Bonding effectiveness and multi-interfacial characterization of two direct buildup resin core systems bonded to post-space dentin
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The aim of the present study was to evaluate the bonding effectiveness of two resin core buildup systems using conventional methods in the field of adhesive dentistry and a new non-destructive method.
Materials and methods
Twenty-four single-rooted human teeth were built up with dual-cure one-step self-etch adhesive and composite systems (SY1: Clearfil DC bond and Clearfil DC core automix, SY2: Clearfil bond SE one and Clearfil DC core automix one). The prepared samples were sectioned into approximately 1 × 1-mm-thick beams and subjected to micro-tensile bond strength (μTBS) testing (n = 24). The fractured beams after μTBS testing were analyzed by SEM and energy-dispersive X-ray (EDX) spectrometry. The three teeth filled with each resin core system were sectioned and embedded in epoxy resin to observe the dentin–bonding interface under TEM (n = 6). Moreover, three of each resin core-filled teeth without any processing were examined using μCT (n = 6).
Two-way ANOVA revealed that the two factors “root region” (p < 0.001, F = 15.22) and “system” (SY1 < SY2; p < 0.001, F = 22.52) had a significant influence. The μTBS gradually decreased from the coronal side to the apical side of the root canal. Morphological evaluation revealed that SY2 was superior in terms of resin curing at the apical side. μCT non-destructive evaluation clearly revealed gap formation in SY1.
SY2, which included a new light-independent catalyst, showed better bonding effectiveness and adhesive interface to dentin compared to that of SY1.
The new catalyst, which is activated by contact with adhesive and resin composite, can be used for resin core buildup restorations.
KeywordsDirect buildup resin core Mild self-etch adhesive Bonding effectiveness Interfacial characterization Non-destructive observation Micro-computed tomography
This work was supported by KAKENHI Grant-in Aid for Scientific Research (B) (26293410). The authors would like to express our gratitude to Kuraray Noritake Dental for the generous donation of materials, and, in part, by the Nanotechnology Platform of the Ministry of Education, Culture, Sports, Science and Technology (MEXT) at the Research Center for Ultra-High Voltage Electron Microscopy, Osaka University.
Compliance with ethical standards
This article does not contain any studies with human participants or animals performed by any of the authors. The use of extracted human teeth was approved by the ethical committee of the Osaka University Faculty of Dentistry.
Conflict of interest
The authors declare that they have no conflicts of interest.
This work was supported by KAKENHI Grant-in Aid for Scientific Research (B) (26293410).
For this type of study, formal consent is not required.
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