Social acceptability of dental appearance and benefits of fixed orthodontic treatment: a 17-year observational cohort study.

Objectives: This study reports on the social acceptability of dental appearance and benefits of fixed orthodontic treatment (FOT) among a cohort of 13-year-old adolescents in 1988/1989 followed through to age 30 years in 2005/2006.

Methods: Adolescents were categorized into nominal treatment need groups based on the dental aesthetic index (DAI) score at age 13 (DAI: ≤ 25 "No Need"; 26-30, "Elective"; 31-35, "Desirable"; and ≥36, "Mandatory"). At age 30, calibrated examiners again assessed the DAI of traced participants. A reduction in the baseline DAI score of at least five units was considered a benefit. The change in DAI scores was examined by receipt of FOT. The number needed to treat (NNT) was estimated as an indicator of the efficacy of FOT.

Results: Of the 421 cohort participants examined at follow-up, 148 had undergone FOT; 34 percent of those with FOT were classified at age 13 as "No Need" (n = 50); 21 percent as "Elective" (n = 31); 17 percent as "Desirable" (n = 26); and 28 percent as "Mandatory Need" (n = 41). The DAI score reduced significantly for those with and without FOT. The NNT from FOT for those individuals in the "No Need" category was 17 [95 percent confidence interval (CI) - 26-6]; "Elective" 6 (95 percent CI - 27-3); "Desirable" 5 (95 percent CI 3-51) and "Mandatory Need" 14 (95 percent CI - 16-4).

Conclusions: FOT provided a significant benefit only for individuals in the "Desirable" group at age 13. FOT appeared to offer little long-term benefits in the social acceptability of dental appearance for the majority of individuals who underwent FOT.