Effect of early treatment on stability of occlusion in patients with Class II malocclusion.

INTRODUCTION: The purpose of this study was to evaluate the effect of early treatment on the stability of occlusion in patients with Class II malocclusions. The peer assessment rating (PAR) index was used to evaluate changes in occlusion after treatment of subjects treated in 1 phase or 2 phases. This study was a prospective, randomized, controlled clinical trial. METHODS: Dental casts were obtained from the participants, who were randomized into 3 phase-1 early treatment groups: bionator, headgear/bite plane, or observation. Phase 2 consisted of continued treatment of the bionator and the headgear/biteplane subjects and comprehensive treatment of the observation subjects. PAR scores were obtained for 208 subjects at end of treatment; 173 (83%) had at least 1 follow-up visit, with a median follow-up time of 5.0 years. PAR scores were calculated for each subject at key treatment and posttreatment time points. Linear mixed-effect models were used to evaluate the impact of phase-1 treatment group, years posttreatment, end of treatment PAR score, and other covariates that could affect stability on the posttreatment PAR score. RESULTS: Factors significantly affecting posttreatment PAR scores were PAR score at end of treatment (P <.0001), years posttreatment (P =.0064), and PAR score at the start of phase 2. Although phase-1 treatment was not statistically significant, those with early treatment had lower PAR scores at the start of phase 2 than the observation subjects (means [SD]: bionator 17.5 [7.4], headgear/biteplane 15.3 [7.0], observation 22.2 [8.6], P <.0001). Thus, early treatment had an indirect effect. CONCLUSIONS: Factors that affect posttreatment PAR score stability include PAR score at the end of treatment, years posttreatment, and PAR score at the start of phase-2 treatment. The early treatment modalities have limited positive impact on posttreatment stability PAR scores in Class II malocclusion patients due to their effect on PAR scores at the start of phase-2 treatment.

Effectiveness of early treatment of Class II malocclusion.

The purpose of this study was to examine and report the effectiveness of early treatment with the headgear/biteplate and the bionator in patients with Class II malocclusion regardless of the mechanism of correction and to compare early-treatment results with changes over a similar time period in an observation group. The role of factors such as compliance was examined to determine their contribution to effective treatment. The experimental design was a prospective, longitudinal, randomized controlled trial. At the end of the early-treatment period, all 3 groups differed significantly (overall, P = .001) in percentage of treatment goal achieved, with median values of 83% for the bionator group, 100% for the headgear group, and 14% for the observation group. In both treated and observation subjects, the percentages of goal achieved varied by initial molar class severity (treated, P =.0205; observation, P = .0040) and race (treated, P = .0314; observation, P = .0416). Significant correlations in the treated subjects were identified between percentage of goal achieved and bone age (13 bones) (r = 0.16; P = .037), bone age (20 bones) (r = 0.16; P = .043), compliance (r = 0.26; P = .0005), and initial overjet (r = -0.26; P = .0095). Significant correlations were not detected in the observation group. Sex, treatment group, age, mandibular plane angle, pretreatment, and retention did not significantly affect percentage of goal achieved among the treated and the observation subjects. Correlation between normalized compliance scores and percentage of goal achieved was high for both bionator (r = 0.50) and headgear subjects (r = 0.49) at the end of treatment. Multivariate analysis suggested that headgear may be superior to bionator/biteplane in achieving a Class II correction during early treatment.