Aims: To study the prevalence of three-rooted mandibular permanent first molars (PFM) among Saudi population in Al Zulfi.
Materials and methods: Subjects were selected from the patients' records, College of Dentistry, Majmaah University, Al Zulfi, Kingdom of Saudi Arabia. Healthy patients with the presence of both mandibular PFM, orthopantomogram (OPG) and/or intraoral periapical (IOPA) radiographs were included in the study. All patients included were evaluated by a single examiner using OPG and IOPA radiographs. The occurrence of three roots, status of the tooth and associated anomalies were considered for analysis. Descriptive statistics performed using IBM SPSS (Version 21.0) at a 95% confidence interval (p < 0.05) while the Chi-square test and Fisher test were used for the incidence, and comparison of occurrence of the third root in PFM in the mandibular arch.
Results: A sample of 433 subjects was selected randomly based on our inclusion criteria. Only 24 (5.5%) subjects had evidence of three-rooted mandibular PFM with the mean age of 27.67 years. The frequency of bilateral and unilateral three-rooted mandibular PFM was 2.3% (10) and 3.2% (14), respectively. Overall 41.6% of subjects were witnessed with the bilateral occurrence and unilateral occurrence was 58.4% [(57% (8) were on the right and 42% (6) were left side] (p < 0.05). However, no significant relationship was observed between the left and right occurrence of three-rooted mandibular PFM (p < 0.05). Thirty-four (7.8%) PFM were presented with three roots and among them, 70% (24) received treatment. Dilacerations (12.5%), taurodontism (37%) and hypodontia (4%) were associated with three-rooted PFM in the mandibular arch. Kappa statistics showed excellent intra-examiner reliability (κ = 0.9).
Conclusion: The prevalence of three-rooted PFM was 5.5% in the present study and unilateral occurrence is very common. Over 70% of these PFM received dental treatment in Saudi Arabia population. Always, IOPA radiographs are required to confirm the evidence of three-rooted mandibular PFM where three-dimensional imaging is not available.
Clinical significance: An Eagle's eye of an endodontist on three-rooted PFM is of utmost importance in the treatment protocol when the tooth is planned for root canal therapy.
Keywords: Dental anomaly; First permanent molar Third root..