Inkrementelle Strukturen im Schmelz der Milchzähne

The neonatal line (NNL) is a distinct incremental marking in the dental enamel, especially in deciduous teeth. In the course of tooth development the NNL represents the position of the enamel-forming front at the time of birth in all the teeth already forming hard tissues at this time. If birth is survived for a certain period of time, deposition of new enamel can be detected outside the NNL. The material properties of teeth, the lack of remodeling, and the known chronology of incremental structures in enamel make teeth an important source of information of vital data in retrospective analyses. Counting enamel incremental markings with circadian periodicity in postnatal enamel enables the determination of the duration of the postnatal lifespan. The lack of an NNL indicates death in utero. In this respect an important contribution can be made by structural analyses of teeth to the investigation of decomposed remains of fetuses and young infants.     

Vitapex用于乳牙根管治疗的临床疗效观察

目的观察Vitapex在乳牙根管治疗中的临床疗效。方法选择乳牙牙髓炎或根尖周炎患儿73例（97颗牙）,常规根管预备后,用Vitapex糊剂行根管充填,随访观察1年。结果成功83颗,失败7颗,成功率为92.2％。结论Vitapex用于乳牙根管治疗的临床疗效较好,是较为理想的乳牙根管充填材料。     

Morphological features of the microdistribution of naturally occurring 10Pb/2l0Po and 226Ra in the teeth of children and juveniles

PURPOSE: To examine the microdistribution of natural alpha-radioactivity in deciduous teeth of children and the permanent teeth of juveniles extracted for orthodontic purpose from across the UK. MATERIALS AND METHODS: The microdistribution of 210Pb-supported 210Po and 226Ra in 708 deciduous and permanent teeth and 32 foetal teeth was measured on 1442 TASTRAK alpha-particle track detectors. RESULTS: Of the various findings, a number are of special interest. Around half of the 210Pb activity in the outer enamel of deciduous teeth appears to have been acquired in utero as a result of transplacental transfer. In deciduous and permanent teeth, 226Ra is concentrated mainly in the circumpulpal region, while the highest levels of 210Po are on the highly calcified outer enamel surface. Furthermore, activity concentrations recorded on this surface were In-normally distributed. CONCLUSIONS: 210Pb-supported 210Po activity on the outer enamel surface of permanent teeth constitutes an assay of cumulative environmental exposure with which to assess exposure in bone, both in utero and in childhood. Such assessment can be used to study geographical variations in the alpha-activity in teeth. More work is also required to determine the concentrations of both 210Po and 210Pb in the foetal skeleton.     

Multiple impacted permanent and deciduous teeth

Multiple impacted teeth may be related to syndromes and metabolic disorders. In some cases, however, impaction of multiple teeth is not accompanied by a fixed complex of symptoms. A 55-year-old woman attended our clinic, as she was not comfortable with her prosthetic appliances because of erupted teeth. Panoramic and occlusal radiographs revealed 13 impacted teeth (12 permanent and 1 deciduous) in the maxilla and 15 impacted teeth (11 permanent and 4 deciduous) in the mandible. In total the patient had 28 impacted teeth. In our case, medical and family history and extraoral examination were not suggestive of any syndrome or metabolic disorder. In conclusion, radiographic examination may reveal multiple impactions in clinical absence of teeth. Lack of eruptive force and rotation of tooth buds may cause multiple impactions and additional examinations may be necessary to exclude systemic and metabolic conditions.     

修复方式对乳磨牙大面积缺损的治疗效果研究

目的探讨儿童乳磨牙牙体大面积缺损不同修复方式的临床效果。方法选择大面积缺损的300颗乳磨牙,随机分成三组,分别进行预成冠、铸瓷高嵌体、光固化复合树脂充填治疗。1年后复诊,参照美国公共健康协会的修正标准对修复效果进行综合评价。结果在牙体完整性和磨耗方面,三种修复方式组间差异无统计学意义;在修复体情况、继发龋、邻接关系方面,预成冠和铸瓷高嵌体优于树脂充填;而在边缘密合性方面,铸瓷高嵌体优于预成冠,预成冠又优于充填治疗。结论与树脂充填相比,虽然预成冠和铸瓷高嵌体的操作复杂、成本也较高,但是临床评价结果最好,在乳磨牙大面积缺损病例中可推广使用。     

