Evaluation of the efficiency of polymerization of composite resins in proximal restorations

• Autor(a) principal: Obeid, Alyssa Teixeira
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: http://www.teses.usp.br/teses/disponiveis/25/25148/tde-05092019-212152/
• topic: Composite resins; Hardness tests; Polimerização; Polymerization; Resinas compostas; Testes de dureza

Statement of the problem. The insertion and polymerization of the first resin composite layer in the proximal cavity of class II restorations require attention to achieve cervical sealing as well as good physical properties and clinical longevity. Objective. To evaluate the polymerization efficiency of four resin composites (Filtek Z250XT- 3M ESPE, Filtek One Bulk-Fill-3M ESPE, Filtek Bulk-Fill Flow-3M ESPE and Opus Bulk Fill- FGM) in the cervical region of class II restorations. Material and methods. Sixteen groups (n = 12) were prepared by inserting 2mm increments of the resin composites in a bipartite matrix and being cured with a lightsource of 1000mW/cm2 in continuous mode during 20 or 40 seconds directly on the material (M group) or through a slot preparation (S group) in typodont teeth and all were stored at 37 +/- 1°C, for 24 hours. The Knoop microhardness was evaluated with 25-g-load and 5-s dwell time. Data were analysed with three-way Anova and Tukeys HSD ( = 5%). Results. The results of relative hardness did not show significant difference for the M groups, regardless of the time and type of resin. All the resins had a relative hardness higher than 0.80. In contrast, for S groups, Z250 20s (0.39+0.08) and Bulk FGM 20s (0.47+0.04) showed significant lowest ratios. Bulk Flow 20s (0.70+0.12) and 40s (0.72+0.09), One Bulk 20s (0.65+0.05) and 40s (0.71+0.06) presented no statistical difference with group Z250 40s (0.63+0.05). Conclusion. It would beneficial to increase the time of photoactivation for resins Z250XT and Bulk FGM, differently for Bulk Flow and One Bulk in class 2 proximal slot restorations to ensure adequate hardening.