Outcome of a scheme for specialist orthodontic care, a follow-up study in 31-year-olds.

Changes in the occlusion after orthodontic treatment have in several studies been analyzed by the use of the PAR Index developed by Shaw & Richmond. The use of the PAR Index has been shown by O'Brien & Shaw to be a reliable and reproducible method to evaluate orthodontic treatment results. The purpose of the study was to examine the long-range orthodontic treatment outcome by following a group of patients into adulthood to the age of 31 years. For the study 115 individuals from a previous randomized study were invited for follow-up examination at age 31 years. Seventy-two individuals, 32 males (44.4%) and 40 females (55.6%) of the original sample attended for clinical examination. Study casts were obtained and questionnaires addressing the patient's awareness and opinion of the treatment were distributed. In addition twenty-four subjects responded by returning filled-in questionnaires. The mean change in wPAR scores from start to retention represents a mean relative improvement in occlusion of 78.7%. The mean wPar score improvement from age 19 to 31 years was 11.9%. The relative mean wPar score change dropped to 53.5% at age 31 years. The differences in wPAR recordings between the recorded stages were all statistically significant. The treatment outcome as expressed by mean wPAR scores at age 31 years was significantly better among individuals treated with extractions compared to those treated without extractions. The mean wPAR scores of the individuals with retainers at age 31 years were significantly lower when compared to the mean score for those without retainers (unpaired t-test, p = 0.020). This clearly indicates the benefit of long-term retention. The changes in the concern scores from 19 to 31 years of age were small. At age 31 years only 8 of the 96 respondents (8.3%) expressed concern about the treatment outcome.