CBCT在下颌阻生第三磨牙拔除术前风险评估中的应用

目的：运用CBCT评估下颌阻生第三磨牙拔除术中下牙槽神经损伤的手术风险,并指导拔牙手术径路选择。方法：对曲面体层片显示下颌第三磨牙根端与下颌神经管接触重叠,评估下牙槽神经易损伤病例42例,65侧下颌阻生第三磨牙,进行CBCT检查。两组医师（每组口腔外科医师和颌面影像科医师各1名）分别根据曲面体层片和CBCT图像评估拔除下颌第三磨牙时下牙槽神经损伤的风险程度并进行手术设计,应用x2检验两种影像评测结果之间的差异度。结果：评估拔除下颌阻生第三磨牙时出现下牙槽神经损伤的可能性经曲面体层片和CBCT对比研究差异具有统计学意义（P＜0．001）。与曲面体层片相比,CBCT为临床医师提供了阻生磨牙与下颌神经管之间三维影像的空间距离,有效辅助了牙拔除手术方式的设计（P＜0．001）。结论：拔除下颌阻生第三磨牙可能造成下牙槽神经损伤的评估中,与曲面体层片相比,CBCT可以更好地评估手术风险,能指导术者帮助选择更恰当的术式。     

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...     

下颌阻生第三磨牙与下颌管位置的曲面体层X线片和锥形束CT观察

目的 观察分析在曲面体层x线片上人群中下颌阻生第三磨牙(impacted mandibular third molar,IMTM)与下颌管位置关系的类型,并对二者关系密切的病例行锥形柬CT(conc beam computed tomography,CBCT)检查,了解二者实际位置关系.为临床制定IMTM拔除手术方案提供参考.方法 观察390例(645侧)曲面体层X线片,将IMTM与下颌管的位置关系的影像分为3种类型:①无接触类,二者影像无任何重叠或接触;②点状接触类,二者之间影像仅为点状接触;③部分重叠类,二者影像部分重叠或有较大范围接触.统计3种类型的构成比.曲面体层X线片显示IMTM与下颌管影像呈部分重叠或较大范围接触的部分病例行CBCT检查,观察曲面体层X线片IMTM与下颌管关系密切者中,IMTM实际突破下颌管壁所占的比例.结果 390例(645侧)IMTM的曲面体层X线片影像中,无接触类441侧(68.4%);点状接触类149侧(23.1%);部分重叠类55侧(8.5%).对31例(50侧)曲面体层X线片上显示IMTM与下颌管呈部分重叠或较大范围接触的CBCT检查发现,25侧(50%)IMTM突破下颌管壁.结论 ①曲面体层X线片可以排除90%以上IMTM与下颌管关系不密切的病例;②曲面体层X线片IMTM与下颌管影像呈部分重叠或较大范围接触表现的病例有必要行CBCT进一步检查.     

锥形束CT中下颌第三磨牙与下颌管的关系及其与阻生类型的相关性分析

目的:研究在曲面断层片上表现为下颌管与下颌第三磨牙影像重叠的患者,其二者在锥形束CT(CBCT)上的位置关系,为临床风险评估提供参考。方法:研究184颗(146例患者)在曲面断层片上表现为与下颌神经管有影像重叠的下颌第三磨牙,在CBCT上其牙根与下颌神经管的位置关系。分析两者之间位置关系与阻生类型、性别、曲面断层片上下颌神经管骨白线是否可见的相关性。测量下颌第三磨牙与下颌神经管接触的患者其接触的长度及宽度,分析接触长度、宽度与牙根和下颌神经管相对位置的相关性。结果:CBCT图像上下颌第三磨牙与下颌神经管之间是否接触,与其在颌骨内的深度相关,低位阻生接触可能大(P=0.002),与性别相关,女性多(P=0.020);当曲面断层片中下颌神经管骨白线不可见时,接触可能大(P=0.001)。当下颌神经管与牙根舌侧接触时,接触的长度、宽度可能较大。结论:CBCT与曲面断层片相比能更好地体现下颌阻生第三磨牙与下颌神经管的关系,提供更准确的术前风险评估。     

