title: Effect of cyclic loading on the bond strength of class II restorations with different composite materials.
abstract: This study evaluated the effect of cyclic loading on the bond strength of Class II restorations using different composite materials. Class II preparations with gingival margins located in dentin were performed on the mesial surface of 80 bovine incisors. The teeth were randomly allocated to eight groups (n=10) according to resin composite (Filtek Z250, Filtek Supreme, Tetric Ceram HB and Esthet-X) and use of cyclic loading. The restorations were bonded with the Single Bond adhesive system. Simulated aging groups were cyclic loaded for 200,000 cycles with 80N load (2Hz). The specimens were vertically sectioned (two slabs per restoration) and further trimmed into an hour-glass shape at the adhesive interface to obtain a final bonded area 1 mm2. Samples were placed in an apparatus and tested under tension using a universal testing machine. The data were analyzed using two-way ANOVA and Tukey test with a 95% confidence level. Aged groups presented significantly lower means when compared to the groups that were not aged (p=0.03). However, significant differences among composite materials were not observed (p=0.17). Regardless of the restorative composite material used, it could be concluded that the bond strength of Class II restorations at the gingival wall was affected by simulated cyclic loading.
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil. dea.cavalcanti@uol.com.br
authors.forename: Andrea Nóbrega
authors.initials: AN
authors.lastname: Cavalcanti
authors.forename: Fabio Hiroyuki Ogata
authors.initials: FH
authors.lastname: Mitsui
authors.forename: Flávia
authors.initials: F
authors.lastname: Silva
authors.forename: Alessandra Rezende
authors.initials: AR
authors.lastname: Peris
authors.forename: Ana
authors.initials: A
authors.lastname: Bedran-Russo
authors.forename: Giselle Maria
authors.initials: GM
authors.lastname: Marchi
mesh_terms: D000134:Acid Etching, Dental; D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D001732:Bite Force; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003737:Dental Cavity Preparation / Q000145:classification; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent / Q000145:classification*; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry; D008422:Materials Testing; D011897:Random Allocation; D013314:Stress, Mechanical; D013718:Tensile Strength; D013997:Time Factors
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C466112:Esthet-X; C474035:Filtek Supreme; C444701:Filtek Z250; C121818:Tetric ceram; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate