Push-Out Bond Strength and SEM Evaluation in Roots Filled with Two Different Techniques Using New and Conventional Sealers

Abstract

The aim of this study was to evaluate the influence of calcium-silicate-based sealer (Endosequence-BC-Sealer) in roots, filled with thermo-plasticized injectable technique aided by Calamus-Flow-Delivery-System, on bond strength to radicular dentin, in comparison with conventional epoxy-resin-based sealer (AH-Plus) along with cold-lateral-compaction technique. Root canals of mandibular-premolar teeth (n = 80) were instrumented using Protaper Universal rotary files and were randomly divided into four experimental groups (n = 20) as follows: (1) AH-Plus + cold-lateral-compaction technique; (2) Endosequence-BC-Sealer + cold-lateral-compaction technique; (3) AH-Plus + thermo-plasticized injectable technique; and (4) Endosequence-BC-Sealer + thermo-plasticized injectable technique. Horizontal disc shaped samples from each group (n = 60/group) were obtained and push-out bond strength testing was performed at a cross-head speed of 0.5 mm/min. Data were analyzed statistically using nonparametric Kruskal-Wallis analysis and Mann-Whitney test (p < 0.001). The statistical analysis revealed a significant difference amongst the groups (p < 0.001). The highest bond strength values were found in group 1 compared with all the other experimental groups (p < 0.001), whereas the lowest bond strength values were found in group 4 (p < 0.001). It was concluded that thermo-plasticized injectable technique with Calamus-Flow-Delivery-System lowered the bond strengths of the sealers, especially Endosequence-BC-Sealer. Therefore, this technique is not recommended to calcium-silicate-based sealers. Further studies are needed to confirm the findings of this study.

Keywords: Calamus Flow Delivery System; Endosequence-BC-Sealer; bond strength; obturation materials; push-out test.

Figure 1

(A) Scanning electron micrograph (×2000) of a sample in group 1 (AH/CLC). Radicular dentinal wall is densely covered with AH Plus sealer and resin tags (indicated with an arrow) occluding the dentinal tubules; (B) Scanning electron micrograph (×2000) of a sample in group 3 (AH/C). Dentinal wall is partly covered with the sealer and tags protruding from the sealer; (C) Scanning electron micrograph (×2000) of a sample in group 2 (ES/CLC). The area is covered with the sealer but there is no visible sealer tags in dentinal tubules; (D) Scanning electron micrograph (×2000) of a sample in group 4 (ES/C) where there is almost debonding of the sealer from the radicular dentinal wall and no sign of tag elements.