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。     

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。     

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。     

微创拔除压迫下牙槽神经的第三磨牙方法分析

目的: 应用牵引拔牙、截冠和超声骨刀微创拔牙技术拔除压迫下牙槽神经的第三磨牙,观察术后产生下唇麻木等并发症的发生情况。方法: 选择60例全景片和锥形束CT（CBCT）显示下颌第三磨牙牙根压迫下牙槽神经的患者,分别采用3种方法拔牙各20例,术后检查下唇麻木情况。结果: 应用牵引拔牙技术和截冠方法拔除压迫下牙槽神经的第三磨牙,术后无人发生下唇麻木,而应用超声骨刀微创拔牙的患者中有1例出现轻微的下唇麻木症状,经用药1个月后好转。结论: 牵引拔牙技术、截冠和超声骨刀3种方法均可有效避免智牙拔除后下唇麻木的并发症。     

下颌阻生第三磨牙与下颌管重叠时的三维位置关系与拔除方法研究

目的 探讨曲面体层X线片示下颌阻生第三磨牙根尖部与下颌管重叠时的三维位置关系分类,以指导临床采用恰当方法拔出下颌阻生第三磨牙.方法 选取在曲面体层X线片上牙根与下颌管有重叠的57颗下颌阻生第三磨牙,行锥形束CT(cone beam computed tomography,CBCT)检查,了解两者间的三维位置关系,拟定安全的拔除手术方案.结果 55例患者的57颗患牙的CBCT影像中,22颗患牙牙根(38.6％)突破下颌管壁位于下颌管内;30颗患牙(52.6％)的牙根位于下颌管的舌侧,未与下颌管发生接触;4颗患牙(7.0％)的牙根位于下颌管的颊侧,未与下颌管发生接触;1颗患牙(1.8％)的双根跨于下颌管间.57颗患牙均顺利完成拔牙手术,1例患者(1.8％)出现短暂的下唇麻木于术后1个月后恢复.结论 曲面体层X线片上下颌阻生第三磨牙根尖部与下颌管重叠的病例中,下颌第三磨牙的根尖多位于下颌管的舌侧或位于下齿槽神经管内,CBCT检查对拟定正确安全的拔除术式和降低下齿槽神经损伤发生率具有重要的意义.     

正畸牵引法辅助拔除接触下牙槽神经管的埋伏阻生牙1例报告

阻生下颌第三磨牙拔除是口腔颌面外科的一种常见手术.由于低位阻生的下颌第三磨牙牙根位置常与下牙槽神经(inferior alveolar nerve,IAN)关系密切,神经损伤是该手术的严重并发症之一.目前,国际上主要有3种避免IAN损伤的方法:截冠法、部分牙冠切除术和正畸牵引法.本文报告1例下颌第三磨牙近中斜位低位阻生的患者,采用改良正畸牵引法,分两步将牙根牵离神经管,牵引完成后顺利拔除患牙.     

牙冠去除技术拔除邻近下牙槽神经的49例阻生智牙临床分析

目的:通过观察下颌智牙截冠后牙根移动速率与患者年龄、性别、牙根数目、阻生方向、新骨形成特点等因素之间的相关性,综合评价牙冠去除技术的临床适用范围.方法:49例智牙通过锥形束CT(CBCT)确定牙根与邻近下颌神经管的关系,测量截冠后牙根移动距离,并分析牙根移动速率特点.对牙根移动速率与患者年龄、性别等因素的相关性进行推导...     

