Real-time in-depth imaging of gap formation in bulk-fill resin composites

摘要

Objectives. This study visualized in real-time the gap forming of bulk-fill resin composites during polymerization using optical coherence tomography (OCT).Methods. Light-cured bulk-fill resin composites; Tetric N-ceram Bulk Fill (TNB), SonicFill (SNF), Surefil SDR (SDR), dual-cured bulk-fill resin composite Bulk EZ (BEZ), and light-cured core resin composite Clearfil Photo Core (CPC) were investigated. Swept-source OCT real-time cross-sectional monitoring was obtained during resin composite placement and curing procedure. Gap formation was observed in bonded cylindrical resin composite molds (4-mm depth, 3-mm diameter) and free shrinkage volume was observed at the top and bottom of a tube with similar dimensions (n =10). OCT 3D data were analyzed to calculate sealing floor area percentage (SFA%) and volumetric shrinkage in bonded tube (VS%). Data were analyzed by ANOVA at significance level of 0.05. The bottom-top degree of conversion ratio (DC%-R) through 4-mm depth was measured using the Xp1oRA Plus micro-Raman spectroscopy.Results. BEZ showed no gap formation at the cavity floor in any specimens while SNF showed the highest gap formation; the statistical order in terms of SFA% was BEZ (100 0) TNB (84.97 +/- 2.98) CPC (52.13 +/- 8.23) = SDR (45.97 +/- 9.21) SNF (16.23 +/- 6.00) (p0.05). On the other hand, total VS% was statistically ordered as BEZ (3.40 +/- 0.14) SDR (3.22 +/- 0.09) TNB (1.82 +/- 0.11) SNF (1.65 +/- 0.04) = CPC (1.56 +/- 0.04) (p 0.05). Unlike BEZ, the light-cured resin composites showed larger shrinkage at specimen bottom than top. TNB showed the lowest DC%-R followed by SNF (p 0.05).Significance. Light-cured bulk-fill resin composites showed various degrees of gap formation and shrinkage at 4-mm deep cavity. The dual-cured bulk-filled resin composite showed no decrease of degree of conversion through the depth and the highest cavity adaptation despite its tendency for higher volumetric shrinkage. (C) 2019 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.