Effect of different combinations of calcium, magnesium and phosphate on the inorganic composition of rat molars in vitro.

Second upper molars from 3-day-old rats were cultured by the Trowell method for 14 days. One of each pair of molars was kept as an uncultured control; the other was cultured. Explants were exposed to eight different combinations of Ca, Mg and P additions to BGJb medium. This resulted in eight groups of explants (control, Ca, Mg, P, CaMg, CaP, PMg and CaMgP) and their eight uncultured contralateral groups. The additions were calculated to double the original measured media concentration. Cultured and uncultured germs were analysed for dry weight (D), ash weight (A), Ca, Mg and P content. The organic fraction (D-A) was calculated. The analysis of covariance by means of multiple regression revealed that Ca-addition to the culture medium stimulated D, A, Ca and P in the explants; P-addition was stimulatory for D, A, D-A and P whereas Mg addition was inhibitory for A, D-A and Ca. A positive interaction for all the tooth-germ variables was demonstrated after CaMg addition; an antagonistic effect was found for the tooth-germ variables D, A, Ca and P after CaP addition. The value of the tooth-germ variables at the time of explantation (covariate) had no significant effect on the value for the variables of the explants (except on their P content). The highest absolute values for all the variables were obtained after CaMg and CaMgP additions. Furthermore, taking into consideration morphological results, the addition of CaMgP can be recommended as medium supplement in the organ culture of rat tooth germs.