Three dimensional analysis and comparison of human anterior teeth and experimentally created bitemark depressions

A system was proposed to scan dental models to record three-dimensional features seen in the anterior teeth to create a database of dental profiles. Dental casts were randomly selected to create indentations in cowhide leather. Reid Bite Reader was used to measure the bite forces generated by Reynolds Controlled Bite Force Generator to make the teeth impressions. Using the Immersion MicroScribe® 3D, information from the 53 bitemark depressions and 62 sets of dental casts were transferred to an Excel Spreadsheet. Software was developed to perform the 3D comparison using metric and pattern analysis. Statistical analysis showed 100% success when comparing both arches together of the dental casts with the bitemarks or different dental casts.

Epidermis and Enamel: Insights Into Gnawing Criticisms of Human Bitemark Evidence.

Critics describe forensic dentists' management of bitemark evidence as junk science with poor sensitivity and specificity and state that linkages to a biter are unfounded. Those vocal critics, supported by certain media, characterize odontologists' previous errors as egregious and petition government agencies to render bitemark evidence inadmissible. Odontologists acknowledge that some practitioners have made past mistakes. However, it does not logically follow that the errors of a few identify a systemic failure of bitemark analysis. Scrutiny of the contentious cases shows that most occurred 20 to 40 years ago. Since then, research has been ongoing and more conservative guidelines, standards, and terminology have been adopted so that past errors are no longer reflective of current safeguards. The authors recommend a comprehensive root analysis of problem cases to be used to determine all the factors that contributed to those previous problems. The legal community also shares responsibility for some of the past erroneous convictions. Currently, most proffered bitemark cases referred to odontologists do not reach courts because those forensic dentists dismiss them as unacceptable or insufficient for analysis. Most bitemark evidence cases have been properly managed by odontologists. Bitemark evidence and testimony remain relevant and have made significant contributions in the justice system.

Forensic Dental Age Estimation: An Overview.

Forensic age estimation is a scientific process that estimates an individual's true chronologic age by assessing skeletal and dental development and maturation. Although human growth and maturation is unique to each individual, dental techniques for estimating age are currently considered the best in assessing true chronologic age particularly during the age range when the dentition is undergoing morphologic development. This article reviews the principles, methodology and commonly used techniques in forensic age estimation cases.

Analysis of radiocarbon, stable isotopes and DNA in teeth to facilitate identification of unknown decedents.

The characterization of unidentified bodies or suspected human remains is a frequent and important task for forensic investigators. However, any identification method requires clues to the person's identity to allow for comparisons with missing persons. If such clues are lacking, information about the year of birth, sex and geographic origin of the victim, is particularly helpful to aid in the identification casework and limit the search for possible matches. We present here results of stable isotope analysis of (13)C and (18)O, and bomb-pulse (14)C analyses that can help in the casework. The (14)C analysis of enamel provided information of the year of birth with an average absolute error of 1.8±1.3 years. We also found that analysis of enamel and root from the same tooth can be used to determine if the (14)C values match the rising or falling part of the bomb-curve. Enamel laydown times can be used to estimate the date of birth of individuals, but here we show that this detour is unnecessary when using a large set of crude (14)C data of tooth enamel as a reference. The levels of (13)C in tooth enamel were higher in North America than in teeth from Europe and Asia, and Mexican teeth showed even higher levels than those from USA. DNA analysis was performed on 28 teeth, and provided individual-specific profiles in most cases and sex determination in all cases. In conclusion, these analyses can dramatically limit the number of possible matches and hence facilitate person identification work.

Root morphology and anatomical patterns in forensic dental identification: a comparison of computer-aided identification with traditional forensic dental identification.

An online forensic dental identification exercise was conducted involving 24 antemortem-postmortem (AM-PM) dental radiograph pairs from actual forensic identification cases. Images had been digitally cropped to remove coronal tooth structure and dental restorations. Volunteer forensic odontologists were passively recruited to compare the AM-PM dental radiographs online and conclude identification status using the guidelines for identification from the American Board of Forensic Odontology. The mean accuracy rate for identification was 86.0% (standard deviation 9.2%). The same radiograph pairs were compared using a digital imaging software algorithm, which generated a normalized coefficient of similarity for each pair. Twenty of the radiograph pairs generated a mean accuracy of 85.0%. Four of the pairs could not be used to generate a coefficient of similarity. Receiver operator curve and area under the curve statistical analysis confirmed good discrimination abilities of both methods (online exercise = 0.978; UT-ID index = 0.923) and Spearman's rank correlation coefficient analysis (0.683) indicated good correlation between the results of both methods. Computer-aided dental identification allows for an objective comparison of AM-PM radiographs and can be a useful tool to support a forensic dental identification conclusion.

