AbstractThe CPITN is used widely in estimating periodontal treatment needs and, in many cases also to make generalizations about periodontal disease. It is therefore imperative that the heirarchical scoring method used to allocate CPITN scores is validated, and that the presentation of CPITN data reflect the true distribution of periodontal conditions. Data from one study carried out in Melbourne, Australia and one in Jakarta, Indonesia were used to compare CPITN scores on a mouth, sextant and tooth basis. Clinical periodontal components were compared with CPITN scores to establish the validity of the CPITN hierarchical scoring method. The distributions of CPITN scores varied widely on a mouth, sextant and tooth basis, and CPITN scores frequently differed from those indicated by the periodontal components. It was concluded that CPITN data should be presented not only as the % of subjects with each score, but also as the % of sextants, and. if possible, the % of tooth sites with each CPITN score. It was also concluded that there is an advantage in measuring components (calculus and bleeding) as well as CPITN in order to limit the overestimation of treatment needs, particularly for anterior teeth.