A similar error is widespread concerning the most effective method of solving the problem of protecting the teeth from decay. In a recent publication Clark and Butler (6) state "Dental caries is caused by the action of bacteria or germs, which normally inhabit the mouth. These germs, acting in the presence of food debris and certain elements in the saliva, result in the formation of an acid which attacks the enamel covering the exposed parts of the tooth, after which the underlying softer parts become rapidly destroyed. Many other factors are actual and potential causes of dental decay and its progress, such as - 1. Low resistance of the teeth to decay because of developmental defect (antenatal and postnatal). 2. Faulty diet (both of the mother during pregnancy and of the child). 3. Neglect of dental attention through ignorance of the parents. 4. The cost of dental attention, a serious consideration with families of low economic status. 5. Failure of the child to call attention to the condition of the teeth, either because it is too young or because of fear. 6. Lack of dental facilities, so common in rural sections." It is pointed out by these authors that a very high percentage of undernourished children show marked evidence of dental decay. They cite the results of the examination of 270 children by the Public Health Service, which showed that 33 per cent of these had from 1 to 4 cavities, 48 per cent had from 4 to 8, and some had 9, 10 and 11 cavities. It is to be regretted that this excellent paper fails to emphasize the importance of including in the campaign for the preservation of the teeth, an effort to change the character of the nation's diet, in order that developmental defects shall grow less common and less severe as time passes. Emphasis is laid entirely upon the importance of the dental hygienists, who limit their work to cleaning and polishing all surfaces of the teeth above the gum margins, to the dental clinic for the repair of the teeth already in a state of decay and to the teaching of mouth hygiene. Such a program is based upon the belief that cleanliness of the oral cavity is of first importance as a preventive measure for preserving the teeth. Terman (7) says: "We know that a clean tooth, a tooth that is kept clean, cannot decay." Butler (8), in a recent article states ".. it is but a matter of a few generations before civilized man will be edentulous or without teeth. The possibility of persuading the people of to-day to subsist upon a coarser diet is most remote and it will be at once seen that our only hope in this direction lies in some prophylactic measure." He further states: "Just as in preventive medicine lies the greatest good in all medical science, so, too, in dental prophylaxis is to be found the nearest solution of this problem. The establishment of a dental clinic in a school and the employment of competent persons to care for the mouths of the younger children comes nearest to the requirements." And he further says: "Every hygienic measure adopted strengthens the position of others that may be in practice, but in the whole field of hygiene there is no single part that can approach the hygiene of the mouth in importance."