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

Juri Hayashi; Jorge Espigares; Tomohiro Takagaki; Yasushi Shimada; Junji Tagami; Tomoko Numata; Daniel Chan; Alireza Sadr

doi:10.1016/j.dental.2019.01.020

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

Dent Mater. 2019 Apr;35(4):585-596. doi: 10.1016/j.dental.2019.01.020. Epub 2019 Feb 25.

Authors

Juri Hayashi¹, Jorge Espigares², Tomohiro Takagaki², Yasushi Shimada³, Junji Tagami², Tomoko Numata⁴, Daniel Chan⁵, Alireza Sadr⁶

Affiliations

¹ Department of Restorative Dentistry, Biomimetics Biomaterials Biophotonics Biomechanics & Technology Laboratory, School of Dentistry, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195-7456, USA; Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
² Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
³ Department of Operative Dentistry, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
⁴ Analytical Technology Center, Horiba Techno Service Co., Ltd., 2-6 Awaji-cho, Kanda, Chiyoda-ku, Tokyo 101-0063, Japan.
⁵ Department of Restorative Dentistry, Biomimetics Biomaterials Biophotonics Biomechanics & Technology Laboratory, School of Dentistry, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195-7456, USA.
⁶ Department of Restorative Dentistry, Biomimetics Biomaterials Biophotonics Biomechanics & Technology Laboratory, School of Dentistry, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195-7456, USA; Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. Electronic address: arsadr@uw.edu.

PMID: 30819550
DOI: 10.1016/j.dental.2019.01.020

Abstract

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 XploRA 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) (p<0.05). 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.

Keywords: Bulk-filled; Composite resins; Degree of conversion; Dental restoration failure; Optical coherence tomography; Polymerization; Self-cured; Shrinkage.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Composite Resins*
Cross-Sectional Studies
Dental Caries*
Humans
Materials Testing
Polymerization

Substances

Composite Resins