The effect of hydrochloric acid (HCl) on permanent molars: A scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) study

It is well established that acid disposal is a potentially effective method used by criminal syndicates to hinder the identification of victims. This study documents the effects of continuous immersion in hydrochloric acid (HCl, 37%) on molars using macroscopic analysis, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The goal of this study is to aid in distinguishing visually unrecognizable fragments of dental remains when drastic changes in morphology have occurred as a result of acid exposure. Macroscopic, SEM, and EDS analysis were conducted on seven maxillary molars before and after HCl treatment. Molars reduced in weight relative to the length of time immersed in HCl and the dissolution time was over 40 hours longer than reported in previous studies, at just over 66 hours. SEM and EDS analysis showed acid-treated teeth exhibited morphological patterns such as cracking and layering visible at high magnification. Calcium/phosphorous ratios fell within the expected range of 1.6-2.5, indicating that HCl-treated teeth are still identifiable as osseous or dental tissue even when not visually identifiable as teeth. This is the first study to present SEM images of molar cementum before and after immersion in HCl and to present EDS results. This information can assist researchers and investigators in determining the presence of dental tissue in a forensic context associated with acid disposal.