Phosphohydrolase Activities in Developing and Mature Dental Tissues

Abstract

Phosphohydrolases, Dental Tissues, Tooth D evelopm ent, MineralizationIn the course o f the odontogenesis o f bovine incisors several clearly distinguishable phos phohydrolase activities are observed in the pulp and in dental hard tissues. Using various sub strates and inhibitors, unspecific alkaline phosphatase, two isoenzymes o f acid phosphatase, Ca2+-activated ATPase and inorganic pyrophosphatase are characterized. The enzymatic ac tivity o f alkaline phosphatase in pulp and hard tissues is significantly high at the beginning o f dentine and enamel mineralization. The specific activity o f this enzyme decreases quite fast with the beginning o f root form ation, then more slowly, until it reaches a constant final value. Histochemical studies show that during mineralization the maximum o f alkaline phosphatase activity is in the subodontoblasts. Lower enzyme concentrations are found in the stratum intermedium and in the outer enamel epithelium during that process.The specific activities o f ATPase, acid phosphatases and pyrophosphatase show little tem poral variation during tooth developm ent, but they also appear in a characteristic spatial pattern in the dental tissues.