Abstract
Objective: The aim of this study was to evaluate the influence of using the dental operating microscope (DOM) and ultrasonics for the detection of second mesiobuccal (MB2) canal orifice in maxillary first molars. Materials and Methods: Sixty subjects seeking root canal therapy for maxillary first molar were assessed for the presence of MB2 canal using endodontic explorer without magnification. Teeth in which the MB2 canal orifice could not be located were examined under magnification using DOM. If the MB2 canal orifice could not be found even after using DOM, ultrasonic tips were used to prepare 3-mm-long trough from the mesiobuccal canal orifice toward the palatal canal and examined under DOM for location of the canal. Results: With naked eye, the MB2 canal was located in 12 teeth; with the use of the DOM, the MB2 canal was located in 21 additional teeth; and with the combined use of ultrasonic tip and DOM, the MB2 canal was located in 9 more teeth. Statistical comparisons between the tested techniques were done by analyzing the Receiver Operating Characteristic (ROC) curves; a statistically significant difference was found (P < 0.001). Conclusion: The results of this study indicate that the DOM and ultrasonics provide increased opportunity for the dentist to detect canal orifices.