Analysis of gap formation at tooth-composite resin interface: effect of C-factor and light-curing protocol

• Published in: Journal of applied oral science Vol. 15; no. 4; pp. 270 - 274
• Main Authors: dos Santos, Gustavo Oliveira, da Silva, Antônio Henrique Monteiro da Fonseca Thomé, Guimarães, José Guilherme Antunes, Barcellos, Alexandre de Araújo Lima, Sampaio, Eduardo Martins, da Silva, Eduardo Moreira
• Format: Journal Article
• Language: English
• Published: Brazil Faculdade de Odontologia de Bauru da Universidade de São Paulo 01.08.2007; Faculdade De Odontologia De Bauru - USP; University of São Paulo
• Subjects: C-Factor; Composite resins; DENTISTRY, ORAL SURGERY & MEDICINE; Gap formation; Light-curing protocol; Original; Polymerization shrinkage; Light-curing protocol; C-Factor; Gap formation; Composite resins; Polymerization shrinkage
• ISSN: 1678-7757; 1678-7765; 1678-7765; 1678-7757
• DOI: 10.1590/s1678-77572007000400006

The aim of this study was to evaluate the effect of C-factor and light-curing protocol on gap formation in composite resin restorations. Cylindrical cavities with 5.0 mm diameter and three different depths (A=1.0, B=2.0 and C=3.0 mm) were prepared on the occlusal surface of 30 human molars and restored in a single increment with P 60. The composite resin was light-cured according to two protocols: standard - 850 mW/cm(2) / 20 s and gradual - 100 up to 1000 mW/cm(2) / 10 s + 1000 mW/cm(2) / 10 s. After storage in distilled water (37 degrees C/7 days), the restorations were cut into three slices in a buccolingual direction and the gap widths were analyzed using a 3D-scanning system. The data were submitted to ANOVA and Student-Newman-Keuls test (alpha=0.05). ANOVA detected a significant influence for the C-factor and light-curing protocol as independent factors, and for the double interaction C-factor vs. light-curing protocol. Cavities with higher C-factor presented the highest gap formation. The gradual light-curing protocol led to smaller gap formation at cavity interfaces. The findings of this study suggest that the C-factor played an essential role in gap formation. The gradual light-curing protocol may allow relaxation of composite resin restoration during polymerization reaction.