Use of diagonal teeth measurements in predicting gender in a Turkish population

Mesiodistal and buccolingual measurements, commonly used as a means of sex determination from teeth, can sometimes cause difficulties. The aim of this study is to test whether diagonal measurements can make it possible to take more accurate measurements. The results of diagonal measurements of dental casts taken from 30 males and 30 females have been evaluated by discriminant function statistics. Intra- and interobserver error tests did not indicate any statistically significant differences between the findings of two observers. Seven of the 14 measurements on the maxilla and 10 of the 14 measurements on the mandible have been found to be significantly greater in males. According to the results of the stepwise discriminant function statistics, the most contributory measurements to the function were upper first incisor mesiobuccal-distolingual (MBDL) and distobuccal-mesiolingual, lower second incisor MBDL, and lower canine MBDL. The highest reliability was obtained in MBDL measurements. It was realized that diagonal measurements of teeth, especially of canines, revealed clear dimorphic differences. Classification accuracy was found to be 83.3% for total sample, 78.3 for upper jaw, and 85.0% for the lower jaw. Accuracy rate was higher in the lower teeth. Commonly seen orthodontic anomalies, such as tooth rotations, crowding, attritions, deep dentin-enamel junction defects, and certain types of fillings, could make it difficult to correctly take width measurements or could cause other mistakes to occur. This explains the reason why this research has been considered to be of some use in diagonal measurements, which is an accurate method, particularly when employed for the front teeth.     

Preliminary Validation of Handheld X‐Ray Fluorescence Spectrometry: Distinguishing Osseous and Dental Tissue from Nonbone Material of Similar Chemical Composition

One of the tasks of a forensic anthropologist is to sort human bone fragments from other materials, which can be difficult when dealing with highly fragmented and taphonomically modified material. The purpose of this research is to develop a method using handheld X‐ray fluorescence (HHXRF) spectrometry to distinguish human and nonhuman bone/teeth from nonbone materials of similar chemical composition using multivariate statistical analyses. The sample materials were derived primarily from previous studies: human bone and teeth, nonhuman bone, nonbiological materials, nonbone biological materials, and taphonomically modified materials. The testing included two phases, testing both the reliability of the instrument and the accuracy of the technique. The results indicate that osseous and dental tissue can be distinguished from nonbone material of similar chemical composition with a high degree of accuracy (94%). While it was not possible to discriminate rock apatite and synthetic hydroxyapatite from bone/teeth, this technique successfully discriminated ivory and octocoral.     

Dental CT imaging as a screening tool for dental profiling: advantages and limitations

The use of dental processing software for computed tomography (CT) data (Dentascan) is described on postmortem (pm) CT data for the purpose of pm identification. The software allows reconstructing reformatted images comparable to conventional panoramic dental radiographs by defining a curved reconstruction line along the teeth on oblique images. Three corpses that have been scanned within the virtopsy project were used to test the software for the purpose of dental identification. In every case, dental panoramic images could be reconstructed and compared to antemortem radiographs. The images showed the basic component of teeth (enamel, dentin, and pulp), the anatomic structure of the alveolar bone, missing or unerupted teeth as well as restorations of the teeth that could be used for identification. When streak artifacts due to metal-containing dental work reduced image quality, it was still necessary to perform pm conventional radiographs for comparison of the detailed shape of the restoration. Dental identification or a dental profiling seems to become possible in a noninvasive manner using the Dentascan software.     

Clinically Detectable Dental Identifiers Observed in Intra‐oral Photographs and Extra‐oral Radiographs,Validated for Human Identification Purposes

Screening the prevalence and pattern of dental identifiers contributes toward the process of human identification. This research investigated the uniqueness of clinical dental identifiers in photographs and radiographs. Panoramic and lateral cephalometric radiographs and five intra‐oral photographs of 1727 subjects were used. In a target set, two observers examined different subjects. In a subset, both observers examined the same subjects (source set). The distance between source and target subjects was quantified for each identifier. The percentage of subjects in the target set being at least as close as the correct subject was assessed. The number of molars (34.6%), missing teeth (42%), and displaced teeth (59.9%) were the most unique identifiers in photographs and panoramic and lateral cephalometric radiographs, respectively. The pattern of rotated teeth (14.9%) was the most unique in photographs, while displaced teeth was in panoramic (37.6%) and lateral cephalometric (54.8%) radiographs. Morphological identifiers were the most unique, highlighting their importance for human identifications.     

