FOOD HABITS 121 



brushing the teeth is just before retiring, that the bacteria 

 may not continue their destructive activities during sleep. 



The best cleaning material for the teeth as for the skin 

 or for clothes is a good white soap. If you buy a dollar's 

 worth of tooth paste or powder, you get several cents' worth 

 of soap, together with some cheap perfume and a little powder 

 added to scrub. The perfume does not help to keep the 

 teeth clean ; and it has been questioned whether the powder 

 does not do more harm than good. If we begin with the 

 younger children, we shall find that they can quickly learn 

 to use plain soap on the toothbrush and do not need the 

 fancy-smelling pink addition to make tooth-brushing an 

 agreeable habit. 



In brushing the teeth, the motion of the brush should be 

 circular, so as to reach all the spaces between the teeth. If 

 you brush crossways, the depressions along the edges of the 

 teeth will not be reached at all. It is well, also, in setting out 

 to fix a toothbrush habit, to remember that the back teeth and 

 the inner faces of the teeth need to be considered as well as 

 the fronts of the front teeth. 



Unfortunately, the use of soap or other alkaline substances 

 causes the salivary glands to secrete mucin the substance that 

 makes the saliva glary or sticky. Now this mucin furnishes a 

 sticky covering for the teeth, in which the bacteria can remain 

 and do their destructive work. Experiments have shown that 

 the use of some weak acid (as citric acid from lemons, or acetic 

 acid from vinegar) stops the secretion of mucin and makes 

 the mouth a cleaner place, so far as the welfare of the teeth 

 is concerned. It is therefore recommended that dilute vinegar 

 be used for cleaning the teeth, at least in the last cleaning 

 before going to bed. If the vinegar is used after soap, the 

 latter must first be thoroughly rinsed out with plain water. 



Some people need to use on their teeth an antiseptic or 

 bacteria-killing mouth wash. Such a mouth wash, however, 

 is to be used in addition to brushing, and not as a substitute. 



