ABSTRACT
Purpose: of this cross-sectional study was to determine the proportion of permanent mandibular first molar teeth with three roots in the Egyptian population. Material and methods: In total, 479 digital periapical radiographs were screened & evaluated to obtain 312 samples for the study. The 312 studied subject,137 male and 175 females, aged range from 19 to 70 years .Symmetry, gender, and frequency of occurrence of third root in mandibular first molars were assessed and analyzed using the chi square test. Two examiner evaluated the radiographic characteristics of the radix entomolaris (RE). Cohen kappa test was used to assess intraexaminer variability. Results: The prevalence of RE where 2.91 % (4/10)in male, 3.42% (6/10) in female. Total Prevalence of RE in mandibular first molar were 3.12 %. There was no significant difference regarding to gender as p=0.862. The Prevalence RE showed no statistically significant regarding to the position either unilateral or Bilateral )p=0.342) Conclusion: The overall prevalence of the RE is 3.12% in the mandibular first in the Egyptian population.