On the applicability of secondary dentin formation to radiological age estimation in young adults

The literature provides linear regression formulas for dental age estimation that is based on radiological two-dimensional measurements of the pulp size. The aim of the present study was to explore whether the previously presented regression formulas could lead to statistically sound results and to appropriate repeatability when applied to young individuals. Orthopantomograms (OPGs) of 44 Austrian individuals, aged between 13 and 24 years, were selected at random. In accordance with the reported method, six teeth on each OPG were chosen to carry out the measurements. Statistical analysis was performed in order to assess the difference between the estimated and the true chronological age. The regression formulas reported by Kvaal et al. (1995) led to a consistent underestimation; the regression formulas reported by Paewinsky et al. (2005) resulted in a constant overestimation of age. The statistical analysis of intraobserver and interobserver variation revealed a variation width below 2%, respectively.     

A Reappraisal of Developing Deciduous Tooth Length as an Estimate of Age in Human Immature Skeletal Remains

This study provides an update on a quantitative method for immature age estimation based on postnatal deciduous mandibular tooth length. Two known sex and age skeletal collections from Western Europe were sampled (n = 97). Linear regression models for age estimated were calculated for each individual tooth, each sex, and sex combined sample using classical calibration. Prediction errors, residuals, and percentage of individuals whose real age fell within the 95% prediction interval were calculated. The teeth which develop earlier in life, the incisors and the first molar, showed the greatest precision, while the canine showed the least. This method has greater applicability to archeological skeletons or to children in developing countries than for use in North American or European forensic contexts. The method can be applied to incomplete or poorly preserved remains of unknown sex, particularly when dental radiographs are not an option or when teeth have been removed from the alveolus or crypt.     

Determination of season at death using dental cementum increment analysis

Dental cementum anchors teeth into their sockets via the periodontal ligament. In mammals, dental cementum is laid down in alternating opaque and translucent bands representing winter (dormant) and summer (growth) seasons. Each pair of bands represents 1 year of life. Estimates of age at death based on counting pairs of bands are highly accurate. If the timing of the transition between winter and summer bands could be identified in humans, dental cementum increment analysis could be used to specify the season at death. This pilot project attempts to determine when these transitions occur and thus provide forensic anthropologists with a technique that would refine our estimates of postmortem interval. Extracted teeth were obtained from a local oral surgeon, embedded, sectioned, ground, polished, and examined under transmitted polarized light. The outermost increment was identified and measured along with other randomly chosen like bands. A transition from translucent to opaque bands was observed in teeth extracted in early October, while teeth extracted in early April exhibited nascent translucent bands. Further, significant correlations were observed between band thickness and number of days into either season, suggesting that band width increases as either season progresses. In this blind study, extracted teeth were effectively sorted into the spring/summer or fall/winter season 99% of the time.     

Sex discrimination potential of buccolingual and mesiodistal tooth dimensions

Abstract:  Tooth crown dimensions are reasonably accurate predictors of sex and are useful adjuncts in sex assessment. This study explores the utility of buccolingual (BL) and mesiodistal (MD) measurements in sex differentiation when used independently. BL and MD measurements of 28 teeth (third molars excluded) were obtained from a group of 53 Nepalese subjects (22 women and 31 men) aged 19–28 years. Stepwise discriminant analyses were undertaken separately for both types of tooth crown variables and their accuracy in sex classification compared with one another. MD dimensions had recognizably greater accuracy (77.4–83%) in sex identification than BL measurements (62.3–64.2%)—results that are consistent with previous reports. However, the accuracy of MD variables is not high enough to warrant their exclusive use in odontometric sex assessment—higher accuracy levels have been obtained when both types of dimensions were used concurrently, implying that BL variables contribute to sex assessment to some extent. Hence, it is inferred that optimal results in dental sex assessment are obtained when both MD and BL variables are used together.     

利用牙齿推断年龄的研究进展

牙齿是人体最坚硬的器官之一,其抗腐蚀能力强,多项形态特征具有增龄性变化,因此利用牙齿推断年龄在法医学中得到广泛应用。由于牙齿的生理性变化的复杂性及环境因素的影响,不同牙齿推断年龄的方法各具其应用价值,同时也存在一定的局限性,法医工作者需要依据具体情况选择适合的方法并加以综合运用,以提高年龄推断的准确性。本文对国内外利用牙齿推断年龄的研究现状进行综述,并对各种推断方法进行比较评价,希望能为相关研究和实践提供参考。     

Testing a Novel 3D Printed Radiographic Imaging Device for Use in Forensic Odontology

There are specific challenges related to forensic dental radiology and difficulties in aligning X‐ray equipment to teeth of interest. Researchers used 3D printing to create a new device, the combined holding and aiming device (CHAD), to address the positioning limitations of current dental X‐ray devices. Participants (N = 24) used the CHAD, soft dental wax, and a modified external aiming device (MEAD) to determine device preference, radiographer's efficiency, and technique errors. Each participant exposed six X‐rays per device for a total of 432 X‐rays scored. A significant difference was found at the 0.05 level between the three devices (p = 0.0015), with the MEAD having the least amount of total errors and soft dental wax taking the least amount of time. Total errors were highest when participants used soft dental wax—both the MEAD and the CHAD performed best overall. Further research in forensic dental radiology and use of holding devices is needed.     

