Tehran University of Medical Sciences
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Mohammad Hossein Nekoofar

Accuracy of two root canal length measurement devices integrated into rotary endodontic motors when removing gutta-percha from root-filled teeth

Authors: Uzun, O. - Topuz, O. - Tinaz, C. - Nekoofar, M. H. - Dummer, P. M. -
Keywords: *Dental Instruments , Dental Pulp Cavity/*anatomy & histology , Electrical Equipment and Supplies , Gutta-Percha , Humans , Incisor/anatomy & histology , Odontometry/*instrumentation , Retreatment , Root Canal Preparation/*instrumentation , Tooth Root/*anatomy & histology ,
Int Endod J, Vol.41, No.9, 2008,Page:725-32
AIM: To evaluate ex vivo the accuracy of the integrated electronic root canal length measurement devices within TCM Endo V and Tri Auto ZX motors whilst removing gutta-percha and sealer from filled root canals. METHODOLOGY: Forty freshly extracted maxillary and mandibular incisor teeth with mature apices were selected. Following access cavity preparation, the length of the root canals were measured visually 0.5 mm short of the major foramen (TL). The canals were prepared using the HERO 642 system and then filled with gutta-percha and AH26 sealer using a lateral compaction technique. After 7 days the coronal temporary filling was removed and the roots mounted in an alginate experimental model. The roots were then randomly divided in two groups. The access cavities were filled with chloroform to soften the gutta-percha and allow its penetration using the Tri Auto ZX and the TCM Endo V devices in groups 1 and 2, respectively. The 'automatic apical reverse function' (ARL) of both devices was set to start at the 0.5 setting and the rotary instrument inserted inside the root canal until a beeping sound was heard and the rotation of the file stopped automatically. Once the auto reverse function had been initiated, the foot pedal of the motor was inactivated and the rubber stop placed against the reference point. The distance between the file tip and rubber stop was measured using a digital calliper to 0.01 mm accuracy (ARL). Then, a size 20, 0.02 taper instrument was attached to each device and inserted into the root canals without rotary motion until the integrated ERCLMDs positioned the instrument tips at the 0.5 setting as suggested by the devices. This length was again measured using a digital calliper (EL). The Mann-Whitney U-test was used to investigate statistical differences between the true canal length and those indicated by the two devices when used in 'automatic ARL and when inserted passively (EL). RESULTS: In the presence of gutta-percha, sealer and chloroform, the auto-reverse function for the Tri Auto ZX