title: The influence of C-factor, flexural modulus and viscous flow on gap formation in resin composite restorations.
abstract: This study analyzed the influence of C-factor, flexural modulus and viscous flow on gap formation in resin composite restorations. Two resin composites, a mini-filled hybrid (P 60) and a nanofilled (Supreme), were used. The flexural modulus was obtained from bar-shaped specimens submitted to three-point bending. Viscous flow was obtained from the difference between the initial and final diameter of resin composite disks submitted to a load of 10 N for 120 seconds. Gap analysis was conducted in three types of cylindrical cavities (C-factor of 1.8, 2.6 and 3.4) that were prepared on the occlusal surfaces of human molars. The gap width at the dentin-resin composite interface was measured using a 3D scanning system (Talyscan 150). The data were analyzed by ANOVA and Student-Newman-Keuls' test, t-test and linear regression analysis (alpha = 0.05). The cavities with C-factor 3.4 presented the highest Gap formation (p < 0.0001). The lowest Gap formation was found in cavities restored with Supreme resin composite (p < 0.0001). P 60 presented significantly higher flexural modulus and lower viscous flow than Supreme (p < 0.0001). Regression analyses detected a significant influence of flexural modulus and viscous flow on gap formation (p < 0.05).
authors: Department of Restorative Dentistry, School of Dentistry, Federal Fluminense University, Rio De Janeiro, Brazil. emsilva@vm.uff.br
authors: Eduardo
authors: E
authors: Moreira da Silva
authors: Gustavo Oliveira
authors: GO
authors: dos Santos
authors: José Guilherme Antunes
authors: JG
authors: Guimarães
authors: Alexandre de Araújo Lima
authors: Ade A
authors: Barcellos
authors: Edwardo Martins
authors: EM
authors: Sampaio
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects; D003737:Dental Cavity Preparation / Q000379:methods*; D018772:Dental Marginal Adaptation; D003799:Dental Stress Analysis; D004548:Elasticity; D006801:Humans; D008027:Light; D016014:Linear Models; D008422:Materials Testing; D008963:Molar; D044367:Phase Transition; D018583:Pliability; D018709:Statistics, Nonparametric; D014783:Viscosity
chemical_list: D003188:Composite Resins; C474035:Filtek Supreme; C443708:P60 Condensible Resin Composite