THE HYGIENE OF NUTRITION 365 



of the food, but it is certainly better to err in the direc- 

 tion of excessive rumination than to become careless in 

 regard to it. The teeth are to be conserved and used. 

 It might be thought that the vigorous employment of 

 the teeth could only hasten their wear and tear. This 

 is probably the case at a time when their life is extinct 

 or limited to a small central core, but at an earlier period 

 mastication appears to be good for the teeth. This is 

 because they are made to sink and rise in their sockets 

 with a massaging effect upon the gums and some pro- 

 motion of the circulation in the pulps. 



According to the usual teaching the best protection 

 to the teeth is afforded by the use of an alkaline mouth 

 wash such as milk of magnesia. If this is used at bed- 

 time it should not be rinsed out but left in the by-places 

 of the mouth to guard against the development of an 

 acid reaction. The brushing of the teeth may be over- 

 done; it should cleanse their surfaces but should not 

 be so directed as to encourage recession of the gums. 

 It is often assumed that people with poor teeth are pay- 

 ing the penalty for their neglect. Sometimes, of course, 

 this is a fact, but it is also true that many people have 

 superb teeth which they owe entirely to good fortune 

 and not to conscientious care. 



The assistance of the dentist must be had at short 

 intervals by many subjects. Teeth which are in need 

 of filling or other treatment are most detrimental. They 

 are not merely disfiguring and responsible for bad breath, 

 but their presence deters the possessor from using proper 

 force in mastication. It is believed in addition that 

 defective teeth are often foci from which most injurious 

 infections are spread to other parts of the system. The 

 ugly fact stands out that our teeth, being incapable of 

 self-repair, force upon us an early reminder of our 

 mortality. 



