Daniel Awad1, Nicoleta Ilie. 1. Department of Restorative Dentistry, Dental School, Ludwig-Maximilians University, Goethestrasse 70, Munich, Germany.
Abstract
OBJECTIVE: The aim of this study was to investigate the effect of polymerisation and ageing on the incremental bond strength (IBS) and fracture mechanics of experimental and commercial, well established ormocer-based materials. METHODS: An experimental dimethacrylate-diluent-free ormocer was compared with two commercial products (Admira (VOCO); Ceram X Duo (Dentsply)). For Ceram X Duo, the strength between dentin shades (DD) and between dentin and enamel shades (DE) was measured. In order to simulate clinical conditions, when a direct access to the composite surface is impeded, the curing unit was applied at different distances (1, 3 or 6 mm) from the sample's surface. IBS was measured after the samples were stored in distilled water (24 h/37 °C) and after ageing (5,000 cycles between 5 and 55 °C followed by storage (28 days/37 °C) in distilled water). Additionally, the degree of cure (DC) was measured in a thin film (~50 μm). A multivariate analysis, an additional one-way ANOVA with Tukey HSD post hoc test (α = 0.05), an independent t test (α = 0.05), and Weibull statistics were used to assess the results. RESULTS: After 24 h, the values for IBS were statistically the same. Differences revealed after ageing, whereby the experimental material achieved the significant highest and Admira the lowest results. By evaluating after 24 h and after ageing, the experimental material obtained the smallest Weibull modulus "m". The predominant breaking mechanism is cohesive, even though the number decreases in favour for the mixture and adhesive fractures after ageing. Clear differences arose with regard to DC. The experimental material reached considerably lower values (31.9-33.2 %) unlike Ceram X Duo (45.6-48.3 %) and Admira (52.9-58.8 %). CONCLUSIONS: The IBS and the DC are far more dependent on the parameter filler volume percent and material than on the polymerisation distance. CLINICAL SIGNIFICANCE: A dimethacrylate-diluent-free ormocer matrix offers a better stability opposite ageing but achieves a lower DC and reliability.
OBJECTIVE: The aim of this study was to investigate the effect of polymerisation and ageing on the incremental bond strength (IBS) and fracture mechanics of experimental and commercial, well established ormocer-based materials. METHODS: An experimental dimethacrylate-diluent-free ormocer was compared with two commercial products (Admira (VOCO); Ceram X Duo (Dentsply)). For Ceram X Duo, the strength between dentin shades (DD) and between dentin and enamel shades (DE) was measured. In order to simulate clinical conditions, when a direct access to the composite surface is impeded, the curing unit was applied at different distances (1, 3 or 6 mm) from the sample's surface. IBS was measured after the samples were stored in distilled water (24 h/37 °C) and after ageing (5,000 cycles between 5 and 55 °C followed by storage (28 days/37 °C) in distilled water). Additionally, the degree of cure (DC) was measured in a thin film (~50 μm). A multivariate analysis, an additional one-way ANOVA with Tukey HSD post hoc test (α = 0.05), an independent t test (α = 0.05), and Weibull statistics were used to assess the results. RESULTS: After 24 h, the values for IBS were statistically the same. Differences revealed after ageing, whereby the experimental material achieved the significant highest and Admira the lowest results. By evaluating after 24 h and after ageing, the experimental material obtained the smallest Weibull modulus "m". The predominant breaking mechanism is cohesive, even though the number decreases in favour for the mixture and adhesive fractures after ageing. Clear differences arose with regard to DC. The experimental material reached considerably lower values (31.9-33.2 %) unlike Ceram X Duo (45.6-48.3 %) and Admira (52.9-58.8 %). CONCLUSIONS: The IBS and the DC are far more dependent on the parameter filler volume percent and material than on the polymerisation distance. CLINICAL SIGNIFICANCE: A dimethacrylate-diluent-free ormocer matrix offers a better stability opposite ageing but achieves a lower DC and reliability.
Authors: Juliana Malacarne; Ricardo M Carvalho; Mario F de Goes; Nadia Svizero; David H Pashley; Franklin R Tay; Cynthia K Yiu; Marcela Rocha de Oliveira Carrilho; Marcela Rocha de Oliveira Carrilho Journal: Dent Mater Date: 2006-01-06 Impact factor: 5.304