The ratio of second mesiobuccal canal (MB2) in first and second maxillary molars on CBCT and periapcal (PA) film Film MB2 canal PA CBCT P n% n% With MB2 3 5, 8 24 46, 2 <0, 0 5 No MB2 49 94, 2 28 53, 8 Total 52 100, 0 52 100, 0 Pearson chi2 = 4.0986 Pr = 0.043 46.2% of First and Second maxillary molars had MB2 canal in CBCT, different from that in the periapcalfilm (5.8%) (p <0.05).