Release of lysosomal hydrolases from bone explants affected by dental plaque

Lysosomal hydrolases as indicators of plaque-induced bone resorption in tissue culture were studied. Fetal rat bones cultured in a synthetic medium containing sonicated and filtrated human dental plaque were used as bones to be resorbed. Acid phosphatase and beta-glucuronidase were found to be the most suitable enzymes for studying the degradation rate of bone cell lysosomes. When dental plaque is used as a resorbing agent, special attention has to be paid to the fact that plaque extract contains similar lysosomal hydrolase activity. Plaque hydrolases in the present study were quite stable in culture medium. No significant adsorption of enzymes by fetal rat bones occurred while remarkable adsorption by synthetic hydroxyapatite was found. The present results indicate that dental plaque is able to release lysosomal hydrolases from bone explants. This release corresponds to the degree of resorption measured by 45Ca release from bones.