Effect of high temperatures on teeth fixed with an orthodontic bracket. An in vitro study.

In cases of incineration, where the identification of victims by conventional methods is impossible, teeth and dental materials become an available source of evidence - thanks to their ability to resist high temperatures. Currently, there is no experimental research to determine the behavior of the bracket and the dental structure when it is attached to the tooth after being exposed to high temperatures. An experimental in vitro study was carried out on 60 upper and lower premolar teeth (30 with a cemented bracket and 30 teeth without a bracket) that were exposed to six temperature ranges (200 °C, 400 °C, 600 °C, 800 °C, 1000 °C and 1200 °C). With the help of an Optiks® binocular stereomicroscope, macroscopic changes were described for each temperature; in addition, the mesio-distal diameter of the crown of the teeth and the bracket were measured before and after the incineration. A comparison of the diameters between the groups [the experimental group and the control group] and between the different temperatures was made. Both teeth, with brackets and without brackets showed macroscopic changes, such as fissures, cracks, fragmentation, enamel bursting and enamel and dentin separation according to the temperature range exposed. The detachment of the bracket was presented at 600 °C - leaving a mark on the dental surface. At above 1000 °C, the crown of the tooth with bracket acquired a pink color and the surface of the bracket became rough and opaque. At above 400 °C, both groups experienced an expansion in the crown dimension without significant differences. The results of this research suggest that teeth with attached brackets are equally resistant as the teeth without brackets, and that the adhesion of these attachments to the dental structure leave characteristics that allow them to be differentiated from teeth without braces -as well as suggesting the orientation to the temperature exposure.