Role of physical properties of dental restorative biomaterials in criminalistics

Abstract

Role of physical properties of dental restorative biomaterials in criminalistics Cristiana Palmela Pereira,1–4 João Franco Costa,5 Jorge Costa Santos,6,7 Maria Cristina de Mendonça6,7 1Legal Medicine and Forensic Sciences, Faculty of Medicine, University of Lisbon, Lisbon, 2Departments of Pharmacology and Therapeutic and Dental Morphology, Faculty of Dental Medicine, University of Lisbon, Lisbon, 3Integrate Research from the Research Centre of Statistics and Applications of the University of Lisbon, Lisbon, 4South Branch of the Portuguese National Institute of Legal Medicine and Forensic Sciences, Lisbon, 5Judicial Police, Lisbon, 6Medical Legal Doctors, South Branch of the Portuguese National Institute of Legal Medicine and Forensic Sciences, Lisbon, 7Faculty of Medicine, University of Lisbon, Lisbon, Portugal Abstract: The body of an 89-year-old woman was discovered at home by a member of her family. Only part of the body, the legs, were found intact without burn damage. The rest of the body was burned to ashes without the possibility to identify the cadaver. Forensic Dentistry had two main goals to resolve in this forensic pathology casework, and they were: 1) establish the identification of the cadaver; and 2) estimate the temperature and the direction of the fire by the analysis and interpretation of the skeletal intraoral dental materials altered by thermal processes. This case study manuscript focuses only on the second objective. The effects of fire on teeth are influenced by the temperature applied and by its duration. Additionally, adjacent tissues as well as temperature alterations caused by substances used to quench the fire have been shown to affect the thermal impact on teeth and their restoration. Bodies may be subjected to various temperatures, depending on the origin of the fire and the conditions that promote continuation of the blaze. Fire effects on certain dental materials can indicate the direction and the temperature of a fire. This is based on the physical, mechanical, and chemical changes of different dental materials resulting from high temperatures. The distinct properties of various dental materials, well defined, can influence and predict their performance under different degrees of fire. In this case study, the cadaver had two main groups of dental materials: metal alloys and polymers. The importance of the detailed degree of predictability of fire performance data from thermal decomposition data should not be underestimated; polymers cannot burn if they do not break down and metal alloys cannot burn if the melting point is not reached, independent of the variable time of the fire. Keywords: fire investigation, forensic dentistry, dental materials properties