下颌阻生第三磨牙与下颌骨角区骨折关系的临床观察

下颌骨角区是下颌骨骨折好发的区域之一[1]。在临床治疗的下颌骨角区骨折中 ,常见该区伴有不同程度阻生的第三磨牙存在 ,对此已有学者进行研究并报道[2 ]。本文就我科收治的89例下颌骨角区骨折病例进行回顾性临床总结。以探讨下颌阻生第三磨牙对下颌骨角区骨折发生的临床相关解剖因素。1　临床资料1.1　本组 89例病例 ,男性 52例 ,女性 3 7例。年龄范围 19～54岁 ,平均 3 3岁。1.2　骨折原因 :65例为交通事故伤 ,11例为高处坠落伤 ,13例为打击伤。2　结　果2 .1　本组病例均在术前作X线摄片 ,并行下颌骨角区骨折的开放整复 +微型钛板坚强内…     

下颌第三磨牙阻生伴邻近第二磨牙病变临床治疗

下颌第三磨牙阻生常导致邻近第二磨牙发生病变,第二磨牙病变程度的不同决定了阻生的第三磨牙拔除与否。本文旨在对下颌第三磨牙阻生伴邻近第二磨牙病变的临床治疗方法做一综述,以期为牙体牙髓科医生的临床操作提供指导。     

下颌第三磨牙是下颌角骨折的危险因素吗?

下颌骨骨折常发生在角部。人们把下颌角部骨折的发生率高于其它部位的原因归因于下颌第三磨牙的存在。已有人提倡拔除阻生的下颌第三磨牙以预防下颌骨骨折。然而,以往的文献报道不能提供必需的资料支持这种设想。本文研究的目的在于评价下颌骨骨折样本中下颌第三磨牙对角部骨折的影响。     

下颌阻生第三磨牙与下颌管关系分型的研究

目的:探讨下颌阻生第三磨牙与下颌管密切关系的系统分型.方法:3237例下颌阻生第三磨牙的曲面体层X线摄像,其中296例阻生牙牙根与下颌管关系密切(间距≤1 mm)增摄CBCT检查,结合临床资料进行分析.结果:下颌阻生第三磨牙与下颌管密切关系有根侧型30.40％、邻管型50.33％、入管型4.72％、卧管型13.51％、...     

基于锥形束CT的下颌阻生第三磨牙与下颌管位置关系研究

目的 应用锥形束CT(cone beam CT,CBCT)分析下颌阻生第三磨牙与下颌管的三维位置关系,为下颌阻生第三磨牙拔除术前风险评估和制定手术方案提供依据。方法 选取2017年1月至2022年2月就诊于上海市松江区中心医院口腔科需行下颌阻生第三磨牙拔除术的患者732例(1063颗患牙)。所有患者曲面体层片显示下颌阻生第三磨牙牙根与下颌管接触或重叠,调整CBCT十字观察轴的位置和角度形成坐标轴,在冠状面根据下颌管在坐标中的位置,对下颌管与下颌阻生第三磨牙的位置关系进行分类,包括颊侧、颊侧偏下、下方偏颊、下方居中、下方偏舌、舌侧偏下和舌侧,每类可再分为接触、非接触亚类。测量并比较各类下颌管与下颌阻生第三磨牙的接触率和距离差异。结果 1063颗下颌阻生第三磨牙牙根与下颌管的接触率为53.6%,各类接触率比较,差异有统计学意义(χ²=352.945,P <0.001)。其中,舌侧和舌侧偏下的接触率分别为97.2%、96.7%,明显高于除下方偏舌外的其他分类接触率;下方偏舌、下方居中及颊侧的接触率分别为79.2%、70.2%、60.0%,均高于下方偏颊和颊侧偏下的...     

