Quantitative comparison of calcium hydroxide removal by EndoActivator, ultrasonic and ProTaper file agitation techniques: an in vitro study.

Calcium hydroxide (CH) dressing residues can compromise endodontic sealing. This study aimed to evaluate the amount of remaining CH in root canals after mechanical removal by four groups of irrigation techniques including needle irrigation only, ProTaper file, EndoActivator, and ultrasonic file. Fifteen extracted single-rooted teeth were collected and used for all four groups. The samples were firstly prepared by ProTaper rotary instruments, and then sectioned longitudinally through the long axis of the root canals, followed by final reassembling by wires. CH was kept in the canals for 7 days setting. The removal procedure began with 5 mL of 2.5% sodium hypochlorite (NaOCl) followed by 1 mL of 17% ethylenediaminetetraacetic acid and a final irrigation with 5 mL of 2.5% NaOCl solution for all groups. No additional agitation of the irrigant was performed in group 1, while agitation for 20 s between irrigants was done with F2 ProTaper rotary file in group 2, EndoActivator with tip size 25/.04 in group 3 and by an ultrasonic file 25/.02 in group 4. The total activation time was 60 s. The roots were then disassembled and captured by digital camera. The ratio of CH coated surface area to the surface area of the whole canal as well as each third of the canal was calculated. The data were statistically analyzed by one-way ANOVA using post hoc Tukey test. Results showed that none of the four techniques could remove all CH. No significant difference was found between EndoActivator and ultrasonic techniques. However, they both removed significantly more CH than ProTaper and needle irrigation (P=0.0001). In conclusion, the sonic and ultrasonic agitation techniques were more effective in removing intracanal medicaments than the ProTaper rotary file and needle irrigation in all thirds of the canal.

Efficacy of ProTaper Universal Rotary Retreatment system for gutta-percha removal from oval root canals: a micro-computed tomography study.

INTRODUCTION: The aim of this study was to use micro-computed tomography to evaluate the amount of remaining root filling material in oval canals filled by using 2 obturation techniques after retreatment with the ProTaper Universal Retreatment with or without solvent. METHODS: Forty mandibular incisor teeth with oval canals were prepared to the ProTaper Universal F3 and filled with gutta-percha and iRoot SP sealer by using continuous wave of condensation or cold lateral condensation techniques. The root fillings were removed with the ProTaper Universal Retreatment system, and the canals were prepared further with ProTaper F4. The operating time was measured. Preoperative and postoperative micro-computed tomography imaging was used to assess the percentage of volume of residual filling material in the canals. RESULTS: Remaining filling material was observed in all specimens. The mean volume of remaining material was higher in the continuous wave of condensation groups than in the cold lateral condensation groups, especially in the apical portions of the root canals (P < .05). The time required to reach a working length was significantly less in the solvent groups than in the nonsolvent groups (P < .05). However, in the nonsolvent groups, less time was required to achieve satisfactory gutta-percha removal and root canal refinement than in the solvent groups (P < .05). CONCLUSIONS: None of the retreatment techniques were able to completely remove all gutta-percha/sealer from the oval canals. More root filling material was left in the root canals filled by using the continuous wave condensation technique than those filled by using the cold lateral condensation technique after retreatment. In the nonsolvent groups, less time was needed to achieve satisfactory gutta-percha removal and root canal refinement than in the solvent groups.