Racemization in enamel among different types of teeth from the same individual

We measured the quantity of D-aspartic acid (degree of racemization of aspartic acid) in the enamel of different types of teeth from the same individual. We studied the correlation between the degree of racemization and the time of formation of each particular tooth, as well as the applicability of the degree of racemization to estimation of chronological age. If the environmental condition of the teeth is the same, the degree of racemization is expected to be highest in teeth that completed formation in the earliest period of time. Different degrees of racemization in enamel were found among different types of teeth, even in the same individual. The degree of racemization in enamel was found to be higher in molars than in incisors, and showed a tendency that did not necessarily coincide with the time of formation. This seemed to be due to the fact that the environmental temperature was higher in the molar region located deeper in the oral cavity than the front region, and that enamel was more affected by breathing air than dentin because the D/L ratios in enamel were lower than those in dentin. Using enamel, a better estimation of chronological age was obtained from calculations based on the degree of racemization of each type of tooth than from all the different teeth together. However, these estimated ages were not better than those from dentin.     

Diagnosis of occlusal caries lesions in deciduous molars by coherent light scattering pattern speckle

BackgroundThis study presents the correlation between laser speckle images and detection of incipient caries lesions from changs in the microstructure of the surface of tooth enamel.MethodsWe used 30 healthy deciduous molar teeth collected from the Biobank Human Teeth, Faculty of Dentistry, University of São Paulo who had carious lesions induced by the pH cycling method. The samples were evaluated for the diagnosis of caries by two methods ICDAS and speckle pattern of coherent light scattering after 5, 10 and 15 days and the results were statistically analyzed using α = 0.05 significance level.ResultsA significant difference was observed between the image of the speckle scattering of healthy and injured areas within the 3 study groups, but not when comparing the three groups, showing us that it is an innovative technique that needs further study, but can be used as a diagnostic method for the detection of early caries lesions.ConclusionIt can be concluded that the analysis of scattering speckle pattern is a diagnostic technique that provides information on the microstructure of the surface of tooth enamel which has sensitivity for detection of incipient caries lesions.     

Morphological features of the microdistribution of naturally occurring 210Pb/210Po and 226Ra in the teeth of children and juveniles

Purpose: To examine the microdistribution of natural α‐radioactivity in deciduous teeth of children and the permanent teeth of juveniles extracted for orthodontic purpose from across the UK.

Materials and methods: The microdistribution of ²¹⁰Pb‐supported ²¹⁰Po and ²²⁶Ra in 708 deciduous and permanent teeth and 32 foetal teeth was measured on 1442 TASTRAK α‐particle track detectors.

Results: Of the various findings, a number are of special interest. Around half of the ²¹⁰Pb activity in the outer enamel of deciduous teeth appears to have been acquired in utero as a result of transplacental transfer. In deciduous and permanent teeth, ²²⁶Ra is concentrated mainly in the circumpulpal region, while the highest levels of ²¹⁰Po are on the highly calcified outer enamel surface. Furthermore, activity concentrations recorded on this surface were ln‐normally distributed.

Conclusions: ²¹⁰Pb‐supported ²¹⁰Po activity on the outer enamel surface of permanent teeth constitutes an assay of cumulative environmental exposure with which to assess exposure in bone, both in utero and in childhood. Such assessment can be used to study geographical variations in the α‐activity in teeth. More work is also required to determine the concentrations of both ²¹⁰Po and ²¹⁰Pb in the foetal skeleton.     

Artificial intelligence system for automatic deciduous tooth detection and numbering in panoramic radiographs

Objective:This study evaluated the use of a deep-learning approach for automated detection and numbering of deciduous teeth in children as depicted on panoramic radiographs.Methods and materials:An artificial intelligence (AI) algorithm (CranioCatch, Eskisehir-Turkey) using Faster R-CNN Inception v2 (COCO) models were developed to automatically detect and number deciduous teeth as seen on pediatric panoramic radiographs. The algorithm was trained and tested on a total of 421 panoramic images. System performance was assessed using a confusion matrix.Results:The AI system was successful in detecting and numbering the deciduous teeth of children as depicted on panoramic radiographs. The sensitivity and precision rates were high. The estimated sensitivity, precision, and F1 score were 0.9804, 0.9571, and 0.9686, respectively.Conclusion:Deep-learning-based AI models are a promising tool for the automated charting of panoramic dental radiographs from children. In addition to serving as a time-saving measure and an aid to clinicians, AI plays a valuable role in forensic identification.     

