Inter-examiner variation in the assessment of age-related factors in teeth

Inter-observer variations in the registration of dental age-related characteristics have not previously been studied. Examination and registration were made by 6 dentists with varying experience in age estimation. A total of 13 age-related dental characteristics in 30 teeth extracted from adults were assessed macroscopically, by stereomicroscope and from radiographs. The measurements were analysed in a microcomputer, using the SPSS/PC+ statistical package. The results showed that, except for the score on surface roughness, significant differences were found between some of the observers for all types of measurements, when a pairedt-test analysis was made. The correlation coefficients between the observers varied and were rather weak for the surface roughness score. The study revealed systematic differences among the observers as well as differences in interpreting the definitions of the scores for the different parameters. Thus age estimation using statistical methods is seen to be dependent upon the experience of the individual observer and interpretation. Care should therefore be taken not to rely too much upon the results of an odontological age estimation. The possible implications of these results for forensic work are also discussed.     

DNA analysis of root canal-filled teeth

Teeth are markedly useful as samples for DNA analysis; however, intact teeth are not always available. This study examined the possibility of identifying autosomal and Y-chromosome short tandem repeat (STR) types in samples from 34 teeth (15 intact and 19 root canal filled) that had been preserved for 10–33 years after dental extraction. The aim was to explore the feasibility of individual identification by DNA analysis of samples obtained from highly decomposed and skeletonized corpses. Only one out of 24 autosomal STR loci was not identified in two of the 15 intact teeth, whereas all 23 loci of the Y chromosome STR were detected. One or two autosomal STR loci remained unidentified in eight of the 19 root-filled teeth, and four or five of the 23 Y STR loci were undetected in three cases. However, the types were identified in about 20 loci in all samples, and the composition of the root canal filling material did not appear to interfere with the PCR. This study demonstrates that the storage period of the teeth had no influence on our results indicating that root canal filled teeth can be used for DNA analysis.     

Application of the INAA technique for elemental analysis of metallic biomaterials used in dentistry

The sensitive nuclear analytical technique Instrumental Neutron Activation Analysis (INAA) has been applied on several types of metallic biomaterials (Heraenium CE, Ventura Nibon, Wiron 99 and Ducinox which are currently used for restoration in the dental clinics) to study its performance in elemental analysis and identify eventual limitations. The investigation has been performed by two NAA Laboratories and aimed at getting an answer to the question on how the biomaterials compositions influence the patients’ health over the course of time, taking into account the EC Directive 94/27/EC recommendations concerning Ni toxicity.     

乳牙根尖周炎根管治疗疗效及对恒牙发育影响的临床观察

 对诊断为下颌乳磨牙根尖周炎行根管治疗的31名患儿,年龄3～7岁,共52颗患牙进行回顾性调查,结果表明:轻、中型乳牙根尖周炎行根管治疗术,无碍于继承恒牙胚的正常发育,重型乳牙根尖周炎,应拔除患牙,以便恒牙正常发育及替换.     

基于人为因素分析及分类系统的放射治疗安全事件人为因素分析及事故链探究

目的 分析放射治疗安全事件中的人为因素并确定这些人为因素之间的关系,寻找放疗安全事件的潜在事故链。方法 基于放射肿瘤事件学习系统纳入60例放疗安全事件,利用人为因素分析及分类系统(HFACS)进行致因识别及频率统计分析,基于分析结果采用潜在类别分析(LCA)方法对事故致因的关联性进行研究。结果 计划设计阶段的错误是最常见的事件类型,占比35%,组织氛围、监督不充分以及人员因素分别是HFACS各个层级中最主要的事件致因,其频率指数分别为4.66%、15.68%和16.20%。LCA分析确定了3条常见放疗事故链,其中两条事故链起源于组织氛围问题,一条事故链起源于组织过程问题,并通过不同的人为因素"漏洞"向下传递。结论 HFACS可帮助溯源导致放射治疗安全事件的各层级人为因素,本研究发现了放疗安全事件的高频致因和3条事故链,可为建立针对性的安全防御措施提供指导。     

玻璃纤维桩在前牙残冠修复中的应用

目的探讨纤维桩在前牙残冠修复中的临床应用价值。方法将147例病人160颗前牙残冠残根随机分为纤维桩(A组)和金属铸造桩核修复组(B组),每组80颗牙,随访观察2年。结果A组78例桩冠修复体完好,成功率为97.5%,B组72个桩冠修复体良好,成功率为90.0%。两组相比纤维桩修复组较金属铸造桩核组治疗成功率高(P<0.05)。结论 用预成的根管玻璃纤维桩系统进行前牙残冠修复,具有操作简单、方便、减少根折,缩短就诊次数等优点。     

