Introduction: Determination of working length and its control throughout root canal preparation remains challenging.
Objectives: The purpose of this study was to evaluate accuracy of auto apical reverse (AAR) mode in an integrated motor and a standard electronic apex locator (EAL) in maintaining working length (WL) without violation of apical constriction (AC) under stereomicroscope.
Materials and methods: Sixty extracted mesiobuccal roots of mandibular molars were selected. Actual lengths (AL) were measured and EAL readings were measured corresponding to ‘‘0.5'' mark in both devices. Teeth were randomly divided into two groups (n=30), Group I: Canal preparation with rotary instruments while activating AAR function of MM-control motor, whereas Root ZX-II was used for WL determination in Group II. In both groups; difference between AL and post-preparation length (AL2) were calculated. Position of file tips relative to AC was designated zero if coinciding, negative for coronal and positive when apical to it under the stereomicroscope. Means of absolute values and percentages of electronic measurements distribution between devices were compared using t-test and Chi-square test, respectively.
Results: Alterations in AL and AL2 between the two groups showed no significant difference; however, AL2 in Group I increased significantly (P