Presence of isthmi in mandibular mesial roots and associated factors: an in vivo analysis

Abstract

Purpose To investigate the prevalence of isthmi and middle mesial (MM) canals in the mesial roots of mandibular first molars (MFM) in a Mongoloid subpopulation and to evaluate their association with demographic and anatomic characteristics. Methods Cone-beam computed tomography (CBCT) images of 496 patients with 823 MFMs were selected and analyzed. The following data were collected: patient age and gender, side, presence and distribution of MM canal and isthmus, distance between mesiobuccal (MB) and mesiolingual (ML) orifices, and MB–ML root canal system (RCS) morphology. Logistic regression was used to determine the association between demographic and anatomic characteristics and the presence of isthmi in the apical third. Results The overall prevalence of isthmus and an MM canal in MFM was 64.6% and 10.8%, respectively. The highest prevalence of isthmi and MM canals was found in patients of ≤ 20 and of 41–60 years, respectively ( p < 0.05). The prevalence of isthmi declines with age. A total of 41.3% of the MFMs had isthmi in the apical third of the mesial roots. Younger age, shorter MB–ML orifice distance, and Weine type II RCS increased the probability of the presence of an isthmus in the apical third ( p < 0.05). Conclusion The prevalence of isthmus in MFM is high in the subject population, but the prevalence of MM canals is not as high as previously reported. Demographic and anatomic characteristics could aid clinicians to better predict the presence of MM canal and an isthmus.

Prevalence of Middle Mesial Canals and Isthmi in Mandibular Molars Using Cone Beam Computed Tomography

“…21 No difference in the distribution of MMC based on side and gender have been reported, similar to present study. 15,22 Prevalence of MMC in other studies was higher in younger patients compared to older patients. 22,25 Present study could not find any significant difference based on age.…”

“…(10.8%). 15,21 The reported prevalence of MMC differs with the ethnicity of the studied population, geographic location and study methodology. 17 Another reason for the difference could be the finer voxel size of CBCT in the other studies (76 µm in Tahmasbi et al's study and 160 µm in Baugh et al's study) compared to present study (200 µm).…”

“…Prevalence of isthmus in present study (32.8%) is less as compared to 64.6% and 69.6% found in similar CBCT studies. 15,21 A Brazilian in vitro study found 33.3% isthmus in mesial roots of mandibular first molars. 23 The incidence of isthmus in mandibular molars in Pakistani population was not reported in any study.…”

“…The Sample size was calculated to be one hundred and forty-nine teeth using OpenEpi online calculator with expected prevalence of 10.8%, confidence level of 95% and confidence limit at 5%. 15 It was later increased to one hundred and eighty-nine teeth. Sixty randomly selected medium field of view CBCT images from database of Oral & Maxillofacial Radiology department taken between February 2017 and January 2019 were included in the study.…”

“…Similarly, in surgical endodontic treatment, root end preparation and retrograde filling can be more challenging because of the complex morphology of mesial roots. 15 The reported incidence of MMC in mandibular molars varies with the population being studied. Previously it was reported as between 1-15% with slightly less incidence in mandibular second molars compared to mandibular first molars.…”