Fábio Herrmann Coelho de Souza

Influence of filling technique and bevel preparation on marginal sealing of conventional and low shrinkage composite restorations

AIM: The aim of this study was to evaluate two composite restorations (conventional methacrylate-based and low shrinkage-based silorane), associated or not to beveling and incremental technique, in relation to the microleakage and marginal gap formation tests. MATERIAL AND METHODS: 30 sound human molars had their mesial and distal surfaces prepared with and without bevel. The teeth were divided into six groups according to the type of resin (conventional nanofilled or silorane resin), and restorative filling technique (incremental technique or builk). Microleakage and marginal gap formation data were statistically analyzed by Kruskal-Wallis and Chi-Square tests, with a significance level set at 5%. RESULTS : Group 1 (Z350 XT, without bevel, incremental technique) presented highest rate of microleakage and marginal gap in most of the restorations, with statistically significant differences. Groups 4 and 6 (P90, beveled, builk and P90, beveled and incremental technique) had lower rates of microleakage and absence of marginal gaps in most of the restorations. CONCLUSION : It’s concluded that the silorane showed lower rates of marginal gaps and microleakage, when compared to the conventional methacrylate-based resin. Bevel preparation was effective in reducing microleakage and marginal gaps for both resins used. Incremental technique was not necessary when associated with low shrinkage composite resin.

Efeito da intensidade de luz, distância e tempo de fotoativação sobre a interface esmalte-resina composta - análise por microscopia eletrônica de varredura

The aim of this study was to analyze the marginal adaptation in enamel / composite resin interface by scanning electronic microscopy when varying light intensity, distance and light curing time of the material. Twelve teeth were used for preparing forty-eight cavities (2,2 mm diameter x 4 mm deep) in buccal, lingual, mesial and distal surface). The cavities were restored applying a nanofilled resin (SupremeTM, 3M-ESPE) in a single layer, and cured by the following variables: 180 or 580 mW.cm-2, 20 or 40 seconds of irradiation time, 0 mm or 8 mm of distance. The groups were described as: G1 - 20s x 180 mW.cm-2 x 0 mm; G2 - 40s x 180 mW.cm-2 x 0 mm; G3 - 20s x 580 mW.cm-2 x 0 mm; G4 - 40s x 580 mW.cm-2 x 0 mm; G5 - 20s x 180 mW.cm-2 x 8 mm; G6 - 40s x 180 mW.cm-2 x 8 mm; G7 - 20s x 580 mW.cm-2 x 8 mm; G8 - 40s x 580 mW.cm-2 x 8 mm. The restorations were prepared for SEM evaluation intending to analyze enamel / composite resin interface. The results were submitted to Kruskal-Wallis analysis (α = 0,05). Groups 1, 2, 5 and 6 showed better marginal fitting when compared to groups 3, 4 and 7. Group 8 did not show statistical difference. It is possible to conclude that, between groups, the less marginal adaptation was found at the low intensity. Both light curing time and distance did not show influence on marginal adaptation.