A study on fractural behavior of dentin-resin interface

Abstract

The fracture toughness test is believed as a clinically relevant method for assessing the fracture resistance of the dentinal restoratives. The objectives of this study were to measure the fracture toughness (K1C) and microtensile bond strength of dentin-resin composite interface and compare their relationship for their use in evaluation of the integrity of the dentin-resin bond.A minimum of six short-rod specimens for fracture toughness test and fifteen specimens for microtensile bond strength test was fabricated for each group of materials used. After all specimens storing for 24 hours in distilled water at 37℃, they were tensile-loaded with an EZ tester universal testing machin. Statistical analysis was performed using ANOVA and Tukey' s test at the 95% confidence level, Pearson' s coefficient was used to verify the correlation between the mean of fracture toughness and microtensile bond strength. FE-SEM was employed on fractured surface to describe the crack propagation.Fracture toughness value of Clearfil SE Bond (SE) was the highest, followed by Adper Single Bond 2 (SB), OptiBond Solo (OB), ONE-STEP PLUS (OS), ScotchBond Multi-purpose (SM) and there was significant difference between SE and other 4 groups (p < 0.05). There were, however, no significant difference among SB, OB, OS, SM (p > 0.05). Microtensile bond strength of SE was the highest, followed by SB, OB, SM, OS and OS only showed significant lower value (p < 0.05). There was no correlation between fracture toughness and microtensile bond strength values. FE-SEM examination revealed that dentin bonding agent showed different film thickness and different failure pattern according to the film thickness.From the limited results of this study, it was noted that there was statistically no correlation between K1C and μ TBS. We can conclude that for obtaining the reliability of bond strength test of dentin bonding agent, we must pay more attention to the test procedure and its profound scrutiny. [J Kor Acad Cons Dent 32(3):208-221, 2007]

The study of fractural behavior of repaired composite

“…In a case of dentin-composite interface, many studies reported there was no significant correlation even though they had a similar pattern. 13,15,39 Dhuru and Lloyd have mentioned that the fracture stress of the repair may be a function of both the interfacial strength and defect produced by the operators'repair technique.…”

“…Therefore, the bond strength test alone is not sufficient to decide whether a treatment has enhanced the resistance to fracture or not. 12,13 A reliable and valid method for the evaluation of bonded interfaces is needed to help predict, understand and assess clinical bonding failures.…”