Vol 15, No X, 2013 1 Repair Bond Strength in Aged Methacrylate- and Silorane-based Composites Atais Bacchi a / Rafael Leonardo Xediek Consani b / Mario Alexandre Coelho Sinhoreti c / Victor Pinheiro Feitosa d / Larissa Maria Assad Cavalcante e / Carmem Silva Pfeifer f / Luis Felipe Schneider g Purpose: To evaluate the tensile bond strength at repaired interfaces of aged dental composites, either dimeth- acrylate- or silorane-based, when subjected to different surface treatments. Materials and Methods: The composites used were Filtek P60 (3M ESPE, methacrylate-based) and Filtek P90 (silorane-based, 3M ESPE), of which 50 slabs were stored for 6 months at 37°C. The surface of adhesion was abraded with a 600-grit silicone paper and the slabs repaired with the respective composite, according to the fol- lowing surface treatment protocols: G1: no treatment; G2: adhesive application; G3: silane + adhesive; G4: sand- blasting (Al 2 O 3 ) + adhesive; G5: sandblasting (Al 2 O 3 ) + silane + adhesive. After 24-h storage in distilled water at 37°C, tensile bond strength (TBS) was determined in a universal testing machine (Instron 4411) at a crosshead speed of 0.5 mm/min. The original data were submitted to two-way ANOVA and Tukey’s test (α = 5%). Results: The methacrylate-based composite presented a statistically significantly higher repair potential than did the silorane-based resin (p = 0.0002). Of the surface treatments for the silorane-based composite, aluminum-ox- ide air abrasion and adhesive (18.5 ± 3.3MPa) provided higher bond strength than only adhesive application or the control group without surface treatment. For Filtek P60, the control without treatment presented lower repair strength than all other groups with surface treatments, which were statistically similar to each other. The interac- tion between the factors resin composite and surface treatment was significant (p = 0.002). Conclusion: For aged silorane-based materials, repairs were considered successful after sandblasting (Al 2 O 3 ) and adhesive application. For methacrylate resin, repair was successful with all surface treatments tested. Key words: resin composites, silorane, adhesive dentistry, bond strength. J Adhes Dent 2013; 15: xx-xx Submitted for publication: ?????; accepted for publication: ?????; XXX a PhD Student, Campinas State University, FOP/UNICAMP, Piracicaba, Brazil. Experimental design, hypothesis, manufactured repaired slabs, wrote manu- script. b Professor, Campinas State University, FOP/UNICAMP, Piracicaba, Brazil. Ex- perimental design, proofread manuscript. c Professor, Campinas State University, FOP/UNICAMP, Piracicaba, Brazil. ex- perimental design, statistical evaluation, proofread the manuscript. d PhD Student, Campinas State University, FOP/UNICAMP, Piracicaba, Brazil. Experimental design, performed TBS and fracture pattern analysis. e Professor, Fluminense Federal University, Niterói, RJ, Brazil. Experimental design, contributed substantially to discussion. f Professor, Oregon Health and Science University, Portland, OR, USA. Experi- mental design, contributed substantially to discussion. g Professor, Veiga de Almeida University and Fluminense Federal University, Niterói, RJ, Brazil. Idea, hypothesis, experimental design, proofread manu- script. Correspondence: Ataís Bacchi, Campinas State University, FOP/UNICAMP, Av. Limeira, 901 Piracicaba 13414-903, Brazil. Tel: +55 19 82088795, Fax: +55 19 3421 0144. e-mail: atais_bacchi@yahoo.com.br R esin-based composites (RBCs) are widely used in restorative dentistry due to their esthetics and their suitability for use with minimally invasive cavity prepara- tion. As filler technology advanced – allowing this mate- rial to replace amalgam – polymerization shrinkage, a main shortcoming of polymer-based materials, became an important concern. The methacrylate-containing ma- terials, largely used in clinical practice due to their wide commercial availability, have shrinkage values in the range of 1% to 5%. 13,22 More current materials instead make use of the ring-opening polymerization of silorane molecules in an attempt to overcome polymerization shrinkage. 36,40 The organic matrix is formed by silox- ane and oxirane components, and due to ring-opening cationic polymerization, silorane-based composites ex- hibit low shrinkage of approximately 1% by volume. 11,40 Moreover, in evaluations of degradation resistance, it was shown that silorane-based composites present C o p y r i g h t b y Q u i n t e s s e n z Alle Rechte vorbehalten