Is there correlation between polymerization shrinkage, gap formation, and void in bulk fill composites? A μCT study

Abstract

This in vitro study aimed to evaluate the volume of polymerization shrinkage (VS), gap (VG), and void (VV) using computerized microtomography (μCT) in bulk fill resin composites and conventional class I restorations, and to establish a correlation between these factors. Class I cavities (4 x 5 x 4 mm), C-factor = 4.2, were performed on caries-free human third molars and randomly divided into five groups (n = 6): FSI (Filtek Supreme XTE incremental insertion); FSS [(Filtek Supreme XTE single insertion(SI)]; TBF [(Tetric Bulk Fill: SI and manual filling (MF)]; SFM (Sonic Fill: SI/MF); and SFS (SonicFill: SI and sonic filling). The teeth were scanned and analyzed by μCT at T0, after filling the cavity with resin, and at T1, after polymerization for VG and VV, and for VS (T1-T0). There was statistically significant difference in VS in μCT for the FSI and FSS groups and between SFS and FSS as well as some difference in VV for FSI and bulk fill resin composites and no difference in VG between the conventional technique and bulk fill composites. Bulk fill resin composites presented similar VS and gap formation to those of incrementally inserted conventional resin composites. There is a moderate and weak positive correlation between polymerization shrinkage and gap formation and void, respectively. The final gap formation was more dependent on the initial gap than on polymerization shrinkage or void volume.

Evaluation of Two Resin Composites Having Different Matrix Compositions

“…The polymerization shrinkage values reported in this study were in agreement with many studies that have reported the polymerization shrinkage of the resin composite in the range of 1.2%–2.7% [ 19 , 43 , 44 , 45 ]. Junior et al [ 45 ] reported that the polymerization shrinkage of the incrementally placed Filtek Supreme was 1.2 ± 1.0%, and the slight difference could have been caused by the difference in the layer thickness used in their study (≈1.3 mm). Kamalak et al [ 19 ] evaluated the volumetric shrinkage of the flowable Filtek Ultimate (Supreme) and flowable Filtek Bulk Fill using µCT Skyscan 1172 and the CTAn software.…”

Effect of access cavity design on gaps and void formation in resin composite restorations following root canal treatment on extracted teeth

“…Almeida Jr et al . (2017), evaluating bulk fill composites, reported that the final gap formation was more dependent on the initial gap that was present rather than the polymerization shrinkage. In the present study, the similarities in the results between UEC and TEC can be related to the low viscosity of the composite associated with the cavity dimensions.…”

The use of a liner under different bulk-fill resin composites: 3D GAP formation analysis by x-ray microcomputed tomography

“…The sample size was calculated based on the estimated effect size between groups according to the literature 15 , 16 . It was determined that 10 samples were needed for each group to achieve a medium effect size (d=0.50), with 80% power and a 5% type 1 error rate in this study.…”

“…All evaluations were performed with the VOI achieved from the ROI centered on the delimitations of the restorative materials. 3D images were obtained by CTvox (Version 3.1.1 r1191, Skyscan, Kontich) 15 . The volume of gap formation was calculated through analysis of the tooth-restoration interface and is described in mm 3 .…”