近中阻生下颌第三磨牙与下颌第二磨牙牙根外吸收的CBCT研究

目的: 通过CBCT观测研究近中阻生下颌第三磨牙(mandibular third molar,MTM)的临床特征与下颌第二磨牙牙根外吸收(mandibular second molar external root resorption,MSMERR)的关系。方法: 随机选取2021年6月1日~2021年12月31日于北京市石景山医院口腔科就诊的近中阻生MTM患者的CBCT影像资料为研究对象,观察同侧MSMERR存在与否,对患者的性别、年龄、MTM的阻生角度、MTM萌出高度、MTM近中以及MSM远中釉牙骨质界之间的距离(MTMMCEJ-MSMDCEJ)以及接触点位置等进行记录,并分析各个因素对下颌第二磨牙ERR的影响。结果: (1)MSMERR的概率为15.89%;(2)MSMERR与年龄、MSM咬颌平面与MTM咬颌平面夹角(a)°以及MTMMCEJ-MSMDCEJ距离有关;(3)当患者年龄≥35岁,MSM咬颌平面与MTM咬颌平面夹角(a)°为45°~60°以及MTMMCEJ-MSMDCEJ大于6 mm时,MSMERR危险程度增加。结论: 当年龄大于35岁、影像学检查发现MTM与MSM夹角在45°~60°、或者MTMMCEJ-MSMDCEJ大于6 mm时,可视为预防性拔除MTM的指导原则。     

上颌中高位阻生第三磨牙引起相邻第二磨牙牙根外吸收的CBCT研究

目的: 探讨上颌中高位近中 水平或垂直阻生智齿与相邻上颌第二磨牙牙根外吸收(ERR)之间的关系。方法: 收集2019~2022年就诊的88例患者共计93颗患牙的临床资料,对上颌中高位近中 水平或垂直阻生第三磨牙引起相邻第二磨牙ERR的相关因素进行分析。结果: 上颌第二磨牙ERR的患病率为44.1%,性别和年龄不同,上颌第三磨牙阻生方向不同,第二磨牙ERR发生率差异无统计学意义(P＞0.05);上颌智齿阻生深度不同第二磨牙ERR发生率差异有统计学意义(P＜0.05)。结论: 上颌第三磨牙高位阻生更易导致相邻第二磨牙ERR的发生,建议临床上尽早预防性拔除。     

下颌完全埋伏阻生智齿引起邻近第二磨牙牙根外吸收及牙周改变的CBCT研究

目的:探讨下颌近中、水平、倒置完全埋伏阻生智齿与邻近第二磨牙牙根外吸收及牙周组织病变之间的关系。方法:收集2019～2022年我院收诊的140例患者共计251颗此类患牙的临床资料(CBCT影像资料),对下颌近中、水平、倒置完全埋伏阻生第三磨牙引起相邻第二磨牙牙根外吸收及局部牙周改变的相关情况进行检查并统计分析。结果:下颌近中、水平、倒置完全埋伏阻生智齿导致邻近下颌第二磨牙牙根外吸收的患病率为22.7%,远中边缘骨吸收(或牙周破坏)发生率为68.5%,多数情况下均存在下颌第二磨牙远中牙槽骨吸收,其中轻度占主要(36.2%)。不同年龄和性别及下颌第三磨牙阻生方向不同,第二磨牙远中牙槽骨吸收发生率差异有统计学意义(P<0.05);不同年龄、性别、下颌第三磨牙深度及角度不同,牙根外吸收发生率及严重程度差异均有统计学意义(P<0.05)。结论:下颌近中、水平、倒置智齿完全埋伏阻生时易导致第二磨牙牙根外吸收的发生及周围牙周组织的破坏,应给予足够重视,建议尽早拔除。     

140例下颌阻生智齿牙根形态观察

下颌智齿阻生率高,常引起冠周炎、颌面部间隙感染、患牙及邻牙龋坏等并发症而需拔除。由于该牙位于口腔后部,加之其牙根形态多变,阻生方式多样而增加了拔除难度,使之成为牙拔除术的主要难点之一。本文对140例下颌阻生智齿的牙根形态进行观察,旨在了解下颌阻生智齿牙根形态与其阻生类型、拔牙断根发生之间的关系。     

下颌阻生智齿致下颌第二磨牙龋损的临床观察

下颌阻生智齿可引起多种并发症的发生,致下颌第二磨牙远中邻面或颈部龋损是其中之一[1],但其危害程度并未引起足够重视。作者自行设计表格,进行相应记录。对1993年7月～1997年6月间528例下颌智齿阻生且下颌第二磨牙无龋损患者进行追踪随访,其结果报告如下。１材料与方法有下颌阻生智齿且下颌第二磨牙无龋损病例528例（双侧者只随机选择一侧进行随访）,男271例,女257例,年龄18～45岁,平均30岁。其中已拔除下颌阻生智齿者312例,随访306例,为拔牙组。不同意拔除下颌阻生智齿者216例,随访213例,为非拔牙组。追踪随访时间均为4a。在…     