下颌第三磨牙的存在状态与不同骨面型之间的关系

目的：探讨成人下颌第三磨牙的存在状态与矢状向和垂直向骨面型之间的关系。方法：对200例正畸患者的曲面断层片和头颅侧位片进行测量分析。根据下颌第三磨牙的存在状态分为萌出组,垂直阻生组,近中阻生组,水平阻生组（阻生组根据Winter,s分类方法）。对组间的变量进行统计学分析。结果：萌出组与各阻生组的ANB角、Wits值、ANS－Me和Go－Po＇之间的差异有统计学意义。萌出组与近中阻生组和水平阻生组的SN／MP、FH／MP和Co－Go／Co－Po之间的差异有统计学意义。结论：下颌第三磨牙的存在状态与不同骨面型之间都存在一定的关系。矢状向骨性II类和低角短面患者更易发生下颌第三磨牙阻生。     

近中阻生的下颌第三磨牙萌出情况与其倾斜角度的关系研究

目的:3年随防观察近中阻生的下颌第三磨牙萌出情况与其倾斜角度的关系。方法:72名在校本科生,年龄18~20岁,共108颗近中阻生的下颌第三磨牙,研究开始和观察3年后分别拍摄全颌曲面断层片,检查下颌第三磨牙倾斜程度和萌出水平。结果:在3年观察结束时,71.4%(30/42)最初倾斜角度在5°~10°之间的下颌第三磨牙变为直立。33.3%(6/18)最初倾斜角度在15°~20°之间的下颌第三磨牙变为直立。25%(3/12)最初倾斜角度在25°~30°之间的下颌第三磨牙变为直立。最初倾斜角度在35°及以上的下颌第三磨牙没有一颗变为直立的。结论:在一定程度上,可以根据阻生的下颌第三磨牙近中倾斜的角度来预测第三磨牙日后的萌出状况。有些近中阻生,倾斜角度小于35°的下颌第三磨牙经过一定时间是有可能完全萌出而不必预防性拔除的。     

全颌曲面断层片预测下颌第三磨牙拔除致下颌角骨折风险的研究

目的：利用全颌曲面断层片预测下颌第三磨牙拔除致下颌角骨折的风险。方法：筛选2009年6月，2010年6月期间我科186张（共347颗下颌第三磨牙）全颌曲面断层片，计算下颌第三磨牙区剩余骨高度（b）与下颌骨高度（a）的比值（b／a值），分析该比值在人群中的分布情况。结合6例智齿拔除致下颌角骨折病例的b／a值，分析该比值用于预测下颌第三磨牙拔除术致下颌角骨折风险的临床意义。结果：347颗第三磨牙区b／a值符合正态分布，比值低于0．3的病例2例，占0．58％；分析文献中6例智齿拔除术致下颌角骨折病例b／a值均小于0．3，符合第三磨牙区b／a值的人群分布特征，属于小概率事件。结论：下颌第三磨牙拔除术后剩余骨高度与该区下颌骨高度的比值低于0．3者有较高下颌角骨折风险，全颌曲面断层片可以作为提示此风险的一种有效手段。     

下颌第三磨牙萌出状态与第二磨牙远中邻面龋坏的相关性研究

目的:研究下颌第三磨牙萌出状态与第二磨牙远中邻面龋坏的相关性。方法 :临床收集因下颌第三磨牙不适而就诊的患者204例,运用锥形束CT分析下颌第二磨牙远中邻面龋坏与第三磨牙阻生类型(高位、中位、低位)、阻生角度以及两磨牙的釉牙骨质界距离(cementoenamel junction,CEJ)等因素是否存在相关性。结果:在下颌第三磨牙存在的情况下,第二磨牙远中邻面龋坏发生率高达78.4%;性别差异无统计学意义(P=0.165);高位、中位和低位阻生的龋坏发生率差异无统计学意义(P=0.646);而当第三磨近中阻生角度为40~80°时,第二磨牙远中邻面最易发生龋坏,与其他阻生角度组的差异有统计学意义(P<0.001);当第二磨牙与第三磨CEJ距离在6~9 mm时,第二磨牙远中邻面龋坏高于其他组,差异有统计学意义(P<0.001)。结论:下颌第三磨牙近中阻生角度、第三磨牙与第二磨牙的CEJ距离与第二磨牙远中邻面龋坏的发生密切相关。当第三磨近中阻生角度在40~80°间,且两磨牙间的CEJ距离在6~9 mm时,第二磨牙远中邻面更容易发生龋坏,此类阻生齿建议尽早拔除。     

123.下颌第三磨牙是下颌角骨折的危险因素吗?

