Effect of troughing procedure on detection of mesiobuccal 2nd canal in calcified and non-calcified maksillary molars

The aim of this study is to examine the impact of troughing (groove preparation) on detecting the mesiobuccal second canal (MB2) in maxillary molars, which are the most frequently missed and thus untreated canals during endodontic treatment, both in cases where calcification is present and where it is not. From previously collected maxillary molar teeth that had been extracted for various reasons and had micro-CT images, 200 teeth were selected for this study. Some of the included teeth had a single mesiobuccal canal, some had two mesiobuccal canals, and some had two mesiobuccal canals with calcification present in the MB2 orifice. Without knowing which teeth had MB2 or calcification, a traditional access cavity was prepared using a dental operating microscope (OMS3200 Pro, Zumax, China) and high-speed handpieces with diamond burs (G&Z Instrumente, Lustenau, Austria) under water cooling. After the traditional access cavity preparation, an attempt was made to detect the MB2. Teeth where MB2 was detected were notes as "1" in, while those where MB2 was not detected were noted as "0". For teeth where MB2 was not detected with the access cavity preparation, a 2 mm deep troughing procedure was performed by the same clinician using a Satelec P5 Nevtron XS ultrasonic device (Satelec Acteon, Mericnac, France) with a Woodpecker E3D ultrasonic tip (Guilin Med. Ins., China). After the troughing procedure, an attempt was made again to detect MB2, and the results were noted. Complications encountered during the troughing procedure were recorded and included in the statistical analysis of the study. The data collected in our study were evaluated using IBM SPSS V.26 (IBM SPSS Statistics, Inc., Armonk, NY) statistical software. The data were tested with McNemar analysis to determine statistical significance. A significance level of α=0.05 was used. When the micro-computed tomography (micro-CT) images of the 200 teeth included in the study were examined, it was found that 173 of them had MB2. After the traditional access cavity preparation by the clinician, MB2 was detected in 142 out of 173 teeth (82%). After applying the troughing procedure to the remaining samples, MB2 was detected in an additional 16 teeth. Following McNemar testing, it was found that the troughing procedure significantly increased the detection of MB2 (p < .05). Out of 16 MB2s with calcified orifices, 9 were detected after traditional cavity preparation without troughing. Following the troughing procedure, MB2 was found in 3 additional teeth; however, in 4 teeth, despite the 2 mm deep troughing procedure, the MB2 orifice could not be detected. It was observed that the troughing procedure did not significantly increase the detection rate of MB2s with calcified orifices (p > .05). No perforations occurred during the access cavity preparation and troughing procedures.