表达hEGF导入基因的角朊细胞促进体外培养的正常角朊细胞增殖

目的 观察含外源性人表皮细胞生长因子（ｈＥＧＦ）基因改造的角朊细胞（ｈＥＧＦ－ＭＨＫ），对正常培养的角朊细胞（ＮＨＫ）增殖的影响；探讨转ｈＦＧＦ对创面愈合的生物学效应及作用机理。方法 收集含真核表达质粒ｐｃＤＮＡ３－ｈＥＧＦ的Ｈｅｇｆ－ＭＨＫ细胞培养上清，采用放射免疫分析法检测收集的上清液中ｈＥＧＦ含量；以１０％的浓度加入由正常人皮肤组织分离培养的ＮＨＫ细胞培养基内；ＭＴＴ法测定ＮＨＫ细胞增减１５     

多层螺旋CT齿科软件对埋伏牙的应用价值

目的:探讨多层螺旋CT齿科扫描软件对埋伏牙的临床应用及诊断价值。方法:对18例正畸患者行多层螺旋CT容积扫描,采用特殊的齿科扫描软件Dentascan对图像进行后处理。结果:Dentascan软件能清楚地重建出牙及牙槽骨的矢状面和冠状曲面图像,共显示18例24颗埋伏牙,清晰地显示其异常结构及与牙列的关系。结论:多层螺旋CT扫描+齿科Den-tascan软件后重建技术在埋伏牙的诊断中具有较高的应用价值,结合轴位图像能为临床医师提供全方位的影像信息,有助于治疗方案的优选。     

双生儿牙齿冠宽咬合特征遗传变异研究

对居住北京城区54对平均年龄21.3岁的同性别双生儿恒牙列牙齿冠宽、前牙覆、覆盖、第一恒磨牙关系进行测量,结果:同卵组与异卵组牙齿冠宽的对内之差、各牙齿的分散度和遗传度,均与遗传因素明显相关。同卵组双生儿的牙齿宽度无显著差异,异卵组双生儿的对内之差差异显著;各牙齿冠宽差异的分散度较大。但同卵组、异卵组前牙覆、覆盖、第一恒磨牙关系的一致率无显著性差异,表明咬合特征的形成受环境因素影响较大。     

In vitro comparison of digital and conventional bitewing radiographs for the detection of approximal caries in primary teeth exposed and viewed by a new wireless handheld unit

Objectives

The aim of this study was to compare the diagnostic quality of a new wireless handheld unit (ADX4000; Dexcowin Co. Ltd, Korea) on conventional bitewings and its LCD screen for the detection of approximal caries in primary teeth.

Methods

In total, 108 approximal surfaces of primary teeth were examined in vitro by 3 observers. Conventional films were viewed under subdued lighting conditions on a conventional view box. Digital 3.5 inch images were displayed on the built-in monitor of the ADX4000 and digital 17 inch images were viewed on a 17 inch monitor. The true caries diagnosis was based on histological assessment of the approximal surfaces after sectioning the primary teeth. Receiver operating characteristic (ROC) curve (A_z) analysis was used to assess the diagnostic quality of imaging modalities.

Results

The areas under the ROC curves ranged from 0.786 (digital 17 inch) to 0.813 (digital 3.5 inch). No statistically significant differences were found between the three modalities for detecting approximal caries.

Conclusions

It was concluded that the diagnostic quality of conventional film and digital images, which were exposed and viewed by a new wireless handheld unit, was comparable.     

儿童埋伏牙多层螺旋CT检查中的辐射剂量评价

目的 探讨适合儿童埋伏牙多层螺旋CT(MSCT)检查的低剂量曝光条件。方法 80例经16层螺旋CT检查出埋伏牙的患儿,按曝光量不同分为5、25、125及250mAs4组,由放射科2名正主任医师及3名副主任医师采用双盲法评价图像质量,并记录不同毫安秒扫描时的加权CT剂量指数(CTDI_w)、剂量长度乘积(DLP),使用SAS9.1统计分析系统进行统计学处理。结果 4组的扫描图像均能准确显示埋伏牙结构及其相邻关系。5mAs扫描组在牙槽突骨小梁及牙龈等周围软组织的分辨能力较25、125及250mAs组下降,但仍能满足诊断要求。5mAs组CTDI_w值及DLP值仅为250mAs组的2%。结论 5mAs的MSCT低剂量扫描可以满足儿童埋伏牙诊断需要,减少了患儿接受的辐射剂量。     

