Abstract
The aim of this study was to evaluate the bond strength of a composite resin to glass-fiber post (GFP) treated or not with phosphoric acid, silane coupling agent, and unfilled resin. GFPs were etched or not with 37% phosphoric acid and different surface coating applied: silane coupling agent, unfilled resin, or both. Composite resin blocks were built around a 4-mm height on the GFP. Unfilled resin (20 s) and composite resin (40 s) were light activated by a light-emitting diode unit. The specimens were stored in distilled water at 37 °C for 24 h. Microtensile bond test was performed using a mechanical testing machine until failure (n=10). The data were analyzed using two-way ANOVA followed by Student-Newman-Keuls' test (p<0.05). Failure modes were classified as adhesive, mixed, or cohesive failures. Additional specimens (n=3) were made to analyze the bonded interfaces by scanning electron microscopy. The statistical analysis showed the factor 'surface coating' was significant (p<0.05), whereas the factor 'HP etching' (p=0.131) and interaction between the factors (p=0.171) were not significant. The highest bond strength was found for the silane and unfilled resin group (p<0.05). A predominance of adhesive and cohesive failures was found. Differences regarding the homogeneity and thickness of the unfilled resin layer formed by different GFP surface treatments were observed. The application of silane and unfilled resin can improve the bond strength between GFP and resin composite.
Highlights
Several clinical failures of endodontically treated teeth are often associated with post cementation flaws [1]
Different restorative materials can be used in clinical practice, so it is difficult to predict the clinical performance of restorations anchored by glassfiber post (GFP) in relation to incompatibilities between adhesives and resin cements or composites [6]
The acid etch did not present influence on the bond strength, when silanization of the post was not carried out, the use of the HP etching before the unfilled resin increased the bond strength between composite resin and GFP (p=0.05)
Summary
Several clinical failures of endodontically treated teeth (e.g. root fracture) are often associated with post cementation flaws [1]. The glass-fiber posts (GFPs) have two important advantages in relation to other types of posts: [1] the elastic modulus close to that of dentin, and [2] the core build-ups cemented by an adhesive technique [2,3]. These characteristics may improve the retention as well as the mechanical performance of the restored teeth endodontically treated [4]. Different restorative materials can be used in clinical practice, so it is difficult to predict the clinical performance of restorations anchored by GFPs in relation to incompatibilities between adhesives and resin cements or composites [6]
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