A test of the differential accuracy of the maxillary versus the mandibular dentition in age estimations of immature skeletal remains based on developing tooth length

Liversidge and colleagues developed a method for predicting the age of immature skeletal remains based on the length of developing teeth. This quantitative method combines dental data from both jaws, except for the permanent lateral incisor, and because there are reasons to suspect that these two types of data are not identical and should not be combined, it raises concerns regarding the accuracy of the technique when applied differently to each jaw. In this study, the differential accuracy of the method was test when applied to the maxillary and mandibular dentition. The test sample is comprised of 57 Portuguese subadult skeletons of known age at death. Results suggest an overall high consistency between estimates obtained from both jaws, but for the permanent dentition only. In the deciduous dentition the age estimates obtained from the maxillary teeth tend to be greater than the age estimates obtained from the mandibular pair, and the differences are significant for the incisors and canine. Additionally, ages obtained from the maxillary deciduous canine also differ significantly from true chronological age. In the permanent dentition there were no differences between the ages provided by both jaws but both the maxillary and mandibular second molars show a significant tendency to underestimate true chronological age. Although this study cannot validate completely the method presented by Liversidge and colleagues, it does provide an important test to its accuracy and calls for further research into its overall performance, particularly with respect to the results obtained from both jaws.     

Sexual dimorphism in teeth: discriminatory effectiveness of permanent lower canine size observed in a XVIIIth century osteological series

Recent studies have shown that the most dimorphic tooth is the mandibular canine. We have carried out a study on a random sample of 146 skeletons dating from the plague outbreak in Marseilles (1722). We studied 1284 maxillary and 1432 mandibular permanent teeth. Sexual dimorphism was tested on 89 individuals. We selected a set of four dental indices and calculated the dimorphism percentage by ratio expression male/female. Dimorphic ranking was made, by allotting the first rank to the tooth presenting the highest dimorphism and the last rank to the one presenting the lowest ratio. Comparisons of means were made on both sexes (sex determined by post-cranial data) through a Student's test (t-test). We noted that lower canines and lateral incisor are the most interesting teeth in the dimorphic dental determination. The lower index presented the highest relative risk with RR = 1.56 [1.04-2.32]. In 58% of the cases, the lower dental index enabled a correct sex determination (determined on the basis of the post-cranial skeleton). These results showed the existence of a relative dental dimorphism (male > female mesiodistal diameters) with humans. In conclusion, this method, using dental measurements, may be used as an additional technique to determine sex on fragmentary adult skeletons, immature material, missing pieces or ambiguities on post-cranial remains.     

The application of Kvaal's dental age calculation technique on panoramic dental radiographs

INTRODUCTION: Literature reports on a method for dental age calculation which is based only on radiological measurements on periapical dental radiographs: the relationship between chronological age and the two-dimensional dental pulpal size was analysed by means of multiple regression analyses. The purpose of the present study was to evaluate whether this approach could be feasible and could lead to statistically sound results with adequate repeatability when applied on panoramic radiographs. MATERIALS AND METHODS: One hundred and ninety seven panoramic radiographs were collected at random from patients of whom the age ranged from 19 to 75 years. According to the reported technique, six teeth were selected on the panoramic radiograph: in the maxilla the central and lateral incisor and second bicuspid, and in the mandibula the lateral incisor, cuspid and first bicuspid. The same exclusion criteria as in the original paper were respected. Statistical analysis was carried out in order to spot significant differences between the chronological age and the calculated age. RESULTS: When the age was calculated based on measurements of all six teeth or of all three mandibular teeth, no significant differences were found between the real age and the calculated one. In all other instances using the individual teeth separately or using all three maxillary teeth statistical analysis revealed significant differences. CONCLUSION: There appears to be no significant difference between applying the original technique on standard long-cone periapical radiographs or on orthopantomograms, especially when carrying out measurements on all six selected teeth.     

Patterns of Variation and Match Rates of the Anterior Biting Dentition: Characteristics of a Database of 3D‐Scanned Dentitions

An understanding of the variability of the anterior human dentition is essential in bitemark analysis. A collection of 1099 3D laser scans of paired maxillary and mandibular arches were studied using geometric morphometric methods. Analyses were performed without scale (shape only) and with scale (shape and size). Specimens differing by no more than experimentally obtained measurement error were counted as matches, or as indistinguishable. A total of 487 maxillary (396 size preserved), 131 mandibular (83 size preserved), and one paired dentition (two size preserved) matches were found. Principal component analysis and partial least squares revealed interpretable patterns of variation and covariation in dental shape, principally dominated by variation in dental arch width. The sensitivity of match rate to assumed degree of measurement error was also determined showing rapid increases in match rate as measurement error increased. In conclusion, the concept of dental uniqueness with regard to bitemark analysis should be approached with caution.     