Statistical Evidence for the Similarity of the Human Dentition

Abstract: Recent scrutiny of forensic science has focused on unreliability of expert witness testimony when based on statements of individuality. In bitemark analysis, assumptions regarding uniqueness of the dentition have been based on use of the product rule while ignoring correlation and nonuniformity of dental arrangement. To examine the effect of these factors, two separate sets of scanned dental models (n = 172 and n = 344) were measured and statistically tested to determine match rates. Results were compared to those of a prior study. Seven and 16 matches of the six anterior lower teeth were found in the respective data sets. Correlations and nonuniform distributions of tooth positions were observed. Simulation tests were performed to verify results. Results indicate that given experimental measurement parameters, statements of dental uniqueness with respect to bitemark analysis in an open population are unsupportable and that use of the product rule is inappropriate.     

A Test of Age Estimation Methods on Impacted Third Molars in Males

This study tests the relationship between third molar impaction and its concomitant effect on age estimation methods. Data were collected on radiographs of males analyzed in the Defense POW/MIA Accounting Agency Laboratory (n = 114). Radiographs of skeletonized individuals were scored for dental development, and age was assigned based on the appropriate ancestry‐based method. Differences between identified age and estimated dental age were assessed to determine whether molar impaction affected root development and age estimations. Results indicate that impacted teeth tend to be underdeveloped and result in age estimates that are too low. While these results are of note to anthropologists and odontologists performing dental age estimates, more work is needed to explore the effect of impaction on development among a more diverse sample.     

Gender Determination of Adult Individuals by Three‐Dimensional Modeling of Canines

Gender determination is a fundamental issue in forensic anthropology. Many techniques based on bone and dental remains have been proposed. It is not always possible to implement the techniques using bones, but teeth are often perfectly preserved. It has been demonstrated that the canine has the greatest sexual dimorphism, and the aim of this work was to provide an easy and accurate dental technique for determining the gender in the absence of other skeletal elements. The sample was composed of 210 CT scans with four healthy canines. The 840 canines were modeled using MIMICS^® 10.01 software. The total volume of each tooth was determined. Seven mathematical models were determined by binary logistic regressions and ranked in order of relative performance. The seven proposed predictive models thus performed (0.910 ≤ AUC ≤ 0.938), with overall rates of correct predictions between 82.38 and 85.24%. The 4‐canine model is the most powerful for predicting the gender.     

颌面数字X线片的法医学同一认定

目的探讨颌面数字X线片(DigitalRadiology,DR)的全口牙型32位编码和测量6项骨性指标的变化特征,评估其在法医学同一认定的价值。方法随机选取颌面DR全景片300例,按设计的编码标准和原则对其全口牙型逐一编码,分析编码的多样性;随机选取颌面DR侧位片100例,由口腔放射科医生和培训过的法医研究生各一人对6项骨性指标(N-S,N-Me,Cd-Gn,Cd-Go,NP-SN,MP-SN)进行准确测量,计算指标的变异系数(CV),并对两人测量结果的一致性进行相关分析。结果(1)300例个人全口牙型编码,总体多样性为75%;牙齿有病变或治疗组的多样性为99.53%;(2)颌面DR侧位片中6项指标变异系数较大;(3)两次测量结果的相关系数均接近1,表明所选指标的测量结果稳定,有高度一致性。结论颌面DR全景片全口牙型32位编码和颌面DR侧位片中6项骨性指标可用于同一认定。     

Yet another method for marking incisal edges of teeth for bitemark analysis

Over the years many methods have been proposed and presented for marking or "highlighting" the incisal edges of anterior teeth on a dental stone model -- one of the critical steps in production of transparent overlays for bitemark analysis. A method is presented here that is an extension and refinement of the "paint the edges" method shown at least as early as 1966 by Gustafson. This method uses "invisible ink" and ultraviolet illumination to produce a very high contrast image of the incisal edges of the teeth on the model. The advantages of this new method are that it is nondestructive, it does not leave visible marks on the models, operator subjectivity in selecting the portions of anterior teeth to be highlighted is reduced, and the author submits that this technique lends itself to easy construction of overlays using computer image-processing software such as Adobe Photoshop and ImageJ.     

Accuracy and reliability of cone beam computed tomography of the jaws for comparative forensic identification: a preliminary study

Conventional computed tomography is an emerging modality in forensic identification but is not sufficiently accurate for use in dental identification primarily because of problems with metallic dental restoration-induced streak artifact. In this study, the accuracy and reliability of recording forensic information from cone beam computed tomography (CBCT) scans of the jaws when compared to conventional panoramic radiographs has been analyzed under experimental conditions. Information could be recorded with near-perfect repeatability and reproducibility. Information could also be recorded accurately, the sensitivity being 96.6% (95% CI, 95.1-98.1) and specificity being 98.4% (95% CI, 96.2-100). The metal dental restoration-induced streak artifact was at a level that permitted, in most cases, accurate observations. This is considered an important step in validating CBCT as a tool in comparative dental identification of bodies. It may have a role in mass fatalities and in chemical, biological, radiological, and nuclear incidents, but further studies are required to assess the feasibility of this.     