正畸治疗中磨牙的拔除和保留（四十二）——下颌第三磨牙获得性间隙对其生长发育的意义

目的：揭示第三磨牙在牙根发育完成前受正畸治疗干预而获得充足的发育空间，其牙根生长发育的特征及意义。方法：随访21例第三磨牙牙根未发育完成前接受拔除第一或第二磨牙进行正畸治疗的青少年，调查其下颌第三磨牙牙根发育完成后的牙根融合率、根分又程度及根长，并与下颌第二磨牙对应数值进行比较。结果：下颌第三磨牙在牙根生长完成发育前获得充足的生长空间后其牙根的分叉率、分叉程度均高于下颌第二磨牙，其牙根长度与下颌第二磨牙相仿。结论：下颌第三磨牙牙根融合可能是因空间不足受挤压所致，利用第三磨牙代替第二磨牙的正畸治疗应尽量选择在第三磨牙牙根未发育完成前进行。     

埋伏阻生第三磨牙致第二磨牙牙根外吸收临床处理策略分析及病例报告

目的探讨对于埋伏阻生的第三磨牙导致第二磨牙牙根外吸收的治疗方案选择及预后分析。 方法纳入2019年1月至2021年12月期间于南方医科大学口腔医院因埋伏阻生第三磨牙导致相邻第二磨牙牙根外吸收而就诊的35例病例为观察对象，通过临床及锥形束CT（CBCT）检查，根据Ericson分类将吸收程度分为以下三类予以处理：（1）轻度吸收：16例。拔除阻生第三磨牙并在第二磨牙远中同期行骨移植术；（2）中度吸收：11例。拔除阻生第三磨牙同时保护其近中牙囊；（3）重度吸收：8例。拔除阻生第二磨牙，择期修复或行正畸治疗。于术后7 d、1个月及6个月对病例进行临床及影像学检查，随访术区及第二磨牙预后情况。 结果15例第二磨牙牙根轻度吸收及10例中度吸收病例术后6个月随访，CBCT显示牙根外吸收程度较术前无加重，第二磨牙牙髓活力正常；1例轻度吸收病例失访，1例中度吸收病例出现第二磨牙牙髓坏死；8例重度吸收病例在拔除第二磨牙后进行种植或正畸治疗。 结论通过术前CBCT检查可准确判断埋伏阻生第三磨牙导致第二磨牙牙根外吸收程度。对于牙根外吸收轻度及中度病例采用不同的干预方法可有效地阻断第二磨牙的牙根外吸收进程，且尽可能保留第二磨牙的牙髓活力。     

牙根先脱位法拔除下颌低位水平阻生第三磨牙的微创化意义

目的:评价牙根先脱位法拔除下颌低位水平阻生第三磨牙的临床效果.方法:选取126例拟拔除下颌低位水平阻生第三磨牙的患者,术前曲面体层片及CBCT均显示第三磨牙为下颌低位水平阻生,随机分为试验组和对照组,其中试验组采用牙根先脱位法,对照组采用传统牙冠先脱位法,并记录相关临床资料.结果:试验组与对照组在拔牙时间、术后疼痛VA...     

Diagnostic accuracy of panoramic radiography,stereo-scanography and cone beam CT for assessment of mandibular third molars before surgery

Abstract

Objective. To compare the diagnostic accuracy of panoramic imaging, stereo-scanography and cone beam computed tomography (CBCT) for assessment of mandibular third molars. Material and methods. One hundred and twelve patients (147 third molars) underwent radiographic examination by panoramic imaging, stereo-scanography and CBCT. Tooth angulation, root morphology, number of roots and relation to the mandibular canal were assessed. The same variables were assessed intra- and post-operatively and served as reference for the radiographic assessments. The diagnostic accuracy for each variable was compared between the three modalities and accuracy was further expressed as sensitivity and specificity and tested between the modalities for identifying the relation to the mandibular canal. Results. There were no significant differences between the modalities regarding tooth angulation, root morphology and number of roots. However, CBCT was more accurate than stereo-scanography for determining root bending in the bucco-lingual plane (p = 0.02). Moreover, sensitivity for direct contact to the mandibular canal (panoramic imaging: 0.29, stereo-scanography: 0.57, CBCT: 0.67) was higher for CBCT than for panoramic images (p = 0.05) and specificity for no direct contact to the mandibular canal (panoramic imaging: 0.78, stereo-scanography: 0.53, CBCT: 0.68) was higher for panoramic images and CBCT than for scanograms (p < 0.001). Conclusion. Panoramic imaging, stereo-scanography and CBCT seem equally valuable for examination of tooth angulation, number and morphology of roots of mandibular third molars. However, CBCT was more accurate for assessment of root bending in the bucco-lingual plane and more accurate than panoramic images to identify direct contact to the mandibular canal.     

