MINERAL ELEMENT ANALYSIS OF CARIOUS AND SOUND RAT DENTIN BY ELECTRON-PROBE MICROANALYZER COMBINED WITH BACKSCATTERED ELECTRON IMAGE

We recently demonstrated the advantages of back-scattered electron ima ges (COMPO) in the visualization of dentinal caries, and the relations hip of the change in the dentin fluorescence pattern in caries lesions . However, the exact nature of these changes is not known. In this pap er, the nature of the changes in the areas with reduced mineral conten t in COMPO images was investigated. We examined the relation of change s in mineral elements and the appearance of soft carious and sound den tin in COMPO images using a scanning electron microscope (SEM) equippe d with an electron probe microanalyzer (EPMA). Rat molars with small d entinal caries lesions just under the DEJ were chosen for the study. T he Ca, P, Na, Mg, Zn, F, and total contents were determined by EPMA fr om five different dentin sites, and the Ca/P and Mg/Ca ratios were cal culated. Generally, the lowest contents were found in caries lesions a nd highest in mantle dentin, with the exceptions of Mg and Zn. The Ca/ P ratio was lowest in mantle dentin and highest in carious dentin. The results confirm that the change in fluorescence in the dentinal carie s lesion is correlated with the very initial changes in mineral conten t, and that EPMA used in combination with COMPO images is a useful too l for determining small changes in mineral elements in the carious and adjacent areas of dentin.