Usefulness of Forensic Dental Symbols© and Dental Encoder© database in forensic odontology

Abstract: A new universal graphic dental system, Forensic Dental Symbols^©, has been created to provide precision in the construction of dental records, improve standardization, and increase efficiency in dental identification procedures. Two hundred and thirty‐four different graphic symbols representing the most frequent clinical status for each tooth were designed. Symbols can be then converted to a typographic font and then are ready to use in any computer. For the appropriate use, manipulation, and storage of dental information generated by the Forensic Dental Symbols^©, Dental Encoder^© database has been created. The database contains all the information required by INTERPOL Disaster Victim Identification (DVI)‐dental‐forms. To explore the possibilities that Dental Encoder^© offers, an antemortem dental database from a Spanish population of 3920 military personnel had been constructed. Data generated by Dental Encoder^© were classified into sex and age groups. The program can perform an automatic search of the database for cases that match a selected clinical status presented in a single tooth or a combination of situations for several teeth. Moreover, Dental Encoder^© allows information to be printed on INTERPOL DVI‐dental‐forms, or the inclusion of any completed form into any document, technical report, or identification of dental report.     

The Effects of Racemization Rate for Age Estimation of Pink Teeth

Pink teeth is thought to result from the seepage of hemoglobin caused by dental pulp decomposition. We investigated whether racemization can be applied for age estimation in cases of pink teeth where the whole tooth is used. The pink teeth used were three cases and the normal teeth for control were five mandibular canines of known age. Age of the pink teeth was calculated on the basis of regression formula obtained from the five control teeth. Only a slight error was noted between the actual and estimated ages of the pink teeth (R² = 0.980, r = 0.990): Cases 1–3 actually aged 23, 53, and 59 years were estimated to be 26, 52, and 60 years. Based on our results of testing pink teeth of known age, we suggest that racemization techniques allow for the age estimation of pink teeth using the same methods for normally colored teeth.     

中国汉族6～18周岁人群下颌恒牙钙化的性别差异研究

目的通过对中国汉族男女6～18周岁人群全口曲面断层影像上所显示的下颌左侧牙齿钙化程度进行比较研究,探究牙齿生长发育的性别差异,为建立用牙齿推断中国汉族儿童及青少年年龄的线性回归模型提供理论依据。方法通过对13491张(男6568张,女6923张)中国汉族6～18周岁儿童及青少年全口曲面断层影像的牙齿钙化规律进行研究,建立牙齿钙化的分级标准,并对下颌恒牙进行分级评分;数据用SPSS 13.0软件处理。结果非参数检验结果显示大部分年龄组下颌左侧8颗恒牙钙化分级值性别间的差异有统计学意义(P0.05);在8颗恒牙发育程度同等条件下,女性年龄比男性小0.303岁。结论中国汉族6～18周岁人群牙齿发育存在着性别差异;在利用牙齿钙化程度建立推断中国汉族儿童及青少年年龄的方程模型时,应分性别建模。     

Ultraviolet illumination as an adjunctive aid in dental inspection

Tooth-colored resin fillings have become increasingly popular as restorative materials. Their presence in the dentition presents a challenge to the clinician and the forensic odontologist, as detection of the fillings can be difficult both visually and radiographically. As they necessarily form part of the unique dentition of an individual, recognition of the resins is important for forensic identification. Alternative light sources have been used with success in various fields of forensic science. In recent years small LED flashlights emitting at specific wavelengths in the ultraviolet light (UV) range have been developed. Their low cost, small size, and ready availability makes their use practical in both forensic dental inspection and clinical settings. UV inspection is of interest because enamel, dentin and dental materials all have differing fluorescent properties when illuminated by UV light. It was one goal of this research to quantitatively assess the fluorescence properties of modern restorative resins in order to predict their behavior during inspection using UV illumination. The second goal was to demonstrate practical use of UV in dental inspection with examples of how different materials fluoresce. Quantitative measurements were obtained for optical emission wavelength and intensity for 15 modern resins using a spectrophotometer. Results indicated that resin brands fluoresce at different wavelengths and with varying intensities. Practical use and comparison of the flashlights revealed that the most useful excitation wavelengths for resin detection were in the UVA range (365 and 380 nm). Porcelain restorations and composite resin fillings exhibited different responses to these two wavelengths and thus use of both is recommended for forensic dental inspection.