Zhao Luyang, Long Yifei, Xu Guikun, Long Jie
The State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China.
Department of Oral and Maxillofacial Surgery, West China College of Stomatology, Sichuan University, Chengdu, China.
Dent Traumatol. 2023 Dec;39(6):575-585. doi: 10.1111/edt.12874. Epub 2023 Aug 2.
BACKGROUND/AIM: Although previous studies have revealed the influence of the mandibular third molar (M3) on mandibular condylar fracture risk and that the presence of M3 could result in different incidences of condylar and angle fractures, there have been no analyses of the influence of M3 on fracture patterns. Moreover, evaluations of M3 position using panoramic radiography have shown insufficient accuracy. This study investigated the relationship between condylar fracture patterns and M3 position using panoramic radiography and computed tomography.
This retrospective study included 280 patients with unilateral mandibular condylar fractures and ipsilateral M3 admitted to West China Hospital of Stomatology between January 2016 and June 2022. Patient medical records, panoramic radiographs, and computed tomography images were collected. The vertical and horizontal positions of M3 were classified using the Pell and Gregory system. M3 angulation was defined as the angle between the long axis of M3 and the mandibular occlusal plane. Condylar fracture patterns were classified as intracapsular (Types A-C) or extracapsular (neck and base). Data were analyzed using McNemar-Bowker test, Pearson chi-squared test, and Fisher's exact test.
Classification of M3 position differed significantly between panoramic radiography and computed tomography images (p < .05). There was a significant association between the mandibular condylar fracture pattern and M3 horizontal position on computed tomography (p < .05). Class I M3 position on computed tomography was associated with a higher incidence of intracapsular than extracapsular fractures, along with a higher incidence of Type B than base fractures; the opposite relationships were observed for Class II. No such association was identified on panoramic radiography.
Mandibular condylar fracture patterns were presumably influenced by M3 horizontal position on computed tomography. The imaging modality affected the classification of M3 position and subsequent analyses. Computed tomography is recommended for future studies to improve accuracy and reliability.
背景/目的：尽管先前的研究已经揭示了下颌第三磨牙（M3）对下颌髁突骨折风险的影响，并且M3的存在可能导致髁突骨折和角部骨折的发生率不同，但尚未有关于M3对骨折类型影响的分析。此外，使用全景X线片评估M3位置的准确性不足。本研究使用全景X线片和计算机断层扫描研究髁突骨折类型与M3位置之间的关系。
本回顾性研究纳入了2016年1月至2022年6月期间在四川大学华西口腔医院就诊的280例单侧下颌髁突骨折且同侧有M3的患者。收集患者的病历、全景X线片和计算机断层扫描图像。M3的垂直和水平位置采用佩尔和格雷戈里系统进行分类。M3的角度定义为M3长轴与下颌咬合平面之间的夹角。髁突骨折类型分为囊内骨折（A - C型）或囊外骨折（颈部和基部）。数据采用麦克尼马尔 - 鲍克检验、Pearson卡方检验和Fisher精确检验进行分析。
全景X线片和计算机断层扫描图像对M3位置的分类存在显著差异（p < 0.05）。计算机断层扫描显示下颌髁突骨折类型与M3水平位置之间存在显著关联（p < 0.05）。计算机断层扫描上I类M3位置与囊内骨折发生率高于囊外骨折相关，且B型骨折发生率高于基部骨折；II类则观察到相反的关系。全景X线片上未发现此类关联。
下颌髁突骨折类型可能受计算机断层扫描上M3水平位置的影响。成像方式影响了M3位置的分类及后续分析。建议未来研究使用计算机断层扫描以提高准确性和可靠性。
