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- The study of fractural behavior of repaired composite
- Sang-Soon Park, Wook Nam, Ah-Hyang Eom, Duck-Su Kim, Gi-Woon Choi, Kyoung-Kyu Choi
- J Korean Acad Conserv Dent 2010;35(6):461-472. Published online November 30, 2010
- DOI: https://doi.org/10.5395/JKACD.2010.35.6.461
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Abstract
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ePub Objectives This study evaluated microtensile bond strength (µTBS) and short-rod fracture toughness to explain fractural behavior of repaired composite restorations according to different surface treatments.
Materials and Methods Thirty composite blocks for µTBS test and sixty short-rod specimens for fracture toughness test were fabricated and were allocated to 3 groups according to the combination of surface treatment (none-treated, sand blasting, bur roughening). Each group was repaired immediately and 2 weeks later. Twenty-four hours later from repair, µTBS and fracture toughness test were conducted. Mean values analyzed with two-way ANOVA / Tukey's B test (α = 0.05) and correlation analysis was done between µTBS and fracture toughness. FE-SEM was employed on fractured surface to examine the crack propagation.
Results The fresh composite resin showed higher µTBS than the aged composite resin (
p < 0.001). Mechanically treated groups showed higher bond strength than non-mechanically treated groups except none-treated fresh group in µTBS (p < 0.05). The fracture toughness value of mechanically treated surface was higher than that of non-mechanically treated surface (p < 0.05). There was no correlation between fracture toughness and microtensile bond strength values. Specimens having high KIC showed toughening mechanism including crack deviation, microcracks and crack bridging in FE-SEM.Conclusions Surface treatment by mechanical interlock is more important for effective composite repair, and the fracture toughness test could be used as an appropriate tool to examine the fractural behavior of the repaired composite with microtensile bond strength.
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Original Article
- A study on fractural behavior of dentin-resin interface
- Gil-Joo Ryu, Gi-Woon Choi, Sang-Jin Park, Kyung-Kyu Choi
- J Korean Acad Conserv Dent 2007;32(3):208-221. Published online May 31, 2007
- DOI: https://doi.org/10.5395/JKACD.2007.32.3.208
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Abstract
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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 µTBS. 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.
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