Effect of relining on fiber post retention to root canal

André Luís Faria-E-Silva,Luís Roberto Marcondes Martins,Celso De Freitas Pedrosa-Filho,Daniele Machado Da Silveira,Murilo De Sousa Menezes

doi:10.1590/s1678-77572009000600012

Abstract

One of the clinically relevant problems dentists face when restoring endodontically treated teeth is the mismatch between fiber post and post space diameters, which results in an excessively thick resin cement layer. Fiber post relining appears as a solution for this problem.Objectives:The aim of this study was to evaluate the effect of fiber post relining with composite resin on push-out bond strength.Material and Methods:Twenty bovine incisors were selected to assess post retention. The crowns were removed below the cementoenamel junction and the root canals were treated endodontically and flared with diamond burs. The roots were allocated into two groups (n=10): G1: fiber posts without relining and G2: fiber posts relined with composite resin. The posts were cemented with a dual-cured resin cement and the specimens were sectioned transversally. Three 1.5-mm thick slabs were obtained per root and identified as cervical, medium and apical thirds. The push-out test was performed at a crosshead speed of 0.5 mm/min until post dislodgement occurred. The failure mode of fractured specimens was analyzed under scanning electron microscopy. Data were analyzed by split-plot ANOVA and post-hoc Tukey's test at a pre-set alpha of 0.05.Results:Relined fiber posts presented higher retention values than non-relined post in all thirds. No statistically significant differences (p>0.05) were found among thirds for relined posts. All failures occurred at the interface between resin cement and root dentin.Conclusions:Relining with composite resin seems to be an effective method to improve the retention of fiber posts to flared root canals.

Highlights

Intraradicular posts are commonly used to restore endodontically treated teeth when their remaining coronal tissue can no longer provide adequate support and retention for the restoration[11,16]
The aim of this study was to evaluate the effect of post relining with composite resin on the push-out bond strength of fiber posts luted to flared root canals
The scanning electron microscopy (SEM) images showed that all failures occurred at the interface between the resin cement and root dentin

Summary

Introduction

Intraradicular posts are commonly used to restore endodontically treated teeth when their remaining coronal tissue can no longer provide adequate support and retention for the restoration[11,16]. Despite the high retention and thin cement layer, these conventional posts present high elastic modulus and can lead to root fracture, according to several in vitro studies[8,20], though clinical evaluations have presented high success rates for cast metal posts[1,8,17] Another option to restore endodontically treated tooth is to use fiber posts. Flared canals from carious extension, trauma, pulpal pathosis and iatrogenic misadventure compromise the adaptation of fiber post to canal walls[6] In these two cases, if the post does not fit well, especially at the coronal level, the resin cement layer would be excessively thick, and bubbles are likely to form in it, predisposing to de-bonding[14]

Objectives

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Results

Conclusion