CLINICAL EVALUATION OF UREA-AMMONIATED DENTIFRICES 63 rived from permanent office records and filed periodic radiographs. Until our clinical reports, and ex- cepting Stephan's limited experi- ment, dental literature has never contained substantial evidence that the toothbrush and a dentifrice, to- gether or separately, appreciably prevented caries (9). Admittedly, those who recognized this fact continued with conventional oral hygiene methods for about the same reasons that they bathed or wore clean clothes. The development of a therapeutic dentifrice yielding 3 to 5% active therapeutic ingredients in the mouth, and improved con- cepts of home care should give en- couragement to both the teachers and the followers of oral hygiene procedures. WHEN TO BRUSH The long known but sometimes doubted adage, "a clean tooth will not decay," {s once more coming to the fore. We have known about cleaning teeth but only now are we learning something about how to keep them clean. Much publicity is currently being directed at the hitherto accepted, but now al- legedly unsound, "clean teeth im- mediately after meals to prevent decay." We are sure that present carbo- hydrates furnish the substrate upon which caries-associated .bacteria thrive. Theoretically, removing this food would cut short the caries at- tack, but this seems practical only until we scrutinize what occurs while we eat. That we eat too fre- quently (from the standpoint of caries control) is accepted. Fur- ther, our meals are not momentary snacks, but last on an average at least 30 to 45 minutes. There may be five or six intakes of sugar at various stages of any meal, and Volker showed that such ingestion of sugar results in a nearly instant and prolonged appreciable sugar concentration in saliva (10). It has also been reported that the break- down of sugar to lactic acid in the mouth is not a delayed or long drawn out process, but is explosive in rapidity (11). Since in 30 to 50 minutes the acid is buffered and dissipated by the saliva, most of the caries attack is usually ended before hygiene can be attempted. It has been proved that the use of a strong urea dentifrice will alkalin- ize food plaques for some hours, even twenty, if enough is applied for a long enough time (12). A logical solution would seem to be to clean the teeth before meals with enough urea to penetrate into plaques so that when sugar enters the mouth: 1. Existent plaques have al- ready been thinned and are more readily penetrated by natural anticaries mech- anisms. 2. Residual artificially intro- duced urea inhibits the enzyme systems associated with acid formation. 3. Acid which is formed (if any) is alkalized by the pre- viously "treated" plaque material.

64 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS While this seems simple to carry out, it must be remembered that re- sults depend upon amount of urea times length of time urea is kept in the mouth. Casual brushing with a weak dentifrice will have little more effect than the pastes and powders of yesterday. Naturally, there is only benefit to be gained from clean- ing the teeth after meals also, if possible. It is better if food debris can be removed before it has the opportunity to form more tenacious deposits. In the previous paragraphs casual mention is made repeat- edly of acid, associating it with dental caries. For more than half a century it has been a majority opinion that aciduric bacteria can be blamed for dental caries, together, of course, with the carbohydrates upon which they subsist. How- ever, for some time now an increas- ing number of authorities have been holding proteolytic bacteria, not aciduric, responsible (13). Actually, the two hypotheses can be recon- ciled. Many proteolytic organisms and their enzymes function best in acid media and it is quite possible that decay vanishes if either acid- uric or proteolytic bacteria fail to thrive. It does not seem important at the moment to decide the one and only cause of caries, when it is evi- dent that caries can be aborted if ad- herent bacteria-laden food plaques are destroyed and vulnerable tooth surfaces bathed in natural saliva. BRusu-F•.usH METHOD When a dentist dislodges a tem- porary stopping filling and scatters the pieces around, he usually re- quests the patient to empty the mouth afterward. It is not uncom- mon to find perhaps five of possibly ten pieces of temporary stopping right back in the cavity again. The reason for this is that the mouth is only a potential space and the force of muscles during expectoration squeezes debris in the direction of any real void. Now food debris lodged in the mouth has made room for itself and it is likely that much loosened food returns after brushing from where it was dislodged unless there is adequate and forceful rins- ing. Excellent results can be seen in our practice from a system we call the "brush-flush method." A tea- spoonful of the powdered dentifrice is placed in a glass with about an inch (1-2 oz.) of warm water and stirred with the t6othbrush. A sip of the mixture is forcibly swished around the mouth, between the teeth, and expectorated. The tooth- brush is dipped into the stirred mix- ture and then three or four teeth are scrubbed in an accepted way, followed by another sip and forcible rinsing. Then several more teeth are brushed and so on until com- pleted. If a paste is preferred, it should be supplemented by the liquid. Dental floss and stimulators can be used with increased effi- ciency when employed in conjunc- tion with forcible rinsing with the stirred ammoniated mixture, be- cause of the dissolving of mucin.