数字化根尖片诊断牙根吸收的可靠性研究

目的对比数字化根尖片和普通根尖片在评价牙齿长度及牙根吸收方面的差异。方法选取20颗上颌恒中切牙建立体外牙根吸收研究模型。模拟牙根吸收前、后的情况,分别从6个投照角度拍摄普通根尖片和数字化根尖片。分别统计数字化根尖片和普通根尖片反映牙齿实际长度和实际牙根吸收的差异。结果在同一X线投照角度下,数字化根尖片与普通根尖片的影像长度误差之间有显著性差异,牙根吸收误差之间无显著性差异。结论数字化根尖片下的牙齿影像长度比普通根尖片更接近实际的牙齿长度。数字化根尖片与普通根尖片在对牙根吸收的测量诊断上没有明显差别。     

两种根尖片诊断牙根吸收的比较

目的探讨数字化根尖片和普通根尖片在评价牙齿长度和牙根吸收方面的差异。方法选取20颗离体上颌恒中切牙，磨除根尖部约0．5mm，以模拟牙根吸收。分别从6个投照角度拍摄普通根尖片和数字化根尖片。配对秩和检验比较数字化根尖片和普通根尖片反映牙齿长度和牙根吸收的差异。结果在同一种X线投照角度下，数字化根尖片与普通根尖片牙齿长度影像误差的差异有统计学意义（P〈0．05），牙根吸收影像误差的差异无统计学意义（P〉0．05）。结论数字化根尖片上牙齿影像长度比普通根尖片更接近牙齿的实际长度。数字化根尖片与普通根尖片在牙根吸收的测量诊断上差异无统计学意义。     

Assessment of root resorption and root shape: periapical vs panoramic films.

A radiographic examination is an essential part of the diagnostic process in orthodontics. However, what radiographs are needed to properly evaluate root shape and position? Most clinicians order panoramic or periapical radiographs in addition to the cephalometric radiograph. The purpose of this study was to find out whether one type of film is more accurate than the other in the pretreatment evaluation of root shape and the posttreatment computation of apical root resorption. Pretreatment and posttreatment panoramic films and full-mouth periapical films from 42 patients who completed fixed orthodontic treatment were assessed for tooth length and root shape. Panoramic films showed significantly greater average apicaL root resorption than periapical films for the 743 teeth surveyed. The greatest differences were found in the lower incisors, the least in the maxillary incisors. Classification of root shape was significantly different between the 2 types of radiographs. Root dilacerations and other abnormal shapes, clearly visible on periapical films, often appeared normal on panoramic films. The findings strongly suggest that root shape is much harder to assess on panoramic films. We conclude that, in cases where the apices are obscured or other factors are present that might suggest higher risk for root resorption or vertical bone loss, periapical films should be ordered. The use of panoramic films to measure pre- and posttreatment root resorption may overestimate the amount of root loss by 20% or more.     

全景及根尖片对正畸相关牙根吸收诊断准确性的研究

目的以CBCT对样本牙根吸收的诊断结果为金标准,检验全景片（OPG）及根尖片对正畸相关牙根吸收（RRAOF）定性及分级半定量诊断结果的准确性。方法纳入完成固定正畸治疗的32例患者的121颗上前牙,正畸治疗前后均拍摄OPG、上前牙根尖片、上前牙CBCT。由3名放射专科医生按照Levander and Malmgren分度法对纳入样本的3种图像的牙根吸收程度分别进行评估,并以CBCT的诊断结果为金标准,检验OPG及根尖片对相同样本牙根吸收定性及分级半定量诊断结果的准确性。结果OPG、根尖片对相同样本RRAOF的定性及分级半定量诊断结果,与CBCT相比较均存在统计学差异（P<0.05）。根尖片和OPG对RRAOF定性诊断的敏感性分别为71.6%和78.4%,特异性分别为25.5%和51.1%,准确度分别为53.7%和67.8%。结论根尖片与OPG对正畸相关牙根吸收的诊断准确性较差。     

Diagnostic accuracy of digitized periapical radiographs validated against micro-computed tomography scanning in evaluating orthodontically induced apical root resorption

The aim of this study was to validate the use of digitized periapical radiographs in evaluating orthodontically induced apical root resorption against micro-computed tomography (micro-CT) scanning as a criterion standard test. In a standardized experimental protocol, 29 premolars in 16 subjects were tipped buccally for 8 wk. Nineteen contralateral premolars not subjected to orthodontic movement served as controls. Standardized periapical radiographs were taken before and after the experimental period (Rx method). These teeth were extracted and scanned using a micro-CT technique with a 9 mum resolution. Two calibrated examiners assessed blindly the presence or absence of apical root resorption on digitized radiographs and three-dimensional reconstructions of the scans. Significant differences were detected between the orthodontically moved teeth and controls: 86% of the orthodontically moved teeth and 21% of the control teeth showed apical root resorption when using micro-CT as a validation method. A total of 55% of the experimental teeth and 5% of the control teeth showed resorption when assessed using Rx method. The Rx method showed a specificity of 78% and a sensitivity of 44%, which means that less than half of the cases with root resorption identified using a CT scanner were identified by radiography. Nearly all the orthodontically moved teeth showed apical root resorption. Apical root resorption may be underestimated when evaluated using digitized periapical radiographs.     

