Marco Aurélio Guimarães

Heat Induced Changes to Dental Resin Composites: A Reference in Forensic Investigations?*

Abstract:  The objective was to investigate color change and surface damage in dental resin composites exposed to high temperatures over different time intervals for comparative purposes. Samples were prepared using two resins ‐ Z100® (R1) and Charisma ® (R2), heated at the following temperatures: 200°C, 400°C, 600°C, 1000°C, for 15, 30 and 45 min (n = 104 for each resin sample). Color (ΔE*) and brightness (ΔL*) changes were analyzed by spectrophotometry using the CIE L*a*b* system and surface changes by Scanning Electron Microscopy (SEM). R1 showed more intense color changes after heat exposure than R2. ΔL* values were found to be the best parameter for evaluation of light and color change. A biphasic pattern after thermal exposure was detected, from dark brown to light white. SEM showed more intense alterations in R2 than in R1. These results indicate that the parameters observed in both resins are useful as a guide in forensic analyses.

Assessment of methods of homicide in a Brazilian city: a preliminary study

Homicides in the city of Ribeirão Preto, state of São Paulo, Brazil, were analyzed with regard to methods (firearms or others) and gender, in a retrospective study from 1993 to 1997. There was a progressive increase in the number of homicides, mainly after 1995, with an increment of 86.6% in 1997 in comparison to 1993. The incidence of homicides was higher among males, with firearms being the most common method in this group since 1993. In addition, a 10% increase in this method was observed since 1995, in association with a proportional reduction in the use of other methods. The incidence of homicides among females remained stable until 1996 and increased by 51.3% in 1997. Simultaneously, firearms have become the most common method among female victims (71.4%), pattern similar to that observed among males. Attention is drawn to the social and economic conditions and their relationships with drug traffic in the city.

A new approach for the analysis of facial growth and age estimation: Iris ratio

The study of facial growth is explored in many fields of science, including anatomy, genetics, and forensics. In the field of forensics, it acts as a valuable tool for combating child pornography. The present research proposes a new method, based on relative measurements and fixed references of the human face—specifically considering measurements of the diameter of the iris (iris ratio)—for the analysis of facial growth in association with age in children and sub-adults. The experimental sample consisted of digital photographs of 1000 Brazilian subjects, aged between 6 and 22 years, distributed equally by sex and divided into five specific age groups (6, 10, 14, 18, and 22 year olds ± one month). The software package SAFF-2D® (Forensic Facial Analysis System, Brazilian Federal Police, Brazil) was used for positioning 11 landmarks on the images. Ten measurements were calculated and used as fixed references to evaluate the growth of the other measurements for each age group, as well the accumulated growth (6–22 years old). The Intraclass Correlation Coefficient (ICC) was applied for the evaluation of intra-examiner and inter-examiner reliability within a specific set of images. Pearson’s Correlation Coefficient was used to assess the association between each measurement taken and the respective age groups. ANOVA and Post-hoc Tukey tests were used to search for statistical differences between the age groups. The outcomes indicated that facial structures grow with different timing in children and adolescents. Moreover, the growth allometry expressed in this study may be used to understand what structures have more or less proportional variation in function for the age ranges studied. The diameter of the iris was found to be the most stable measurement compared to the others and represented the best cephalometric measurement as a fixed reference for facial growth ratios (or indices). The method described shows promising potential for forensic applications, especially as part of the armamentarium against crimes involving child pornography and child abuse.

Approaching Utility in Forensic Anthropology

Abstract Efficacy and cost-effectiveness have emerged as important topics in forensic science. So far, however, social research has tended to neglect infrequently used and highly specialized sub-disciplines of forensic science. This paper begins to address this deficiency with regard to one such sub-discipline, namely forensic anthropology, the analysis of skeletal remains in the interests of criminal justice. A simple attrition model is derived from the quantitative analysis of caseloads encountered at two contrasting regional medico-legal institutes: Sheffield Medico-Legal Center (SMLC) in the United Kingdom and the Centro de Medicina Legal (CEMEL) in Ribeirão Preto, São Paulo, Brazil. The pattern of cases encountered in these samples (n = 105) is assessed against 36 measures of case provenance and type, methods employed in casework, case demography, and contribution to the investigation recorded in a matrix of 3,780 data items. Representativeness in relation to forensic anthropology casework in general is established via comparison with four published surveys—Smithsonian (n = 474), Tennessee (n = 513), Montevideo (n = 344), and Porto Alegre (n = 276). The model may be improved via systematic case recording, including courtroom finalizations and verdicts. It suggests case conversions would be increased via scene attendance, improved communication and integration, end-to-end performance management, feedback on evidential reliability, and tailoring of research and education to reflect caseload. Following contemporary expectations in social research, the model is used to identify policy changes that would contribute to crime reduction and prevention. The value of forensic anthropology to public health and safety and its significance to human rights is discussed. Males predominated all of the studies considered in this analysis, whether victims of homicide, suicide, accident, or natural causes. These findings appear to offer compelling evidence to support human rights policies that recognize the right to life and health for males as well as females in countries at all stages of socioeconomic development. The right to life is the most fundamental human right to which one is entitled without distinction as to race, sex, language, or religion. Despite its longevity, forensic anthropology has many attributes of a nascent discipline. Its definition and its disciplinary boundaries are uncertain, and—outside of the United States, at least—standards and regulation are inconsistent. The paper represents an attempt to offer a comprehensive, if preliminary, approach to utility in forensic anthropology in anticipation that it will provoke debate and further research.

