A Periodontitis Severity Index.

A Periodontitis Severity Index (PSI) was developed and then tested in a population of 154 patients attending the University of Mississippi School of Dentistry screening clinic. Patients were grouped by age decade. The premises of the PSI follow: (1) Periodontitis is diagnosed on the concurrence of clinically apparent marginal inflammation and vertical loss of supporting periodontium (the severity of the associated clinical inflammation does not seem to be related to the severity of the tissue loss) and (2) a Schei ruler is used to determine from the radiograph the percentage of bone loss for a tooth surface. For each patient, a 0 to 1 Clinical Inflammation Score (CIS) was determined at the mesial and distal of every tooth. A CIS of 0 reflected no demonstrable clinical inflammation, whereas a CIS of 1 meant that clinical inflammation could be detected. A modified Schei ruler was used to determine the percentage of bone loss at each interproximal site. A Bone Loss Score (BLS) was calculated on a 0 to 10 whole number continuum. A BLS of 0 meant no bone loss, 1 = up to 10%, etc., up to BLS 10 = 90 to 100% loss. The PSI was then calculated for each mesial and distal surface. PSI = BLS X CIS. The PSI could be 0 if either no bone loss could be determined or the gingiva was healthy. In the presence of marginal inflammation, the PSI value was directly proportional to the percentage of bone loss. Mean PSI values were calculated for each age group. The PSI tended to increase with age. The PSI offers several advantages.(ABSTRACT TRUNCATED AT 250 WORDS)