Acquired Openbite Treated by Temporary Anchorage Devices- Evaluation of The Treatment Results
Date Issued
2012
Date
2012
Author(s)
Wang, Shin-Huei
Abstract
Objectives：
Anterior openbite was probably the most challenging type of malocclusion among the orthodontic field. Certain amount of this malocclusion was attributed to temporomandibular joint disorder. These patients often exhibited attrition facet over the occlusal surface and loss of mamelon over the incisal edges, suggesting they had occlusal contact during the previous years. As a result, we further classified this kind of malocclusion as “acquired openbite”.The patient with acquired openbite not only suffered from compromised occlusal function and chewing efficiency, but also concerned about the worsened facial appearance. They often had increased lower facial height, retrusive chin and increment in the mandibular plane angle. The traditional orthodontic mechanism could only achieve anterior teeth extrusion. By that way, we could not improve the facial esthetics of the patient. Only receiving orthognathic surgery can both the occlusal function and facial esthetics be improved concomitantly. In the recent years, as the rapid development of temporary anchorage devices (TADs), offering the practitioners a different way for treating anterior openbite. Molar intrusion via TADs was a valid alternative for those patient who had less severity or rejected surgical treatment protocol. However, there was no definitive diagnosis of the temporomandibular joint disorder in the previous literatures, nor follow up study after the bite closing.
Therefore, the objective of this study is to elucidate the benefit of this new method for treating acquired openbite ,verify its stability and evaluate the alteration in the skeletal facial pattern and the dimension of airway. We also use MRI as a conjunctive tool to justify the condition of the temporomandibular joint area.
Materials and methods：
Our study comprised both the prospective and retrospective design. The prospective study sample included 7 females with acquired openbite receiving treatment at the TMD department,NTUH. Orthodontic treatment started after the symptoms and signs of TMD subsided and the TMJ condition stabilized. The patients received orthodontic treatment with TADs for bite closure. The questionnaire and MRI examination were performed after positive overbite achieved.
The cephalometric analysis included both the prospective and retrospective samples to achieve better statistic power. The retrospective samples were the acquired openbite patients received orthodontic treatment with TADs for posterior intrusion. The differences between pre-treatment and post-treatment cephalometric measurements were analyzed by the pair-t test.
Results：
All patients achieved improved overjet and positive overbite after the treatment. The MRI showed no inflammatory sign after bite closing. The paired-t test revealed decreased upper posterior dental height, decreased mandibular plane angle, decreased facial height and increased airway dimension after bite closing.
Conclusion：
Orthodontic treatment in conjunction with TADs could achieve upper posterior teeth intrusion thus eliminating the mandibular plane angle. The counter-clockwise rotation of the mandible not only corrected the anterior openbite but also improved the chin projection. As a consequence, posterior teeth intrusion via TADs could be a valid alternative treatment protocol for patients with acquired openbite.
Subjects
temporomandibular joint disorders
acquired openbite
temporary anchorage devices(TADs)
posterior teeth intrusion
MRI
Type
thesis
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