Introduction:The aim of this study was to assess the morphology of canal and root of mandibular first and second premolars using CBCT.
Materials and Methods: In this descriptive cross-sectional study, 200 CBCT images were assessed if the CBCT image included at least one mandibular premolar, and had good quality. The CBCT images were excluded if the mandibular premolars had open apex, filling, calcification, previous root canal treatment, root fracture, post and core, root resorption, severe erosion or peri-apical lesion. A total of 800 premolars were assessed in this study. Patients’ gender and tooth location (left/right) were recorded along with the number of canals and roots, morphology of root canals, the length of canals, the thickness of root and the presence of C-shape canals. Data were analyzed using SPSS version 20 and T test were applied at the significant level of 0.05%.
Results: 50% (400) of the studied teeth were first premolars and 50% (400) were second premolars. No gender tendency was found. The most prevalent canal type was type 1 according to Vertucci. The mean length of canals was 13.62±1.47 mm. The assessment of root thickness in MB, MM, ML and MD showed that, the thickset root wall was in the middle one-third and the thinnest was in the apical one-third. No C-shape canal was found in first and second premolars.Conclusion: Within the limitation of this study, the most prevalent canal type was type 1 Vertucci; the thickset root wall was in the middle one-third and the thinnest was in the apical one-third; no C-shape canal was found in the Iranian population. Clinicians should be aware of the complexity of root canal anatomy to achieve favorable treatment outcomes.