Some thoughts on epidemiologic indexes for assessing the need for treatment of periodontal diseases.

Various indexes have been developed and used to collect information on the prevalence, aetiology and prevention of periodontal disease, but few efforts have been made to utilize this information to assess treatment needs in the populations examined. Recently, Johansen et al. (1973) have developed the Periodontal Treatment Needs System and Møller and Beck (1976) included an assessment of treatment requirements in the Collaborative Study of Dental Manpower Systems sponsored by WHO and the USPHS. The value of these various indexes and the problems encountered in their application to field studies are discussed in detail. The lessons learned have been incorporated into the second edition of the booklet Oral Health Surveys (WHO, 1977), but it is contended that the methods advocated are still less than perfect. Particular doubt is cast on the recommendation for the use of a periodontal probe in field surveys often conducted in primitive conditions and by examiners with minimal training and experience. It is suggested that the critical depth of 3 mm is too small to be regarded as requiring radical treatment. The need for a treatment index is questioned in the light of the probability that treatment needs could not be fully met even in developed countries.