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

Author(s)

Fronza, Bruna Marin ^[1] ; Rueggeberg, Frederick Allen ^[2] ; Braga, Roberto Ruggiero ^[3] ; Mogilevych, Borys ^[4] ; Silva Soares, Luis Eduardo ^[4] ; Martin, Airton Abrahao ^[4] ; Ambrosano, Glaucia ^[5] ; Giannini, Marcelo ^[1]

Affiliation

^[1] Univ Estadual Campinas, Piracicaba Dent Sch, Dept Restorat Dent, BR-13414903 Piracicaba, SP - Brazil

^[2] Georgia Regents Univ, Coll Dent Med, Dept Oral Rehabil, Augusta, GA 30912 - USA

^[3] Univ Sao Paulo, Sch Dent, Dept Biomat & Oral Biol, BR-05508000 Sao Paulo, SP - Brazil

^[4] Univ Paraiba Valley, Inst Res & Dev, BR-12244000 Sao Jose Dos Campos, SP - Brazil

^[5] Univ Estadual Campinas, Piracicaba Dent Sch, Dept Stat, BR-13414903 Piracicaba, SP - Brazil

• Document type: Journal article
• Source: Dental Materials; v. 31, n. 12, p. 1542-1551, DEC 2015.
• Web of Science Citations: 43

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. (C) 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 13/05247-4 - Evaluation of physicochemical properties of bulk-fill composite resins
• Grantee: Bruna Marin Fronza
• Support Opportunities: Scholarships in Brazil - Master