Volume analysis of heat-induced cracks in human molars: A preliminary study

Abstract

Context:Only a few methods have been published dealing with the visualization of heat-induced cracks inside bones and teeth.Aims:As a novel approach this study used nondestructive X-ray microtomography (micro-CT) for volume analysis of heat-induced cracks to observe the reaction of human molars to various levels of thermal stress.Materials and Methods:Eighteen clinically extracted third molars were rehydrated and burned under controlled temperatures (400, 650, and 800°C) using an electric furnace adjusted with a 25°C increase/min. The subsequent high-resolution scans (voxel-size 17.7 μm) were made with a compact micro-CT scanner (SkyScan 1174). In total, 14 scans were automatically segmented with Definiens XD Developer 1.2 and three-dimensional (3D) models were computed with Visage Imaging Amira 5.2.2. The results of the automated segmentation were analyzed with an analysis of variance (ANOVA) and uncorrected post hoc least significant difference (LSD) tests using Statistical Package for Social Sciences (SPSS) 17. A probability level of P < 0.05 was used as an index of statistical significance.Results:A temperature-dependent increase of heat-induced cracks was observed between the three temperature groups (P < 0.05, ANOVA post hoc LSD). In addition, the distributions and shape of the heat-induced changes could be classified using the computed 3D models.Conclusion:The macroscopic heat-induced changes observed in this preliminary study correspond with previous observations of unrestored human teeth, yet the current observations also take into account the entire microscopic 3D expansions of heat-induced cracks within the dental hard tissues. Using the same experimental conditions proposed in the literature, this study confirms previous results, adds new observations, and offers new perspectives in the investigation of forensic evidence.

Thermal Alteration to the Body

“…As bone is heated, increasing intensity and duration cause changes in the organic and inorganic phases of the bone structure and chemistry resulting in colour alterations from pale yellow through orange shades to brown, black, grey and then white (Bonucci and Graziani 1975;Devlin and Herrmann 2008;Ellingham et al 2015;McCutcheon 1992;McKinley 2000;Munro et al 2007;Nicholson 1993;Shipman et al 1984;Thurman and Wilmore 1980;Ubelaker 1978) (Table 21.1). Similar changes have been recorded in tooth structures (Beach et al 2008;Kharkanis et al 2009;Sandholzer 2014;Sandholzer et al 2014;Schmidt 2008). This colour change is mainly associated with the decomposition phase as organic content is reduced, while extended burning at higher temperatures usually results in white calcined bones indicating removal of organic matter and possible inversion and fusion in accordance with linked primary-level changes in bone (Ellingham et al 2015;Thompson 2004).…”

Influence of Heating Regimes on Dimensional and Colorimetric Changes of Teeth

“…Whilst in animal and human bone heat-induced warping and deformation can occur at higher temperatures (Shipman et al, 1984;Thompson, 2005), morphological changes in human teeth even at high temperatures were found to be negligible (Sandholzer et al, 2013(Sandholzer et al, , 2014a.…”

Evaluation of macroscopic changes and the efficiency of DNA profiling from burnt teeth

“…The changes in color observed turned from brown, black, grey/blue and finally chalky white; which corresponds to an incinerated stage of burning [15] (Fig. 1).…”