ProTaper和K3预备对上颌前磨牙根管形态影响的研究

目的比较ProTaper和K3预备对根管形态的影响。方法选取正畸减数拔除含颊舌双根管的上颌前磨牙40颗,随机分为2组,分别采用机用镍钛器械ProTaper和K3预备根管,预备前、后进行三维成像,记录预先设立的根管横断面、颊舌向切面、近远中向切面三个位点的三维数据,评价根管预备的效果。结果 K3组相对于ProTaper组对牙本质的切削量少,对根管形态的影响较小,ProTaper组和K3组有显著性差异(P<0.01);结论 K3组预备后的根管形态优于ProTaper组。K3预备后能较好的保持根管形态,对根管壁牙本质的切削量少,较少地削弱了余留牙体组织的抗折力。     

锥形束CT在阻生齿拔除术中的应用

目的:应用锥形束CT(CBCT)观测及分析阻生齿与邻近解剖结构的关系,为临床手术提供参考依据.方法:在第三磨牙拔除术前摄曲面断层X线片检查,对于与下牙槽神经管接触或部分重叠的病例35例,进行锥形束CT检查.结果:锥形束CT对阻生齿拔除术能更好的进行阻力分析.结论:锥形束CT检查对于第三磨牙拔除术手术方案的选定具有一定的指导意义.     

Comparison of scattered entrance skin dose burden in MSCT,CBCT, and X-ray for suspected scaphoid injury: Regional dose measurements in a phantom model

IntroductionScaphoid radiography has poor sensitivity for acute fracture detection and often requires repeat delayed imaging. Although magnetic resonance (MR) imaging is considered the gold standard, computed tomography (CT) is often used as an alternative due to ease of access. Cone-Beam CT (CBCT) offers equivalent diagnostic efficacy to Multi Slice CT (MSCT) at reduced dose. We aimed to establish the difference in scattered dose between modalities for scaphoid imaging.MethodsAnatomical regional entrance surface dose measurements were taken at 3 regions on an anthropomorphic torso phantom positioned as a patient to a wrist phantom undergoing scaphoid imaging for three modalities (CBCT, MSCT, four-view projection radiography). Exposure factors were based on audit of clinical exposures. Each dose measurement was repeated three times per anatomical region, modality, exposure setting and projection.ResultsUnder unpaired T-test CBCT gave significantly lower mean dose at the neck (1.64 vs 18 mGy), chest (2.78 vs 8.01) and abdomen (1.288 vs 2.93) than MSCT (p < .0001). However CBCT had significantly higher mean dose than four-view radiography at the neck, chest and abdomen (0.031, 0.035, and 0.021 mGy) (p < .0001).ConclusionCBCT of the wrist carries a significantly higher scattered radiation dose to the neck, chest and abdomen than four view scaphoid radiography, but significantly lower scattered dose than MSCT of the wrist of equivalent diagnostic value.Implications for practiceThe use of CBCT for scaphoid injury carries significantly lower scattered dose to radio-sensitive structures investigated here than equivalent MSCT, and may be of greater use as an early cross-sectional investigation for suspected scaphoid fracture.     

下颌第二前磨牙双根3根管治疗1例

下颌前磨牙根管形态较为复杂,可能存在多根管,给根管治疗带来难度。插诊断丝的X线片,和多角度投射有助于发现其他根管。CBCT可更加直观的看到根管形态,从而有利于分析根管的分布。报告1例CBCT在下颌第二前磨牙双根3根管治疗中的诊断作用。     

藏族和汉族上颌第一恒磨牙近中颊根的CBCT对比研究

目的:比较藏族和汉族上颌第一恒磨牙近中颊根数据,为临床提供参考。方法:随机收集藏族和汉族患者上颌第一恒磨牙近中颊根CBCT图像440例,测量根长、弯曲度、弯曲位置、是否有第二近颊根(MB2)、MB-MB2距离。结果:藏族第一恒磨牙近中颊根长度较汉族长,差异有统计学意义(P<0.05)。近中颊根根管弯曲度比较,藏汉族有统计学差异,汉族以2级(10°<根管弯曲度<30°)居多,而藏族不仅2级较多,3级(根管弯曲度>30°)也较汉族多。根管弯曲位置方面,汉族以根管中分的弯曲居多,而藏族不仅根管中分的弯曲较多,根管口和根尖弯曲也较多,差异有统计学意义(P<0.05)。藏汉族的MB2发生率、MB-MB2距离比较差异无统计学意义。结论:藏族和汉族上颌第一恒磨牙近中颊根的根长、根管弯曲度、根管弯曲位置有差别,藏族牙根更长,弯曲度更大,特别是根尖区弯曲度,值得临床注意。而MB2发生率和MB-MB2距离藏汉族无差异。     

三维冠根整合数字化模型在口腔临床中的应用研究

目的建立牙齿三维冠根整合数字化模型并进行虚拟排牙,探讨其在口腔临床中的应用。方法获取15例患者锥形束CT(CBCT)的全牙列模型和结构光的牙冠模型,行迭代最近点算法对两种模型进行全局配准,在最佳匹配后截取CBCT牙根和基于结构光扫描的牙冠整合成新的牙齿模型。利用自行研发软件Teeth Arrangement对整合后的牙齿模型按照理想标准进行排列并导入颌骨进行在线验证。最后采用同行评估等级(peer assessment rating,PAR)指数评价排牙效果。结果 15例患者的结构光扫描模型与CBCT配准偏差数据符合正态分布,上颌配准偏差为(0.135±0.015)mm,下颌配准偏差为(0.130±0.022)mm。15例患者的排牙模型导入颌骨中,全部出现了不同程度的牙根突出颌骨。采用PAR指数对排牙前数字化模型与石膏模型错程度分析,两者具有高度一致性(ICC> 0.800)。全部患者排牙前后模型PAR加权值减少90%以上,排牙前后效果比较为改善;2/3患者PAR加权值减少22分以上,排牙前后效果比较为极大改善。结论将牙齿三维冠根整合数字化模型应用到口腔临床具有可行性及必要性。     

