Incidence of four canals in root-canal-treated mandibular first molars in a Saudi Arabian sub-population

AIM: The aim of this in-vivo study was to assess the incidence of three roots and four root canals in clinical cases of root-treated mandibular first molars in a Saudi Arabian population. METHODOLOGY: A clinical study of 251 root-canal treated permanent mandibular first molars was conducted. The teeth were examined clinically and radiographically. RESULTS: The results showed that 5.97% of the examined teeth had three roots, 57.76% had four root canals (two mesial and two distal) and 42.3% had three root canals (two mesial and one distal). CONCLUSIONS: The occurrence of four root canals in the mandibular first molar of a Saudi Arabian subpopulation was high.