Comparison of Roth appliance and standard edgewise appliance treatment results

A retrospective comparison of Roth appliance and standard edgewise appliance treatment results was made using two indices. The first, the ideal tooth relationship index (ITRI), scored dental casts for the presence of ideal tooth contacts. The second judged posttreatment dental casts on the basis of criteria established by Andrews in his "Six Keys to Normal Occlusion." The sample consisted of 120 orthodontically treated cases completed by two practitioners who have used both the Roth and standard edgewise appliances. Thirty cases of each appliance type were collected from each practitioner. The overall posttreatment ITRI percentage scores showed no significant differences between the appliances. Practitioner differences existed for the anterior intraarch, anterior interarch, and posterior buccal interarch relationships. These differences were related to both treatment time and finishing arch wire size. The results of the Six Keys Analysis showed that the angulation and inclination of the maxillary posterior teeth were better with the Roth appliance. However, success in achieving some components of the six keys did not translate into an increased percentage of ideal tooth contacts as measured by the ITRI. Despite using the Roth appliance, experienced clinicians still found it difficult to achieve all six keys to normal occlusion.