22 July 2022

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Prevalence of the lingual canal in mandibular premolars

Lara Figini

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In mandibular premolars, several morphologic variations of the root and root canals have been reported in the literature including the presence of radicular grooves, C-shaped configuration1, furcation canals, apical ramification, 3-rooted morphology, and double canals. Double canals are generally classified as Vertucci's type V configuration and refer to the presence of a second root canal positioned lingually and are more likely to occur in the first premolars. The orifice of the lingual canal usually has a sharp entry angle and is located at the middle (69%) or apical (31%) thirds, which may contribute to it going unnoticed clinically.

Materials and Methods
In a multicenter study with meta-analysis, published on Journal of Endodontics, August 2021, the authors performed a worldwide analysis of the prevalence of the lingual canal in mandibular premolars and evaluated the influence on patient demographics in 23 countries, using cone-beam computed tomographic images. Cone-beam computed tomographic images of 300 first premolars and 300 second premolars in 23 countries (13,800 teeth in total) were evaluated to identify the presence of a lingual canal, evaluate its configuration and data relating to ethnicity, age and to the sex of the patients following a screening methodology. Statistical significance was set at 5%.

Results
A lingual canal in the mandibular first premolars was found in 23.8% of cases and in the second premolars in 5.3%. Asians and patients over the age of 60 were associated with lower rates of presence of a lingual canal, while Africans and younger groups were associated with higher rates. The prevalence of a lingual canal in males (27.9%) was found to be higher than that in females (20.0%) for only the first premolar. Males were associated with 1,533 and 1,597 more likely to have a lingual root canal in the first and second premolar respectively.

Conclusions
From the data of this study, which must be confirmed in other similar studies, it can be concluded that the lingual root canal is present in the first lower premolars in 23.6% and in the second lower premolars in 5.3%. Ethnicity, geographic region, age, and gender affect prevalence.

Clinical implications
Knowing the worldwide prevalence of a mandibular premolar lingual root canal and the demographic factors that may influence its proportions may help to anticipate possible technical difficulties in root canal treatment.

(Photocredit: Dott. Renzo Raffaelli)

For additional information: Worldwide Prevalence of a Lingual Canal in Mandibular Premolars: A Multicenter Cross-sectional Study with Meta-analysis