Uptake of32P-labelled phosphate into developing rat incisor enamel

Four Chemically Distinct Stages in Developing Enamel from Bovine Incisor Teeth

“…The rigidity is probably due to its in creased mineral content and lower protein content. In rat incisor enamel, the analo gous white opaque zone [Hiller et al, 1975;Robinson et al, 1977] is the site of active mineral transport into the tissue [Robinson et al, 1974] Reith and Butcher, 1967], In addition to an increased mineral content and loss of matrix protein, the transition from stage 2 to stage 3 was also characterised by changes in amino acid composition. The high con centrations of glutamic acid, proline and histidine were reduced, shifting the amino acid composition from that of amelogenin to that of the mature enamel or 'tuft' protein described by Robinson et al [1975] for bovine and human teeth.…”

“…The evidence from histology [d o c k et at., 1942;Suga and Gustafson, 1963], mi croradiography [Clock et at., 1942;Suga and Gustafson, 1963;Avery et al, 1961], autoradiography [Belanger, 1957;Crabb and Darling, 1962;Hammarstrom, 1967] and chemical studies [Deakins, 1942;Glock et al, 1942;Robinson et al, 1974;Hiller et al, 1975] is somewhat contradictory. Some authors suggest that enamel mineralisation is a continuous process moving centrifugally from the dentine, and others, that it occurs discontinuously in two stages, the first cor responding to formation and the second to maturation.…”

X‐ray microtomographic study of mineral distribution in enamel of mandibular rat incisors

“…Two assumptions are needed : the growth rate of the mandibular rat incisor is 0n6 mm per day (Robinson et al 1974 ;Smith & Warshawsky, 1975), and the time origin is taken as the beginning of the maturation phase. The latter is taken as the position where the mean mineral concentration reaches 1 g cm V $ as determined from Equation 2 with parameters from Table 2 (see Discussion).…”

Pattern of Mineral Uptake in Developing Bovine Incisors

“…The possible significance of this hia tus and its consequences as regards the sen sitivity of enamel to external influences has been discussed previously by Robinson et al [1974; Weatherell et al [1975], and Deutsch et al [1979]. Fluoride and oth er ions appear to accumulate in this region, which might explain why fluoride can affect the enamel even w'hen its concentration in the blood is relatively low.…”

“…At a later stage, much of this matrix disappears from the tissue [Robinson et al, 1977 which therefore becomes po rous. A second more massive uptake of cal cium and phosphate then occurs, occluding the porosity and producing mature, highly mineralised enamel [Robinson et al, 1974, Some of the evidence for this se quence of events was obtained by measuring the changes in mineral content of the devel oping enamel on the basis of both dry weight and volume. Both sets of results showed a rapid increase in mineral content but the rise in mineral content per weight occurred much earlier than the rise in min eral content per volume.…”