In vitro evaluation of a method for obtaining periapical radiographs for diagnosis of external apical root resorption

This in vitro study was conducted to evaluate a method to obtain reproducible periapical radiographs, using individualized positioning devices, of upper central incisors submitted to simulated orthodontic movement. Linear measurements of tooth length were carried out on 29 extracted human central incisors. The teeth were radiographed in a tissue simulator, at different inclinations in the bucco-lingual direction (0 initial, 0 control, -10, -5, +5, and +10 degrees). The radiographs were digitized and quantitative analysis of tooth length was carried out using an electronic ruler. The linear measurements of tooth length were reproducible (r = 0.99) for repeated measurements as well as in the comparison of the initial and control images at 0 degree, where measurements did not differ significantly (analysis of variance, P = 0.827) in radiographs with different angulations. These results show that the method proposed for obtaining in vitro periapical radiographs results in reproducible images of tooth length, even when orthodontic movement is simulated by inclination of the tooth up to 20 degrees in the bucco-lingual direction.     

根管治疗中根尖片使用的临床分析

目的了解专科医生、全科医生、实习医生在根管治疗中使用根尖片的现状,分析根充质量与根尖片使用的关系。方法以在四川大学华西口腔医院门诊完成根管治疗的患者的患牙为调查对象,根据治疗医生的不同将调查对象分为专科医生组、全科医生组和实习医生组,对调查对象的根尖片应用情况进行问卷调查,并对术后根充片进行根充质量评价。采用卡方检验分析3组医生的根尖片使用频率,秩和检验分析根充质量与根尖片使用的关系。结果412例患者571颗牙的根管治疗中,专科医生组、全科医生组和实习医生组的术前片使用率分别为95.3%、89.5%和92.1%,初尖片使用率为5.2%、1.1%和5.8%,主尖片使用率为94.8%、72.1%和97.4%,根充片使用率为97.9%、76.3%和95.3%。3组初尖片、主尖片、根充片使用率均有统计学差异（P<0.05）。根充质量合格病例和不合格病例的根尖片使用张数分别为（3.14±0.639）和（2.84±0.736）张,二者之间有统计学差异（P<0.05）。结论专科医生和实习医生较全科医生更加规范使用根尖片。根尖片的使用频率与根充质量有关,规范化使用根尖片有利于提高根管治疗的质量。     

The accuracy of the cementoenamel junction identification on periapical films

In the study of orthodontically induced inflammatory root resorption, many researchers use the cementoenamel junction (CEJ) as a bisecting reference point to measure the amount of root shortening. The accuracy of the identification of the CEJ point might affect the conclusions of those studies. This study aims to find the effects of angular changes between the tooth and the film on the validity and reproducibility of identifying three different CEJ points, ie, the most apical CEJ point between the crown and the root, the most mesial CEJ point, and the most distal CEJ point. An extracted maxillary central incisor was placed in a special jig and radiographed at four different tooth to film angulations. Eight examiners were asked to identify the buccal and palatal CEJ, whereas six examiners were asked to identify the mesial and distal CEJ points, all on a computer monitor. The distances between the identified points and the apex were computed and compared with the actual ones. The angular changes between the tooth and the film did have a statistically significant effect on the identification of some of these CEJ points. The difference was significant on the identification of the buccal and palatal points but not on the mesial and the distal ones.     

牙根吸收发生早期指征的动物实验研究

目的:针对动物实验中观察到牙根吸收发生早期出现的尖周稀疏聚集期,研究其在牙根吸收发生进程中的作用。方法:选用成年杂种雄性犬5只,以其中3只犬的全部上颌切牙和2只犬的一侧上颌切牙为实验组(共24个);以2只犬的另一侧上颌切牙和5只犬的全部下颌切牙为对照组(共36个)。以种植钉为支抗,实验组牙齿施加约350 g的持续性压低重力;对照组处于非加力状态。通过X线片观察,研究尖周稀疏区在实验牙出现的情况,以及牙根吸收的发生情况。另选用实验犬3只,以A区切牙为实验组,B区切牙为对照组,按上述方法对实验组牙齿进行过大矫治力压低处理,当观察到实验组牙齿有尖周稀疏区出现时,处死动物,制作石蜡切片,进行HE染色,观察尖周区的组织形态学变化。结果:实验组21个牙齿(占87.5%)有尖周稀疏聚集期出现,出现的时间在持续性压低重力后(2.6±0.54)周;对照组则均无尖周稀疏区出现,与实验组相比有显著性差异(P<0.05),实验组牙齿继续压低处理8周,24个牙中有17个观察到有变短性牙根吸收情况。其中15个有尖周稀疏聚集期,占根尖吸收牙总数的88.2%,2个无尖周稀疏聚集期,占牙根吸收总数的11.2%,两者相比差异有统计学意义(P<0.05)。组织形态学观察可见,在尖周稀疏聚集期根尖未见明显牙根吸收,根尖所对应的牙槽骨区域则出现明显的骨吸收情况,呈空泡、脂肪样变性。结论:尖周稀疏聚集期的出现为持续性压低重力作用的结果,可能为牙根吸收发生过程的早期阶段。在这一阶段采取适当措施,可能阻断牙根吸收的发生。     