第三磨牙阻生引起相邻第二磨牙牙根外吸收的回顾性研究

目的　研究第三磨牙阻生与相邻第二磨牙牙根外吸收（external root resorption,ERR）的关系,并为此类病例的防治处理提供依据。方法　回顾性分析南方医科大学深圳口腔医院2013—2017年收治的85例第三磨牙阻生患者的105颗阻生牙及相邻第二磨牙ERR情况。利用CBCT对第二磨牙ERR进行检测。采用χ2检验或Fisher确切概率法分析第二磨牙ERR检出率及其严重程度与临床特征的关系。结果　第二磨牙ERR的检出率为44.8%,男、女差异无统计学意义（P＞0.05）;各年龄组比较发现,≤20岁组与＞20～30岁、＞30～40岁和＞40岁三组之间的差异有统计学意义（P＜0.05）,而后三组间差异无统计学意义（P＞0.05）。第二磨牙ERR的检出率随第三磨牙阻生角度的变大和位置的变深逐渐增加。第二磨牙ERR的严重程度在上、下颌之间的差异有统计学意义（P＜0.05）;在性别、年龄、阻生第三磨牙类型的差异无统计学意义（P＞0.05）。结论　第二磨牙ERR检出率无性别差异,与年龄及阻生第三磨牙位置、角度、深度相关。发生于下颌的第二磨牙ERR要比上颌的严重。对于造成第二磨牙ERR的阻生第三磨牙要积极拔除,特别是发生于下颌者。     

下颌第三磨牙阻生导致第二磨牙牙根吸收1例报告

本文报道1例由于下颔第三磨牙阻生导致下颌第二磨牙远中根外吸收的病例。通过对患者进行详细的临床检查和诊断丝影像学检查，发现易被诊断为下颌第二磨牙远中颈部深龋导致的牙髓根尖周病实为牙根外吸收．拔除患牙后证实了诊断的正确性。临床工作中为了避免误诊或漏诊．应建立正确识别阻生智牙造成邻牙牙根吸收的意识．注意借助各种临床及辅助手段仔细检查。本病例提示应早期拔除异常萌出的智牙，以保护第二磨牙，维持牙列的完整性。     

下颌阻生智齿拔除后第二磨牙远中牙槽骨变化的临床研究

目的追踪调查下颌阻生智齿拔除后,邻近的第二磨牙远中牙槽骨的远期预后。方法挑选因下颌智齿水平或近中阻生而在2年前要求拔牙的患者,在接受拔牙时,邻近第二磨牙远中牙槽骨已经发生水平吸收的病例,共计104例。复查内容包括：下颌第二磨牙牙周深度探诊,摄术后数字牙片,测量近远中牙槽骨垂直高度,然后与拔牙前的相应数据做比较。采取多项措施减少误差以保证数据可比性。结果72.1%的下颌第二磨牙远中牙周探诊深度≥6mm;术后远中牙槽骨可以再生,高度大于术前（P〈0.01）,但仍小于近中牙槽骨高度（P〈0.01）;年龄对牙槽骨增量无影响。结论下颌阻生智齿拔除后,邻近的第二磨牙远中牙槽骨可以再生,但无法恢复至正常水平;应提倡一期植入人工骨改善其远期预后。     

曲面断层片诊断阻生上颌尖牙造成的切牙牙根吸收的有效性研究

目的：评价全口曲面断层片对上颌阻生尖牙造成的切牙牙根吸收诊断的有效性。方法：选取上颌尖牙阻生病例19例,拍摄全口曲面断层片及螺旋CT扫描,邀请10名口腔正畸学研究生通过曲面断层片判断阻生尖牙造成的切牙牙根吸收的数目和位置,以螺旋CT扫描结果为实际牙根吸收量,计算曲面断层片诊断的灵敏度和特异度。结果：曲面断层片对上颌尖牙阻生造成的切牙牙根吸收诊断的灵敏度为46.3%、特异度为86.5%。阴性诊断有一定的参考价值,阳性诊断因为缺少可靠的牙根吸收定性指标而准确性较低。结论：不能单独依靠曲面断层片做出是否存在切牙牙根吸收的诊断。     

CBCT辅助诊断左上颌第一磨牙牙根外吸收1例

患者,女,48岁,因左上后牙咬合疼痛6天就诊。x线片显示36根尖周远中明显低密度影。CBCT扫描示36腭根根分叉部位明显吸收,累及腭侧根管,三维重建示腭根烦侧及近、远中吸收,腭倾根管暴露。     

