New methodology to evaluate bond strength of root-end filling materials.

Jorge Henrique Stefaneli Marques,Carlos Eduardo Saraiva Miranda,Manoel Damião Sousa-Neto,Liviu Steier,Jardel Francisco Mazzi-Chaves,Fuad Jacob Abi Rached-Júnior,Silvio Rocha Correa Da Silva,Yara Teresinha Corrêa Silva-Sousa

doi:10.1590/0103-6440201300189

Jorge Henrique Stefaneli Marques, Carlos Eduardo Saraiva Miranda + Show 6 more

Open Access

https://doi.org/10.1590/0103-6440201300189

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Abstract

This study evaluated the bond strength of root-end filling materials to root-end cavities using a new methodology. Twenty maxillary central incisors were subjected to biomechanical preparation (#80 hand file) and sectioned transversally 2 mm short of the apex and 4 mm coronally to this point. The root cylinders were embedded in acrylic resin and positioned at 45° to the horizontal plane for preparation of root-end cavities with a diamond ultrasonic retrotip. Two groups (n=10) were formed according to the root-end filling material: MTA and Super EBA. A gutta-percha cone (#80) was tug-backed at the limit between the canal and the root-end cavity. The cavity was filled and the gutta-percha cone was removed after complete setting of the sealer. The specimens were placed in an Instron machine with the root-end filling turned downwards. The push-out shaft was inserted in the space previously occupied by the gutta-percha cone and run at a crosshead speed of 1.0 mm/min for pushing out the root-end filling material. Data were analyzed by ANOVA (α=5%). Super EBA (6.03±1.31) presented higher bond strength (MPa) than MTA (1.81±0.45) (p>0.05). There was a predominance of cohesive failures for Super EBA and mixed for MTA. The protocol of specimen preparation is effective and introduces a specific methodology for assessing bond strength of root-end filling materials to dentin. Among the materials, Super EBA presented the highest bond strength.

Highlights

Selection of a root-end filling material that has adequate physicochemical properties and fulfills the criteria of biocompatibility, cytotoxicity, apical seal and marginal adaptation is of utmost importance for a good clinical prognosis
No specific methodology is available for testing the bond strength of root-end filling materials to root dentin and all studies derive their results from the push-out test originally designed for root canal sealers [1,2,8,9,10]
Middle root third slices have been frequently used as a substrate for evaluating the bond strength of root-end filling materials [1,2,8,9,10,11], without considering the fact that the density, diameter and number of dentinal tubules in this region are greater than in the apical third [12]

Summary

Introduction

Selection of a root-end filling material that has adequate physicochemical properties and fulfills the criteria of biocompatibility, cytotoxicity, apical seal and marginal adaptation is of utmost importance for a good clinical prognosis. There is not a specific methodology for evaluating the bond strength of root-end filling materials and, for this reason, the same specimen preparation protocol and testing standards originally designed for root canal sealers through push-out test [3,4,5,6] have been employed in retrofilling research as well.

Results

Conclusion