Tissue Microarray Analysis Applied to Bone Diagenesis

Taphonomic processes affecting bone post mortem are important in forensic, archaeological and palaeontological investigations. In this study, the application of tissue microarray (TMA) analysis to a sample of femoral bone specimens from 20 exhumed individuals of known period of burial and age at death is described. TMA allows multiplexing of subsamples, permitting standardized comparative analysis of adjacent sections in 3-D and of representative cross-sections of a large number of specimens. Standard hematoxylin and eosin, periodic acid-Schiff and silver methenamine, and picrosirius red staining, and CD31 and CD34 immunohistochemistry were applied to TMA sections. Osteocyte and osteocyte lacuna counts, percent bone matrix loss, and fungal spheroid element counts could be measured and collagen fibre bundles observed in all specimens. Decalcification with 7% nitric acid proceeded more rapidly than with 0.5 M EDTA and may offer better preservation of histological and cellular structure. No endothelial cells could be detected using CD31 and CD34 immunohistochemistry. Correlation between osteocytes per lacuna and age at death may reflect reported age-related responses to microdamage. Methodological limitations and caveats, and results of the TMA analysis of post mortem diagenesis in bone are discussed, and implications for DNA survival and recovery considered.

Orthodontic Use of Documentation in Identification of a Skeletonized Body in Legal Dental Practice

The analysis of dental records is an essential tool for human identification. The present study aimed to highlight the importance of dental records for identification of skeletonized bodies. In form of conclusion, the method of dental identification using dental records represents a valid option for forensic dentistry. ˚

Utility in Forensic Anthropology: Findings Contributing to Case Conversion

Abstract In Approaching Utility in Forensic Anthropology, Evison, Francisco, and Guimarães (2012) propose an attrition model for the study of the impact of forensic anthropology in the justice system and consider wider implications for crime prevention and public health and safety. In this short supplementary article, brief illustrations of case findings are offered to demonstrate their significance in case progression—or conversions—in the investigative and prosecutorial process. The examples, it is suggested, support the specific arguments for improved communication and integration, feedback on evidential reliability, and tailoring of research and education to reflect caseload proposed via the attrition model, as well as policy advances that would improve efficacy in public health and safety.

Procedural and political aspects of forensic exhumation in Brazil

Exhumation may be defined as the legally sanctioned excavation and recovery of the remains of lawfully buried or – occasionally – cremated individuals, as distinct from forensic excavations of clandestinely buried remains conducted as part of a criminal investigation and from unlawful disinterment of human remains, commonly referred to as ‘bodysnatching’. The aim of this article is to review the role of exhumation – so defined – in the activities of CEMEL, the Medico-Legal Centre of the Ribeirao Preto Medical School-University of Sao Paulo, in international, regional and local collaborations. Exhumations form part of routine forensic anthropology casework; scientific research in physical and forensic anthropology; and forensic casework conducted in collaboration with the Brazilian Federal Police; and are carried out as part of humanitarian investigations into deaths associated with the civil–military dictatorship of 1964 to 1985. This article aims to offer a non-technical summary – with reference to international comparative information – of the role of exhumation in investigative and scientific work and to discuss developments in their historical and political context.

Photoanthropometric face iridial proportions for age estimation: An investigation using features selected via a joint mutual information criterion

Age assessment from images is of high interest in the forensic community because of the necessity to establish formal protocols to identify child pornography, child missing and abuses where visual evidences are the mostly admissible. Recently, photoanthropometric methods have been found useful for age estimation correlating facial proportions in image databases with samples of some age groups. Notwithstanding the advances, newer facial features and further analysis are needed to improve accuracy and establish larger applicability. In this investigation, frontal images of 1000 individuals (500 females, 500 males), equally distributed in five age groups (6, 10, 14, 18, 22 years old) were used in a 10 fold cross-validated experiment for three age thresholds classifications (<10, <14, <18 years old). A set of novel 40 features, based on a relation between landmark distances and the iris diameter, is proposed and joint mutual information is used to select the most relevant and complementary features for the classification task. In a civil image identification database with diverse ancestry, receiver operating characteristic (ROC) curves were plotted to verify accuracy, and the resultant AUCs achieved 0.971, 0.969, and 0.903 for the age classifications (<10, <14, <18 years old), respectively. These results add support to continuing research in age assessment from images using the metric approach. Still, larger samples are necessary to evaluate reliability in extensive conditions.

Comparação dos padrões de atratividade de Hermetia illucens (Diptera, Stratiomyidae) associada a carcaças de Rattus norvergicus enterradas e tratadas com hormônios esteróides

Hermetia illucens (L.) (Diptera, Stratiomyidae) is an abundant species in the entire American continent. Nevertheless, there are few studies in Brazil dealing with aspects of its biology and ecology, particularly associated with forensic studies. In this study we intended to observe the effects of steroids hormones in the corporal decomposition of buried Rattus norvergicus from the Wistar variety in the attraction of H. illucens. Besides the presence of several insect species commonly found in carcasses, a great amount of immature H. illucens was observed. This species represented approximately 22% of all collected specimens and it was only found in the animals that have received treatment with sexual steroids, such as testosterone, progesterone and estradiol. Among the animals under treatment, the greater abundance was verified in those who had received testosterone (68%). The presence of immatures of H. illucens only in the animals that received hormone treatments in experiments accomplished in two consecutive years strongly suggests a possible attraction of this species for bodies with different amounts of sexual hormones. This behavior can also be relevant for the forensic entomology in regard to the post-mortem interval (PMI) estimation, particularly when the PMI is based on information about the necrophagous insects life cycle and ecology.