Abstract
The study of the unerupted tooth germ in the formative and developmental stages of the tooth is of great value in all areas of dentistry, and particularly in pedodontic practice. In this study, collagenous and non-collagenous components of the tooth germ were fractionated and the uronic acid content was analysed from the non-collagenous fractions in order to investigate the physiological functions of substrate components in the serial process of both tooth germ formation and eruption.
Bovine permanent tooth germs were classified into the following three stages: Stage I; tooth germ which has slight formation of dentin, Stage II ; about- half of the root formed, and Stage III; full length of the root almost completed. The dental sac and dental papilla (pulp) of these stages were investigated.
By DEAE cellulose chromatography, it was found that 0.16 M NaCl-soluble (NH4) 2SO4 fractions of the dental papilla (pulp) eluted with 150 mM NaCl showed an obvious increase, though the fractions of the dental sac exhibited heterogenous changes. Collagen content in the 1.0 M NaCl-soluble (NH4) 2SO4 fractions notably increased, 10 to 20%, and apparent changes in the amino acid composition were observed, particularly in stage II. In the acetate-insoluble fractions, the percentages of collagen content showed gradual increases, respectively.[Dental sac: stage 1=72%, stage 11=82%, and stage 111=93%; Dental papilla (pulp): stage 1=78%, stage 11=82%, and stage 11=96%]. The noncollagenous content decreased obviously.[Dental sac: Stage 1=28%, Stage II=18%, and Stage III=7%, Dental papilla (pulp): stage I=22%, stage II=18%, and stage III=4%].
The amount of non-collagenous amino acid residues in the insoluble fraction was estimated from the hydroxyproline. A dramatic decrease was seen in the amounts of both acidic and basic non-collagenous amino acids during the three stages of tooth development. This finding suggests that such polar amino acids may be involved in the initiation of calcification.