下颌管与下颌第三磨牙牙根相对位置关系的CBCT研究

目的:对曲面断层X线片提示下颌第三磨牙与下颌管关系密切的患者,应用锥形束计算机断层扫描(CBCT)进一步观察测量,为临床制定下颌第三磨牙拔除的手术方案及预防术后并发症做参考。方法:对曲面断层X线片显示下颌阻生第三磨牙(impacted mandibular third molar,IMTM)牙根与下颌管接触或部分重叠的患者168例(210)侧进一步行CBCT检查,观察下颌第三磨牙与下颌管的相对位置。结果:下颌管壁完整者93侧(44.3%),其中72侧(77.4%)下颌管位于IMTM牙根颊侧(1.95±0.95)mm;19侧(20.0%)在其正下方(2.61±1.37)mm;1侧(1.1%)位于其舌侧3.98mm;1侧(1.1%)位于牙根间。下颌管不完整者117侧。其中有较小范围缺损者(缺损最大径≤2mm)42侧(20.2%);而下颌管相对IMTM的位置,位于颊侧有23侧(54.8%),位于正下方14侧(33.3%),位于舌侧5侧(11.9%)。有较大范围缺损者(缺损最大径>2mm)75侧(36.1%);下颌管相对IMTM的位置,位于颊侧有20侧(26.7%),平均缺损最大径(6.42±2.45)mm,平均缺损面积(12.86±10.84)mm2;位于正下方43侧(57.3%),平均缺损最大径(7.90±2.87)mm,平均缺损面积(12.73±8.75)mm2;位于舌侧12侧(16.0%),平均缺损最大径(8.06±2.14)mm,平均缺损面积(21.40±11.84)mm2。结论:对于曲面断层片上提示IMTM与下颌管关系密切的患者,有必要进行CBCT检查,进一步了解其相对位置。     

下颌低位阻生第三磨牙牙根与下颌管的位置关系X线片观察

目的 了解下颌低位阻生第三磨牙牙根与下颌管位置关系。方法 对76例110颗下颌低位阻生第三磨牙常规拍摄下颌曲面体层片,由一名高年资医生按同一标准随机读片,统计构成比。结果 管上型40颗,占牙总数36.3%,涉管型70例占63.7%。结论 下颌低位阻生第三磨牙应常规拍摄下颌曲面体层片以明确牙根与下颌的位置关系,涉管型者应该引起术者高度警惕。?     

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%、骑管型1.01%、混合型0.34%六种类型。结论:下颌阻生第三磨牙与下颌管密切关系的系统分型,对口腔专业教学和临床均有实用意义。     

下颌阻生第三磨牙拔除术中牙根存留与否的临床探讨

目的:探讨下颌阻生第三磨牙拔除术中牙根存留的适应证及其与下牙槽神经损伤的关系.方法:对135例下颌阻生第三磨牙拔除术中断根的处理作回顾性分析,探讨下颌阻生第三磨牙(impacted mandibular third molar,IMTM)与下颌管的位置关系.结果:①135例曲面体层X线片影像中,IMTM与下颌管的位置关系有3种类型,无接触类99例(73%)、点状接触类21例(16%)、部分重叠或较大重叠类15例(11%).②IMTM断根存留18例(13%).③IMTM断根拔除术后下唇感觉异常1个月后消失17例(94%),1例(6%))8个月后症状消失.结论:IMTM拔除术中断根存留的适应证为小于3mm的断根、无牙髓感染的断根、断根与下颌管为第三类接触者.     

CBCT观察影像重叠的下颌第三磨牙与下颌管的位置关系

目的:观察在曲面断层片(Orthpantomography,OPG)中表现为重叠影像的下颌第三磨牙和下颌管在CBCT(cone beam CT)中的位置关系。方法:对在OPG上表现为下颌第三磨牙和下颌管影像重叠的116名患者(136颗牙)进行CBCT扫描。利用软件(I-view)对所得图像测量分类。通过SAS软件对所得数据进行x~2检验。结果:136颗牙中,在下颌第三磨牙和下颌管接触方面的概率上与性别无关(P=0.0758);而当OPG中下颌管与第三磨牙重叠时,骨白线的存在与否与两者是否接触是有关的(P=0.0003)。结论:下颌CBCT和OPG相比,可以更准确地反映下颌管和下颌第三磨牙的位置关系。     

236颗下颌阻生第三磨牙锥形束CT影像的观察分析

[摘要] 目的 探讨锥形束CT(CBCT)三维重建技术用于分析阻生下颌第三磨牙的应用。方法 对下颌阻生第三磨牙的136例(236颗牙)患者CBCT影像资料利用NNT图像分析软件通过容积再现、多层面重建和曲面重建等技术对第三磨牙阻生情况进行分类统计。结果 236颗阻生下颌第三磨牙:高位垂直阻生最多(102颗),占43.22%,颊向阻生最少(1颗);15.68%与下颌神经管接触;与邻牙间隙>0、=0和<0分别为115、75和46颗;26.69%邻牙有龋坏;42.80%造成邻牙远中牙槽骨吸收。结论 CBCT扫描技术和分析软件的应用可提供下颌阻生第三磨牙位置的准确数据,为拔除手术方案的制定提供客观依据。     

Comparison between panoramic radiography and cone-beam computed tomography findings for assessment of the relationship between impacted mandibular third molars and the mandibular canal

Objectives

The aim of this study was to assess the relationship between the mandibular canal and impacted mandibular third molars using cone-beam computed tomography (CBCT) and to compare the CBCT findings with panoramic radiographic signs.

