Assessment of Orthodontic Treatment Results: Two-Phase Treatment (Early Intervention) vs. One-Phase Treatment (Late Intervention)

Abstract

There is still a lack of consensus among orthodontists regarding the degree of success of different treatment modalities applied during the early to late mixed dentition stages. The purpose of this study was to compare the treatment outcome of one-phase with two-phase treatment with objective evaluation criteria. The null hypothesis is that there is no difference in the treatment quality between early and late treatment groups, among cases finished in year 1998, 1999 and 2000 or among three Angle's Classes or between extraction and non-extraction cases. Pre-treatment and post-treatment records of all patients treated in the orthodontic clinic at the Indiana University School of Dentistry who had their treatment completed during the three years (1998, 1999, 2000) were evaluated by American Board of Orthodontics (ABO) objective grading system and clinical assessment criteria developed in the IUSD orthodontic section. The results of the study showed that there were 512 cases finished in these 3 years. Among these 512 cases the treatment was most often started at age 12, followed by age 13. Poor occlusal contact and improper third order of molars, longer treatment time, and poor dentition were major contributors that made the treatment quality poor. Early debond tended to occur more often with boys than girls. Generally Angle's Class I cases and the cases finished in year 1998 had better treatment results. Although the early treatment group had longer treatment time than late treatment group, the final treatment quality was comparable with that of the late treatment group.