下颌骨具有特殊的弓形解剖结构,且暴露于外力的作用下,故其薄弱部位如正中联合部、颏孔区、下颌角、髁状突颈部等处易发生骨折.下颌第三磨牙的存在和萌出状态与下颌角部骨折多发性之间是否存在一定的关系,许多学者众说纷纭.本文的目的在于评估下颌角骨折与下颌第三磨牙的存在和萌出状态之间的关系. 　　材料和方法作者共收集了615例年龄在17～75岁之间的下颌骨骨折病例和全口曲面断层片,其中79%为男性,21%为女性.引起损伤的原因分为车祸、坠落伤、斗殴、运动损伤等.根据X线片确定患者是否存在第三磨牙,如有,估计其阻生程度并进行分类,同时也记录骨折发生的数量及部位.统计的数据分析采用t检验和x2检验. 出版日期：2001年9月20日 请看PDF全文     

Impacted mandibular third molars and their influence on mandibular angle and condyle fractures – A retrospective study

BackgroundPrevious retrospective analyses prove that impacted mandibular third molars (M3s) increase the risk of angle fractures and decrease the risk of concomitant fractures to the condyle.Study designA retrospective cohort was designed for patients reported to the Department of Oral and Maxillofacial Surgery from January 2011 till June 2013. The study variables are presence or absence of third molar, if it is present, their position, classified using the Pell and Gregory system; angulation, classified using Shiller's method. The outcome variables were angle and condyle fractures.Materials and methodsHospital records and panoramic radiographs were used to determine and classify these variables.The study sample comprised of 118 mandibular angle and condyle fractures in 110 patients.Database was constructed and analysed using SPSS version 10.0.ConclusionThis present retrospective study concluded that the presence of impacted third molar predisposes the angle to fracture and reduces the risk of a concomitant condylar fracture. However absence of impacted third molar increases the risk of condylar fracture. The highest incidence of angle fracture was observed in position A impacted mandibular third molars. And there is no significant relationship, concerning ramus position and angulation of impacted mandibular third molars with the angle fracture.     

Three-dimensional bone microstructures of the mandibular angle using micro-CT and finite element analysis: relationship between partially impacted mandibular third molars and angle fractures

Abstract –  The mandibular angle is one of the areas of the mandible that are prone to bone fractures, and the presence of an impacted third molar has been found to be associated with increased risk of angle fractures. The factors involved in bone fractures are the amount and direction of load, and the biomechanical and anatomical properties of bone. In the present study, micro-focused X-ray computed tomography was performed to observe and analyze the three-dimensional (3D) bone microstructure of the mandibular angle, and finite element analysis was conducted to examine the relationship between angle fractures and the presence or absence of mandibular third molars. 3D bone microstructure showed no marked difference between mandibles with and without third molars. Finite element analysis showed that, in the mandible with a third molar, stress was concentrated around the root apex of the third molar, and was transmitted in a direction matching the clinical findings of angle fractures. The results obtained in this study suggest that the presence of an impacted third molar changes the concentration and transmission of stress in the mandible, thus increasing the risk of an angle fracture.     

Impact of impacted mandibular third molars in mandibular angle and condylar fractures

Previous retrospective analyses prove that impacted mandibular third molars (M3s) increase the risk of angle fractures and decrease the risk of concomitant fractures to the condyle. The authors have attempted to verify these relationships and identify the underlying mechanism of injury. A retrospective cohort was designed for patients attending the Division of Oral and Maxillofacial Surgery from January 2001 till October 2008. The primary predictor variable was M3. The secondary predictor variables were: M3 position, classified using the Pell and Gregory system; angulation, classified using Shiller's method; and the number of visible dental roots. The outcome variables were angle and condyle fractures. Hospital charts and radiographs were used to determine and classify these variables. The study sample comprised 1102 mandibular fractures in 600 patients. For patients injured by moderate traumatic force resulting in two fractures of the mandible, the presence/absence of impacted M3s played an important role in angle/condylar fractures. Patients with impacted M3s were three times more likely to develop angle fractures and less likely to develop condylar fractures than those without impacted M3s. This study provides clinical evidence to suggest that the removal of unerupted mandibular third molars predisposes the mandible to condyle fractures.     

