant(P<0.05). Three factor analysis of variance found that the main effect of EDC, aging and solvent alone was significantly different(P<0.05), and there was an interaction effect between EDC and aging(P<0.05). The fracture modes of immediate groups were mainly mixed failure, while the interface fracture was the most common in the aging groups. SEM observation showed that all the hybrid layers were uniform and complete in the immediate groups, and the largest crack in S0a group and a few cracks in Ba group. CONCLUSIONS: EDC pretreatment in water, ethanol, and acetone solvents can improve both the immediate and aging bonding strength of acetone-based etch-and-rinsing adhesive system. Acetone acts as the solvents of EDC maximizes the shear bond strength among the aging groups.