Abstract
This study evaluated the efficiency of different techniques for removal of filling material from root canals, using computed tomography (CT). Sixty mesial roots from extracted human mandibular molars were used. Root canals were filled and, after 6 months, the teeth were randomly assigned to 3 groups, according to the root-filling removal technique: Group A - hand instrumentation with K-type files; Group B - reciprocating instrumentation with engine-driven K-type files; and Group C rotary instrumentation with engine-driven ProTaper system. CT scans were used to assess the volume of filling material inside the root canals before and after the removal procedure. In both moments, the area of filling material was outlined by an experienced radiologist and the volume of filling material was automatically calculated by the CT software program. Based on the volume of initial and residual filling material of each specimen, the percentage of filling material removed from the root canals by the different techniques was calculated. Data were analyzed statistically by ANOVA and chi-square test for linear trend (?=0.05). No statistically significant difference (p=0.36) was found among the groups regarding the percent means of removed filling material. The analysis of the association between the percentage of filling material removal (high or low) and the proposed techniques by chi-square test showed statistically significant difference (p=0.015), as most cases in group B (reciprocating technique) presented less than 50% of filling material removed (low percent removal). In conclusion, none of the techniques evaluated in this study was effective in providing complete removal of filling material from the root canals.
Highlights
Endodontic retreatment is indicated when signs or symptoms of infection are still present or reappear after the original treatment
The evolution of retreatment techniques and instruments associated to a better understanding of the factors involved in endodontic failure have pointed to conventional endodontic retreatment as the best choice
In the studies of Masiero and Barletta [6] and Gergi and Sabbagh [7], radiographs were taken after removing the filling material from the root canals, digitized and analyzed by means of software packages developed for civil engineering and architecture, the AutoCAD 2000 (Autodesk Inc., San Rafael, CA, USA) and AutoCAD 2004
Summary
Endodontic retreatment is indicated when signs or symptoms of infection are still present or reappear after the original treatment. Several methodological resources have been used in endodontic retreatment research, all of them showing some limitations. The currently used methods include longitudinal cleavage of the teeth [1], association of longitudinal and transversal cleavage for evaluation of the cervical, middle and apical thirds separately [2], cleavage associated to photographic records [3], and cleavage and photographs associated to the radiographic examination [4]. Longitudinal cleavage of teeth may result in displacement of the filling debris to be evaluated [5] and compromise the accuracy of the measurements. In the studies of Masiero and Barletta [6] and Gergi and Sabbagh [7], radiographs were taken after removing the filling material from the root canals, digitized and analyzed by means of software packages developed for civil engineering and architecture, the AutoCAD 2000 (Autodesk Inc., San Rafael, CA, USA) and AutoCAD 2004 (Mechanical Desktop Power Pack, Braz Dent J 19(4) 2008
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