Alahmed Ahmed A, Alabduljabbar Rakan M, Alrashed Ziyad M, Uthappa Roshan, Thomas Toby, Alroomy Riyadh, Mallineni Sreekanth K
Department of Restorative Dental Sciences, College of Dentistry, Majmaah University, Al Zulfi, Riyadh, Kingdom of Saudi Arabia.
Department of Restorative Dental Sciences, College of Dentistry, Majmaah University, Al Zulfi, Riyadh, Kingdom of Saudi Arabia, Phone: +966-538504353, e-mail:
J Contemp Dent Pract. 2020 Feb 1;21(2):197-201.
To study the prevalence of three-rooted mandibular permanent first molars (PFM) among Saudi population in Al Zulfi.
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 ( < 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.
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] ( < 0.05). However, no significant relationship was observed between the left and right occurrence of three-rooted mandibular PFM ( < 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 ( = 0.9).
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.
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.
研究沙特宰赫兰地区人群下颌第一恒磨牙（PFM）三根的发生率。
研究对象选自沙特阿拉伯王国宰赫兰地区Majmaah大学牙科学院的患者记录。纳入研究的为有双侧下颌PFM、全景片（OPG）和/或口内根尖片（IOPA）的健康患者。所有纳入患者均由一名检查者使用OPG和IOPA片进行评估。分析三根的出现情况、牙齿状况及相关异常。使用IBM SPSS（版本21.0）在95%置信区间（<0.05）进行描述性统计，同时使用卡方检验和Fisher检验分析下颌牙弓中PFM第三根的发生率及出现情况的比较。
根据纳入标准随机选取433名受试者。仅24名（5.5%）受试者有下颌三根PFM的证据，平均年龄为27.67岁。双侧和单侧下颌三根PFM的发生率分别为2.3%（10例）和3.2%（14例）。总体而言，41.6%的受试者为双侧出现，58.4%为单侧出现[（57%（8例）在右侧，42%（6例）在左侧]（<0.05）。然而，下颌三根PFM左右侧出现情况之间未观察到显著相关性（<0.05）。34颗（7.8%）PFM有三根，其中70%（24颗）接受了治疗。牙根弯曲（12.5%）、牛牙样牙（37%）和牙缺失（4%）与下颌牙弓三根PFM有关。Kappa统计显示检查者内部可靠性极佳（=0.9）。
本研究中三根PFM的发生率为5.5%，单侧出现非常常见。在沙特人群中，超过70%的这些PFM接受了牙科治疗。在无法获得三维成像的情况下，始终需要IOPA片来确认下颌三根PFM的证据。
当计划对牙齿进行根管治疗时，牙髓病医生对三根PFM的敏锐观察在治疗方案中至关重要。