Deciduous teeth development in fetuses using postmortem computed tomography image analysis

Fetal age is estimated widely by body length and weight and skeletal or dental development and maturation. Regarding dental development, dental development charts reported by Schour and Massler and Ubelaker are well known. We tried to calculate the calcification rate of the deciduous teeth, mandibular cortical bone, and clavicle in fetuses utilizing postmortem computed tomography (CT) image analysis. The CT values within the circumferential area of the region of interest were automatically calculated using a software, and the calcification rate was calculated by performing single regression analysis. Our results showed that deciduous tooth calcification could be detected in over 19-week-old fetuses using CT images. The calcification of bones (mandibular cortical bone and clavicle) started earlier than the calcification of deciduous teeth. However, the calcification rate of the bones was slower compared to that of the deciduous teeth. The calcification rate of the deciduous teeth in fetuses using CT value may be effective to estimate fetal age and evaluate deciduous teeth development, suggesting that our established method is effective for age estimation in forensic dentistry.     

Evaluation of the maximum length of deciduous teeth for estimation of the age of infants and young children: proposal of new regression formulas

The methodology used to identify individuals in forensic anthropology requires a minimum degree of precision and accuracy and should be based on identified and representative samples. Achievement of these objectives in infant skeletons is hampered by the scarcity of appropriate samples. The dental age estimation methods of Liversidge et al. (Am J Phys Anthropol 90: 307–313, 1993) and Deutsch et al. (Growth 49: 207–17, 1985) were applied to the Granada osteological collection of identified infants (Granada, Spain) in order to evaluate its applicability in a Mediterranean population. Significant differences were found between the estimated and real ages in both cases. Based on the measurements obtained in 140 fetuses and infants, new regression formulas were developed to estimate age from the metric study on deciduous teeth. Independent functions are provided for each deciduous maxillary and mandibular tooth in each sex, along with the margin of error (95 % confidence interval). These formulas appear to offer one of the best methods available for estimating the age of Mediterranean infants in forensic anthropology settings.     

Spatial Distribution of Naturally Occurring 210Po and 226Ra in Children's Teeth

Deciduous and permanent teeth extracted from juveniles for orthodontic purposes have been analysed using α-sensitive plastic track detectors for the spatial distribution of total α-activity and naturally occurring ²¹⁰Pb-supported ²¹⁰Po and ²²⁶Ra. The distribution of these radionuclides is nonuniform, with ²¹⁰Po being primarily associated with outer enamel and ²²⁶Ra with the pulp. The observations suggest that ²¹⁰Pb/²¹⁰Po concentrates at the interface of enamel with saliva or blood, by means of unidirectional ionic exchange with calcium. In contrast, ²²⁶Ra concentrates in the predentine band at the interface with pulp and with systemic blood circulation, where its uptake is permitted by the incomplete calcification in this band. Activity concentration was measured in 900 teeth. Total concentration on the outer enamel surface of deciduous teeth, permanent teeth from children ?10 years and permanent teeth from children > 10 years give respective mean values of 8·63±0·26, 5·76±0.48 and 7·00±0·15 Bq kg^?1. ²²⁶Ra concentration on the corresponding longitudinal sections comprising pulp, dentine and annular enamel give respective mean values of 0·715±0·055, 0·418±0·083 and 0·514±0·029 Bq kg^?1. Mean activity concentration in 32 foetal teeth was 2·05±0·31 Bq kg^?1. The results form the basis of more detailed studies of (1) age-dependent uptake of α-radionuclides in teeth and their microdistribution, and (2) the geographical variation in activity concentration with respect to environmental factors such as domestic radon exposure.     

