Scanning electron microscopy and energy-dispersive X-ray microanalysis studies of afibrillar cementum and...

We examined afibrillar cementum (AFC) and cementicle-like structures (CLS) in human teeth by scanning electron microscopy and energy-dispersive X-ray microanalysis. The AFC showed a spur- or island-, plate- and mass-like structure with appositional laminations, while large masses in the enamel fissures enclosed CLS showing concentric appositional rings. Such AFC was observed in enamel fissures, an abnormal enamel pit, dens invaginatus and root furcations with enamel droplets, as well as on the cervical enamel surfaces, where ameloblasts are differentiated at the later or last stage of enamel formation. Cementicle-like structures were occasionally found independent from AFC and some CLS contained epithelial cell-like or ameloblast-like remnants in the core, surrounded by a few or many concentric rings. In addition, cementicles (CEC) in the root furcations also contained the remnants of Malassez's epithelial-rest cells surrounded by a few concentric rings. In some areas, AFC was mixed with enamel structures. These results show that the organic material in some parts of AFC and CLS may be derived from epithelial cells similar to that of CEC. Calcification values of AFC and CLS were significantly higher than that of fibrillar cementum, and the minute crystals are probably apatite.