The accuracy of the auto-stop function of different endodontic devices in detecting the apical constriction.
BACKGROUND
Electronic apex locators (EALs) are modern devices used to determine the working length during root canal preparation. The newest endodontic motors provide an integrated EAL with auto-stop function to prevent instrumentation beyond the predefined working length during rotary root canal preparation. The aim of this study was to compare the accuracy of the auto-stop function of the VDW.Gold RECIPROC motor (VDW, Munich, Germany), the EndoPilot motor (Schlumbohm, Brokstedt, Germany) and the manual measurement with Raypex 6 (VDW, Munich, Germany) to detect the apical constriction (AC).


METHODS
Ninety human teeth were chosen and randomly assigned to three experimental groups (30 teeth each): VDW.Gold RECIPROC motor continuous measuring (RCM), EndoPilot continuous measuring (ECM) and Raypex 6 manual measuring (RMM). When the measurement file reached the AC, the file was fixed in the tooth. The tooth was embedded in acrylic resin and the root tip was exposed, so that the histologic structure of the root canal and the file tip was visible for microscopic analysis. Afterwards, the distance of the file tip to the AC (DAC) was automatically computed with a specially developed software tool.


RESULTS
The mean DAC were -13.18 μm (SD 88.46 μm) for RMM, -22.70 μm (SD 91.57 μm) for RCM and 18.74 μm (SD 88.11 μm) for ECM. The differences were not statistically significant (P = 0.181). The rates for instrumentation beyond the AC were not statistically different (Chi2 = 4.753, p = 0.096).


CONCLUSIONS
All measurement methods showed a high accuracy in detecting the AC. The auto-stop function of these endodontic motors is a reliable addition to the endodontic armamentarium.
['Christofzik|David W|DW|', 'Bartols|Andreas|A|http://orcid.org/0000-0002-7789-6330', 'Khaled|Mahmoud|M|', 'Größner-Schreiber|Birte|B|', 'Dörfer|Christof E|CE|']
D003762:Dental Instruments D004867:Equipment Design D006801:Humans D066298:In Vitro Techniques D011897:Random Allocation D018915:Root Canal Preparation D019227:Tooth Apex
Apical constriction Apex locator Reciproc EndoPilot Raypex 6