Robert G. Kesel

Ammonia production in the oral cavity and the use of ammonium salts for the control of dental caries

Abstract 1. 1. Ammonia nitrogen developed in human saliva by natural processes has the ability to inhibit the growth of L. acidophilus. 2. 2. The inhibition of the lactobacilli is not due to the alkalinity which the ammonia might provide, for the same alkalinity established by sodium acetate had no inhibiting action. 3. 3. Dibasic ammonium phosphate used orally in a mouth rinse and dentifrice caused a marked reduction in the oral lactobacilli counts but has not reduced the number in some of the subjects to a level that would indicate an arrest of dental caries. 4. 4. In vitro experiments indicate that a combination of 5 per cent dibasic ammonium phosphate and 3 per cent urea is more effecetive as an antibacterial and antiacidic agent than is either of these substances alone. 5. 5. It appears from bacteriologic observations that the use of an ammoniumcontaining dentifrice and mouth rinse as employed by the average individual may not completely check caries activity. Other measures, particularly dietary management, may be necessary to establish at least initial control.

Amino acids in human saliva.

During our investigation of dental caries preliminary experiments revealed that caries inactive individuals have enzyme systems capable of converting several amino acids to ammonia (1,-2). The presence of these amino acids in the saliva previously had not been reported. The reason that our knowledge on this subject is incomplete can be explained in part by the lack of proper analytical procedures. Micro-biological methods for the estimation of amino acids are now well established (2), and have been found to afford easier and simpler procedures by which the amino acid content of body fluids can be determined.

Testing Caries Activity By Acid Production in Saliva

A quick, simple, accurate method of evaluating dental caries activity of individuals, before the actual dissolution of enamel begins, would be a valuable aid in studies and treatments of dental caries because knowledge of caries activity would permit the dentist to plan his dental treatment program more intelligently and investigators could study methods of controlling dental caries more efficiently. Several methods of testing for dental caries activity have been reported, most of them based upon interpretations of studies of the oral flora, or upon the action of oral bacteria on carbohydrates. A brief outline of the better known tests follows:

The amino acids and their deaminating systems present in human saliva

Abstract 1. 1. The free ammonia content of saliva from caries-free and caries-active individuals has not been proved to be significantly different. 2. 2. The source of ammonia nitrogen is not entirely urea; amino acids in saliva contribute to its formation. 3. 3. At least eleven amino acids have been shown to be present in human saliva by using microbiologic procedures. 4. 4. Values are reported for these acids in the saliva of three groups classified according to caries activity. 5. 5. There is as yet no apparent correlation between the amount of these substances present in the saliva and caries activity.

Endodontic significance of the penetration of S35-labeled penicillin in extracted human teeth.

Abstract It has been found that the dentine and pulp tissue of all the teeth used in these experiments were permeable to radioactive penicillin. It was further established in one case that the material in the dentine remained in the original form of the penicillin molecule. Further investigation is indicated to prove the latter is true in all cases. The advantage of penicillin therapy in endodontia is experimentally supported by these studies. It must be remembered that these experiments were conducted, on freshly extracted human teeth.

Recent developments in the biologic production of ammonia and the use of ammonia and carbamide in caries prevention

Abstract 1. 1. More ammonia is formed in saliva than can be derived from the conversion of salivary urea. 2. 2. Amino acids are an important source of ammonia, and seventeen have been found to occur in saliva. 3. 3. Sugar in saliva has a depressing effect on ammonia production as well as a stimulating effect on acid formation. 4. 4. The salivary content of four amino acids was influenced by the nitrogen content of the diet. 5. 5. Dibasic ammonium phosphate (5 per cent) and urea (3 per cent) when in combination have a synergistic effect in inactivating glycolytic bacterial enzyme systems in saliva that produce lactic acid and in inhibiting the growth of lactobacilli and yeasts. 6. 6. Clinical studies indicate that the conscientious use of a dentifrice containing these agents produces a reduction in caries activity, but a larger number of young individuals must be studied before conclusions can be drawn.

An appraisal of various methods for caries control.

Abstract In summarizing what may be used for caries control, I think the following procedures can be recommended without hesitancy: 1. 1. Dietary management with the marked restriction in refined carbohydrate consumption, at least during periodic intervals. 2. 2. The discontinuance of in-between meal eating of fermentable carbohydrates. 3. 3. The more diligent use of the toothbrush and the brushing done immediately after eating if possible. 4. 4. The topical application of 2 per cent sodium fluoride solution to the clean enamel surface. 5. 5. The use of a dentifrice containing a nontoxic substance specific for the reduction of lactobacilli in the oral cavity. A note of caution should be added and that is that we should not promise too much from these procedures. Too often the patient and even the dentist expect that when this regime is followed conscientiously no more cavities will result. Disappointment is expressed if a year or two later some caries is discovered. We doubt that any procedure that requires patient effort will ever be 100 per cent effective. Therefore, we must not claim that our preventive measures will irradicate dental caries. But in our opinion we can look forward to a reduced incidence of this disease.