The Effect of Chemicals on Microorganisms 215 



of acid produced by some organisms is considerable. In fact, 

 some investigators claim that the enamel of teeth can be visibly 

 etched by the acids produced by bacteria lodged in the crevices 

 between the teeth. Not one of the fancy-designed toothbrushes 

 is able to remove effectively these entrenched organisms, adver- 

 tising claims to the contrary. The use of dental floss is one means 

 of dislodging these hidden microbial cultures. Since much decay 

 of the teeth occurs in the tight, hidden crevices, there is some 

 support for the claims that microbial end products are capable of 

 attacking the relatively resistant enamel on our teeth. 



Some years ago considerable research was directed toward 

 studies of the lactobacilli, those high acid-producing bacteria found 

 in varying numbers in the mouth. Claims were presented that 

 persons harboring an abundant flora of lactobacilli appeared to 

 have an abnormally high number of dental caries. The correlation 

 between these two factors needs further clarification. 



If acids in the mouth are the cause of the breakdown of tooth 

 enamel, it appeared logical to some persons to pursue a practice 

 recorded in ancient writings. The Chinese reported that some 

 factor in urine appeared to reduce tooth decay. Ammoniated 

 dentifrices have been an outgrowth of this revived information. 

 By incorporating into dentifrices chemicals capable of neutralizing 

 acids, tooth pastes and powders can not only aid in the mechanical 

 removal of organic matter and bacteria, but the alkaline ions can 

 conceivably help to neutralize acids and thus aid in reducing tooth 

 decay. The lasting effect of one such treatment is rather short- 

 lived, but it is probably fair to state that the ammoniated denti- 

 frices may do some good. 



The deodorizing power of chlorophyll— that green-pigmented 

 constituent of higher plants— has been capitalized upon by manu- 

 facturers in recent years. As is true for so many new products put 

 on the market, the claims for chlorophyll as an ingredient of tooth- 

 pastes, soaps, dog biscuits, etc., have been rather sweeping. As 

 some doubting wit has phrased it: 



Why reeks the goat on yonder hill 

 While he feeds all day on chlorophyll? 



