RESUMEN
Background: In Vietnam, using dental loupe and ultrasonic tip to detect MB2 canal in mesiobuccal roots of maxillary molars is appropriate and necessary. Objective: The purpose of this study is to assess the effectiveness of magnification and dentine removal when locating the second mesiobuccal canal (MB2) in mesiobuccal roots of maxillary molars. Subject and methods: 49 mesiobuccal roots of maxillary molars were collected and studied. Conventional access of the cavity was prepared. After that, the MB1 and 2 canals in mesiobuccal roots were located in three stages. Stage 1: canals were located with no magnification. Stage 2: additional canals in the same teeth were located under magnification with a dental loupe. Stage 3: additional canals in the same teeth were located by removing dentine from the pulp chamber floor within 3mm from the MB1 canal towards the palatal canal in a groove 2 mm deep using ultrasonic tip (P5, Salatec). Result: The frequency of MB2 canal detection for an ultrasonic tip, dental loupes, and no magnification groups was 77.6%, 59.2% and 24.5%, respectively. Conclusion: Based on these results, more emphasis should be placed on the importance of using magnification dental ultrasonic tip to locate the MB2 canal.