Evaluation of push-out bond strength of two fiber-reinforced composite posts systems using two luting cements in vitro

INTRODUCTION: The concept of using a “post” for the restoration of teeth has been practiced to restore the endodontically treated tooth. Metallic posts have been commonly used, but their delirious effects have led to the development of fiber-reinforced materials that have overcome the limitations of metallic posts. The use of glass and quartz fibers was proposed as an alternative to the dark color of carbon fiber posts as far as esthetics was concerned. “Debonding” is the most common failure in fiber-reinforced composite type of posts. This study was aimed to compare the push-out bond strength of a self-adhesive dual-cured luting agent (RelyX U100) with a total etch resin luting agent (Variolink II) used to cement two different FRC posts. MATERIALS AND METHODS: Eighty human maxillary anterior single-rooted teeth were decoronated, endodontically treated, post space prepared and divided into four groups (n = 20); Group I: D.T. light post (RTD) and Variolink II (Ivoclare vivadent), Group II: D.T. light post (RTD) and RelyX U100 (3M ESPE), Group III: Glassix post (Nordin) and Variolink II (Ivoclare vivadent) and Group IV: Glassix post (Nordin) and RelyX U100 (3M ESPE). Each root was sectioned to get slices of 2 ± 0.05-mm thickness. Push-out tests were performed using a triaxial loading frame. To express bond strength in megapascals (Mpa), load value recorded in Newton (N) was divided by the area of the bonded interface. After testing the push-out strengths, the samples were analyzed under a stereomicroscope. RESULTS: The mean values of the push-out bond strength show that Group I and Group III had significantly higher values than Group II and Group IV. The most common mode of failure observed was adhesive between dentin and luting material and between post and luting material. CONCLUSIONS: The mean push-out bond strengths were higher for Groups I and III where Variolink II resin cement was used for luting the fiber post, which is based on the total etch adhesive approach. In most of the samples, failure was observed between cement–dentine interface, followed by post–cement interface, which shows difficulty in bonding between post–cement–dentine interface.