不同分辨率锥形束CT和全景片在根尖吸收诊断中的对比研究

目的 比较不同分辨率锥形束CT（CBCT）和全景片在根尖吸收诊断中的差异。方法 选取160颗单根前磨牙,用以模拟4种不同程度的根尖吸收：无（完整的牙根）、轻度（根尖区近中、远中、颊面、舌面1.0 mm直径和深度的洞形）、中度（0.4、0.8、1.2、1.6 mm根尖缩短）、重度（2.4、2.8、3.2、3.6 mm根尖缩短）。模拟完成后,对所有牙齿拍摄CBCT（0.2和0.3 mm分辨率）和全景片获取3组X线图像。经校正后,3名正畸临床医师通过对图像资料的分析对所有样本的根尖吸收程度进行诊断。采用McNemar检验对比分析采用不同成像技术诊断不同程度根尖吸收的正确率。结果 采用全景片诊断全部根尖吸收样本的正确率为57.5%,而采用0.2和0.3 mm分辨率CBCT的正确率分别为85%和81.3%。对全部样本的诊断,0.2 mm分辨率CBCT和全景片以及0.3 mm分辨率CBCT和全景片的差异均有统计学意义（P〈0.01）。然而,对无、轻度、重度和全部根尖吸收样本的诊断,0.2和0.3 mm分辨率CBCT间差异无统计学意义（P〉0.05）。结论 相比于全景片,CBCT对根尖吸收具有更高的检出率。在根尖吸收的诊断中,0.2和0.3 mm分辨率CBCT诊断效能无明显差异,但0.3 mm分辨率CBCT对患者的辐射水平更低。     

Comparison of cone-beam computed tomography and periapical radiography for detecting simulated apical root resorption

Objective:To compare the diagnostic accuracy between cone-beam computed tomography (CBCT) and periapical radiography for detecting simulated external apical root resorption (EARR) in vitro.Materials and Methods:The study sample consisted of 160 single-rooted premolar teeth for simulating EARR of varying degrees according to four setups: no (intact teeth), mild (cavity of 1.0 mm in diameter and depth on root surface), moderate (0.4 mm, 0.8 mm, 1.2 mm, and 1.6 mm root shortening), and severe (2.4 mm, 2.8 mm, 3.2 mm, and 3.6 mm root shortening). Two groups of radiographic images were obtained via CBCT and periapical radiography. The absence or presence and the severity for all resorption lesions were evaluated blindly by two calibrated observers.Results:With the CBCT method, the rates of correct classification of no, mild, moderate, and severe EARR were 96.3%, 98.8%, 41.3%, and 87.5%, respectively; with the periapical radiography method, the rates were 82.5%, 41.3%, 68.8%, and 92.5%, respectively. Highly significant differences were found between the two imaging methods for detection of mild (P < .001), moderate (P < .001), and all EARR (P < .001). For detection of all EARR, the sensitivity and specificity values were 75.8% and 96.3% for CBCT, compared with 67.5% and 82.5% for periapical radiography.Conclusion:CBCT is a reliable diagnostic tool to detect simulated EARR, whereas periapical radiography underestimates it. However, if a periapical radiograph is already available to the diagnosis of EARR, CBCT should be used with extreme caution to avoid additional radiation exposure.     

Risk factors for root resorption of second molars associated with impacted mandibular third molars

External root resorption (ERR) affecting mandibular second molars (M2) may occur when the adjacent third molar (M3) is impacted in close proximity. This retrospective cohort study aimed to assess the presence, severity, and location of ERR on M2 due to M3 using cone beam computed tomography (CBCT) scans and to identify associated factors. The angle between the axis of M2 and M3 was measured. ERR on M2 was classified as absent, slight, moderate, or severe. The location of contact between M3 and M2, the size of the dental follicle, and patient demographic characteristics were recorded. A total of 433 patients with 640 M3 were included. A male predilection was found with regard to ERR (P = 0.0004). ERR was identified on 31.9% of M2 and was slight in 30.2%, moderate in 1.4%, and severe in 0.3% of cases. The presence of ERR was associated with direct contact between M2 and M3 (P < 0.0001), the angle between M2 and M3 (P < 0.0001), the inclination of M3 (P = 0.001), and the location of contact (P = 0.0005). This study showed ERR to be a frequent finding. ERR is associated with a mesioangular position of M3 in more than one third of cases, and a proximity ≤0.5 mm between M2 and M3 favours ERR.     

Root resorption of mandibular second molar teeth associated with the presence of the third molars

Although pressure resorption of second molars is associated with impacted and/or erupting third molars, the relationship between pressure resorption and age is unclear. In order to investigate this relationship, 3883 dental radiographs were studied in 3174 individuals of various ages. The incidence of superimposition of the second molar on the third molar was not elevated in any subgroup except that of women of 16-40 years of age. There were no age or sex differences for the incidence of second molar root resorption. In older individuals, root resorption associated with a completely impacted third molar was more frequent than with a partially impacted third molar, and root resorption at the apex was mainly seen in individuals over 50 years of age. There was a higher incidence of superimposition and root resorption in men than women. Apical root resorption may be seen long after the formation of completely impacted third molars in both genders.     

