Acrylic splint Herbst and Hanks telescoping Herbst: a retrospective study of emergencies, retreatments, treatment times and failures.

INTRODUCTION: The Herbst appliance has been reported to be one of the most efficient for the correction of class II malocclusions. However, there are many complications that make its use difficult for clinicians and patients (splint loosening, telescope breakage, splint breakage, low comfort). The aim of this study was to evaluate and compare emergencies, retreatments, failures and overall treatment time of two types of Herbst appliances: the HT Herbst and the acrylic splint Herbst. MATERIALS AND METHODS: Two hundred and eight patients with Class II malocclusion were selected consecutively in a private practice. They were treated either with an acrylic splint Herbst (155 pt, mean age 10.3 +/- 3.7) or with a HT Herbst (53 pt, mean age 11.3 +/- 4.2 years). Tables were used for each patient to record the following complications, if present: detached Herbst, broken and repaired Herbst, broken and rebuilt Herbst (emergencies), Herbst that had to be re-made for lack of patient cooperation (retreatments) and appliances that had to be removed (failed treatment). RESULTS: Results showed that the HT Herbst and the acrylic splint Herbst have the same retreatment probability and the same treatment time. Moreover, the HTH has a lower risk of functional impairment: the acrylic splint Herbst has an emergency probability that is twice as high as the HTH. On the other hand, the HTH has a failure frequency that is nearly 6 times higher than the traditional Herbst although the statistical analysis could not provide any certain conclusion about it. CONCLUSION: In cases where a higher relative risk of failure for the traditional Herbst was confirmed, the HTH proved to be a better appliance than the traditional Herbst.