Evaluation of Dentin Thickness around Second Mesiobuccal Canal in Maxillary First Molar Using Cone Beam Computed Tomography (CBCT)

Document Type : Original Article


1 Department of Endodontics, Dental School, Urmia University of Medical Sciences, Urmia, Iran

2 Dental School, Urmia University of Medical Sciences, Urmia, Iran


Background and aim: Maxillary first molars exhibit a variety of anatomies in the mesiobuccal root, with a concavity on the distal wall limiting the canal's preparation to prevent strip perforation. This study evaluated the dentin thickness around the second mesiobuccal canal (MB2) in the maxillary first molar using cone-beam computed tomography (CBCT).
Materials and methods: The present retrospective descriptive cross-sectional study conducted on 120 CBCT images of patients referred to Radiology Centers of Urmia (Iran) between 2017 and 2019. Samples were collected using a convenience sampling method. A professional radiologist prepared all the CBCT images that had the least exposure required with proper image resolution. The first and second mesiobuccal canals (MB1 and MB2) were both detected. Two endodontists evaluated the dentin thickness around the MB2 canal in the mesial, distal, and palatal walls and its distance to MB1 at coronal, middle and apical cross-sections. Statistical significance level set at 0.05 and all analyses performed using SPSS version 23 software.  
Results: In all three sections, the lowest dentin thickness was in the distal wall. The highest was in the palatal wall; this difference was statistically significant in all sections (p<0.05). Minimum distances of MB2 from mesial, distal and furcation surfaces and from MB1 canal were significantly different in coronal (p = 0.008), middle (p = 0.004) and apical (p = 0.001) sections.
Conclusion: The low thickness of distal wall indicates more conservative considerations in endodontic and prosthodontic treatments. The CBCT seems to be an effective and non-invasive method in examining root and canal morphology. It may be used as preoperative radiography to assess the dentin thickness in danger zones to prevent iatrogenic errors.


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