The kinetics and mechanisms of reactions of human tooth enamel in buffered solutions of high fluoride concentrations

The experimental results were quantitatively compared with the theory based on a physical model representing the reaction and with the experiments involving synthetic hydroxyapatite discs. The experimental initial rates self-consistently compared well with the theoretical predictions. An analysis of the experimental initial rate data yielded a reaction constant, κ, for the reaction representing apatite dissolution and calcium fluoride precipitation. It is proposed that the value for κ is a result of both supersaturation with respect to calcium fluoride and undersaturation with respect to apatite at the apatite-calcium fluoride reaction sites. This finding is also consistent with the analysis of the experiments with synthetic apatite discs.Important similarities and significant differences were found between the experiments with the enamel sections and with synthetic apatite discs. The experiments with the synthetic apatite discs were reported to proceed “normally” as predicted by the physical model over the entire course of the reaction. In contrast to these findings, while the initial rates of the enamel-fluoride reaction were found to proceed relatively rapidly and according to the theoretical predictions, the rates at later times were drastically reduced. This “choking off” was observed to be most severe in the experiments at low pH and high fluoride concentrations, and little or no “choking oft” was observed at low fluoride concentrations and high pH.     

Dermatography, a treatment for sequelae after head and neck surgery: a case report.

Two patients with discolouration fo skin grafts after head and neck surgery, were treated with dermatography, a refined method of tattooing, and with intra-cicatricial keloidectomy, of which the results are described.     

Attitude of a group of South Africans toward advertising by dentists in private practice]

The advertising of dental services in South Africa is controlled by rules and regulations of the South African Medical and Dental Council. According to these, advertising is not permissible with the exception of specified professional information which may be made known only by means of a nameplate and an entry in a telephone directory. Questionnaires were sent to a randomised sample of 2,100 persons in order to determine the attitude of South Africans towards advertising by private practitioners. According to information obtained from this study there is a strong indication that consumers of dental services prefer a freer form of advertising by dentists in the private practice.