Research and EducationAdditive effects of touch-activated polymerization and extended irradiation time on bonding of light-activated adhesives to root canal dentin
Section snippets
Material and methods
The study protocol was approved by the dental research ethics committee of Tokyo Medical and Dental University (No. D2013-022-03). Fifty single-rooted human mandibular premolars (length <21 mm), extracted for orthodontic purposes, were collected and stored in a 0.1% thymol solution at 4 °C. After the crowns were removed 2 mm coronal to the cementoenamel junction, the root canals were enlarged with K-files up to size 40, with the working length determined 1 mm from the apical foramen.
Results
The repeated measures ANOVA (Table 2) revealed that the effects of dentin region, bonding system, and light-irradiation time were statistically significantly different (P<.001). The interactions between the bonding systems and the dentin region were also significantly different (P<.001), whereas the interaction between light-irradiation time and both dentin region (P=.111) and bonding system (P=.221) were not. Moreover, the interaction among the 3 factors was also statistically similar (P
Discussion
The results of this study revealed that the addition of a touch-polymerization activator to light-activated adhesives SEB and PBU significantly improved their μTBS to root canal dentin. Hence, the first null hypothesis was rejected. The effect of extended light-irradiation time was significant according to the repeated measures ANOVA, but the 3-way ANOVA for SEB and PBU indicated that the extension significantly affected the bond strengths only in the apical region. Therefore, the second null
Conclusions
Based on the findings of this in vitro study, the following conclusions were drawn:
- 1.
The bond strength of light-activated adhesives to root canal dentin may be improved by extending the light-irradiation time and adding a touch-polymerization activator.
- 2.
Their effect may be additive, especially in the apical region, but it depends on whether the touch-polymerization activator contains an additional photoinitiator.
CRediT authorship contribution statement
Wahyuni S. Dwiandhany: Conceptualization, Methodology, Investigation, Writing - original draft. Ahmed Abdou: Methodology, Investigation, Formal analysis, Writing - review & editing. Antonin Tichy: Methodology, Writing - review & editing. Kazuhide Yonekura: Methodology, Investigation. Masaomi Ikeda: Validation, Writing - review & editing. Keiichi Hosaka: Conceptualization, Resources. Junji Tagami: Conceptualization, Resources, Supervision. Masatoshi Nakajima: Conceptualization, Methodology,
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