Abstract— The purpose of this study was to examine the effect of the smear layer on the penetration depth of Sealapex, Roth 811, and CRCS root canal sealers into the dentinal tubules. Forty recently extracted, human single‐rooted teeth were used. The crowns were cut and removed at the cemento‐enamel junction level and the root canals were prepared to a #60 K‐file. The teeth were then randomly divided into two groups of 20, group A and group B. The smear layer was removed from all teeth in group A with EDTA and NaOCl. The smear layer remained in all teeth in group B. Two roots in each group were used as controls. Six roots from each group were obturated with Roth 811 sealer and gutta‐percha through lateral condensation. The same process was repeated using sealers CRCS and Sealapex. Each root was then divided in two and prepared for scanning electron microscope observation. The removal of the smear layer allowed penetration of all three sealers into the dentinal tubules to a depth of between 35 μm and 80 μm. Although the CRCS sealer penetrated only up to the 35 mm point, it offered better or complete obturation of the dentinal tubules. The presence of smear layer at the root canal walls obstructed the penetration of all sealers into the dentinal tubules.

The purpose of this in vitro study was to evaluate and compare the efficacy of three irrigating solutions after hand and mechanical instrumentation. Sixty intact, single, straight-rooted, human teeth were used in this study. They were instrumented using K-files sizes 15 to 50 with hand or mechanical instrumentation. Mechanical instrumentation was with one of two handpieces, the Endocursor or Endolift. Instrumentation time for each file was 1 min. Each change of file was followed by irrigation with 1 mL 1% NaOCl. A flush of 2 mL of one of three irrigating solutions Largal Ultra, Tubulicid Plus or 50% citric acid, was administered at the end of the instrumentation and a final flush of 5 mL distilled water completed the treatment. The specimens were prepared and viewed under the scanning electron microscope. There were no significant differences in the smear layers produced by the three methods of instrumentation. The use of Largal Ultra and Tubulicid Plus removed considerable amounts of the smear layer regardless of the method of instrumentation. The use of 50% citric acid, on the other hand, removed the smear layer only partially whilst producing rather diverse findings.

Properly prepared straight root canals of freshly extracted maxillary canines and central incisors were used to evaluate the sealing ability of the sectional thermoplasticized gutta-percha obturation technique, with or without sealer and the single-phase thermoplasticized gutta-percha filling technique. The teeth were divided into 3 groups (A, B, C) of 20 teeth and were obturated using the 3 thermoplasticized gutta-percha techniques. Group A: single phase with sealer; group B: sectional technique without sealer; and group C: sectional technique with sealer. The obturated teeth were immersed in India ink for 3 days followed by clearing procedures. The teeth were then examined under a stereo microscope and the linear leakage was recorded. Statistical unpaired Student's t-tests showed significantly less dye penetration in teeth obturated using the sectional technique with sealer (group C) than in teeth obturated with the single-phase technique with sealer (group A) or the sectional technique without sealer (group B).

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