Obturation of internally prepared cavities [simulating internal resorption] with three different techniques

There is controversy as to which instrumentation and/or obturation techniques to choose for the treatment of the internal resorption defects. This in vitro study compared the instrumentation and obturation quality of simulated internal resorption cavities [IRC] with 3 different techniques. Ninety extracted human roots were used and sectioned transversely 5 mm from the apex and hemi-circular cavities were prepared in both sections. The sections were glued back together using superglue and embedded in plaster mold, thus obtaining root canals with cavities simulating internal resorption. The samples were randomly divided into 3 groups of 30 roots and instrumented by protaper rotary files, hybrid technique, or stepback technique, then each group subdivided into three subgroups of 10 roots and obturated with cold lateral condensation, warm vertical compaction, or injectable thermoplasticized technique. After obturation, the samples were radiographed in Bucco-lingual and Mesiodistal view. After that, the plaster molds were removed, and the samples were then sectioned at the previous level and the quality of the obturation of the IRC were viewed under stereomicroscope. There was highly significant difference between protaper rotary files compared with hybrid and stepback techniques. The results of obturation techniques radiographically and by stereomicroscope showed that there was highly significant difference in between injectable thermo-plasticized compared with other two techniques. The pro-taper rotary files and injectable thermo-plasticized technique gave the best results for treatment of simulated internal resorption cavities [IRC]

Shear bond strength measurement of three different adhesive sealers to dentin and gutta-percha [in vitro study]

Bond strength of the adhesive sealers to both human dentin and gutta-percha is critical property for success of the root canal sealing. This in vitro study aimed to measure the shear bond strength [SBS] of three different adhesive sealers glassionomer based sealers [Ketac-Endo] and [Diaket] and epoxy resin-based sealer [AH 26] to both the gutta-percha and human dentin. Part I: The dentin substrate was obtained from single rooted human teeth. The dentin specimens were treated either with EDTA 15% or phosphoric acid 37% to achieve the removal of smear layer. Three adhesive sealers [glass-ionomer based sealers [Ketac-Endo] and [Diaket] and epoxy resin-based sealer [AH 26] were placed on the dentin surfaces both with and without the use of the bonding agent. Bond strength was tested using a single plane shear test assembly. Part II: Discs of gutta-percha with a diameter of 8 mm and thickness of 4mm were made by softening of the gutta-percha cones and fixed with plaster in rings. Four millimeter long sections of polyethylene tube filled with freshly mixed sealer were placed on the gutta-percha and tested using a single plane shear test assembly. By using t-test, the results revealed that there was highly significant difference between epoxy resin-based sealer and the two other glass-ionomer based sealers at p< 0.01 with in favor of the AH26 sealer. The bonding system and the dentin pretreatment increased the adhesive potential of the AH26 sealer which had higher shear bond strength than the two glassionomer based sealers