Introduction: Understanding root canal morphology is important to achieve successful root canal treatment (RCT). Studies on mandibular premolars showed that, there is a significant variation in the root canal anatomy between different ethnicities. Therefore, this retrospective study aimed to evaluate the root canal anatomy of mandibular premolars in Egyptian population using cone-beam computed tomography (CBCT).

Materials and Methods: 248 CBCT scans were evaluated and the anatomy of 392 mandibular first and 384 second premolars was classified according to Vertuci's classification. Data was statistically analyzed using SPSS software to calculate the incidences of root and canal number, each canal type, bilateral symmetry, and the association between gender and variation in root canal morphology.

Results: First and second premolars with two roots were found in 1.8% and 1% of scans respectively. Most of the mandibular first (80.1 %) and second premolars (93.5%) showed (type I) root canal morphology followed by, type II (6.4 %) and type V (2.1%) in the first and second premolars respectively. While, Type VIII showed the least frequency in both premolars. Only the second premolars showed a statistically significant association between gender and both canal type and number. Bilateral symmetrical anatomy was observed more in the second premolar (94.8 %) than the first premolar (85.7%).
Conclusions: Mandibular premolars in Egyptian population showed great variation in root canal configuration. Therefore, preoperative CBCT evaluation is advantageous to avoid missing of existing extra canals during RCT. New classification systems for root canal morphology is highly recommended in further studies.