基于锥形束CT对邻面接触区釉质厚度的测量与分析

目的    应用锥形束CT（cone beam computed tomography,CBCT）测量上下颌牙列邻面接触区釉质厚度及邻接点距离牙合面和釉牙骨质界的垂直高度,为临床邻面去釉提供参考数据。方法    选取2019年6—10月于吉林大学口腔医院医学影像科行CBCT检查患者50例,根据纳入标准选取符合测量条件的牙齿145颗,运用Invivo软件测量每颗牙齿邻面接触区的釉质厚度及邻接点距离牙合面和釉牙骨质界的垂直高度。结果    从切牙至第一磨牙邻面接触区釉质厚度有逐渐增大的趋势;大多数牙位的远中邻面接触区釉质厚度大于近中（P < 0.05）,仅有上颌第一前磨牙和下颌第一磨牙的近远中邻面接触区釉质厚度差异无统计学意义（P > 0.05）;上下颌左右侧同名牙邻面接触区釉质厚度差异无统计学意义（P > 0.05）;除上颌中切牙-侧切牙、上下颌侧切牙-尖牙邻面接触区外,其余相邻牙齿近远中邻面接触区釉质厚度相似,差异均无统计学意义（均P > 0.05）;上颌邻面接触区平均釉质厚度大于下颌,差异有统计学意义（P < 0.05）;上下颌近远中邻接点到牙合面的垂直距离均小于到釉牙骨质界的垂直距离（均P < 0.05）。结论    不同牙位近远中邻面接触区釉质厚度不同,邻接点距离牙合面和釉牙骨质界的垂直高度也不同,临床邻面去釉时不同牙位去釉量不能按照同一标准进行,应结合CBCT影像资料制定个体化治疗方案。     

下颌升支矢状劈开前移术对成年骨性Ⅱ类下颌后缩女性患者上气道影响的CBCT研究

目的:研究下颌升支矢状劈开前移术对成年骨性Ⅱ类下颌后缩女性患者上气道影响。方法:选取成年骨性Ⅱ类下颌后缩女性患者40例,根据采用不同的治疗方式分为两组:手术组20例采用双侧下颌升支矢状劈开截骨术前移下颌+正畸治疗,代偿组20例采用单纯正畸掩饰治疗。收集患者正畸治疗前和正畸治疗结束时的CBCT数据。分别测量正畸治疗前和正畸治疗结束时气道体积、截面积、矢状径,分析治疗前后变化。结果:代偿组所有测量项目差异均无统计学意义(P>0.05),手术组治疗后气道总体积、最小截面积和下界截面积显著增大(P<0.05)。结论:对于成年骨性Ⅱ类下颌后缩女性患者,双侧下颌升支矢状劈开截骨术前移下颌可以增加气道体积和最小截面积,改善呼吸功能。单纯正畸掩饰治疗对成年女性骨性Ⅱ类下颌后缩患者气道无显著影响。     

Orthodontic management of a complete and an incomplete maxillary canine-first premolar transposition

Maxillary canine and first premolar transposition is a complicated dental anomaly to treat, especially if the clinician''s goal is to orthodontically move the canine into its normal position. Early diagnosis with cone-beam computed tomography simplifies the treatment of this pathology. This case report describes a patient with bilateral transposition, one complete and the other incomplete, involving the maxillary canine and the first premolar (Mx.C.1P). The orthodontic treatment involved the correction of both transpositions. In the complete transposition, the traction was mesial and upward to move the canine into a more apical position with a wider dentoalveolar process for easier crown interchange.     

Evaluation of condyle-fossa relationships in adolescents with various skeletal patterns using cone-beam computed tomography

Objectives:To evaluate the condyle-fossa relationship in adolescents with various skeletal patterns using cone-beam computed tomography (CBCT).Materials and Methods:CBCT images obtained in 120 adolescent patients were used for this study. The patients were divided into 3 groups according to 3 criteria: (1) age (early, middle, and late adolescence); (2) facial height ratio or Jarabak quotient (hyperdivergent, normodivergent, and hypodivergent); and (3) ANB classification (Class I, Class II, and Class III). Temporomandibular joint space (TMJS: AS, anterior space; SS, superior space; PS, posterior space; MS, medial space; LS, lateral space), width and depth of the condyle (MLT, mediolateral thickness; APT, anteroposterior thickness), articular slope (ArS) and vertical height of the fossa (VHF) were measured and compared using CBCT.Results:Differences in condyle-fossa relationships were not significantly different between male and female adolescents, but were significantly different (P < .05) between left and right sides. The mean values showed no statistical differences according to age and skeletal pattern. Most measurements in the sagittal view showed that SS was the greatest, and the mean ratio of AS to SS to PS was 1.00 to 1.27 to 1.19, respectively. The mean values of coronal MS and LS were not significantly different.Conclusions:There were almost no statistical differences in the TMJS in adolescents across various factors except between left and right sides.