Samer Mesmar1, N Dorin Ruse2. 1. Specialist prosthodontist in private practice, Montreal, QC, Canada. 2. Division of Biomaterials, Faculty of Dentistry, The University of British, Columbia, Vancouver, Canada.
Abstract
PURPOSE: Resin composite blocks (RCB) are advocated as alternative to ceramic blocks (CB). Prior to use, adherence to these materials should characterized. This study aimed to test the null hypothesis (H0 ) that material and surface treatment combinations do not influence interfacial fracture toughness (KIC ) of a self-cured adhesive resin cement [RelyX Ultimate (RXU)] to RCB or CB, under nonaged and aged conditions. MATERIALS AND METHODS: Two RCB, Lava Ultimate (LU) and Enamic (EN), and one CB, IPS e.max Press (EMP) were used. Half-size [(6 × 6 × 6 × 6 mm)] specimens were prepared for EMP (n = 30), EN (n = 30), and LU (n = 60). RCB specimens were prepared by wet cutting/grinding, while CB specimens were pressed. Surfaces of EMP and EN were preconditioned with hydrofluoric acid (5%); surfaces of LU were sandblasted with either 27 μm alumina (LUS) or 30 μm silica-modified alumina Rocatec soft (LUR). All specimens were bonded with Scotchbond Universal adhesive and RXU. Additionally, twenty (4 × 4 × 4 × 8 mm) RXU specimens were prepared. All specimens were stored in water at 37°C and tested after 1 and 60 days. Interfacial KIC was determined with the notchless triangular prism specimen KIC test. Results were analyzed with two-way ANOVA and Scheffé multiple means comparisons (α = 0.05). Preconditioned and selected fractured surfaces were characterized with scanning electron microscopy. RESULTS: At 24 hours, LUS-RXU and LUR-RXU had significantly higher interfacial KIC than EN-RXU and EMP-RXU and were not different from KIC of RXU. Aging lead to a significant decrease in KIC of RXU and interfacial KIC of LUS-RXU, LUR-RXU, and EMP-RXU; interfacial KIC of EN-RXU was not affected. Based on the results, H0 was rejected. CONCLUSION: Under the conditions of this study, at 24 hours, interfacial KIC of LUS-RXU and LUR-RXU was superior to EMP-RXU and EN-RXU. Aging in water at 37°C did not affect interfacial KIC of EN-RXU but adversely affected KIC of RXU and the other interfacial KIC . CLINICAL IMPLICATIONS: The results suggest that RXU and its adherence to LU and EMP deteriorates upon exposure to water at 37°C. In making clinical decisions related to material selection, practitioners should consider in vitro results.
PURPOSE: Resin composite blocks (RCB) are advocated as alternative to ceramic blocks (CB). Prior to use, adherence to these materials should characterized. This study aimed to test the null hypothesis (H0 ) that material and surface treatment combinations do not influence interfacial fracture toughness (KIC ) of a self-cured adhesive resin cement [RelyX Ultimate (RXU)] to RCB or CB, under nonaged and aged conditions. MATERIALS AND METHODS: Two RCB, Lava Ultimate (LU) and Enamic (EN), and one CB, IPS e.max Press (EMP) were used. Half-size [(6 × 6 × 6 × 6 mm)] specimens were prepared for EMP (n = 30), EN (n = 30), and LU (n = 60). RCB specimens were prepared by wet cutting/grinding, while CB specimens were pressed. Surfaces of EMP and EN were preconditioned with hydrofluoric acid (5%); surfaces of LU were sandblasted with either 27 μm alumina (LUS) or 30 μm silica-modified alumina Rocatec soft (LUR). All specimens were bonded with Scotchbond Universal adhesive and RXU. Additionally, twenty (4 × 4 × 4 × 8 mm) RXU specimens were prepared. All specimens were stored in water at 37°C and tested after 1 and 60 days. Interfacial KIC was determined with the notchless triangular prism specimen KIC test. Results were analyzed with two-way ANOVA and Scheffé multiple means comparisons (α = 0.05). Preconditioned and selected fractured surfaces were characterized with scanning electron microscopy. RESULTS: At 24 hours, LUS-RXU and LUR-RXU had significantly higher interfacial KIC than EN-RXU and EMP-RXU and were not different from KIC of RXU. Aging lead to a significant decrease in KIC of RXU and interfacial KIC of LUS-RXU, LUR-RXU, and EMP-RXU; interfacial KIC of EN-RXU was not affected. Based on the results, H0 was rejected. CONCLUSION: Under the conditions of this study, at 24 hours, interfacial KIC of LUS-RXU and LUR-RXU was superior to EMP-RXU and EN-RXU. Aging in water at 37°C did not affect interfacial KIC of EN-RXU but adversely affected KIC of RXU and the other interfacial KIC . CLINICAL IMPLICATIONS: The results suggest that RXU and its adherence to LU and EMP deteriorates upon exposure to water at 37°C. In making clinical decisions related to material selection, practitioners should consider in vitro results.