Journal of Dental Research, Vol 73, 1588-1592, Copyright © 1994 by International & American Associations for Dental Research Online Journals
Formation of afibrillar acellular cementum-like layers induced by alkaline phosphatase activity from periodontal ligament explants maintained in vitro
M. C. Groeneveld, V. Everts and W. Beertsen
Department of Periodontology, Academic Centre for Dentistry Amsterdam (ACTA), The Netherlands.
Fibroblasts of the periodontal ligament, by their alkaline phosphatase
(ALP) activity, are considered to play a role in the formation of acellular
cementum. As a means of exploring this hypothesis, periodontal ligament
explants from rat incisors were cultured in direct contact with bovine
dentin slices in the presence of 10 mmol/L beta-glycerophosphate.
Periosteal and pericardial tissue explants were maintained under similar
conditions. After two weeks, the slices were harvested and processed for
electron microscopic examination. Controls included periodontal ligament
explants to which the ALP-inhibitor levamisole was added. The results
suggest that only ALP-positive cultures from periodontal ligament and
periosteum form mineralized layers along the dentin. After
demineralization, layers consisted of fine filamentous or granular material
of moderate electron-density and resembled afibrillar acellular cementum.
Our findings support the hypothesis that periodontal ligament fibroblasts,
by means of their ALP activity, play a pivotal role in the formation of
acellular cementum.
