RESUMEN
In this retrospective study, the Peer Assessment Rating (PAR) index was used to objectively evaluate the effectiveness of Phase I (early) orthodontic treatment provided in an undergraduate teaching clinic. Pre-treatment and post-treatment casts of ninety-three patients were analyzed. All patients selected for Phase I orthodontic treatment had Class I skeletal relationships and did not require complex orthodontic treatment such as growth modification or treatment of occlusions with missing or impacted teeth. The mean age of patients who received Phase I orthodontic treatment was 9.9 years. The mean initial PAR score for the sample was 29.70 +/-9.84. The mean reduction in PAR score was 14.9 points corresponding to a 50.2 percent decrease in the PAR score following Phase I orthodontic treatment. Seventy-three percent of the patients experienced at least a 30 percent reduction in their PAR score following Phase I (early) orthodontic treatment. The mean cost of $381.00 for the Phase I orthodontic treatment was found to be influenced by the length of treatment, type of Phase I treatment provided, age at start of treatment, and percentage reduction in PAR score. The greatest success rate for the Phase I orthodontic treatment occurred with either fixed or a combination of fixed and removable appliances. Over half of the patients recommended for Phase I orthodontic treatment in the undergraduate dental clinic were successfully treated and did not require Phase II treatment. For them, there was both a treatment and a financial benefit to the Phase I orthodontic treatment.