Comparing the crown and root metric properties of double-rooted and single-rooted mandibular canine teeth

To compare the crown and root metric properties of two- and single-rooted/multi-canal mandibular canines (MnCn) with single-rooted/single-canal MnCn.

Cone-beam computed tomography images of 1000 patients (500 women and 500 men) with both right and left MnCn were analyzed. First, the root and canal morphologies of all teeth were examined. Then, the teeth were divided into three groups; (a) 2-rooted, (b) 1-rooted and multi-canals, (c) 1-rooted and single-canal. Crown lengths/sizes and tooth lengths were compared between the three groups. Statistical analyses were performed using Chi-square, one-way ANOVA, Welch, post hoc pairwise comparison, and independent sample t-tests. The significance level was set at 5%.

Of all the teeth, 2.35% were 2-rooted, and 6.3% were 1-rooted/multi-canal. The frequency of double roots was higher in women (p < 0.05). Double-rooted teeth had longer crown lengths but shorter tooth lengths than single-rooted teeth (p < 0.05). In 2-rooted teeth, buccal and lingual root lengths were similar, root bifurcation levels were mostly at the mid-root, and the mean distance of the bifurcation points of the canals to the cemento-enamel junction was 4.09 mm. Double-rooted teeth were mostly observed unilaterally.

Since 2-rooted MnCn do not differ significantly from other teeth in terms of crown sizes, it is not possible to differentiate between single- vs. double-rooted MnCn based on clinical examination.