The Use of Tooth Crown Measurements in the Assessment of Ancestry

As the hardest tissue in the body, teeth have the potential to offer a wealth of biological information to the forensic anthropologist, which can include the assessment of ancestry. Using a large data set of dental measurements, the efficacy of mesiodistal and buccolingual tooth dimensions to discriminate between broad, geographically based groups is explored. A general pattern is identified: African populations have the largest teeth, Asians possess teeth of intermediate size, and Europeans have the smallest teeth. In a discriminant function analysis using crown measurements of all teeth (mandibular and maxillary and excluding the third molar), individuals were correctly classified in 71.3% of cases. When the sex of the individual is known, classification is improved up to 88.1% in females and 71.9% of males (cross‐validated). Based on these results, we argue that dental metrics can be regularly employed as part of the development of the biological profile.     

Age estimation of adults from dental radiographs

Previous studies have shown that with advancing age the size of the dental pulp cavity is reduced as a result of secondary dentine deposit, so that measurements of this reduction can be used as an indicator of age. The aim of the present study was to find a method which could be used to estimate the chronological age of an adult from measurements of the size of the pulp on full mouth dental radiographs. The material consisted of periapical radiographs from 100 dental patients who had attended the clinics of the Dental Faculty in Oslo. The radiographs of six types of teeth from each jaw were measured: maxillary central and lateral incisors and second premolars, and mandibular lateral incisors, canines and first premolars. To compensate for differences in magnification and angulation on the radiographs, the following ratios were calculated: pulp/root length, pulp/tooth length, tooth/root length and pulp/root width at three different levels. Statistical analyses showed that Pearson's correlation coefficient between age and the different ratios for each type of tooth was significant, except for the ratio between tooth and root length, which was, therefore, excluded from further analysis. Principal component analyses were performed on all ratios, followed by regression analyses with age as dependent variable and the principal components as independent variables. The principal component analyses showed that only the two first of them had significant influence on age, and a good and easily calculated approximation to the first component was found to be the mean of all the ratios. A good approximation to the second principal component was found to be the difference between the mean of two width ratios and the mean of two length ratios, and these approximations of the first and second principal components were chosen as predictors in regression analyses with age as the dependent variable. The coefficient of determination (r²) for the estimation was strongest when the ratios of the six teeth were included (r² = 0.76) and weakest when measurements from the mandibular canines alone were included (r² = 0.56). Measurement on dental radiographs may be a non-invasive technique for estimating the age of adults, both living and dead, in forensic work and in archaeological studies, but the method ought to be tested on an independent sample.     

Determining dental sex dimorphism in South Indians using discriminant function analysis

Dental forensics forms a vital branch of forensic science which deals with proper handling, examination and evaluation of dental evidences for identification of victims of crime, accidents or calamities. Therefore skull and teeth often provide the identification material. The aim of the study was to investigate the accuracy of odontometric methods in sex determination of permanent teeth and to compute new formula to differentiate male and female teeth using discriminant function analysis for South Indian population. A total of 100 subjects were selected for the study from a parent population of 4800 students by simple random sampling method. Alginate impressions of the upper dental arch were made and casts were poured immediately. A digital vernier calliper was used for the measurement of all upper anteriors. Twelve different tooth measurements were recorded and from those two indexes have been computed. Statistical analysis was performed using the SPSS version 17.0 software. All the predictor variables were subjected to stepwise discriminant function analysis which optimally separates the genders and a best discriminant function was generated. In all the observed mean dimensions, male values exceed the female values. Student's 't' test for the different predictor variables of all teeth selected between male and females were found significant (p < 0.05). Very high significance was found in mean MD of 11, 12 and 13 and |c| of 23. The variables exhibiting best discriminant powers were mesiodistal width of both upper central incisors, DB-ML of 13 and canine crown module of 13. Sexual dimorphism in the size of permanent teeth differs from one population to the other and hence the standards set for one population could not be applied for another population. Hence this technique would be a simple, quick, cost effective, reliable and accurate for sex determination.     

Age estimation from teeth in children and adolescents

The aim of this cross-sectional study was to evaluate the dental formulas according to age because of possible changes during the last decades. From these dental formulas, the median age of emergence for the permanent teeth was deduced. The study population corresponded to the 1 to 15 year-old children who had consulted either a pediatric dentist or orthodontist in the city of Nice (France). Data were collected from the 5,848 patients' charts that included an orthopantomography. This permitted the observation of emerged teeth and agenesis. Bar charts were used to indicate the dental formula according to age. There was no significant difference in the emergence pattern of both controlateral maxillary and mandibular teeth. Only the anterior tooth emergence significantly differed according to the maxillary. The lower central incisor was the lone tooth with a median age earlier than others; the remaining teeth had an age equivalent to those of previously estimates.     

