Radix Entomolaris and Complex Incisor Anatomy in a Saudi Cohort: A Retrospective Study

Abstract

Background/Objectives: A thorough understanding of tooth anatomy is essential for effective root canal treatment. This study aims to investigate the root canal morphology of mandibular incisors (MIs) and the presence of distolingual roots in mandibular first molars (MFMs) and to explore the potential correlation between these anatomical variations. Methods: A total of 562 CBCT scans were retrospectively analyzed, corresponding to 1124 mandibular central incisors (MCIs), mandibular lateral incisors (MLIs), and MFMs each. The DLR in MFMs was correlated with the complex anatomy in MIs and analyzed using a chi-square test, with the odds ratio obtained through binary regression analysis. Differences related to gender, site, and age were analyzed using the chi-square test. Results: Most MI scans revealed Vertucci Type I canal morphology, with a higher percentage in MCIs (71.1%) than MLIs (64.9%). Additionally, 5.25% of MFM scans indicated a DLR, with a higher prevalence in males (3.5%) and younger individuals (3.4%); however, a statistically significant difference was observed only in MCIs (p = 0.035) across different age groups. The study also identified a highly significant difference in complex canal anatomy, comparing both MIs on either side and the presence of DLR in MFMs (p < 0.001). Furthermore, the relationship between complex canal systems in MIs and MFMs with DLR was confirmed. Conclusions: In conclusion, the Vertucci Type I canal configuration was predominant in both MIs, followed by Type III. The DLR was present in 5.25% of the total scans, and its presence strongly correlated with complex morphology in both MIs.

Keywords: Saudi Arabia; incisors; mandible; molars; root canal morphology.

Figure 1

Demographic data.

Figure 2

Prevalence of distolingual root in mandibular first molars (MFM). N, total number of MFM; one distal root, presence of only one root on the distal side of the MFM; second distal root, presence of an additional distolingual root (DLR) in the MFM.

Figure 3

Radix Entomolaris. (A), intraoral periapical radiograph of MFM showing three roots: mesial, distobuccal, and distolingual (DLR); (B), CBCT image of the same showing the presence of a separate DLR.

Figure 4

Correlation between distolingual root (DLR) in the mandibular first molar (MFM) and incisor root canal anatomy. (A) DLR corresponds with simple anatomy [Vertucci Type I—one canal from the orifice to the apex] in the mandibular incisors represented as (A1) in the coronal third, (A2) in the middle third and (A3) in the apical third; (B), DLR in MFM corresponds with complex anatomy [Vertucci Type II—two canals emerging from the orifice (B1), merging along its length to end as one canal (B2,B3) at the apex]; (C), DLR in MFM corresponding with complex anatomy in incisors [Vertucci Type III—one canal starting from the orifice (C1), dividing into two along its length (C2) and then merging into one before exiting the apex (C3)]; (D), DLR in the MFM corresponds with complex anatomy in incisors [Vertucci Type V—one canal starting from the orifice (D1), continuing along its length (D2) and dividing into two before exiting the apex (D3)]. Note: The DLR is highlighted in red color in the figure. The incisor and the corresponding MFMs with Radix are highlighted in Yellow.