system to cIassify the need for periodontal treatment. Acta Odont. Scand. 31,297-305,
1973.A system to determine the periodontal therapeutic needs of a populationthe Periodontal Treatment Need System (PTNS) is suggested.It is based on defined diagnostic criteria and systematize the needs according to three standardized therapeutic procedures: (I) individual oral hygiene motivation and instruction (OH), (2) scaling and elimination of overhangs (Sc) and (3) periodontal surgery (Su).The classification is: Class 0no need, Class Aneed for OH, Class Bneed for Sc and OH, and Class Cneed for Su, OH and Sc. Class A is given for the mouth and Classes B and C for quadrants. To evaluate the application of the system, 42 patients were treated for inflammatory periodontal disease. The therapy consisted of OH, Sc and Su. The time used for performing the treatment was recorded in each session. The patients were classified according to the system and the average time for each type of therapy was: OH -72 minutes per patient, Sc -32 minutes per quadrant and Su -57 minutes per quadrant. The following guidelines were suggested for the PTNS: Class A -60 minutes, Class B -30 minutes and Class C -60 minutes. The PTNS offered the possibility of estimating the type(s) of treatment needed and the time required for performing it. Thereby, manpower and costs may be calculated. The system appeared to be reproducible and may be useful in planning of periodontal treatment for population groups.