口腔锥形束CT在上颌埋伏牙诊断中的应用价值研究

目的 探讨口腔锥形束CT在上颌埋伏牙诊断中的应用价值.方法 选择我院口腔科于2018年1月至2020年8月期间诊治、检查的120例上颌埋伏牙患者为研究对象,均接受口腔锥形束CT检查,总结分析检查结果,分析其在上颌埋伏牙诊断中的实际应用价值.结果 120例患者上颌埋伏牙均获得清晰显示,其中包括多生牙80颗,阻生牙40颗....     

The comparison of ground reaction forces and lower limb muscles correlation and activation time delay between forward and backward walking

This study aimed to compare the ground reaction forces (GRF) and lower limb muscles correlation and activation time delay between Forward (FW) and Backward (BW) walking. Twenty-four male students participated in this research. Electromyogram activities of gluteus medius, biceps femoris, medial gastrocnemius, soleus and anterior tibialis muscles along with GRFs were measured. Each participant performed two FW and two BW trials bare foot. Statistical parametric mapping (SPM) analysis was performed over anterior-posterior and vertical GRFs time series. The paired t-test was used in SPM analysis. Cross-correlation analysis compared similarity in shape and time delay of EMG pattern. SPM analysis of GRFs showed that these two walking modes have asymmetrical kinetic behavior during most parts of stance phase. Based on cross-correlation analysis, the shape of EMG activation profiles differed, where a phase shift in the muscle activation pattern of approximately 60% occurred. This shift may indicate different control mechanisms, at the spinal level, underpin FW and BW walking modalities.     

Segmentation method of intravascular ultrasound images of human coronary arteries

The goal of this study was to show the feasibility of a 2D segmentation fast-marching method (FMM) in the context of intravascular ultrasound (IVUS) imaging of coronary arteries. The original FMM speed function combines gradient-based contour information and region information, that is the gray level probability density functions of the vessel structures, that takes into account the variability in appearance of the tissues and the lumen in IVUS images acquired at 40 MHz. Experimental results on 38 in vivo IVUS sequences yielded mean point-to-point distances between detected vessel wall boundaries and manual validation contours below 0.11 mm, and Hausdorff distances below 0.33 mm, as evaluated on 3207 images. The proposed method proved to be robust in taking into account various artifacts in ultrasound images: partial shadowing due to calcium inclusions within the plaque, side branches adjacent to the main artery to segment, the presence of a stent, injection of contrast agent or dissection, as tested on 209 images presenting such artifacts.     

A method of calculating human deciduous crown formation times and of estimating the chronological ages of stressful events occurring during deciduous enamel formation

Knowledge of deciduous crown formation times is useful in forensic anthropology and when aging juvenile remains from an archaeological context. Until now, histological techniques for calculating enamel formation times in deciduous teeth have been completely dependent on being able to visualise clear daily incremental markings. In the first part of this study we took twenty deciduous teeth where daily incremental markings were easily visible on both aspects of the crown and used these as the basis for generating regression equations to predict enamel formation times. We were then able to use these regression equations to calculate deciduous crown formation times in a further fifty deciduous teeth where it was not possible to see daily increments. We present here new data for deciduous crown formation times based on these regression equations. In the second part of this study these regression formulae were applied blind to teeth from two individuals with known medical histories. The formulae were able to successfully determine the times of prenatal and postnatal enamel formation relative to the neonatal line and also to correctly estimate the ages at which accentuated ‘stress lines’ occurred during the period of deciduous crown formation.     

Multivariate statistical analysis of radiological data of building materials used in Tiruvannamalai,Tamilnadu, India