关于上颌牙弓性别差异的研究

利用自动显示游标卡尺测量200例（男、女各100例，年龄18～24岁）上颌石膏模型上牙弓宽、长及高等18个指标。经统计分析发现除切牙弓长、尖牙间距对应高及第二双尖牙间距对应高外，其余15项测量指标男性均大于女性（P＜0．05）。逐步判别分析仅用7个测量指标，判别率可达到75．50％。     

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.     

上、下尖牙髓腔/牙体表面积比值的年龄判定价值研究

目的 通过三维重建测量上、下颌尖牙髓腔/牙体表面积比值(Pulp/Tooth area Ratio,PTR)来推断个体年龄,为临床年龄推断的应用提供科学依据.方法 收集口腔门诊患者年龄在16～65岁200例锥形束CT(Cone beam computed tomography,CBCT)影像资料,以4个尖牙为测量对象并...     

Validity of the mandibular canine index (MCI) in sex prediction: Reassessment in an Indian sample

The dentition's use in sex assessment has been explored and advocated owing to its strength and resistance to peri- and postmortem insults. Among the teeth, canines have shown the greatest sexual dimorphism; they are also known for greater resistance to pathological alterations and trauma. These factors have prompted some researchers to explore its use alone in sex prediction. Specifically the mandibular canine index (MCI), which is the ratio of the mesiodistal (MD) dimension of the lower right canine and the inter-canine arch width, was developed by Rao et al. [Forensic Sci. Int. 42 (1989) 249–254] who predicted sex correctly in ～86% of cases in a South Indian sample. These results were verified subsequently by other Indian researchers, both on southern and on northern Indians, although such success rates were not apparent in another South-Asian population as well as a European group. The present study re-examined the method in 203 Indians (103 males, 100 females) of age 19–32 years who originated from diverse states of the country, constituting all major religious and caste affiliations, and found relatively low sex estimation accuracy using the MCI (～51%). This is in spite of the MD dimension of canines as well as inter-canine arch width – the absolute measurements used for deriving the MCI – showing statistically significant sex differences (p < 0.05); also, the application of multivariate statistics, viz. logistic regression analysis, revealed higher accuracy levels of sex estimation for the absolute measurements (～62–66%) vis-à-vis the MCI (～50%). The results herein reinforce recent observations that ratios obtained from teeth, such as the MCI, do not reflect sexual dimorphism that may be present in absolute measurements. Furthermore, we believe that the basis for using MCI as a sex assessment tool is questionable, since it depends on the levels of sexual dimorphism between the absolute dimensions—low sexual dimorphism in one (e.g. MD measurement of canines) and proportionately high sexual differences in the other (e.g. inter-canine arch width), or vice versa, would lead to higher sex estimation accuracy of the MCI; on the other hand, relatively equal levels of sexual dimorphism in both would negate the ability of the MCI to accurately estimate sex. These suggest that the MCI has little utility in sex estimation and that its application should be restricted, if not discontinued altogether, in forensic and anthropological sex prediction.     

上下颌牙齿磨耗推断年龄准确性的比较

目的利用牙齿磨耗不同的分类方法分别推断上、下颌的牙齿年龄,分析各种方法推断上、下颌牙齿年龄的误差,评价上、下颌牙齿用于年龄推断的准确性。方法采用分级法与数量化法分别对164名18~46岁之间的成年人进行牙龄推断,计算出推断牙龄与实际年龄的误差,输入SPSS软件对误差的数据进行统计学分析。结果分别使用不同方法对上、下颌牙齿磨耗程度进行年龄推断的结果差别不大。结论上、下颌牙齿用于牙齿磨耗推断年龄的准确性无明显差异。     

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。     

Studying survivors of near-lethal suicide attempts as a proxy for completed suicide in prisons

Sex determination is a necessary step in the investigation of unidentified human remains from a forensic context. Teeth, as one of the strongest tissues in the human body, can be used for this purpose. Most studies of sexual dimorphism in teeth are based on the traditional mesiodistal and buccolingual crown measurements. The purpose of this study is to examine the degree of sexual dimorphism in permanent molars of modern Greeks using crown and cervical diagonal diameters, and to evaluate their applicability in sex determination. A total of 344 permanent molars in 107 individuals (53 male and 54 female) from the Athens Collection were examined. Crown and cervical diagonal diameters of both maxillary and mandibular molars were measured. It was found that males have larger molars than females and in 19 out of 24 dimensions measured male molars exceeded female molars significantly (P<0.05). The most dimorphic molars are the maxillary second molar, and the mandibular second and first molars. Although other molars were also sexually dimorphic they did not have a statistically significant difference in all dimensions. Cervical diagonal diameters have found to be more sexually diamorphic than crown diagonal diameters. In discriminant function analysis the variables entered more frequently were the cervical diagonal diameters mainly of mandibular molars. Classification accuracy was found to be 93% for the total sample, 77.4% for upper jaw, and 88.4% for the lower jaw. Accuracy rates were higher for cervical than crown diagonal diameters. The data generated from the present study suggest that this metric method can be useful and reliable for sex determination, especially when the traditional dental measurements are not applicable.     

