Publication: Polymerization efficacy affects the long-term mini-interfacial fracture toughness
Issued Date
2017-01-01
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ISSN
17579988
14615185
14615185
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2-s2.0-85019193692
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Mahidol University
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SCOPUS
Bibliographic Citation
Journal of Adhesive Dentistry. Vol.19, No.2 (2017), 157-167
Suggested Citation
Pong Pongprueksa, Jan de Munck, Bruno C. Barreto, Bart van Meerbeek Polymerization efficacy affects the long-term mini-interfacial fracture toughness. Journal of Adhesive Dentistry. Vol.19, No.2 (2017), 157-167. doi:10.3290/j.jad.a38098 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/42477
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Title
Polymerization efficacy affects the long-term mini-interfacial fracture toughness
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Abstract
Purpose: To evaluate the effect of the type and concentration of photo-initiator on the long-term bonding efficacy to dentin in terms of mini-interfacial fracture toughness (mini-iFT). Materials and Methods: The bonding efficacy of the one-step self-etch (SE) adhesive Clearfil S3 Bond Plus and four derivative experimental adhesives (Leuven University Bond [LUB]), which were similar in composition except for the (co)photo-initiators (all prepared by Kuraray Noritake), containing 2.0 wt% camphorquinone (CQ) and 2.0 wt% EDMAB (LUB-CQ/amine_high), 0.35 wt% CQ and 0.35 wt% EDMAB (LUB-CQ/amine_low ), 2.0 wt% TPO (LUB-TPO_ high), and 0.35 wt% TPO (LUB-TPO_low), was measured using a mini-iFT approach after being aged for 6 months and 1 year by water storage at 37°C (control: 1 week mini-iFT). The mini-iFT specimens were loaded until failure in a 4-point bending device to determine the interfacial fracture toughness (KIc). All fractured specimens were evaluated using scanning electron microscopy (SEM). Results: The mini-iFT of Clearfil S3Bond Plus and the adhesives with high photo-initiator concentrations was not significantly different at 6 months, although it dropped significantly at 1 year. For each storage period, the mini-iFT of the adhesives with high photo-initiator concentrations was not significantly different from that of the commercial adhesive, in contrast to the significantly lower mini-iFT measured for adhesives with low concentrations of photo-initiator. SEM fracture analysis revealed that the adhesives with high concentrations of photo-initiator most frequently failed at the top of the hybrid layer at 1 week, while this failure pattern shifted to the bottom of the hybrid layer after aging. Conclusion: A one-step self-etch adhesive should contain photo-initiator in a sufficiently high concentration, as this directly improves its immediate and long-term bonding efficacy to dentin. While the mini-iFT remained stable up to 6 month of aging for both the commercial and the adhesive with a high concentration of photo-initiator, the mini-iFT was found to decrease after 1 year of aging.