Using γ spectrometry, the concentration of the naturally occurring radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K has been measured in soil, sand, cement, clay and bricks, which are used as building materials in Tiruvannamalai, Tamilnadu, India. The radium equivalent activity (Ra_eq), the criterion formula (CF), indoor gamma absorbed dose rate (D_R), annual effective dose (H_R), activity utilization index (AUI), alpha index (I_α), gamma index (I_γ), external radiation hazard index (H_ex), internal radiation hazard index (H_in), representative level index (RLI), excess lifetime cancer risk (ELCR) and annual gonadal dose equivalent (AGDE) associated with the natural radionuclides are calculated to assess the radiation hazard of the natural radioactivity in the building materials. From the analysis, it is found that these materials used for the construction of dwellings are safe for the inhabitants.The radiological data were processed using multivariate statistical methods to determine the similarities and correlation among the various samples. The frequency distributions for all radionuclides were analyzed. The data set consisted of 15 measured variables. The Pearson correlation coefficient reveals that the ²²⁶Ra distribution in building materials is controlled by the variation of the ⁴⁰K concentration. Principal component analysis (PCA) yields a two-component representation of the acquired data from the building materials in Tiruvannamalai, wherein 94.9% of the total variance is explained. The resulting dendrogram of hierarchical cluster analysis (HCA) classified the 30 building materials into four major groups using 15 variables.     

牙齿漂白技术及光敏固化联合应用美容修复重度色素牙

目的：为了使重度色素牙在不破坏牙齿的前提下得到自然的美化。方法：将重度色素牙先经过11％或16％过氧化脲漂白，再行光敏固化贴面。结果：达到了颜色均匀、理想，外形逼真，光泽度好的牙齿自然美容效果。随访6个月—2年，效果满意。结论：将牙齿漂白技术及光敏固化联合应用修复重度色素牙既经济、实用，对牙齿损伤最小又可达到理想的美观效果，易于推广使用。     

人体热平衡的生物物理分析

目的分析人体产热和散热的机理以及影响散热的因素，并讨论维持人体热平衡的因素。方法利用能量守恒原理建立人与环境热交换方程，并根据不同热交换途径以及影响散热的因素建立相关方程。结果温度环境包括温度、湿度、压力、风速以及太阳辐射是影响航天员热平衡的关键因素。结论人体的各种生理活动都必须在体内温度相对稳定的条件下进行，即人体必须同周围环境之间处于相对稳定的热平衡，人才能进行正常的生理行为活动。     

Effect of the shampoo Ultra Clean on drug concentrations in human hair

The influence of the special shampoo Ultra Clean (Zydot Unlimited, Tulsa, Oklahoma) on the results of hair analyses was investigated. Hair samples from persons (n = 14) with a known history of drug abuse were collected at autopsy. The hair samples were divided into separate strands which were analyzed both after washing with Ultra Clean and without treatment. Hair analyses were performed by methanol extraction under sonication, purification by solid phase extraction and GC/MS in SIM mode according to routine procedures for tetrahydrocannabinol (THC), cocaine, amphetamine, methylenedioxyamphetamine (MDA), methylenedioxymethamphetamine (MDMA), methylenedioxyethylamphetamine (MDE), heroin, 6-monoacetylmorphine (6-MAM), morphine, codeine, dihydrocodeine and methadone. All drugs originally present in the hair fibers were still detected after a single application of Ultra Clean. However, a slight decrease in drug concentrations could mostly be observed e.g. cocaine (n = 10) -5%, 6-MAM (n = 12) -9%, morphine (n = 12) -26%, THC (n = 4) -36%. The findings clearly demonstrated that drug substances had not been sufficiently removed from human hair by a single Ultra Clean treatment to drop their concentrations below the limit of detection of the analytical method applied.     

Sex estimation using diagonal diameter measurements of molar teeth in African American populations

Teeth are often recovered in forensic cases due to their postmortem longevity. The goal of the present research was to investigate the degree of sexual dimorphism in the permanent molars of African Americans using crown and cervical diagonal diameters. Discriminant functions developed from a modern Greek population were tested for accuracy of sex estimation in an African American population. One hundred and three (53 males and 50 females) individuals ranging in age from 16 years to 66 years old were used from the Robert J. Terry Anatomical Skeletal Collection. Four diagonal diameter measurements were taken for each of the left mandibular and maxillary molars: mesiobuccal-distolingual crown diameter, mesiolingual-distobuccal crown diameter, mesiobuccal-distolingual cervical diameter, and mesiolingual-distobuccal cervical diameter. The overall percentage of accuracy of the modern Greek discriminant functions when applied to the African American sample was between 53.8% and 63.6%. Males were more accurately classified (93.6%–100%) than females (0%–18.2%). The African American population specific direct discriminant functions showed accuracy rates from 72.6% to 100% for the original data and 40%–72.3% for the cross-validated data. The African American stepwise discriminant functions showed accuracy rates from 63.9% to 77.6% for the original and cross-validated data. Comparisons to other populations were made. The results suggest that, in teeth, there is variation in the degree of sexual dimorphism between populations and discriminant functions for sex estimation in dentition are population specific.