Impacted third molars and risk of angle fracture

The purpose of this study was to assess the influence of the presence, position, and severity of impaction of the mandibular third molars, on the incidence of mandibular angle fractures. A retrospective cohort study was designed for patients presenting to the Division of Oral and Maxillofacial Surgery, Toronto General Hospital (Toronto, Canada), for treatment of mandibular fractures from January 1995 to June 2000. The independent variables in this study were the presence, position and severity of impaction of third molars. The outcome variable was the incidence of mandibular angle fractures. Hospital charts and panoramic radiographs were used to determine and classify these variables. The demographic data included age, sex, mechanism of injury and number of mandibular fractures. The study sample comprised 413 mandibular fractures in 214 patients. The incidence of angle fractures was found to be significantly higher in the male population and was most commonly seen in the third decade of life. Assault remained the most significant aetiological factor. Patients with third molars had thrice the increased risk of angle fractures when compared to patients without (P<0.001). Impaction of third molars significantly increased the incidence of angle fractures (P<0.001). The severity and angulation of third molar impactions were not significantly associated with angle fractures. This study provides evidence that patients with retained impacted third molars are significantly more susceptible to angle fracture than those without. The risk for angle fracture, however, does not seem to be influenced by the severity of impaction.     

Relationship between the risk of mandibular angle fractures and the status of incompletely erupted mandibular third molars.

BACK GROUND: Several studies have shown the increased risk of mandibular angle fractures associated with incompletely erupted mandibular third molars. But only a few reports analysed in detail the relationship of the status of eruption of this tooth and this type of fracture. OBJECTIVES: The purpose of this study was to clarify the influence of the eruption status of incompletely erupted mandibular third molars on the incidence of mandibular angle fractures. METHODS: Four hundred and thirty-six mandibular halves in 218 patients with mandibular fractures, aged between 15 and 40 years old, were analysed using panoramic radiographs. RESULTS: The incidence of angle fractures in the mandibular halves with incompletely erupted mandibular third molars was 30.8% and this was statistically significantly higher than that in another group (p<0.0001). Deeply located mandibular third molars clearly showed a higher incidence of this fracture when compared with the adjacent second molar (p<0.0001). CONCLUSION: The results of this investigation showed that incompletely erupted mandibular third molars close to the inferior border of the mandible have a high risk of angle fractures.     

Do pathologies associated with impacted lower third molars justify prophylactic removal? A critical review of the literature

Surgical removal of impacted lower third molars is widely carried out in general dental practice and in many institutional clinics. Despite the fact that there are well established indications for the removal of impacted lower third molars, prophylactic removal of these teeth is still being universally practiced. Some reports have estimated that the proportion of impacted third molars that are removed when no clinically sound justification for surgery is present is between 18% and 50.7%. Justifications for prophylactic surgery include the need to minimize the risk of disease (cysts and tumors) development, reduction of the risk of mandibular angle fracture, increased difficulty of surgery with age, and that third molars have no definite role in the mouth. This article critically examines the literature regarding the relationship between impacted lower wisdom teeth, cysts and tumor development, and mandibular fractures.     

Does the presence of mandibular third molars increase the risk of angle fracture and simultaneously decrease the risk of condylar fracture?

