title: Effect of intermediate agents and pre-heating of repairing resin on composite-repair bonds.
abstract: This study investigated the composite-to-composite microtensile bond strength and interfacial quality after using different combinations of intermediate agents and pre-curing temperatures of repairing resin. Forty-five composite discs (8x4 mm) of Gradia Direct Anterior (GC Corp), stored in a saline solution at 37 degrees C for one month, were sandblasted (50 microm aluminum oxide), cleaned (35% phosphoric acid) and randomly divided into three groups (n=15) according to the intermediate agent applied: (1) no treatment; (2) unfilled resin (Scotchbond Multi-Purpose Adhesive, 3M ESPE); (3) flowable composite (Gradia LoFlo, GC Corp). Each disc was incrementally repaired (8x8 mm) with the same resin as the substrate. For each group, three subgroups (n=5) were created, depending on the pre-curing temperature of the repairing resin-4 degrees C, 23 degrees C or 37 degrees C. Two bonded specimens per group were prepared to evaluate the composite-to-composite interfacial quality via scanning electron microscope. Microtensile bond strength measurements were performed with the remaining three specimens and failure mode was examined by stereomicroscopy. Two-way ANOVA revealed that temperature (p < 0.001), intermediate agent (p < 0.001) and the interaction (p = 0.002) significantly affected the repair strength. Post-hoc comparisons revealed that bond strengths were significantly lower using a 4 degrees C repairing resin in groups where intermediate agents were used. The highest bond strengths were recorded when flowable composite was used as an intermediate agent under each of the three temperature conditions. Interfacial quality improved by raising the resin temperature from 4 degrees C to 37 degrees C.
authors: Department of Dental Materials and Restorative Dentistry, University of Siena, Siena, Italy.
authors: Federica
authors: F
authors: Papacchini
authors: Elisa
authors: E
authors: Magni
authors: Ivana
authors: I
authors: Radovic
authors: Claudia
authors: C
authors: Mazzitelli
authors: Francesca
authors: F
authors: Monticellia
authors: Cecilia
authors: C
authors: Goracci
authors: Antonella
authors: A
authors: Polimeni
authors: Marco
authors: M
authors: Ferrari
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins; D001840:Dental Bonding; D003793:Dental Restoration, Permanent; D003799:Dental Stress Analysis; D006358:Hot Temperature; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011897:Random Allocation; D019279:Resin Cements; D018709:Statistics, Nonparametric; D013718:Tensile Strength; D014783:Viscosity
chemical_list: D003188:Composite Resins; C470230:Gradia; C523003:Gradia Direct LoFlo; D019279:Resin Cements; C084018:Scotchbond Multi-Purpose