Abstract
The aim of this study was to evaluate the effectiveness of manual and rotary instrumentation techniques for removing root fillings after different storage times. Twenty-four canals from palatal roots of human maxillary molars were instrumented and filled with gutta-percha and zinc-oxide eugenol-based sealer (Endofill) , and were stored in saline for 6 years. Non-aged control specimens were treated in the same manner and stored for 1 week. All canals were retreated using hand files or ProTaper Universal NiTi rotary system. Radiographs were taken to determine the amount of remaining material in the canals. The roots were vertically split, the halves were examined with a clinical microscope and the obtained images were digitized. The images were evaluated with AutoCAD software and the percentage of residual material was calculated. Data were analyzed with two-way ANOVA and Tukey's test at 5% significance level. There was no statistically significant differences (p>0.05) between the manual and rotary techniques for filling material removal regardless the ageing effect on endodontic sealers. When only the age of the filling material was analyzed microscopically, non-aged fillings that remained on the middle third of the canals presented a higher percentage of material remaining (p<0.05) compared to the aged sealers and to the other thirds of the roots. The apical third showed a higher percentage of residual filling material in both radiographic and microscopic analysis when compared to the other root thirds. In conclusion, all canals presented residual filling material after endodontic retreatment procedures. Microscopic analysis was more effective than radiographs for detection of residual filling material.
Highlights
Non-surgical endodontic retreatment is indicated when there is persistence of a disease resulting from incomplete cleaning and shaping, microleakage, technical shortcomings, or complex anatomy [1]
Different filling materials have been tested for the efficacy of retreatment techniques by different methods, including radiography [4,5,6], clearing [6,7,8], projection of photograph onto a screen [1,2,9], stereomicroscopy [2,4,10,11,12,13], scanning electron microscopy [1,14,15,16], evaluation of digitized images using a scanner [3], micro-computed tomography [17] and computed tomography [13]
The aim of this study was to evaluate the effectiveness of manual and rotary techniques for removing 6-year-old filling material compared to non-aged sealer through radiographic and microscopic analyses
Summary
Non-surgical endodontic retreatment is indicated when there is persistence of a disease resulting from incomplete cleaning and shaping, microleakage, technical shortcomings, or complex anatomy [1]. The main goal of retreatment is to regain access to the apical foramen by complete removal of the root canal filling material, thereby achieving sufficient cleaning and shaping of the root canal system and final proper obturation [3]. Removal of obturation material can be effected with endodontic hand files, heat-carrying or ultrasonic instruments, or engine driven rotary files [10]. Several techniques using manual or rotary protocols with or without solvents have been suggested to remove the filling material from root canals [1,16]. Braz Dent J 21(2) 2010 there are no studies testing the influence of the age of the filling material on the capacity for filler removal
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