Apical transportation using Mtwo or Reciproc retreatment systems in severely curved canals: a micro-computed tomographic study.

OBJECTIVE: To assess apical root canal transportation using Mtwo or Reciproc during retreatment of severely curved canals, using a multi-analytical approach. METHODS: Forty mesial canals from mandibular molars (Vertucci type IV) were evaluated before and after endodontic retreatment to compare apical transportation with Mtwo retreatment or Reciproc. The systems were used on the same root but alternating the mesial canals. The analyses were performed by micro-computed tomography. Four evaluations were performed: (a) longitudinal transportation, (b) horizontal transportation, (c) variation in the angle of curvature of the canal, and (d) canal-root width ratio. Horizontal transportation and canal-root width ratio were evaluated in 1-, 3-, and 5-mm levels. RESULTS: Longitudinal transportation occurred in all samples, with a mean of 0.13 mm for Mtwo and 0.17 mm for Reciproc. Horizontal transportation increased as distant from the apex was the evaluated level, in mean. However, the transport was not observed in all samples. The mean angle of curvature was 4.16 for Mtwo and 3.03 for Reciproc. Canal-root width decreased as distant from the apex was the evaluated level. No significant differences were observed considering all tested variables, independently of the retreatment system or evaluated level (p > 0.05). CONCLUSION: Mtwo retreatment and Reciproc presented similar apical transportation (horizontal or vertical). CLINICAL RELEVANCE: Both Mtwo retreatment and Reciproc systems could be considered safe regarding apical transportation.

Canal transportation using Mani GPR or HyFlex NT during the retreatment of curved root canals: A micro-computed tomographic study.

This study assessed the apical transportation using Mani GPR or HyFlex NT during the retreatment of curved root canals. Thirty-eight roots were analysed using micro-CT for the comparison of apical transportation produced by two retreatment systems. Longitudinal transportation, horizontal transportation, variation in the canal angle of curvature and variation in the canal/root width ratio were analysed. Longitudinal transportation was frequently observed, regardless of the system used. The canals retreated with Mani GPR showed a significantly higher horizontal transportation at 1 mm from the root apex (P < 0.01) and greater variation of the canal curvature angle (P < 0.01). The canal/root width ratio was similar between groups (P > 0.05). In conclusion, longitudinal transportation occurred more frequently in the mesial canal walls. Mani GPR showed greater horizontal transportation at 1 mm short of the apex, and higher variation of the canal curvature angle compared with HyFlex NT.

Removal of Root Canal Fillings in Curved Canals Using Either Mani GPR or HyFlex NT Followed by Passive Ultrasonic Irrigation.

This study compared the efficacy of HyFlex NT (HF; Coltene, New York, NY) and Mani GPR (MN; Mani Inc, Tokyo, Japan) systems followed by a supplementary approach with passive ultrasonic irrigation (PUI) in removing the filling material from curved root canals during retreatment. The mesial canals from 20 extracted mandibular molars with Vertucci type IV configuration were instrumented and obturated (N = 40). Each mesial canal was retreated using either HF or MN instruments, alternating the system used per canal from root to root. The final preparation size was 40/0.04 for both systems. The volume of canal filling material was assessed by means of micro-computed tomographic (micro-CT) imaging before and after retreatment, and the working time was recorded. Canals still showing remnants of filling material were subjected to a supplementary approach with PUI, and another micro-CT scan was taken. The percentage of filling material removed with MN instruments and HF was similar (95.5% and 92.7%, respectively) (P > .05). MN required significantly less time to remove the filling material (P < .05). The supplementary approach with PUI significantly enhanced the removal of filling material (P < .05). Both systems were equally effective in removing the root canal filling during retreatment. MN was faster than HF. The supplementary approach with PUI significantly improved filling material removal.

Removal of Root Canal Fillings in Curved Canals Using Either Reciprocating Single- or Rotary Multi-instrument Systems and a Supplementary Step with the XP-Endo Finisher.

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.