Root and Canal Morphology of Mandibular Premolar Teeth in a Kuwaiti Subpopulation: A CBCT Clinical Study

Abstract

Objective: To study the root and root canal morphology of mandibular premolars in a Kuwaiti subpopulation using cone-beam computed tomography (CBCT).

Methods: 152 CBCT images were obtained from the radiology department archives of four dental centers in Kuwait. A total of 476 mandibular premolar teeth were analyzed by two observers. The number of roots, root canal configuration types and canal curvature measurements were examined. The relationship between sex, tooth position, and incidence of an additional canal were compared using the chi-square test, and the level of significance was set at 0.05 (P=0.05).

Results: The number of roots in mandibular first premolars was one in 73.9%, two in 24.9%, three and four in 1.2%. On the other hand, the number of roots in mandibular second premolars was one in 79.2% and two in 20.8%. Based on Vertucci's classification system, 18.7% of the teeth were type II followed by type VI (14.3%). The majority of the examined teeth were straight (74.8%) and the incidence of distal root angulation was about 21%. Canal configurations not included in the Vertucci classification were reported in 102 teeth (21.4%). Variability was significantly higher in the second premolars compared to first premolar (P<0.05).

Conclusion: The Kuwaiti population has complex root canal morphology in mandibular premolar teeth.

Figure 1

CBCT image of second mandibular premolar with joined roots at coronal third (b) then separated at the apical third (c and d) (yellow arrow). Canal configuration is 2-3-2 (a, b, c and d). The roots of the first premolar are fused with type II canal configuration

Figure 2

CBCT image of second mandibular premolar with C-shaped root canal configuration at different levels (a, b, c and d)

Figure 3

Mesiodistal CBCT images of mandibular right first premolar. The image of the canal disappeared in the middle-third (a). Cross-section CBCT image showing two separated roots at the middle-third (b-f). Axial CBCT image at the cervical third showing 2 canals (g), more towered the middle showing 2 canals (h), close to the apical third showing 3 canals with fused roots (i) and 3 canals at the apex (j). Notice the lingual root fused to the distobuccal root. (Arrows points to the canals). Canal configuration is 2-3

Figure 4

CBCT image of radicular groove located in the mesial aspect of the first mandibular premolar root surfaces at different levels (a, b, c and d)

Figure 5

Cross-section CBCT images of mandibular left first premolar showing one root with two canals (a, b). Axial CBCT image at the cervical third showing 2 canals (c), the middle third shows 3 canals (d), close to the apical third showing 4 canals (e) and 2 canals at the apex (f). (Arrows points to the canals). Canal configuration is 2-3-4-2

Figure 6

Cross-section and axial CBCT images of mandibular right first premolar showing one root with two separated canals at the middle-third (a-d). Axial CBCT image at the middle third level (d) showing 5 canals (e) that was traced with black dots (f) and shown with virtual reconstruction image (g). More towered the apical third 4 canals can be seen (h) and 2 canals at the apex (i). See the radicular groove located at the mesio-lingual area (f). (Arrows points to the canals). Canal configuration is 2-5-4-2