Fetal age estimation using MSCT scans of deciduous tooth germs

Evaluation of fetal age is an essential element in many fields such as anthropology, odontology, paleopathology, and forensic sciences. This study examines the correlation between fetal age, femoral diaphyseal length (considered as the gold standard), and deciduous tooth germs of fetuses aged 22 to 40 weeks amenorrhea (WA) based on computed tomography (MSCT) reconstructions. Qualitative and quantitative studies of femoral and deciduous tooth germ lengths were performed on 81 fetuses (39 females and 42 males). R software was used for statistical analyses. Intra-observer and inter-observer variabilities and the interclass correlation coefficient (ICC) were calculated. Correlation coefficients (R ²) and linear regression equations were calculated. Intra- and inter-observer variabilities were very satisfactory (intra-observer ICC?≥?0.96, inter-observer ICC?≥?0.95). Femoral length was significantly correlated with age (R ²?=?0.9). The correlation coefficient between age and height, width, and dental volume was R ²?≥?0.73. Tooth germs were good indicators of fetal age. Our method appears to be reliable and reproducible, and the results of this study agreed with those of the literature. The dental formula provided a precise estimation of fetal age between 25 and 32 WA. Tooth germs were reliable indicators of fetal age, and multislice computed tomography was shown to be an innovative and reliable technology for this purpose.     

Comparison of gamma- and UV-light-induced EPR spectra of enamel from deciduous molar teeth.

From previous work, it is known that CO2- radicals in tooth enamel are induced by gamma as well as by UV-light exposure. The parameters of the EPR signal of the CO2- radical were found to be independent of the source of exposure. However, it would be desirable for retrospective dosimetry to identify other characteristic features of the EPR spectrum of tooth enamel, which would allow differentiation between the two sources of exposure. In the present work, enamel of deciduous molars was exposed to gamma-radiation from a 60Co-source and 254 nm UV-light from a low-pressure mercury lamp. The resulting EPR spectra were deconvoluted, and the native spectrum simulated from spectra of the CO2- radical, and two further EPR lines. Both EPR signals of the native spectrum were located at g=2.0046, but were different in line shape and width. One was a 1 mT wide isotropic signal of Gaussian line shape while the other was a 0.7 mT wide axial signal of Lorentzian line shape. A comparable study of the amplitudes of the native and CO2- signals was done before and after gamma- and UV-light exposure. While the native signals were found to be only slightly sensitive to gamma-radiation, their amplitude increased significantly on UV-light exposure. Feasibilities are discussed to distinguish different radiation sources by exposure-induced alterations of the native EPR spectrum.     

Development of formulae for dental age estimation using digital radiographs in the Mongolian population

This study aimed to examine the applicability of the pulp/tooth ratio (PTR) method for age estimation in Mongolian populations using panoramic radiographs and derive new regression formulae. Moreover, we aimed to assess the accuracy of these formulae in other subjects from the Mongolian population and compare them with the other formulae derived from different Asian populations.The total sample size of the study was 381. The formulae were derived from the examination of panoramic radiographs of 271 individuals aged 15–62 years. Following Cameriere’s method, PTR was calculated for the upper and lower canine teeth. Linear regression analyses were performed between the actual age and that obtained from upper-lower canine PTR and established formulae for age estimation. To verify the formulae, two types of test samples were collected: 73 panoramic radiographs and 37 periapical radiographs. The estimated age was calculated using our new formulae and three other formulae derived from Asian populations.The correlation coefficient between the actual age and that obtained by PTR was significantly negative for both canines. According to our new regression formulae, the differences between the estimated age and actual age showed a bell-shaped curve distribution in both test groups. While using the other formulae derived from the Asian population, the distribution patterns obtained were significantly different in the Mongolian population.This study was the first to examine the relationship between actual age and PTR in Mongolian population, and these results advance the field of forensic science in Mongolia.     

Dental age assessment of young Iranian adults using third molars: A multivariate regression study

