Analysis of the surface roughness and microhardness of dental restorative materials exposed to heat sources and cold temperatures for human identification purposes

Abstract

Background: Fatal accidents involving the action of heat, such as burns, explosions, automobile accidents, and aircraft crashes, among others, or action of cold, such as collisions in snowy locations, severe blizzards, cold waves, earthquakes, and avalanches, are frequent day-to-day occurrences. During post-mortem dental examination of victims, restorative materials such as the composite resin (CR), glass ionomer cement (GIC), and amalgam may be found. The action of the heat or cold on these materials may change their properties. This study aimed to evaluate the changes occurred in the surface roughness and Knoop microhardness of the dental restorative materials of freezing or burnt victims, supporting an adequate comparison with the antemortem data, helping on human identification process. Methods: One hundred eighty caries-free bovine teeth were prepared and separated into groups, according to the restorative material, temperature, and period for analysis. The surface roughness and microhardness were analyzed by a profilometer and a microhardness tester, before and after the action of the heat (100 °C, 200 °C, 300 °C) and the cold temperatures (2.5 °C, − 20 °C, − 80 °C). Results: The results demonstrated that there was no alteration on properties of CR after the heat that caused significant changes in the surface roughness of GIC and amalgam and the microhardness of GIC. The low temperatures produced no significant differences in any of the properties of the restorative materials studied. Conclusion: The surface roughness and Knoop microhardness tests could distinguish the tooth-colored restorative materials irrespective of the action of the heat or cold temperatures.