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.     

Unerupted teeth associated with dentigerous cysts and treated with coronectomy: mini case series

There is a resurgence of interest in coronectomy, but its appropriate application in the management of third molar teeth has yet to be defined. Dentigerous cysts associated with unerupted teeth are most commonly associated with mandibular third molars. In this case series we evaluate outcome after coronectomy of teeth with associated dentigerous cysts in cases where the inferior dental nerve was thought to be at risk, or there was an increased risk of mandibular fracture. We retrospectively studied 21 consecutive patients treated by coronectomy for dentigerous cysts at the Oral Surgery Department at Guy's Hospital. The most commonly affected teeth were mandibular third molars (20/21). One patient had permanent injury to the inferior dental nerve, but no mandibular fracture or recurrence of cyst was reported. One patient required secondary retrieval of the retained root because of eruption. Coronectomy of unerupted teeth associated with dentigerous cysts is an effective treatment when there is high risk of injury to the inferior dental nerve injury or potential for mandibular fracture. Further work with larger numbers and longer follow-up is required to discover the long-term outcome of the electively retained root.     

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。     

牙科数字成像系统、锥形束CT及透明牙对离体第一恒磨牙根管系统诊断价值的对比性研究

目的 对比分析牙科数字成像系统（RVG）、锥形束CT（CBCT)及透明牙3种检查方法在诊断离体第一磨牙根管系统的价值,分析第一磨牙根管影像解剖学与根管解剖学的对应关系,为第一磨牙根管治疗提供影像解剖依据。方法 拍摄269颗离体第一磨牙颊舌向、近远中向RVG和CBCT后,再制作根管染色透明牙,应用RVG、CBCT和透明牙对各牙根中上2/3、根尖1/3区根管系统和管间交通支进行分类统计,以评估CBCT在根管诊断中的应用价值。结果 CBCT对第一磨牙主根管中上2/3区的显示率达96.55%;CBCT、透明牙对第一磨牙根尖1/3区根管系统的显示差异有统计学意义（P<0.05）。上、下颌第一磨牙近中根变异较大,双或多根管与管间交通支发生率均较高。结论CBCT与透明牙在显示第一磨牙主根管系统（牙根中上2/3区）方面基本等效;在根尖1/3区透明牙对细小分歧根管的显示明显优于CBCT;RVG对多根管牙根、根尖细小分歧根管的显示明显受限;上、下颌第一磨牙近中根双或多根管与管间交通支发生率均较高。CBCT对牙根、根管的显示具有清晰直观、准确快捷的优点,是目前无创诊断根管疾病最可靠方法。     

Anatomical differences in lower third molars visualized by 2D and 3D X-ray imaging: clinical outcomes after extraction

The purpose of this study was to evaluate the relationship between third molars and the inferior alveolar canal using panoramic radiographs and cone beam computed tomography (CBCT) scans and to assess clinical outcomes after third molar removal retrospectively. The degree of superimposition, buccolingual position (buccal, central, and lingual) and physical relationship (separation, contact, and involved) were measured using CBCT scanning. Post-extraction complications were recorded. Based on radiographic evaluation, 45.9% of third molar roots were inside the inferior alveolar canal, 21.3% were in contact with the inferior alveolar canal, and 32.8% were separated from the canal. The frequency at which the mandibular canal was separated from the root apex was significantly higher when the canal was in the buccal position (80.0%) than in the central (20.0%) and lingual positions (0.0%). Although on panoramic radiographs all third molars were directly superimposed on the inferior alveolar canal, CBCT showed direct contact or canal involvement in 67.2% and separation of the canal from the root apex in 32.8%. Complications occurred in nine patients: eight had third molar root apices inside or in contact with the inferior alveolar canal. The prevalence of post-extraction complications correlated with the absence of cortication around the inferior alveolar canal.