Methods

This study involved a retrospective radiographic review of 781 impacted third molars in 500 patients who showed a close relationship between the mandibular canal and the third molars on panoramic radiographs. Panoramic radiographic images were evaluated for interruption of the white line, darkening of the roots, diversion of the mandibular canal/roots, and narrowing of the mandibular canal/roots. The authors evaluated CBCT images to determine the course of each canal and its proximity to the roots. The statistical correlations between the panoramic radiography and CBCT findings were examined using the Chi-square test and Fisher’s exact test.

Results

Cone-beam computed tomography examination showed that darkening of the roots and deviation of the canal associated with the absence of corticalization between the mandibular third molar and the mandibular canal on panoramic radiographs were statistically significant, both as isolated findings and in association. No significant associations were observed for the other panoramic radiographic findings, either individually or in association.

Conclusions

The results of this study suggest that darkening of the roots, deviation of the mandibular canal, and interruption of the white line observed on panoramic radiographs, both as isolated findings and in association, were effective for determining the risk relationship between the roots and the mandibular canal, requiring three-dimensional evaluation of such cases.     

Position of the impacted third molar in relation to the mandibular canal. Diagnostic accuracy of cone beam computed tomography compared with panoramic radiography

This study investigated the diagnostic accuracy of cone beam computed tomography (CBCT) compared to panoramic radiography in determining the anatomical position of the impacted third molar in relation with the mandibular canal. The study sample comprised 53 third molars from 40 patients with an increased risk of inferior alveolar nerve (IAN) injury. The panoramic and CBCT features (predictive variables) were correlated with IAN exposure and injury (outcome variables). Sensitivity and specificity of modalities in predicting IAN exposure were compared. The IAN was exposed in 23 cases during third molar removal and injury occurred in 5 patients. No significant difference in sensitivity and specificity was found between both modalities in predicting IAN exposure. To date, lingual position of the mandibular canal was significantly associated with IAN injury. CBCT was not more accurate at predicting IAN exposure during third molar removal, however, did elucidate the 3D relationship of the third molar root to the mandibular canal; the coronal sections allowed a bucco-lingual appreciation of the mandibular canal to identify cases in which a lingually placed IAN is at risk during surgery. This observation dictates the surgical approach how to remove the third molar, so the IAN will not be subjected to pressure.     

下颌阻生智齿相关第二磨牙牙根外吸收：曲面断层片与CBCT对比研究

目的 比较曲面断层片和CBCT在诊断下颌阻生智齿相关第二磨牙牙根外吸收的差异。方法 回顾性分析2019年1月—2020年12月于南京医科大学附属口腔医院就诊的832例(1 074颗)近中/水平下颌阻生智齿病例,分别应用曲面断层片和CBCT评估下颌第二磨牙远中牙根外吸收发生率,并分析曲面断层片诊断错误的相关因素。结果 以CBCT影像学结果判定为标准,下颌智齿相关第二磨牙牙根外吸收的发生率为33.15%(356/1 074),曲面断层片诊断正确率为66.39%。经多因素Logistic回归分析发现：中低位、Ⅲ类阻生智齿,下颌阻生智齿与第二磨牙牙根重叠,下颌阻生智齿与第二磨牙牙根接触是导致曲面断层片诊断错误的危险因素(P<0.05)。结论 曲面断层片诊断下颌阻生智齿相关第二磨牙牙根外吸收正确性较低,推荐选用CBCT检测。     

Preoperative assessment of the relationship between the mandibular third molar and the mandibular canal by axial computed tomography with coronal and sagittal reconstruction

OBJECTIVE: We sought to evaluate the relationship between the mandibular third molar and the mandibular canal by using axial computed tomography with coronal and sagittal reconstruction for third molar surgery. STUDY DESIGN: Forty-seven impacted third molars in 41 patients were found in close association with the mandibular canal during a panoramic radiographic assessment. The relationship between the mandibular third molar and the mandibular canal was evaluated by using computed tomography and compared in terms of operative exposure of the inferior alveolar nerve and postoperative labial dysesthesia. RESULTS: Twenty-four (51%) mandibular canals were buccal relative to the third molar, 12 were lingual, 9 were inferior, and 2 were between roots. At the time of the surgical procedure, the inferior alveolar nerve was visible in 7 patients. Postoperative lower lip dysesthesia occurred in 1 patient whose mandibular canal was in the lingual position. CONCLUSIONS: Axial computed tomography with coronal and sagittal reconstruction provides useful information to surgeons regarding the relationship between the mandibular third molar and the mandibular canal.     