Dental age estimation utilizing third molar development: A review of principles, methods, and population studies used in the United States.

When an individual reaches the age of legal majority, their treatment within the criminal and civil legal systems is changed dramatically in the United States. Forensic odontologists are often asked to assist government agencies in estimating the ages of persons who may or may not have reached that legally important age. The third molars are the only teeth useful as forensic estimators of chronological age in the target age group. This study reviews the principles, methodology, and population data of the most commonly used technique in the United States, the analysis of the third molar development based on modified Demirjian staging. The method analyzes the developing third molar to estimate mean age, age intervals and the empirical probability that an individual has reached the anniversary of her or his eighteenth birthday.

Reliability of third molar development for age estimation in a Texas Hispanic population: a comparison study.

Evaluating third molars from 950 Hispanic individuals aged 12-22 years using Demirjian's schematic for crown and root formation found that Hispanic third molar development was 8-18 months faster than American Caucasians as reported by Mincer, Harris and Berryman in 1993. This represents a statistically significant increase. Earlier development was more apparent in the later stages F through H. Hispanic males reach developmental stages faster than Hispanic females and maxillary third molars reach developmental stages faster than mandibular third molars in both sexes. The earliest age observed for stages B-H (e.g., Stage H first observed at age 13.92 years in females) and the oldest age observed for Stages B-G were developed to facilitate age prediction of unknown individuals. Prediction tables for minimum and maximum age for an observed stage (e.g., if a female maxillary third molar is stage F it means she is older than 13 years) for each sex-jaw group were calculated.

GrinLine identification using digital imaging and Adobe Photoshop.

The purpose of this study was to outline a method by which an antemortem photograph of a victim can be critically compared with a postmortem photograph in an effort to facilitate the identification process. Ten subjects, between 27 and 55 years old provided historical pictures of themselves exhibiting a broad smile showing anterior teeth to some extent (a grin). These photos were termed "antemortem" for the purpose of the study. A digital camera was used to take a current photo of each subject's grin. These photos represented the "postmortem" images. A single subject's "postmortem" photo set was randomly selected to be the "unknown victim." These combined data of the unknown and the 10 antemortem subjects were digitally stored and, using Adobe Photoshop software, the images were sized and oriented for comparative analysis. The goal was to devise a technique that could facilitate the accurate determination of which "antemortem" subject was the "unknown." The generation of antemortem digital overlays of the teeth visible in a grin and the comparison of those overlays to the images of the postmortem dentition is the foundation of the technique. The comparisons made using the GrinLine Identification Technique may assist medical examiners and coroners in making identifications or exclusions.

Computer-aided dental identification: an objective method for assessment of radiographic image similarity.

A pilot study evaluated a computer-based method for comparing digital dental images, utilizing a registration algorithm to correct for variations in projection geometry between images prior to a subtraction analysis. A numerical assessment of similarity was generated for pairs of images. Using well-controlled laboratory settings, the method was evaluated as to its ability to identify the correct specimen with positive results. A subsequent clinical study examined longitudinal radiographic examinations of selected anatomical areas on 47 patients, analyzing the computer-based method in making the correct identification based upon a threshold level of similarity. The results showed that at a threshold of 0.855, there were two false negative and two false positive identifications out of 957 analyses. Based on these initial findings, 25 dental records having two sets of full mouth series of radiographs were selected. The radiographs were digitized and grouped into six anatomical regions. The more recent set of films served as postmortem images. Each postmortem image was analyzed against all other images within the region. Images were registered to correct for differences in projection geometry prior to analysis. An area of interest was selected to assess image similarity. Analysis of variance was used to determine that there was a significant difference between images from the same individual and those from different individuals. Results showed that the threshold level of concordance will vary with the anatomical region of the mouth examined. This method may provide the most objective and reliable method for postmortem dental identification using intra-oral images.

A comparison of animal jaws and bite mark patterns.

The purpose of this study was to compare the jaw shapes and bite mark patterns of wild and domestic animals to assist investigators in their analysis of animal bite marks. The analyses were made on 12 species in the Order Carnivora housed in the Mammalian Collection at the Field Museum of Natural History in Chicago, Illinois. In addition to metric analysis, one skull from each species was photographed as a representative sample with an ABFO No. 2 scale in place. Bite patterns of the maxillary and mandibular dentition were documented using foamed polystyrene exemplars, which were also photographed. A total of 486 specimens were examined to analyze the jaw and bite mark patterns. A modified technique for measuring intercanine distances was developed to more accurately reflect the characteristics seen in animal bite marks. In it, three separate areas were measured on the canines, rather than just the cusp tip. This was to maximize the amount of information acquired from each skull, specifically to accommodate variances in the depth of bite injuries.

