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Aim: The aim of this study was to evaluate the cleaning ability of the Self-Adjusting File (SAF) system in terms of removal of debris and smear layer., Methodology: Root canal preparations were performed in 20 root canals using an SAF operated with a continuous irrigation device. The glide path was initially established using a size 20 K-file followed by the SAF file that was operated in the root canal via a vibrating motion for a total of 4 minutes. Sodium hypochlorite (3%) and EDTA (17%) were used as continuous irrigants and were alternated every minute during this initial 4-minute period. This was followed by a 30-second rinse using EDTA applied through a nonactivated SAF and a final flush with sodium hypochlorite. The roots were split longitudinally and subjected to scanning electron microscopy (SEM). The presence of debris and a smear layer in the coronal, middle, and apical thirds of the canal were evaluated through the analysis of the SEM images using five-score evaluation systems based on reference photographs., Results: The SAF operation with continuous irrigation, using alternating irrigants, resulted in root canal walls that were free of debris in all thirds of the canal in all (100%) of the samples. In addition, smear layer-free surfaces were observed in 100% and 80% of the coronal and middle thirds of the canal, respectively. In the apical third of the canal, smear layer-free surfaces were found in 65% of the root canals., Conclusions: The operation of the SAF system with continuous irrigation coupled with alternating sodium hypochlorite and EDTA treatment resulted in a clean and mostly smear layer-free dentinal surface in all parts of the root canal., (Copyright (c) 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Objective: The purpose of this study was to assess in vitro the effect of commonly used gutta-percha solvents on the microhardness of human enamel and dentin., Study Design: Crowns of human teeth were cut and treated with chloroform, xylene, and halothane. Treatment consisted of exposing the specimens for 5 or 15 minutes to the test solvents. Acid-treated and saline-treated specimens served as controls. After each treatment period, the specimens were rinsed, dried, and prepared for Vicker's microhardness analysis. Vicker's microhardness values for each specimen were recorded before and after treatment, and the differences were statistically compared., Results: A statistically significant decrease in enamel and dentin microhardness was found in most solvent-treated groups; the amount of the decrease was directly related to the exposure time., Conclusions: Chloroform, xylene, and halothane may cause a significant softening effect on both enamel and dentin. This softening is already apparent after 5 minutes of treatment.

Objectives. The aim of the present study was to evaluate the effect of a thin layer of flowable composite on microleakage in Class II direct packable composite resin restorations on young permanent teeth in vitro. Methods. Twenty sound human premolars and molars extracted for orthodontic reasons were selected for this study. The teeth were randomly assigned into two groups of 10 teeth each (groups A and B). Class II cavities were prepared as uniformly as possible in the mesial and distal aspects of each tooth. The gingival margin extended apically approximately 0·5 mm beyond the cemento-enamel junction, in the dentin. Cavities in group A were restored with packable composite and Alert®/Flow-it® flowable composite, while groups B cavities were restored with Pyramid®/Aeliteflo®. The control cavities in groups A1 and B1 were restored with only packable composite. The teeth were immersed in 2% methylene blue solution for 24 h to allow dye penetration into possible existing gaps between the tooth substance and the restorative material. All teeth were subjected to thermocycling. Results. The dye penetration ranged between 6·6 and 7·2 mm. No significant difference was found between the control and the experimental groups. Conclusion. The use of flowable composite resin as intermediate material does not reduce microleakage. [ABSTRACT FROM AUTHOR]