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.     

Testing Discriminant Functions for Sex Determination from Deciduous Teeth*,†

Abstract: Three studies have proposed discriminant functions for sex determination from deciduous tooth crown dimensions, and this study tests the existing functions on a sample of 46 Portuguese immature skeletons of known sex, aged from birth to 10 years. Deciduous teeth were measured in their mesiodistal and faciolingual crown dimensions, and percentage of correct allocation accuracy in determining sex using each specific function was determined. Discriminant functions were also calculated from data collected for this study and tested using cross‐validation. Results show poor overall accuracy (33.3–75%) and poor cross‐validation (46.2–60.0%). This is related to low sexual dimorphism in deciduous tooth crown size, as well as differences in degree of sexual dimorphism and in overall tooth size between different samples. For these reasons, deciduous crown size does not seem to show significant forensic value as discriminator of sex, particularly when methods developed on one population are applied to individuals of another population.     

Accuracy of developing tooth length as an estimate of age in human skeletal remains: the deciduous dentition

Dental age assessments are widely used to estimate age of immature skeletal remains. Most methods have relied on fractional stages of tooth emergence and formation, particularly of the permanent dentition, for predicting the age of infants and very young children. In this study, the accuracy of regression equations of developing deciduous tooth length for age estimation (Liversidge et al.) is tested on a sample of 30 Portuguese subadult skeletons of known age at death. Overall the method shows high accuracy and the average difference between estimated and chronological age is between 0.20 and -0.14 years when using single teeth, and 0.06 years, when using all available teeth. However, there is a tendency for the deciduous molars to provide overestimates of chronological age. Results show that age estimates can be obtained within +/-0.10 years with a 95% confidence interval when several teeth are used. Overall between-tooth agreement in age estimates decreases with increasing age but there is less variability of estimates with more teeth contributing to overall mean age. One seemingly limitation of this method may be the fact that it was developed by combining the maxillary and mandibular teeth. The other is related to the accuracy with which radiographic tooth length can be used as a valid surrogate for actual tooth length. Nevertheless, the advantages of this metric method surpass the limitations of chronologies based on stages of dental development.     

The Effects of Household Corrosive Chemicals on Human Dentition*

Abstract: There is a gap in the literature concerning the chemical effects that household products may produce on human remains. The present study examines the effects of household chemical products on teeth. A total of eight chemicals were utilized for this experiment. The corrosive chemical categories include: hydrochloric acid, sulfuric acid, phosphoric acid, and sodium hydroxide. Two products with each chemical were used, each representing varying concentrations of the corrosive product. Two human teeth were allocated for emergence in the chemical throughout a 24‐h period of exposure. Results demonstrate hydrochloric acid as the most detrimental chemical to the dental samples. Sulfuric acid enacted minimal alterations to the teeth, although some etching and discoloration were noticeable. Phosphoric acid resulted in variable changes of the organic and inorganic contents of teeth. Lastly, exposure of sodium hydroxide resulted in little to no change. As hypothesized, distinct effects are observable of each chemical.     

Accuracy of Dental Age in Nonadults: A Comparison of Two Methods for Age Estimation Using Radiographs of Developing Teeth

This research tests the accuracy of two methods for age estimation, Cameriere's European formula and AlQahtani's London Atlas, on a multi‐population American sample. Digitized radiographs of 360 European American, Hispanic, and American Indian children aged 6–17 years were analyzed. The accuracy of these methods was assessed using the mean and absolute mean difference of the residuals. Results indicate that Cameriere's European formula underestimated age for both sexes, with a mean difference of ?1.19 years for girls and ?1.32 years for boys, prompting the first author to create an American‐specific formula. The London Atlas underestimated age with a mean difference of ?0.18 years for girls and ?0.16 years for boys. Sex and ancestry had no significant affect on accuracy. The results indicate that both methods can be used for age estimation in an American population.     

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.     

牙齿异常者颌面数字全景片同一认定指标及其编码

目的系统筛选颌面影像法医学同一认定的识别指标，制定全口牙型识别指标编码。方法随机选取620例有牙齿治疗史者、150例牙齿有病变无治疗史者的数字全口牙位曲面体层片进行观测，根据牙齿的生理变异、病理改变和治疗特征筛选全口牙型识别指标，并按设计的编码标准和原则对其全口牙型逐一编码，最后分别统计两组全口牙型的多样性以评估其价值。结果620例牙齿有治疗史者中共有619种全口牙型编码，全口牙型多样性为99．84％；150例牙齿有病变无治疗史者中共有146种全口牙型编码，全口牙型多样性为97．33％。结论选出的全口牙型识别指标对牙齿异常者进行法医学同一认定具有实际应用价值。     

Age Estimation of Infants Through Metric Analysis of Developing Anterior Deciduous Teeth

This study provides regression equations for estimation of age of infants from the dimensions of their developing deciduous teeth. The sample comprises 97 individuals of known sex and age (62 boys, 35 girls), aged between 2 days and 1,081 days. The age‐estimation equations were obtained for the sexes combined, as well as for each sex separately, thus including “sex” as an independent variable. The values of the correlations and determination coefficients obtained for each regression equation indicate good fits for most of the equations obtained. The “sex” factor was statistically significant when included as an independent variable in seven of the regression equations. However, the “sex” factor provided an advantage for age estimation in only three of the equations, compared to those that did not include “sex” as a factor. These data suggest that the ages of infants can be accurately estimated from measurements of their developing deciduous teeth.     

Determining Postmortem Interval Using Glycoproteinous Adhesion Deposits by Balanus improvisus on Human Skeletal and Dental Remains

An anthropological analysis was conducted on skeletal and dental remains brought to the Galveston County Medical Examiner's office. The skeletal remains were dry, fragmented, and absent of typical fluvial characteristics. During microscopic examination, semitransparent, circular objects were discovered on the dentition, the mandible, tibial plateau, and distal femur. The objects were glycoproteinous adhesions deposited by the acorn barnacle, Balanus improvisus. B. improvisus is an intertidal barnacle found in estuaries in Galveston Bay. Basal diameter of the adhesions on the dentition were significantly smaller than those found on the postcranial bones (p = 0.010), indicating two consecutive cohorts adhered to the bone and dentition. As settlement typically occurs once a year, this would indicate that the remains were in the fluvial environment for at least 375–410 days. It is important in geographic areas that have prevalent fluvial environments that human remains, particularly dentition, are microscopically examined for marine life evidence.