| ORIGINAL RESEARCH |
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| Year : 2020 | Volume
: 11
| Issue : 1 | Page : 4-10 |
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Polymerization Shrinkage, Shrinkage Stress, and Degree of Conversion in Bulk-Fill Resin Composites After Different Photo-Activation Methods
Sara Majidinia1, Hossein Bagheri2, Shadi Ramezani3, Mohammad Jafari Giv3, Negin Vatanparast3, Fatemeh Namdar3
1 Department of Restorative and Cosmetic Dentistry, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran
2 Dental Materials Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
3 Dental Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
Correspondence Address:
Fatemeh Namdar
Department of Operative Dentistry, School of Dentistry, Mashhad University of Medical Sciences, Vakil-Abad Boulevard, Mashhad
Iran
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/denthyp.denthyp_41_19
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Introduction: The aim of this study was to evaluate the effect of photo-activation methods on the shrinkage behavior of bulk-fill resin composites. Materials and Methods: Three bulk-fill resin composites (Tetric N-Ceram bulk-fill, Xtra fill, and Filtek flowable) were compared in terms of polymerization shrinkage, shrinkage stress, and degree of conversion (DC). Two curing methods were used: 1) conventional and 2) soft-start curing. Five disk-shaped specimens of each bulk-fill composite were fabricated. The deflection disk method and custom-made linear variable differential transformer (LVDT) device evaluated the dimensional changes during polymerization. Universal testing machine was used to measure shrinkage stress. To evaluate DC, the absorbance peaks were obtained using Fourier Transformation Infrared Spectroscopy (FTIR). Data were analyzed by one-way ANOVA and Tukey test. Results: Tetric N-Ceram bulk-fill (conventional mode) showed the highest polymerization shrinkage rate. Filtek flowable resin composite showed least amount of shrinkage stress and highest DC, while Xtra fill (with conventional curing) showed the highest shrinkage stress. Conclusion: Photo-activation method had no effect on decreasing the polymerization shrinkage except for Tetric N-Ceram; also, polymerization shrinkage stress in Filtek flowable composites with both curing methods was less than other groups. DC was product dependent.
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