Abstract Introduction This study compared the efficacy of a reciprocating single-instrument system and a rotary multi-instrument system followed by a supplementary approach with a finishing ...instrument in removing the filling material from curved canals during retreatment. Methods Forty mesial canals from extracted mandibular molars were instrumented and filled. Then, each mesial canal was retreated by using either Reciproc (VDW, Munich, Germany) or Mtwo (VDW) instruments, alternating the technique used per canal from root to root. The working time was recorded, and the percentage of removed filling volume was assessed by means of micro–computed tomography imaging before and after retreatment. Canals still showing filling material remnants were subjected to an adjunctive approach with the XP-Endo Finisher (FKG Dentaire, La Chaux-de-Fonds, Switzerland), and another microCT scan was taken. Data were statistically analyzed with a significance level of 5%. Results The percentage of filling material removed with Mtwo instruments (96%) was significantly higher than Reciproc (89%) ( P < .05), both used up to a final instrument size of 40. Mtwo required less time to remove the filling material than Reciproc ( P < .05). Intragroup analysis in the Reciproc group showed that the R40 instrument removed significantly more filling material than R25 ( P < .05). The supplementary approach with the XP-Endo Finisher was effective in significantly enhancing the removal of filling material ( P < .05). Conclusions The rotary multiple-instrument system was more effective and faster than the reciprocating single-instrument approach in removing previous root canal fillings. As for the Reciproc group, it was observed that the larger instrument promoted significantly better results. The adjunctive finishing instrument XP-Endo Finisher significantly improved filling material removal.
Abstract Introduction This study evaluated the disinfecting ability of chemomechanical preparation with rotary nickel-titanium instruments, followed by 2 distinct adjunctive procedures in the root ...canals of extracted mandibular molars by means of a correlative analytical approach. Methods Twenty-two extracted mandibular molars were selected and anatomically matched between groups on the basis of micro–computed tomographic analysis. In the first phase of the experiment, root canals were contaminated with Enterococcus faecalis and subjected to chemomechanical preparation with BT RaCe instruments and 2.5% NaOCl irrigation. Then either XP-Endo Finisher instrument or passive ultrasonic irrigation was used to supplement disinfection. Micro–computed tomography was used to show whether the percentage of unprepared areas correlated to bacterial counts. In the second phase, the same teeth were contaminated once again, and the adjunctive procedures were used. Samples from the isthmus area of mesial roots and the apical 5-mm fragment of distal roots were obtained by cryopulverization. Samples taken before and after treatment steps in both phases were evaluated by quantitative polymerase chain reaction and statistically analyzed. Results In phase 1, preparation in both groups resulted in substantial decrease of bacterial counts ( P < .001). The adjunctive approaches led to a further small bacterial reduction, which was significant for XP-Endo Finisher ( P < .05). No significant differences were observed between groups for persisting bacterial counts. Correlative analysis revealed no statistically significant relationship between bacterial reduction and the percentage of unprepared areas ( P > .05). In phase 2, both methods had significant antibacterial effects in the main canal, but none of them could predictably disinfect the isthmus/recess areas. Conclusions Both XP-Endo Finisher and passive ultrasonic irrigation exhibited antibacterial effectiveness, but only the former caused a significant reduction in the bacterial counts after chemomechanical preparation. None of them were effective in predictably disinfecting the isthmus/recess areas.
Abstract Introduction The purpose of this study was to compare the shaping properties of TRUShape and Reciproc systems during preparation of oval-shaped canals from contralateral teeth by using ...micro–computed tomography scanning. Methods Thirteen pairs of freshly extracted contralateral mandibular premolars with a single oval-shaped canal were selected and divided into 2 groups according to the root canal instrumentation technique, TRUShape and Reciproc. The final apical size of instrumentation was 40/.06 for both systems. Data were statistically analyzed for the increase in canal volume and surface area and the amount of unprepared areas promoted by the 2 systems. Results Preparation with both systems significantly increased the volume and area of the canals ( P < .001), with no significant differences between them ( P > .05). When the full canal length was evaluated, the amount of uninstrumented areas was significantly larger for Reciproc (30%) than TRUShape (24%) ( P < .05). However, analysis restricted to the apical 4-mm segment revealed no statistically significant difference in untouched areas (25% for Reciproc and 20% for TRUShape) ( P > .05). Conclusions Both instrument systems behaved similarly in promoting the increase of root canal volume and surface area. When the full canal length was evaluated, TRUShape instruments showed less unprepared areas than Reciproc. However, this difference did not occur for the apical part of the root canal. None of the techniques could completely prepare oval-shaped root canals.