Efficacy of conventional and digital radiographic imaging methods for diagnosis of simulated external root resorption

This in vitro study evaluated and compared the efficacy of conventional (Kodak F-speed (Insight), Kodak) and a digital (DRS Gnatus System, Gnatus) radiographic imaging for diagnosis of simulated external root resorption cavities. Human mandibles containing teeth were covered with bovine muscle slices in order to simulate the soft tissues. Nine teeth out of each group of teeth were investigated. Initially, three periapical radiographs of each tooth were taken using a tube shift technique with mesial and distal angulations in both methods. All teeth were subsequently extracted and had 0.7 and 1.0-mm deep cavities prepared on their buccal, mesial and distal surfaces at the cervical, middle and apical thirds. Steel cylinder burs (DORMER? - HSS) with 0.7 and 1.0-mm diameter were used. Each tooth was replaced on its socket and new radiographs were taken. Three examiners, an endodontist (1), a radiologist (2) and a general dentist (3), evaluated the images. Results were compared by z-test and showed a higher number of cavities detected by the digital method compared to the conventional, regardless of the deepness of the cavity. In decreasing order, examiners 2, 3 and 1 exhibited different potentials of detection of cavities with the conventional method. Examiners 1 and 3 exhibited superior potential than examiner 2 for detection of cavities of different sizes with the digital method.     

Early radiographic diagnosis of inflammatory root resorption

Inflammatory root resorption (IRR) is a common sequelae to oral trauma. Anticipating root resorption after trauma and taking some preventive measures may avoid this outcome. Endodontics and radiographic examination play an important role in the early diagnosis and treatment of root resorption. Subtle radiographic clues can lead to timely implementation of appropriate treatment (if any) according to the kind of resorption discovered. This article describes the most current classification of inflammatory root resorption (usually following trauma) and utilizes a clinical study to provide radiographic clues for its early detection.     

Radiographic diagnosis of root resorption in relation to orthodontics

The literature regarding external root resorption in relation to orthodontics and its radiographic diagnosis is reviewed, including a summary of the more common radiographic techniques available. Sample cases are presented which demonstrate the need for good radiographic technique and an awareness of the limitations of certain radiographs. A provisional diagnosis of external root resorption may need to be confirmed by further radiographic views where appropriate.     

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牙根吸收是正畸治疗过程中常见的并发症之一,虽然严重的牙根吸收很少见,但其作为一种无法预料的并发症多年来一直困扰着正畸医生。本文将对正畸相关性牙根吸收的早期诊断与预防做一综述。     

根尖周吸收对Rapex5电子根尖定位仪精确性的影响

目的：探讨根尖周吸收对Rapex5电子根尖定位仪（EAL）精确性的影响。方法：根据病史和X线片,选择40例有根尖周吸收的根管为实验组,40例无根尖周吸收的根管作为对照组。用Raypex5测量根管工作长度,与离体直视根尖剖面最狭窄处测得的根管长度进行比较。以距根尖狭窄-0.5～0 mm为准确。结果：实验组根管工作长度的准确率为67.5%,比对照组（90%）明显降低,差异有显著性（P〈0.05）。结论：Raypex5测定根管工作长度的准确率较高,根尖周吸收对其精确性有一定影响。     

Assessment of external root resorption using digital subtraction radiography.

Digital subtraction radiography was investigated for its capability to detect and quantify experimentally produced external root resorptive defects in teeth. Using a long source to object X-ray technique and E-speed film, serial radiographs of teeth with artificial lesions in a dry human skull (soft tissue simulated) were obtained. Receiver operating characteristic analysis was used to evaluate the diagnostic performance for each imaging system (conventional versus subtraction). To explore the quantitative assessment potential of digital subtraction radiography, images were produced after sequential demineralization by HCl. The acid solution was analyzed for calcium concentration by atomic absorption spectrophotometry. Three-dimensional histogram quantification for each subtracted image was performed. In overall performance for detecting experimentally produced external root resorption, digital subtraction radiography was found to be significantly superior to conventional radiography. In addition, digital subtraction radiography can provide quantification of experimentally produced external root resorptive defects.     

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.     

正畸治疗导致牙根吸收的影响因素和诊断评估

牙根吸收是正畸治疗的常见并发症.正畸治疗中牙根吸收的影响因素及其作用机制尚无明确定论.本文从影响正畸治疗中牙根吸收的生物因素和机械因素作一,并简单介绍临床常用诊断方法 和目前牙根吸收评价方法 的研究进展.