Farklı Döner Eğe Sistemlerinin Kök Kanallarının Temizliği, Obturasyonu ve Apikalden Taşan Materyal Miktarı Üzerindeki Etkilerinin İncelenmesi.
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Evaluation of the effects of different rotary nickel-titanium file systems on root canal cleanliness, obturation and amount of apically extruded intracanal materials. Hacettepe University Institute of Health Sciences, Ph.D. Thesis in Endodontics, Ankara, 2014. The aim of this study is to evaluate the amount of debris and irrigant extruded apically during preparation of oval-shaped root canals with SAF and Reciproc and to evaluate the cleaning efficacy of these files after preparation via SEM and histological sections and also to assess the obturation quality of oval-shaped root canals that prepared with same files and filled with cold and carrier-based gutta-percha techniques by means of bidirectional radiographs, stereological and histological methods. A total of 116 extracted lower human premolars with oval-shaped root canals were used. Teeth, except used during extrusion experiment, were decoronized. 40 teeth used for extrusion experiment were positioned to eppendorf tubes as imitating the upper and lower jaw. 20 teeth were shaped with Reciproc, while the remaining was shaped with SAF. All samples were irrigated with 12 mL of 2.5% NaOCl during experiment. Amount of extruded debris was weighed using a precision balance. 28 teeth were used for the evaluation of cleaning efficiency. Two teeth were only extirpated. The remaining 26 teeth were randomly divided into two groups according to file used: SAF or Reciproc. At the end of the chemomechanical preparation, 3 teeth randomly selected from each group were also irrigated with EDTA as a final irrigant. Remaining ones were irrigated with only NaOCl. Cleaning efficiency of files was evaluated through scoring of taken SEM photographs and by measuring penetration depth of NaOCl into tubules via histological sections of longitudinally splitted samples. The remaining 48 teeth assigned into 4 groups, as in each 12 teeth, according to shaping (SAF and Reciproc) and filling (cold and carrier-based gutta-percha) techniques. Obturation quality was examined radiologically, stereologically and histologically. Data were analyzed with; two-way ANOVA, Bonferroni, Kruskal–Wallis, Mann-Whitney-U, McNemar's chi-square, one-way ANOVA, Tukey HSD and Friedman tests. According to the results obtained, it was showed that shaping techniques as well as the position provide a statistically significant effect on apically extruded debris (p < 0.05). According to SEM analysis less smear layer and debris was observed in control samples that were only extirpated or irrigated with EDTA as a final irrigant. In terms of cleanliness there was no significant difference between samples irrigated only with NaOCl and shaped with either SAF or Reciproc (p> 0.05). Histological measurements were done only in samples shaped with Reciproc. Radiographs taken from mesio-distal direction were reflected the clinically fact situation more than the ones taken from bucco-lingual direction and scores of radiographs taken from mesio-distal direction were consistent with stereological evaluation. Based on the stereological evaluation most of the voids observed in samples shaped with SAF and filled with lateral compaction of cold gutta-percha (p < 0.05). There were no significant differences between groups regarding voids according to histological evaluation (p> 0.05). Shaping technique that removed more dentin from root canal wall clearly affected the amount of apically extruded debris and penetration depth of irrigant. EDTA was more effective in removing smear layer and debris than shaping techniques. Obturation quality was evaluated accurately with unbiased stereological methods, which allows to three-dimensional evaluation of samples without damaging them.