Abstract
BackgroundSecondary caries, degradation of the dentin-resin interface and fracture of the restoration are the most common forms of failure. The aim of this study was to assess the interfacial fracture toughness of three different adhesive approaches and to compare their fracture toughness after surface treatment with antioxidant.Material and MethodsSeventy two dentin blocks with 3×4mm dimension and 3mm thickness were prepared and attached to precured 3×4×12mm composite blocks from both sides. Six adhesive groups (N=12), All-bond universal, Scotchbond universal and Clearfil SE bond with or without antioxidant treatment (Sodium Ascorbate 10% )were applied to dentin surfaces, a 160µ polyethylene paper formed the chevron in adhesive-dentin interfaces. Chevron-notched beam fracture toughness was measured following a modified ISO 24370 standard. The uniform composite-dentin-composite block was subjected to a 4-point test in universal machine. Data were analyzed by Kruskal-Wallis, Wilcoxon signed-rank and Mann-Whitney tests (α =0.05).ResultsDifferent adhesive approaches yielded different significant in fracture toughness rates. A significant increase of fracture toughness was observed between adhesive groups after antioxidant surface treatment. The difference in fracture toughness between Scotchbond universal and All-bond universal were significant.ConclusionsThe highest value of fracture toughness was reported for Clearfil SE bond and the lowest value was found for All-bond universal. Sodium ascorbate as antioxidant surface treatment had a significant effect in increasing the fracture toughness. Key words:Chevron-notched beam fracture toughness, fracture toughness, dentin, adhesive, antioxidant.
Highlights
Secondary caries, degradation of the dentin‒resin interface and fracture of the restoration are the most common failure forms of composite resin restorations [1]
The hypotheses tested were: 1) There is no difference in interfacial fracture toughness between different adhesive approaches and 2) Surface treatment with antioxidants has no effect on the bond strength of adhesive to dentin
The significant increase of fracture toughness was shown for all adhesive groups with antioxidant surface treatment (Table 3)
Summary
Degradation of the dentin‒resin interface and fracture of the restoration are the most common failure forms of composite resin restorations [1]. The positive effect of these collagen crosslinkers on the bond strength of a self-etch adhesive to deep dentin has been reported in the literature [7] It seems that the efficacy of antioxidant depends on the type of adhesive system [11]. The hypotheses tested were: 1) There is no difference in interfacial fracture toughness between different adhesive approaches and 2) Surface treatment with antioxidants has no effect on the bond strength of adhesive to dentin. Six adhesive groups (N=12), All-bond universal, Scotchbond universal and Clearfil SE bond with or without antioxidant treatment (Sodium Ascorbate 10% )were applied to dentin surfaces, a 160μ polyethylene paper formed the chevron in adhesive-dentin interfaces. Sodium ascorbate as antioxidant surface treatment had a significant effect in increasing the fracture toughness
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