Volumetric polymerization shrinkage and its comparison to internal adaptation in bulk fill and conventional composites: A μCT and OCT in vitro analysis

Camila S. Sampaio, Jessica Fernández Arias, Pablo J. Atria, Eduardo Cáceres, Carolina Pardo Díaz, Anderson Z. Freitas, Ronaldo Hirata

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Methods: Box-shaped class I cavities were prepared in 30 third-molars and divided into 5 groups (n = 6): G1- Filtek Z100 (Z100); G2- Tetric Evoceram Bulk Fill (TEC); G3- Tetric EvoFlow Bulk fill (TEF); G4- Filtek Bulk fill (FBU); and G5- Filtek Bulk fill Flowable (FBF). All groups were treated with Adper Single Bond Plus adhesive and light cured (Bluephase 20i). Each tooth was scanned three times using a μCT apparatus: after cavity preparation (empty scan); after cavity filling (uncured scan) and after light curing of the restorations (cured scan). The μCT images were imported into a three-dimensional rendering software, and volumetric polymerization shrinkage percentage was calculated (%) for each sample. In the same images, interfacial gaps in the pulpal floor were qualitatively evaluated. After μCT evaluation, the pulpal floor from each tooth was polished until a thin tooth structure was obtained and OCT images were obtained by scanning the pulpal portion. Gap formation was observed and qualitatively compared to the μCT images. Results: VPS means ranged from 2.31 to 3.96% for the studied resin composites. The bulk fill materials, either high viscosity or flowable, were not statistically different from each other (p > 0.05). The conventional resin composite Z100 presented statistically higher VPS than both high viscosity bulk fill materials studied (p < 0.05), although it was statistically similar to the flowable bulk fill materials studied (p > 0.05). Both μCT and OCT methodologies enabled gap formation visualization, and images from both technologies could be associated. Gap formation was mostly observed for G1-Z100, G4-FBU, and G5-FBF. VPS% and pulpal gap formation could not be completely associated with each other for all groups and samples. Voids were observed in most of the resin composite fillings, and most VPS were observed in the occlusal area of the samples. Significance: Volumetric polymerization shrinkage was material-dependent, although bulk fill materials did not differ from each other. Both μCT and OCT enabled interfacial pulpal gap formation visualization. VPS and gap formation cannot be completely associated with one another.
Original languageAmerican English
Pages (from-to)1568-1575
Number of pages8
JournalDental Materials
Volume35
Issue number11
DOIs
StatePublished - 1 Nov 2019

Keywords

  • Bulk fill composites
  • Flowable composites
  • Gap formation
  • Internal adaptation
  • Micro-computed tomography
  • Micro-CT
  • Optical coherence tomography
  • Resin composites
  • Resin restoration
  • Volumetric polymerization shrinkage

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