BackgroundIn recent years, a noticeable increase in forensic age estimations of living individuals has been observed. Radiologic assessment of the mineralisation stage of third molars is of particular importance, with regard to the relevant age group. To attain a referral database and regression equations for dental age estimation of unaccompanied minors in an Iranian population was the goal of this study. Moreover, determination was made concerning the probability of an individual being over the age of 18 in case of full third molar(s) development.Materials and methodsUsing the scoring system of Gleiser and Hunt, modified by Köhler, an investigation of a cross-sectional sample of 1274 orthopantomograms of 885 females and 389 males aged between 15 and 22 years was carried out. Using kappa statistics, intra-observer reliability was tested. With Spearman correlation coefficient, correlation between the scores of all four wisdom teeth, was evaluated. We also carried out the Wilcoxon signed-rank test on asymmetry and calculated the regression formulae.ResultsA strong intra-observer agreement was displayed by the kappa value. No significant difference (p-value for upper and lower jaws were 0.07 and 0.59, respectively) was discovered by Wilcoxon signed-rank test for left and right asymmetry. The developmental stage of upper right and upper left third molars yielded the greatest correlation coefficient. The probability of an individual being over the age of 18 is 95.6% for males and 100.0% for females in case four fully developed third molars are present. Taking into consideration gender, location and number of wisdom teeth, regression formulae were arrived at.ConclusionUse of population-specific standards is recommended as a means of improving the accuracy of forensic age estimates based on third molars mineralisation. To obtain more exact regression formulae, wider age range studies are recommended.     

In vivo energy dispersive X-ray fluorescence for measuring the content of essential and toxic trace elements in teeth.

The calibration and application of a facility, based on energy dispersive X-ray fluorescent analysis (EDXRF) using 109Cd as an excitation source, for in vivo and in vitro estimation of Ca, Pb, Sr and Zn in tooth enamel is described. During the in vivo measurements, the device ensures tissue protection of face and mouth cavity from radiation, and only a small part of tooth surface under study is irradiated. To calibrate the facility, the contents of Ca, Sr and Zn were analyzed simultaneously in the enamel of 50 teeth by EDXRF and instrumental neutron activation analysis (INAA). Standards prepared from powdered tooth enamel with additions of chemically pure lead compounds were used to calibrate for lead graduation. Enamel calcium is suggested as an internal standard during in vivo EDXRF of teeth. The content of enamel Sr, Zn and Pb was determined by EDXRF in 35 permanent intact teeth of teenagers and adults. It was shown that lead concentration didn't exceed 3 micrograms/g for all the teeth.     

Enamel and dentin mineralization in familial hypophosphatemic rickets: a micro-CT study

Objectives:

The aim of the present study was to analyse the mineralization pattern of enamel and dentin in patients affected by X-linked hypophosphatemic rickets (XLHR) using micro-CT (µCT), and to associate enamel and dentin mineralization in primary and permanent teeth with tooth position, gender and the presence/absence of this disease.

Methods:

19 teeth were collected from 5 individuals from the same family, 1 non-affected by XLHR and 4 affected by XLHR. Gender, age, tooth position (anterior/posterior) and tooth type (deciduous/permanent) were recorded for each patient. Following collection, teeth were placed in 0.1% thymol solution until µCT scan. Projection images were reconstructed and analysed. A plot profile describing the greyscale distance relationship in µCT images was achieved through a line bisecting each tooth in a region with the presence of enamel and dentin. The enamel and dentin mineralization densities were measured and compared. Univariate ANOVA and post hoc Tukey tests were used for all comparisons.

Results:

Teeth of all affected patients presented dentin with a different mineralization pattern compared with the teeth of healthy patients with dentin defects observed next to the pulp chambers. Highly significant differences were found for gray values between anterior and posterior teeth (p < 0.05), affected and non-affected (p < 0.05), as well as when position and disease status were considered (p < 0.05).

Conclusions:

In conclusion, the mineralization patterns of dentin differed when comparing teeth from patients with and without FHR, mainly next to pulp chambers where areas with porosity and consequently lower mineral density and dentin defects were found.     

两种方法治疗前牙外伤性冠折的术后反应及临床疗效比较

目的比较采用一次性根管充填及常规法治疗前牙外伤性冠折的术后反应及临床疗效。方法选择因外伤致恒前牙冠折露髓的65例患者100颗患牙,随机分为两组,每组50颗。试验组予以一次性根管充填治疗,对照组进行常规根管治疗,所有患者均在治疗后7 d及6月复查,观察术后反应并评价近期疗效。结果两组患牙根管充填7 d后复查,术后反应发生率无明显统计学意义(P>0.05);6月后复查,试验组均治疗成功,对照组1例失败,两组成功率比较无显著性差异(P>0.05)。结论与常规根管治疗比较,一次性根管充填术后反应发生率及近期疗效无差别,一次性根管充填治疗前牙外伤性露髓冠折值得临床推广。