Dental effects of interceptive orthodontic treatment in a Medicaid population: interim results from a randomized clinical trial.

Introduction: There are disparities in access to orthodontic treatment for children from low-income families. Systematic programs of limited-care interceptive and preventive orthodontics have been proposed as a solution. The purpose of this randomized clinical trial was to compare dental outcomes and funding eligibility from a group of Medicaid patients randomized to receive interceptive orthodontics (IO) in the mixed dentition or observation (OBS).

Methods: One hundred seventy Medicaid-eligible children were randomized to receive IO or OBS and followed for 2 years, when complete data were available on 72 and 74 children, respectively. The 2-year changes in the peer assessment rating (PAR) were compared using the Student t test. The proportions of children no longer eligible for Medicaid funding as defined by handicapping labiolingual deviation (HLD) scores less than 25 at the 2-year follow-up were compared with the chi-square test.

Results: The IO patients had significantly greater decreases in the PAR scores--50%-compared with the OBS subjects, -6% (P <0.001). Negative and positive overjet and maxillary alignment were the components most affected by IO; they decreased by 11.0, 7.2, and 3.7 PAR points, respectively (P <0.001). Overbite showed little change. At the 2-year follow-up, 80% of the IO patients' malocclusions that qualified initially were no longer deemed medically necessary by the HLD index, compared with 6% in the OBS group (P <0.001).

Conclusions: IO significantly reduces the severity of malocclusions and moves most from the "medically necessary" category to elective but does not produce finished results for most patients. Overjet and alignment were most readily corrected by interceptive treatment. Deep overbites were the least susceptible to IO correction.