Samieirad Sahand, Eshghpour Majid, Dashti Ramina, Tohidi Elahe, Javan Abdollah Rashid, Mianbandi Vajiheh
Assistant Professor, Oral and Maxillofacial Diseases Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
Associate Professor, Oral and Maxillofacial Surgery Department, Mashhad Dental School, Mashhad University of Medical Sciences, Mashhad, Iran.
J Oral Maxillofac Surg. 2019 Mar;77(3):556-564. doi: 10.1016/j.joms.2018.09.028. Epub 2018 Sep 29.
The purpose of this study was to investigate and determine the relations between mandibular third molar (M3) impaction types and mandibular angle and condylar fractures.
A retrospective study was conducted in patients with mandibular angle and condylar fractures referred to the Oral and Maxillofacial Surgery Department of the Shahid Kamyab Hospital (Mashhad, Iran) from 2013 to 2018. Data sources were patients' hospital documents and panoramic radiographs. Predictor variables were the presence and position of impacted M3s. The Pell-Gregory classification was used to identify the horizontal and vertical positions of impaction. The impaction angulation was determined using the Schiller classification. Outcome variables were the presence of angle and condylar fractures. Data were analyzed using SPSS 16 (IBM Corp, Armonk, NY) and χ and Fisher exact tests.
The study sample consisted of 117 patients (63.2% with condylar fractures, 30.8% with angle fractures, and 6% with concomitant fractures of the condyle and angle). Most patients (88.9%) with angle fracture had impacted M3s; however, impacted M3s were absent in 59.5% of condylar fracture cases. Mesioangular and vertical positions were the most prevalent impaction angulation types in patients with mandibular angle fracture. Classes II and B were the most frequent horizontal and vertical impaction types, respectively, according to the Pell-Gregory classification. There was a statistically significant difference between fracture site and the presence or absence of impacted M3s (P < .001). Moreover, a significant relation was observed between horizontal impaction type and fracture site in patients with impacted M3s (P = .001).
The presence of impacted M3s increased the risk of angle fractures and simultaneously decreased the risk of condylar fractures. Fractures of the angle region were more commonly seen in patients with superficially impacted (vs deeply impacted) M3s.
本研究旨在调查并确定下颌第三磨牙（M3）阻生类型与下颌角及髁突骨折之间的关系。
对2013年至2018年转诊至伊朗马什哈德沙希德·卡米亚布医院口腔颌面外科的下颌角及髁突骨折患者进行回顾性研究。数据来源为患者的医院病历和全景X线片。预测变量为阻生M3的存在情况和位置。采用佩尔 - 格雷戈里分类法确定阻生的水平和垂直位置。使用席勒分类法确定阻生角度。结果变量为角部和髁突骨折的存在情况。使用SPSS 16（IBM公司，纽约州阿蒙克）进行数据分析，并采用χ检验和费舍尔精确检验。
研究样本包括117例患者（63.2%为髁突骨折，30.8%为角部骨折，6%为髁突和角部同时骨折）。大多数角部骨折患者（88.9%）有阻生M3；然而，59.5%的髁突骨折病例不存在阻生M3。近中倾斜和垂直位置是下颌角骨折患者中最常见的阻生角度类型。根据佩尔 - 格雷戈里分类法，II类和B类分别是最常见的水平和垂直阻生类型。骨折部位与阻生M3的存在与否之间存在统计学显著差异（P <.001）。此外，在有阻生M3的患者中，水平阻生类型与骨折部位之间存在显著关系（P =.001）。
阻生M3的存在增加了角部骨折的风险，同时降低了髁突骨折的风险。在浅部阻生（相对于深部阻生）M3的患者中，角部区域骨折更为常见。
