The aim of this study was to investigate the number of roots and the morphology of the root canals of maxillary and mandibular premolars in a selected German population.Methods
Randomly selected full-size cone-beam computed tomographic images were collected from 700 patients (45% men and 55% women, average age = 50.21 years). This resulted in a total of 644 first and 512 second maxillary premolars as well as 1044 first and 871 second mandibular premolars. The total number of roots and root canals, the frequency and correlations between the left and right sides, and the incidence in men and women were recorded and statistically analyzed using the Fisher exact and chi-square tests. Canal configurations were classified according to the Vertucci classification.Results
First maxillary premolars mainly had 2 roots (1 root: 36.4%, 2 roots: 62.4%, and 3 roots: 1.2%) with predominantly 2 canals (88.4%). The majority of second maxillary premolars had 1 root (82.6%), but 2 root canals (56.3%) occurred more frequently than 1 canal (43.1%). In the first and second mandibular premolars, 1 root was found predominantly (90.76% and 98.16%, respectively) with 1 canal (77.9% and 96.0%), whereas 2 canals were less common (21.9% and 3.6%). Three roots (0%, <0.11%) and 3 canals (0.2%; 0.4%) were rarely found. Vertucci classifications were heterogeneously distributed. Men showed significantly more roots and root canals compared with women (P < .05), with the exception of the second mandibular premolars.Conclusions
This cone-beam computed tomographic study confirmed previous anatomic and morphologic investigations. When treating premolars, the likelihood of additional root canals should be considered.