Enamel Dissolution Research Articles

The influence of cooked and raw wheat starch on dental caries in the rat

The effects of cooking wheat starch on its cariogenicity in rats and in decalcification tests in vitro were investigated. When rats of a caries-susceptible strain were fed for 8 weeks from weaning on diets containing 66% wheat starch, 32% skim milk powder and 2% dried liver powder, the incidence of caries was extremely low, no matter whether the starch was cooked or raw. In decalcification tests in vitro, mixtures of cooked wheat starch and saliva brought about significantly more dissolution of ground rat dental enamel than mixtures containing raw wheat starch. The behaviour of starch in caries tests is discussed.

MECHANISMS OF ENAMEL DISSOLUTION IN ACID BUFFERS.

A quantitative understanding of the mechanism of human dental enamel dissolution in buffers is important because it should lead to a clear description of the causative factors in caries formation, and it can be profitably employed in the design of meaningful screening methods for potential anti-decay agents. Gray' has reported studies on enamel dissolution, concluding that the rates of dissolution of enamel in his buffers were controlled by the diffusion rates of the reactants and products of the dissolution reaction. He also pointed out that the initial enamel dissolution rate is largely a function of the total buffer concentration, buffer acid strength, and pH. The effects of common and foreign ions on the rates of enamel dissolution were accounted for in a consistent fashion. Gray deduced a semi-empirical equation for the rate of dissolution which rather satisfactorily describes all the experimental findings. This relationship includes the bufferacid dissociation constant, the total buffer concentration, the hydrogen-ion concentration, and other terms, when necessary, for common and foreign ions affecting the rate. The success of this equation suggested that detailed mathematical models could be formulated and tested, employing simultaneous diffusion and chemical reaction, as has been done in describing the dissolution behavior of benzoic acid2 in basic and buffered media. The present communication is a report on the study of two such models. These have been examined with Gray's data. The analyses demonstrate the usefulness of this approach in future studies on dental problems.

Effects of calcium, phosphate and fluoride ions on the rate of softening and dissolution of tooth enamel

Calcium, phosphate, and fluoride ions were tested singly, and combined, for their effect on softening and dissolution of tooth enamel at the following concentrations in mM/1:calcium, 3.0; phosphate, 1.8; fluoride, 0.05. Their effects were evaluated by three procedures: (1) change of hardness of enamel surfaces exposed to synthetic bacterial plaques supplied with culture media, (2) change of hardness of enamel surfaces exposed to acetate buffer adjusted to levels of acidity similar to those developed in (1), and (3) calcium loss from powdered enamel exposed to an acetate buffer similar to that used in (2). With bacterial plaques, only combinations of ions containing fluoride protected the enamel surfaces from softening. For the softening of enamel surfaces by buffers, protection was offered only by the combination of calcium with the phosphate, calcium with fluoride, and calcium with phosphate and fluoride. With powdered enamel, all combinations gave some protection. The differences between the three systems and the synergistic action of fluoride with the calcium and phosphate ions are discussed.

Kinetics of the dissolution of human dental enamel in acid.

Kinetics of the dissolution of human dental enamel in acid.

Dissolution of dental enamel in decalcifying buffers containing different amounts of calcium and phosphorus

Crowns of intact premolars and molars were exposed for 3 hr to 10 ml of acid buffer, pH 4, containing differing amounts of calcium and phosphate at the beginning of the experiments. Acetic and phthalic acid buffers were used at 0.025 and 0.075 molar concentrations. Calcium and phosphate ions were added by dissolution of CaCl 2 or Na 2HPO 4. The presence of calcium and phosphate alone was of little effect on the dissolution rate. A more clearly diminished dissolution rate was found when both calcium and phosphate were present in the buffers. The relative protection against dissolution by the presence of calcium and phosphate became considerably smaller when the molarity of the buffers was raised from 0.025 to 0.075. The presence of calcium or phosphorus in the acid buffers did not change the calcium phosphorus ratio of the dissolved enamel substance. Addition of NaCl or MgSO 4 to acetic acid buffer already containing calcium and phosphate resulted in an increase of the enamel dissolution rate. The results are compared with certain findings in experimental caries studies.

工場の歯科衞生學的研究 : I. 酸取扱工場における歯牙酸蝕症

For the purpose of studying the tooth erosion by acid, the author has investigated the teeth of a factory laborers in North Kyushu, and has carried out a series of experiment concerning the protecting measures against the tooth erosion by acid The results are as follows;- 1. The percentage of laborers suffering from the tooth erosion is twenty six among fifty six, namely fourty percent. 2. It was confirmed that the longer the service years the higher the rate of the patients. 3. Percentage of dental caries, average number of existing teeth, and health index of first molar are respectively worse in the member suffering from the acidic erosion as compared to the healthy member. 4. Average number of eroded teeth is 4.45, and the major part of the tooth number attacked by the erosion was occupied by central incisors, becoming fewer toward posterior teeth. 5. The shape in which the tooth was attacked by the erosion varies according to the types of individual incisal occlusion. 6. Experimentally, extracted teeth were exposed to the acidic air of the factory to know how tooth enamel is dissolved. Dissolution of enamel began in four experimental hour and progressed thereafter. The enamel exposed to acidic air showed a rough surface, while the enamel of the tooth immersed in water remained smooth. 7. For the protection against acidic erosion, ammoniacal silver nitrate was the most advantageous to which succeeded silver flouride and silver ferrocyanate. From the above stated data, a few prophylactic measures will be better adviced. a) Prevention of acid leakage. b) Dilutin of acidic air through good ventilation. c) Hygienic management of factory environment. d) Individual sanitation, routine removing of tooth plaque and deposition. e) Prohition of talking during work, cleansing of mouth after meal, use of alkaline gargle. Use of gas mask are most advisable which will be substituted simply by using gauze mask immersed in bicarbonate of soda solution. Or give chewing gum containing ammonium salt and fluoride for the purpose of neutralizing saliva and cleansing mouth. f) We are convinced that the disease will be supressed in some extent by hardening the tooth enamel through the coating of ammoniacal silver nitrate or silver fluoride. The most efficient is to apply to the tooth crown once a month the Neo-Fluorigen which is consisted from two parts of natrium-fluoride, one part of celluloid, and Ioo part of amylacetate.