Monomer conversion, microhardness, internal marginal adaptation, and shrinkage stress of bulk-fill resin composites

Bruna Marin Fronza, Frederick Allen Rueggeberg, Roberto Ruggiero Braga, Borys Mogilevych, Luis Eduardo Silva Soares, Airton Abrahão Martin, Gláucia Ambrosano, Marcelo Giannini

Research output: Contribution to journalArticle

66 Scopus citations

Abstract

Objective To evaluate degree of conversion (DC), Knoop microhardness (KHN), internal marginal adaptation (IA), and polymerization shrinkage stress (PS) of one conventional and four bulk-fill composites. Methods Bulk-fill composites tested were Surefil SDR (SDR), Filtek Bulk-Fill (FBF), Tetric EvoCeram Bulk-Fill (TEC), and EverX Posterior (EXP). The conventional composite Herculite Classic (HER) was tested using both incremental and bulk-fill insertion techniques. Standardized Class I preparations (4-mm-depth) were made in extracted molars and restored with each product system (N = 5). After 1-week wet storage, restorations were cross-sectioned and DC and KHN were evaluated at four depths (1, 2, 3, and 4 mm) using confocal Raman spectroscopy and KHN techniques, respectively. Epoxy resin replicas of restorations were evaluated using scanning electron microscopy for IA. PS was determined using composite bonded to acrylic rods attached to a universal testing machine (N = 5). Results Within bulk-fill products, only SDR and FBF demonstrated similar DC at all depths, and KHN values did not statistically differ among depths, except for TEC. Neither placement method nor depth affected KHN or DC, except the DC of HER bulk-fill at 4 mm. Incrementally layered HER, and bulk-fills SDR and TEC demonstrated the lowest proportion of internal gaps. Highest and lowest PS values were measured for EXP and TEC, respectively. Significance DC with depth was not uniform among all bulk-fill materials, although no difference in KHN was found. Higher PS correlated positively with higher proportion of interfacial gaps. The incremental technique using conventional composite showed reduced gap formation.

Original languageEnglish (US)
Pages (from-to)1542-1551
Number of pages10
JournalDental Materials
Volume31
Issue number12
DOIs
StatePublished - Dec 1 2015

Keywords

  • Composite resin
  • Dental restoration
  • Gap formation
  • Hardness
  • Methacrylate
  • Polymerization
  • Stress

ASJC Scopus subject areas

  • Materials Science(all)
  • Dentistry(all)
  • Mechanics of Materials

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    Fronza, B. M., Rueggeberg, F. A., Braga, R. R., Mogilevych, B., Soares, L. E. S., Martin, A. A., Ambrosano, G., & Giannini, M. (2015). Monomer conversion, microhardness, internal marginal adaptation, and shrinkage stress of bulk-fill resin composites. Dental Materials, 31(12), 1542-1551. https://doi.org/10.1016/j.dental.2015.10.001