João Felipe Besegato1, Eduardo Inocente Jussiani2, Avacir Casanova Andrello2, Ricardo Vignoto Fernandes2, Fabio Martins Salomão3, Bruno Luiz Santana Vicentin2, Cássia Cilene Dezan-Garbelini4, Márcio Grama Hoeppner5. 1. Department of Restorative Dentistry, State University of Londrina - UEL, Rua Pernambuco 540, 86020-120 Londrina, PR, Brazil. Electronic address: besegato@outlook.com. 2. Department of Physics, State University of Londrina - UEL, Rodovia Celso Garcia Cid, Pr 445 Km 380, 86057-970 Londrina, PR, Brazil. 3. Department of Restorative Dentistry, Araçatuba Dental School, São Paulo State University - UNESP, Rua José Bonifácio 1193, 16015-050 Araçatuba, SP, Brazil. 4. Department of Oral Medicine and Pediatric Dentistry, State University of Londrina - UEL, Rua Pernambuco 540, 86020-120 Londrina, PR, Brazil. 5. Department of Restorative Dentistry, State University of Londrina - UEL, Rua Pernambuco 540, 86020-120 Londrina, PR, Brazil.
Abstract
OBJECTIVE: To investigate the effect of two light-curing protocols on mechanical behavior of three bulk-fill resin composites (BFRC) considering their optical properties. METHODS: One increment of 4 mm thickness of the bulk-fill resin composites Opus Bulk Fill, Tetric N-Ceram and Filtek Bulk Fill Flow were submitted to two different light-curing protocols: Sp - irradiance of 1000 mW/cm2 (20 s); Xp - irradiance of 3200 mW/cm2 (6 s). To assess the influence on the mechanical behavior it was studied polymerization shrinkage by X-ray microtomography (n = 3), Vickers hardness (n = 10) at the top and bottom surfaces of the samples, irradiance reaching the bottom surface (n = 3) and absorbance spectrum during the light-curing time interval (n = 3). Data were analyzed by two-way ANOVA test for parametric data and Kruskal Wallis test, followed by Wilcoxon or Mann-Whitney U post-test, for non-parametric data. RESULTS: All BFRCs contracted when light-cured, with greater contraction for Xp. Filltek Bulk Fill Flow showed highest polymerization shrinkage, for both Sp and Xp. All BFRCs showed minor hardness values on the bottom surface, with greater reduction for Xp. All BFRCs exhibited a decrease in irradiance at 4 mm depth. A decrease in absorbance intensity throughout the light-cure was observed, except for Opus Bulk Fill. CONCLUSIONS: Regardless BFRCs composition, the light-curing protocol with lower irradiance and longer exposure time results in lower polymerization shrinkage and higher hardness. The higher irradiance in a shorter time interval compromises the mechanical behavior of the resin composites, which may result in undesirable clinical outcomes.
OBJECTIVE: To investigate the effect of two light-curing protocols on mechanical behavior of three bulk-fill resin composites (BFRC) considering their optical properties. METHODS: One increment of 4 mm thickness of the bulk-fill resin composites Opus Bulk Fill, Tetric N-Ceram and Filtek Bulk Fill Flow were submitted to two different light-curing protocols: Sp - irradiance of 1000 mW/cm2 (20 s); Xp - irradiance of 3200 mW/cm2 (6 s). To assess the influence on the mechanical behavior it was studied polymerization shrinkage by X-ray microtomography (n = 3), Vickers hardness (n = 10) at the top and bottom surfaces of the samples, irradiance reaching the bottom surface (n = 3) and absorbance spectrum during the light-curing time interval (n = 3). Data were analyzed by two-way ANOVA test for parametric data and Kruskal Wallis test, followed by Wilcoxon or Mann-Whitney U post-test, for non-parametric data. RESULTS: All BFRCs contracted when light-cured, with greater contraction for Xp. Filltek Bulk Fill Flow showed highest polymerization shrinkage, for both Sp and Xp. All BFRCs showed minor hardness values on the bottom surface, with greater reduction for Xp. All BFRCs exhibited a decrease in irradiance at 4 mm depth. A decrease in absorbance intensity throughout the light-cure was observed, except for Opus Bulk Fill. CONCLUSIONS: Regardless BFRCs composition, the light-curing protocol with lower irradiance and longer exposure time results in lower polymerization shrinkage and higher hardness. The higher irradiance in a shorter time interval compromises the mechanical behavior of the resin composites, which may result in undesirable clinical outcomes.
Authors: Franco Mauricio; Julia Medina; Luzmila Vilchez; Oscar Sotomayor; César Muricio-Vilchez; Frank Mayta-Tovalino Journal: J Int Soc Prev Community Dent Date: 2021-04-15