Objectives: The aim of this in vitro study was to evaluate the effect on bond strength of composite repairs using flowable resin as an intermediate agent . Methods: Thirty truncated cones were fabricated with Grandio SO (VOCO) and were thermo-cycled for 5000 cycles for artificial aging. Specimen’s surface was sandblasted with aluminum oxide, cleaned with air/water spray and conditioned with phosphoric acid for 15 s. One coat of Admira Bond Adhesive (VOCO) was applied and light cured for 20 s. Specimens were divided into 3 groups according to the repairing material used (n = 10): Conventional Resin – Grandio SO (R), A thin layer of Flowable resin – Grandio SO Heavy Flow + conventional Resin (FR), and Flowable resin (F). Over the original specimens, a sectional cone-shaped teflon matrix was hold in position and the cones were built according the groups described above. Other thirty specimens were built, 10 of each group, simulating a restoration without repair. Specimens were submitted to tensile stress in a universal testing machine. Data were recorded in MPa and evaluated with ANOVA, Tukey´ s and non-paired “t’’ tests. Results: ANOVA showed significant differences among groups in which repair was performed (p < 0.00). The results of Tukey´ s test for those groups were: R (19.89 + 5.31)ab; F+R (14.49 + 5.59)a; F (20.91 + 3.99)b. The groups followed by the same letter did not show statistical differences. Non-paired “t” test showed that groups R and F repairs were similar to the correspondent groups simulating restoration without repair. Conclusions: The repair with conventional or flowable composite produced bond strength values similar to cohesive strength of the same materials. The use of a thin layer of flowable resin as an intermediate agent in composite repair decreased the bond strength when compared the same method for restoration.
Objectives: The aim of this in vitro study was to evaluate the effect on bond strength of composite repairs using flowable resin as an intermediate agent . Methods: Thirty truncated cones were fabricated with Grandio SO (VOCO) and were thermo-cycled for 5000 cycles for artificial aging. Specimen’s surface was sandblasted with aluminum oxide, cleaned with air/water spray and conditioned with phosphoric acid for 15 s. One coat of Admira Bond Adhesive (VOCO) was applied and light cured for 20 s. Specimens were divided into 3 groups according to the repairing material used (n = 10): Conventional Resin – Grandio SO (R), A thin layer of Flowable resin – Grandio SO Heavy Flow + conventional Resin (FR), and Flowable resin (F). Over the original specimens, a sectional cone-shaped teflon matrix was hold in position and the cones were built according the groups described above. Other thirty specimens were built, 10 of each group, simulating a restoration without repair. Specimens were submitted to tensile stress in a universal testing machine. Data were recorded in MPa and evaluated with ANOVA, Tukey´ s and non-paired “t’’ tests. Results: ANOVA showed significant differences among groups in which repair was performed (p < 0.00). The results of Tukey´ s test for those groups were: R (19.89 + 5.31)ab; F+R (14.49 + 5.59)a; F (20.91 + 3.99)b. The groups followed by the same letter did not show statistical differences. Non-paired “t” test showed that groups R and F repairs were similar to the correspondent groups simulating restoration without repair. Conclusions: The repair with conventional or flowable composite produced bond strength values similar to cohesive strength of the same materials. The use of a thin layer of flowable resin as an intermediate agent in composite repair decreased the bond strength when compared the same method for restoration.
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