Risk factors for external root resorption of maxillary second molars due to impacted third molars as evaluated using cone beam computed tomography

The purpose of this retrospective study was to evaluate risk factors for external root resorption (ERR) on maxillary second molars (MxM2) in association with impacted third molars (MxM3) using cone beam computed tomography (CBCT) scans. The angles between the axes of MxM2/MxM3 (inclination) were measured. Further, ERR on MxM2 was classified as absent, slight, moderate, or severe. Contact location between MxM3 and MxM2, the size of the dental follicle, type of impaction, root formation, and patient demographic characteristics were also assessed. Half of the 84 MxM2 showed ERR (slight 36.9%, moderate 6.0%, severe 7.1%). Patient age was a significant factor for the presence of ERR (P = 0.03). The inclination was also a relevant factor, with transverse MxM3 exhibiting the highest risk of ERR (P = 0.02). The cervical third (28.6%) showed a significantly lower risk percentage of ERR compared to the apical (73.7%) and middle thirds (60.6%) of the root (P = 0.004). Based on these findings, clinicians assessing the need for surgical removal should be able to selectively identify impacted MxM3 at risk of causing ERR on MxM2 early on, especially when the MxM3 is located in close contact with the apical and middle thirds of the MxM2 roots and has a transverse inclination.     

下颌第三磨牙长距离近中移动后牙根吸收的研究

目的 通过对拔除下颌第一磨牙病例的回顾性研究,探讨第三磨牙在长距离近中移动后其牙根的吸收情况,同时比较第三磨牙牙根发育完成与否对牙根吸收的影响。方法 回顾性分析32例拔除下颌第一磨牙的病例,共41颗下颌第三磨牙。根据第三磨牙牙根的发育情况,分为A组(发育完成组)和B组(未发育完成组),采用直接数字化全景片测量矫治前后下颌第三磨牙牙根的长度,研究不同发育阶段的第三磨牙在长距离近中移动后其牙根的变化。结果 A组第三磨牙在长距离近中移动后,近远中牙根分别吸收(0.07±0.66) mm、(0.09±0.62) mm,差异没有统计学意义(P>0.05);B组第三磨牙牙根继续发育,矫治结束后长度增加,差异具有统计学意义(P<0.05);B组较A组下颌磨牙近中移动距离大,差异具有统计学意义(P<0.05)。矫治结束后A组、B组近中牙根长度差异没有统计学意义(P>0.05),但远中牙根B组较A组长,差异具有统计学意义(P<0.05)。结论 下颌第三磨牙长距离近中移动后,其牙根的吸收量较小,不具备临床意义,牙根发育情况对远中牙根存在一定影响,提示临床中磨牙缺失后要在第三磨...     

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。     

锥形束CT在下颌第二磨牙C形根管系统应用的研究

目的　采用锥形束CT（简称CBCT）研究下颌第二磨牙C形根管的解剖形态,为根管治疗提供更加直观的影像学依据。方法　使用CBCT观察441例患者双侧下颌第二磨牙,统计C形根管的发生率以及根管形态。结果　C形根管的发生率为41.72%,C形根管类型变化多样,C形根管的发生率在性别、年龄间无统计学差异。结论　C形根管在下颌第二磨牙有很高的发生率,并且解剖形态有较大差异,CBCT在诊断C形根管方面具有重要作用。     

锥形束CT在下颌第二磨牙C形根管治疗前中后的应用

下颌第二磨牙C形根管存在根管变异和不规则峡区,容易造成根管清理不彻底和充填不足。锥形束CT(CBCT)可清晰地显示C形根管在矢状面、冠状面和横断面的解剖形态。CBCT空间分辨率高,图像清晰;可选择合适的视野,小视野图像更清晰;可以光盘形式最大限度的保存图像信息,方便临床医生在计算机上多层面、多方位的仔细观察;金属伪影少,辐射剂量低,扫描时间短;所显示下颌第二磨牙C形根管图像的矢状面、冠状面和横断面无前后重叠、无变形和无放大等情况,可为了解下颌第二磨牙C形根管形态提供清晰的三维影像。下颌第二磨牙C形根管预备的难度主要有相对独立的根管间有大量的副根管、交通支和根管弯曲,传统器械难以进入峡区;将显微镜和CBCT共同使用,可提高下颌第二磨牙C形根管的治疗效果。在根管预备前行CBCT检查,可提醒术者避免过度切削并防止侧穿。本文就CBCT在下颌第二磨牙C形根管治疗前中后的应用等研究进展作一综述。