以放射線診斷研究台灣人恆齒下顎第一大臼齒具第三牙根之盛行率

Radiographic Survey of the Prevalence of three-rooted Permanent Mandibular First Molars in Taiwan

李甫瑩(Fu-Ying Lee) ； 葉惠津(Hwey-Chin Yeh)

《中華民國牙周病醫學會雜誌》 11卷4期 (2006/12) Pp. 299-309

摘要

人類的恆齒下顎第一大臼齒通常只有兩個牙根，臨床上卻也發現在台灣有為數不少的病患，其恆齒下顎第一大臼齒具有三個牙根，亦即出現了遠心舌側牙根。此第三牙根的出現，可能增加牙髓病治療、拔牙或矯正治療的困難度，提高牙根分叉侵犯的機會，降低牙周治療的預後。有鑑於先前之文獻報告，多認為蒙古人恆齒下顎第一大臼齒出現第三牙根的盛行率較高，惟缺乏台灣居民之盛行率調查報告，因此本篇研究藉向比較同一恆齒下顎第一大臼齒拍攝所得的放射線咬翼片及根尖片，得知根尖片在判讀第三牙根是否存在的可信度與咬翼片無異，並進一步以放射線根尖片，調查台灣人恆齒下顎第一大臼齒發生第三牙根的盛行率。結果顯示在台灣人恆齒下顎第一大臼齒具第三牙根的盛行率為11.95%，約落在多數調查亞洲人的盛行率範圍中；其中，男性的盛行率(12.56%)略高於女性(11.30%)，但並無統計學上的差異；出現在雙側的盛行率(7.41%)較出現在單側的盛行率(4.54%)高；又單獨出現在右側者的盛行率約為單獨出現在左側者的1.6倍。本篇報告提供給臨床牙醫師一個簡易的判讀方法，藉由放射線根尖片及早診斷恆齒下顎第一大臼齒是否具第三牙根，以期達到預防疾病的目的。

關鍵字

恆齒下顎第一大臼齒 ； 解剖型態 ； 盛行率 ； 放射線診斷

並列摘要

There are usually two roots in human permanent mandibular first molars, however, the presence of a third root, the distoligual root, on a permanent mandibular first molar is not accidentally found. The existence of a third root may increase the difficulty of endodontic treatment, extraction procedure, orthodontic movement, serve as a local factor of periodontal breakdown, and likely hamper the periodontal prognosis. The purpose of this study was to investigate the prevalence of three-rooted permanent mandibular first molars in Taiwan. By reading the periapical & bitewing radiographs taken from the same permanent mandibular first molars, we found no difference between two radiographic techniques in observing the occurrence of a third root. We further investigate paired periapical radiographs from 1255 subjects. An overall prevalence of three-rooted permanent mandibular first molar was 11.95%. There was no statistically significant difference between males (12.56%) and females (11.30%), but a much higher bilateral occurrence (7.41%) than that at unilateral (4.54%). The unilateral occurrence at the right side was 1.6 fold higher than that at the left side. Herein, we introduced the prevalence and a simple method in early detection of three-rooted mandibular first molar. Clinicians should be aware of this anatomic variation as a predisposing factor in disease progression.

並列關鍵字

Permanent mandibular first molar ； Anatomy ； Prevalence ； Radiographic survey