Restor Dent Endod.  2020 Feb;45(1):e7. 10.5395/rde.2020.45.e7.

Isthmuses, accessory canals, and the direction of root curvature in permanent mandibular first molars: an in vivo computed tomography study

• Chuppani Dastgerdi A
• Navabi M
• Rakhshan V

• KMID: 2470342
• DOI: http://doi.org/10.5395/rde.2020.45.e7

Abstract

OBJECTIVES
This study was performed to assess the anatomy of mandibular first molars.
MATERIALS AND METHODS
In this in vivo study, cone-beam computed tomography (CBCT) volumes of 312 bilateral intact first mandibular molars from 156 patients (79 men and 77 women; average age, 35.6 ± 11.2 years) were investigated in terms of the direction of each canal's curvature in the buccolingual and mesiodistal dimensions (direction of the position of the apex in relation to the longitudinal axis of the root), the presence of an isthmus (a narrow, ribbon-shaped communication between 2 root canals) in 3 segments (0-2, 2-4, and 4-6 mm) from the apex), and the presence and number of accessory canals (smaller canals besides the main root canals, connecting the pulp to the periodontium). Data were analyzed statistically (α = 0.05).
RESULTS
Mesiolingual canals were mostly buccally and distally inclined, while mesiobuccal and distolingual canals were mostly distally curved. Isthmuses were more common in younger patients (χ2 test, p < 0.05). The average numbers of accessory canals in the apical, middle, and coronal segments were 9.9 ± 4.2, 6.9 ± 2.9, and 9.3 ± 3.0 canals per segment, respectively (analysis of variance, p < 0.001). Age and sex were not associated with the number of accessory canals (p > 0.05).
CONCLUSIONS
The complex anatomy of these teeth deserves attention during non-surgical or surgical endodontic treatment. Around the apex, isthmuses might be more prevalent in younger and female individuals.

Keyword

Anatomy; Endodontics; Cone beam computed tomography

MeSH Terms

Cone-Beam Computed Tomography
Dental Pulp Cavity
Endodontics
Female
Humans
Male
Molar*
Tooth