Eruption times of permanent teeth in male children and adolescents of Tehran (Iran)

The eruption times of permanent teeth and the sequence of tooth eruption were investigated in 952 individuals aged 4 to 24 years. Wisdom teeth were excluded from the evaluation. All individuals were inhabitants of Tehran, Iran. The results were compared to results of international studies on tooth eruption of the 20th century and studies published in recent years. The teeth emerged symmetrically in each jaw. However, teeth erupted earlier in the mandible than in the maxilla, excluding the earlier eruption of maxillary premolars. The sequence of emerging teeth in the maxilla is: first molar, central incisor, lateral incisor, first premolar, second premolar, canine, and second molar. The sequence of tooth eruption of the mandible differs from the maxillary sequence: first molar, central incisor, lateral incisor, canine, first premolar, second premolar, second molar. The sequence of all teeth is: lower first molar, lower central incisor, upper first molar, upper central incisor, lower lateral incisor, upper lateral incisor, upper first premolar, lower canine, lower first premolar, upper second premolar, upper canine, lower second premolar, lower second molar, and upper second molar. The results support current theories that the differences in tooth eruption times between humans of different ethnic origin are small.     

Comparative Analysis of the Effects of Heat on the PCR‐Amplification of Various Sized DNA Fragments Extracted from Sus Scrofa Molars*

Abstract: This study examined the effects of heat on the amplification of DNA from the dental pulp of Sus scrofa molars and investigated the protection afforded to the pulp tissue by the dental enamel, alveolar process, and soft tissue of the head. Segments of defleshed maxilla and mandible encasing the first molar (n = 60) were subject to a range of temperatures for 15 min. Dental pulps were retrieved. Amplifications using three‐primer and four‐primer multiplexes showed no degradation of the largest fragment following exposure to 450°C. Amplifications in the three‐primer multiplex (283 bp) were successful following exposure to 525°C in maxillary samples only. This study revealed the enamel density of maxillary molars to be greater than mandibular molars in Sus scrofa. Following incineration of intact heads for 15 min (n = 10) and 1 h (n = 4) at an average temperature of 625°C, amplifications of the largest fragment (450 bp) were successful from both maxillary and mandibular teeth.     

Model of age estimation based on dental factors of unknown cadavers among Iranians

Two hundred and ten cadavers ranging in age from 25 to 60 were studied. Thirty subjects from each five-year interval were selected, and data were collected using the mandibular anterior and premolar teeth after extraction. Sections ranging from 0.5 to 1.0 mm were measured by a stereo microscope with a precision of 0.1 mm. The following factors were determined: attrition, periodontosis, root resorption, secondary dentine apposition, cementum apposition, and translucency of the root. Statistical analysis used the sum of ranks of the dental factors as an independent variable in a linear regression model to estimate the age of the cadaver. Among the different mandibular teeth, the sum of ranks of the first premolar factors had the best correlation coefficient with age. The sum of the dental factors presented a better model than each of the factors alone. The first premolar is recommended as the first step in the estimation of age.     

The use of odontograms and panoramic roentgenography in personal identification]

Study of dental root surfaces prompted the authors to add to the routine odontogram 28 more maxillary surfaces and 22 mandibular surfaces, this making a total of 210 diagnostic signs. Employment of amplified panoramic roentgenography permitted the authors to detect specific features of the dental cavity, root canals, periodontal fissure structure, the presence of caries and its complications, inflammatory and systemic involvement, injury to the jaws and teeth. Visual examination of dental status and application of panoramic roentgenography will help improve forensic medical personal identification.     

Dental age assessment: the applicability of Demirjian method in eastern Turkish children

In the literature, little is known about the applicability of this method in Turkish children. The aim of this study was, therefore, to evaluate the reliability of Demirjian method of age estimation when used for eastern Turkish children. A retrospective study was performed on a sample of panoramic radiographs taken from 807 healthy eastern Turkish children. The stages of dental maturity of the mandibular left seven permanent teeth for each subject using the eight radiographic dental maturity stages demonstrated by Demirjian were evaluated. A paired t-test was used for statistical analysis. The mean difference between the chronological and dental ages ranged from 0.2 to 1.9 years in girls and from 0.4 to 1.3 years in boys. The differences between the chronological and dental ages were statistically significant in all age groups. The applicability of Demirjian method is not suitable for eastern Turkish population.