The so-called focal infections are today considered to be polyetiologic manifestations, in which there is a summation of various aggressions. Bacterial products, toxic or antigenic substances originating from different foci are but one of the elements susceptible of unleashing the disease. This explains why there are so many foci and so few results after their elimination. Scientific evidence shows that the histologic result of an apicectomy is considerably worse than the radiological evidence might lead to believe. Inflammation may persist for years before it disappears. Radiographs are therefore only a coarse criterion for judging results of healing. When facing a disease caused by focal infection, the possible foci should be eliminated quickly and as radically as possible.