Diagnostic accuracy of cone-beam CT compared with panoramic images in predicting retromolar canal during extraction of impacted mandibular third molars

Objectives: The clinical significance of the existence of a retromolar canal and of its neurovascular content is not yet clear.The aim of the present study was to assess the visibility, diameter and course of the mandibular retromolarcanal (MRC) using cone beam computed tomography (CBCT) scan -had been taken for pre-operative radiographic evaluation of impacted mandibular third molars- compared to panoramic radiographs. Study Design: Subjects eligible for study enrollment were those who underwent preoperative CBCT scan for the extraction of impactedmandibular third molars were determined to be extremely close to the mandibular canal on panoramic radiographs. Radiographs were screened for the presence and course of retromolar canals, and linear measurements. Results: 947hemimandibles in 632 patients were examined.A total of 253 MRCs (144 left, 109 right) were detected with CBCT images (26.7%). Only 29 of these canals were also seen on the corresponding panoramic radiographs. Most MRCs had a vertical course (type VI, 28.46%), followed by slightly curved (type I, 26.09%). The visibility of the MRC on the OPGs, according to the increase in the diameter, was not statistically significant for both sides (p>.05).Statistically difference were found for the width at the point of origin from the mandibular canal (p: .037), the mean distance from the MRC to the second molar (p: .042) and height of MRC when compared the gender. Conclusions: The findings suggest that the MRC isn’t a rare anatomical structure. This study therefore clearly establishes the incidence and importance of the MRC. The detection of the presence of the MRC using CBCT may be crucial for extraction of mandibular third molars. Key words:Accessory innervation, cone beam computed tomography, mandibular anatomy, panoramic radiographs, retromolar canal, retromolar foramen.     

下颌智齿阻生类型及其邻牙远中邻面患龋情况的对称性初探

目的 调查下颌第三磨牙生长情况的对称性及其对相邻第二磨牙远中邻面龋患病情况的影响,为临床早期预防性拔除下颌智齿提供依据。方法 纳入2019年11月1日至2019年11月23日在上海交通大学医学院附属仁济医院口腔科拍摄的全景片196张,调查其双侧下颌第三磨牙的对称性,通过卡方检验分析不同阻生类型的下颌第三磨牙与相邻第二磨牙远中邻面龋患病情况之间的关系。结果 双侧下颌第三磨牙对称者187例,占比95.41%。Winter分类中垂直阻生对称性（79.2%）显著高于近中阻生（47.6%）与水平阻生（59.1%）（P=0.001）; Winter分类为近中阻生（46.4%）和水平阻生（38.4%）的下颌第三磨牙,其相邻第二磨牙远中邻面龋发生率显著高于垂直阻生（23.6%）（P=0.001）。结论 下颌智齿具有对称性;为预防相邻第二磨牙远中邻面龋,近中阻生及水平阻生的下颌第三磨牙应在临床上早期预防性拔除。     

冠根分次去除法在疑或累及下牙槽神经的下颌第三阻生磨牙拔除术中的应用

目的:评价应用截冠法分次拔除紧贴下牙槽神经的下颌阻生第三磨牙的效果。方法:对10例术前全景片及CT均显示牙根紧贴或接触下牙槽神经的下颌阻生第三磨牙患者采用截冠留根法,于釉-牙骨质界去除阻力牙冠,包埋牙根于牙槽骨内;术后观察,待牙根移动远离下牙槽神经后再行拔除术。结果:10例患者术后反应轻微,均无下牙槽神经损伤,无感染情况出现;仅1例牙根未能上移至远离下牙槽神经的位置,留根于牙槽骨内,牙龈创面愈合,随访1年无不适。结论:根尖紧贴或接触下牙槽神经的下颌阻生第三磨牙,经截冠留根术后,断根有上移萌出趋势,可远离下牙槽神经管,后期拔除断根,可明显降低下牙槽神经损伤的风险。