Figure 1 Clinical appearance of the same lesion. The overlying mucosa Sunitinib c-Kit was normal and there was not any sign or symptom. To categorize the canal system in MBR (mesiobuccal root) mesio-distal and bucco-palatal radiographs were obtained. The size 0.8 files were placed into the main mesiobuccal and second mesiobuccal canal. The teeth with no access to the apex were eliminated. Before photographing of pulp chambers millimetric glass scale was placed in order to make measurements to characterize the geometrical location of MB2 canals. The main mesiobuccal, palatal and MB2 canal orifices were marked on the millimetric glass scale. The main mesiobuccal canal and the palatal orifices were connected through a line MB-P and in addition to this line a perpendicular line was drawn from the MB2 canal orifice to the M-P line.

The main mesiobuccal canal was accepted as the origin and the vertical distance from MB2 to MB-P line was measured, as described by G?rduysus et al16 (Figure 2). The images were analyzed by Image-Proplus 4.0 software to measure the relationship between MB2 canal and other canals. Figure 2 On the millimetric glass scale, measurements were made to characterize the geometrical location of MB2 canals. MB: mesiobuccal canal orifice, MB2: second mesiobuccal canal orifice, P: palatal canal orifice. RESULTS The second mesiobuccal canal was found in 78% of the 110 maxillary molars and in 17 (19.8%) of these MB2 canals it was accessible to the apex. The teeth with no access to the apex were discarded and of the remaining 17, 3 (17.6%) had a Vertucci Type IV and 14 (82.

4%) were Vertucci Type II canal system. With the unaided vision 58 MB2 canal orifices and after evaluation with the dental loup an additional 17 MB2 canal orifices were detected. 68% of MB2 canals were located by using methods and 11 additional MB2 canals were identified with the use of the DOM (Figure 1). In 65 (75.6%) molars the MB2 canal orifices was located 0.87 mm distally and 1.73 mm palatally to the main mesiobuccal canal and in the remaining 21 (24.4%) molars was 0.72 mm mesially and 1.86 mm palatally as represented in the Figure 3. Figure 3 The location of MB2 canal orifices to the main mesiobuccal canal. The triangle drawn with the red color shows the standard endodontic access cavity and the rhomboidal shape drawn with the green color shows alternative endodontic access cavity.

DISCUSSION In the present study it was found that 78.18% of maxillary first molar possessed a second mesiobuccal canal. This is consistent with the findings of Burhley et al17 but higher than that reported by Sempira Batimastat and Hartwell.6 In the study of Sempira and Hartwell6 the second mesiobuccal canal had to be negotiated and obturated either separate from MB or within 4 mm of the apex. If two separate orifices blended into a single canal coronally during instrumentation, it was not considered to be a separate canal.