Seven hundred seventy eight bite marks: analysis by anatomic location, victim and biter demographics, type of crime, and legal disposition.

A study of the etiology, anatomic location, victim demographics and legal disposition of bite mark cases was made with the purpose of updating and augmenting previous research in the field. The information may be of interest to a myriad of professional disciplines including Forensic Odontologists, Medical Examiners, Detectives, Profilers, Emergency Room Personnel, Coroners, Psychologists, and Family Service Counselors, as bite marks provide both physical and biological data. While bite marks were found on all anatomic regions of the body some sites are significantly more likely to receive bites, and the frequency that an area is bitten may vary with the type of crime. Sex and age of the victim may also impact the resulting location and frequency of bites. A survey form for bite mark cases was created and mailed to all Diplomates of the American Board of Forensic Odontology. The survey form was also included in the American Society of Forensic Odontology newsletter. The survey requested that the recipient fill out a separate form for each case for which the recipient was the primary investigator of a patterned injury. The data from the resulting surveys were entered into a Microsoft Excel spreadsheet. The responses detailed two hundred thirty two (259) bite mark cases that included seven hundred (778) individual bite marks. Harvey (1976) and Sweet and Pretty (2000) published studies finding the highest percentage of bites to the breasts. In 1983 Vale and Noguchi published the paper indicating that the most frequently bitten area was the upper extremities. The survey forms were sent to approximately 1100 forensic dentist in 26 countries. The forensic experience level of the dentists varied from neophyte to very experienced. The data were analyzed and the results reported and organized in the following categories; Victim Distribution by Gender, Victim Distribution by Age, Child Abuse Distribution by Age and Gender, Sexual Assault Distribution by age and Gender, Homicide Distribution by Age and Gender, Bite Mark Distribution by Gender and Location, Number of Bite Marks per Victim, Bite mark Distribution Comparison to Previous Research, Child Abuse Suspect Age Distribution by Age and Sex, Homicide Suspect Age Distribution by Age and Sex, Sexual Crimes Suspect Age Distribution by Age and Sex, and Bite Mark Incidence by Anatomical Area and Type of Crime. Fifty-two forensic odontologists from seven countries responded. Nineteen responders were Diplomates of the American Board of Forensic Odontology. The number of cases reported by each responder ranged from one to thirty-three and the average number of cases reported was 4.5. In this broad based study, females were bitten more often than males. The average male victim was younger than the average female victim. Males that were victims tended to be either very young or very old. The youngest victim was a two-month-old boy and the oldest victim a 95-year-old woman. Perpetrators were male more often than female and there was an average of 1.4 suspects per case. The results show that most bites occurred on the arm, followed by the breast. If broken down by gender, males were bitten on the arm more than females, and females were bitten on the breast more often than males. The data show patterns in location and number of bites that seem related to both the type of crime and the age of the victim.

Reporting of child abuse: a follow-up survey of Texas dentists.

PURPOSE: Child abuse is a disturbingly common finding in society today. There have been substantial and significant increases in the incidence of child abuse since the last national incidence study was conducted in 1986. Kassebaum first reported the under-reporting of child abuse by Texas dental professionals in a survey in 1986. The objective of the current study was twofold: (1) assess the level of knowledge and attitudes among dental professionals on the important issue of child abuse; (2) evaluate and compare the results of the current study with a similar survey conducted in 1986. METHODS: A 24-question survey similar in format and content to the 1986 questionnaire was mailed to 1,046 Texas dentists, randomly selected from a membership roster provided by the Texas Dental Association. Both general dentists and selected specialists were included in the study group. The questionnaire consisted of multiple-choice and dichotomous yes/no questions. RESULTS: There were 383 responses to the questionnaire, yielding a response rate of 38%. The majority (N=289) of the respondents were general dentists. In answering questions about suspected and reported cases of child abuse, nearly 50% of the responding dentists reported they had suspected at least 1 case of child abuse. In the 1986 study, only 36% of the responding dentists reported they had suspected at least 1 case of child abuse. Between 1986 and 2001, the survey has shown that the percentage of dentists who reported at least 1 case to authorities slightly increased from 19% in 1986 to 25% in 2001, but the ratio of suspected to reported cases had not changed since 1986. CONCLUSIONS: Although the composite percentage of suspecting and reporting cases of child abuse from this survey is higher than the percentage demonstrated in 1986 study, there was no significant change in the relative ratio of reported cases to suspected cases in both surveys. This indicates that under-reporting of child abuse cases is still a significant problem in the dental profession in Texas.