臺灣三牙根的上顎第一小臼齒電腦斷層研究

Three-Root Upper Premolar in Taiwanese Population: Cone Beam Computed Tomography Study

恆牙的上顎第一小臼齒通常有兩個牙根位於頰側和顎側，當發生三個牙根的情況時，對於牙周治療會因為多一個根叉而增加治療的困難度及影響預後。而對於上顎第一小臼齒三個牙根與牙周病的關係，則尚未有學者研究發表。本文的目的是探討：（1）首篇牙周病學研究，以電腦斷層分析三牙根上顎第一小臼齒發生率。（2）三牙根上顎第一小臼齒頰側牙根分叉的位置。（3）以及發生三牙根時牙周根叉侵犯的相關性。研究結果顯示在500位患者共962顆上顎第一小臼齒中，三牙根上顎第一小臼齒的發生率10.9%，頰側根叉分叉的位置在牙骨質琺瑯質交界（cementoenamel junction）下7.17 mm，三牙根上顎第一小臼齒發生牙周頰側根叉侵犯的相關性47.8%，為中度相關性。本研究的結論為臺灣民眾三牙根上顎第一小臼齒的發生率是10.9%，過去臨床醫師容易忽略此一現象。增加頰側根叉（mid-buccal root furcation），不必然伴隨牙周病的發生，但了解此牙根型態，能提早發現，及早診斷與治療，有助於牙周病的根叉處理以及治療預後。

The upper first premolar with two roots, the buccal and palatal roots, has been well documented in most peer-review articles. When furcation involvement occurs in the multi-root molar, the prognosis of the tooth become a concern due to the difficulty in cleaning access by the surgeon and containing grafting material. However, to the best of our knowledge, the incidence, prevalence, location of the mid-buccal furcation entrance and correlation of periodontitis at the three roots-upper first premolar have not been reported =or discussed in peer-review articles so far. The purpose of this article is to outline the first clinical study on the three root-upper first premolar in Taiwan. In addition, it aims to review the incidence and root pattern of the three root-upper first premolar. The study reveals that the incidence of the upper first premolar with three roots is 10.9%. The location of the mid-buccal furcation entrance is 7.17 mm below CE J. The correlation between the upper first premolar with two roots and periodontal furcation involvement is 47.8%, which shows a moderate correlation.
Collectively, the incidence of the three root-upper first premolar is 10.9% in Taiwan’s population. The upper first premolar has a mid-buccal root furcation, which may be a concern but not the main cause of periodontal disease. However, understanding the morphology of the mid-buccal root furcation at the upper first premolar may benefit the furcation management and prognosis of periodontal therapy.