Previous studies have shown that impacted mandibular third molars (M3s) increase the risk of mandibular angle fractures and decrease the risk of mandibular condylar fractures. This study attempted to verify these relationships and identify the influence of mechanism and cause of injury. The incidence of fractures was compared in 700 patients with and without impacted M3s. The results showed that patients with impacted M3s had a lower risk of condylar fracture and a higher risk of angle fracture than those without impacted M3s when injured by moderate trauma force. Such relationships could not have been identified when patients were injured by high trauma force. Patients with impacted M3s had a higher risk of angle fracture than those without impacted M3s no matter how they were injured (assault, fall, motor vehicle accident, other). When patients were injured by assault or in a motor vehicle accident, those with impacted M3s were less likely to have a condylar fracture. M3s were a dominant factor for developing a mandibular angle fracture and preventing condylar fracture. The risk of angle fracture was much more affected by impacted M3s than that of condylar fracture, when injury mechanism and cause were taken into consideration.     

Mandibular third molar space in different antero-posterior skeletal patterns

Retromolar space has long been identified as a major factor in the aetiology of mandibular third molar impaction. The aims of this study were to compare mandibular third molar space between the different antero-posterior (A-P) skeletal patterns, between erupted and impacted third molars in the different A-P skeletal patterns, and to report on the status of third molar eruption/impaction among the studied subjects. A total of 432 mandibular third molars in 270 subjects (132 females and 138 males) were investigated from dental pantomograms (DPTs) and lateral cephalograms (LC). The average age for the total sample was 20.80 ± 2.03 years. The subjects were divided into three groups according to their ANB angle as follows: skeletal Class I (144 third molars in 90 subjects), skeletal Class II (145 third molars in 95 subjects), and skeletal Class III (143 third molars in 85 subjects). Each group was subdivided into impacted and erupted subgroups. DPT and LC were traced and the following variables were measured: retromolar space width, third molar width and angulation, β angle, second molar angulation, mandibular length, and gonial angle. Independent t-test, analysis of variance, and chi-square test were used for statistical analysis. Retromolar space width in the Class III subjects was smaller than in the Class I subjects (P?相似文献   

Iatrogenic mandibular fractures following removal of impacted third molars: an analysis of 130 cases

Immediate and late mandibular fractures are a rare complication of third molar removal. We analysed 130 cases of mandibular fractures following removal of impacted third molars reported in the literature, including four managed in the maxillofacial unit and identified potential risk factors. Its occurrence is likely to be multi-factorial, with age, gender, angulation, laterality, extent and degree of impaction and associated pathologies contributing to the risk of fracture. Postoperative fractures were more common than intra-operative fractures (2.7:1) and occurred most frequently in the second and third weeks (57%). A 'cracking' noise was the most frequent presentation (77%). Intra-operative fractures were more frequent among females (M:F - 1:1.3), and differed from postoperative fractures (M:F - 3.9:1). This study analyses the results, providing suggestions to minimise the risk and to manage a mandibular fracture following removal of a third molar.     

Relationship between lower wisdom tooth position and cyst development, deep abscess formation and mandibular angle fracture.

AIM: There is an ongoing controversy about indications for prophylactic removal of third molars. The purpose of this retrospective study was to clarify the risk of preservation of lower third molars. MATERIAL AND METHOD: In a 5-year period, 316 patients were registered who had received in-patient treatment for deep abscess formation, cyst formation or mandibular angle fracture in relation to lower third molars. A radiological analysis (panoramic radiographs) was performed to determine whether major pathological changes associated with lower wisdom teeth are related to their position. Third molar positions were studied in this in-patient group and in an out-patient group. The latter consisted of 300 consecutive patients with prophylactically removed impacted third molars without any pathology. The relationship between the positions and the different pathological changes associated with impacted lower wisdom teeth was analysed statistically using a new 'position score'. RESULTS: The study revealed that the highest 'position scores' corresponding to a leading aberrant position correlated significantly with cyst formation. Lower scores corresponding to moderately aberrant or slightly irregular position were found with angle fractures, abscess formation, and in the control group as a whole. CONCLUSION: This study indicates that prophylactic third molar surgery for teeth with high and strongly elevated 'position scores' is appropriate in order to prevent cyst formation or mandibular angle fractures in a population at risk for facial trauma. In addition to other factors, 'position score' data could be useful for development of a model for predicting severe complications related to (removal of) impacted lower wisdom teeth.