New Methodology to Evaluate Bond Strength of Root-End Filling Materials

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.

Physicochemical Properties and Dentin Bond Strength of a Tricalcium Silicate-Based Retrograde Material

“…The dentin bond strength evaluation used in the present study was based on Nunes et al (17), which also used root dentin slices with the canal space enlarged by conic diamond drill. With the purpose of assessing the bond strength of root-end filling materials to the apical dentin, Marques et al (18) proposed a new methodology using ultrasound tips to prepare the root-end cavities. Different from this study, the root canal space of the apical dentin was enlarged using diamond drills instead of ultrasound tips aiming to produce root-end cavities with standardized dimensions and to avoid the influence of other variables on bond strength values, such as ultrasound intensity, inclination of the tip during preparation and homogeneous grinding of the dentin walls.…”

Push-out bond strength of different tricalcium silicate-based filling materials to root dentin

“…20 This secction of the roots were embedded individually in aluminum rings (16 mm in diameter and 4 mm in height) containing clear self-curing acrylic resin 20 . The specimens were positioned in a device at 45° to the horizontal plane during preparation and restoration of the root-end cavities stainless steel.…”

Push-out Bond Strength of Root-end Filling Materials

“…Progressive compression test was performed with the force applied from cervical to apical at 1 mm/min speed, from the contact of the device tip to root-end filling material displacement, as used in similar studies (1). The cylindrical tip had 1.3 mm diameter and maintained contact with sealer (15).…”

“…Push-out mechanical tests have been used to evaluate bond strength of filling materials and posts to root dentin (1). However, few studies evaluated the bond strength of root-end filling materials to dentinal walls after retrograde preparation.…”

“…The bond strength between root dentin and root-end filling material should provide adaptation and increased interface between material and dentin (1). Thus, the bond strength of endodontic materials has been evaluated by push-out tests.…”