Electron microscopy of various zones in a carious lesion in human dentine

A simple method to select a particular small area for electron microscopy from a ground section, without mixing it up with other areas, was introduced. Changes in various zones in carious dentine, which were selectively observed by the method, are illustrated. Secondary mineralization was confirmed in the area in which bacterial invasion was actively taking place, as well as in the odontoblastic process in transparent zone. Destruction of the dentine matrix seemed to start from the peritibular matrix. The odontoblastic process was found to resist, to some extent, the invasion of bacteria. The dissolution of dentine crystals and the fragmentation of collagen fibrils were striking in the matrix where destructive changes were severe. The secondarily deposited crystals into the odontoblastic process seemed to remain longer than the original dentine crystals.