FACTORS INFLUENCING THE OUTCOME AND DURATION OF REMOVABLE APPLIANCE TREATMENT

The study models and records of 150 consecutively completed removable appliance cases were analysed and the influence of various factors ass essed on both the change in Peer Assessment Rating (PAR) score produce d by treatment and the duration of treatment. For the purpose of analy sis the material was divided into two groups; a functional appliance/h eadgear group (n=43) and an upper removable appliance group (n=103). T he initial PAR score accounted for 71 per cent of the variation in PAR change in the functional/headgear group when combined with the sex of the patient; females on average showing a further improvement of 3 PA R points over equivalent males. The initial PAR score alone accounted for 68 per cent of the variation in PAR change in the upper removable appliance group. Sixty per cent of the variability in treatment durati on could be explained in the functional/headgear group by the initial PAR score and a binary variable indicating whether three or more appli ances had been required. Fifty-six per cent of the variability in dura tion in the upper removable appliance group was explained by the numbe r of appliances used alone. Regression equations for prediction of out come and duration of removable appliance treatment are given.