2004 Fiscal Year Final Research Report Summary
Neuromuscular and skeletal adaptations following mandibular counterclockwise rotation accompanied by intrusion of molars with Skeletal Anchorage System (SAS) in Implant-Orthodontics
| Project/Area Number |
14571879
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Surgical dentistry
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| Research Institution | Tohoku University |
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Principal Investigator |
SUGAWARA Junji Tohoku University, Graduate School of Dentistry, Associate Professor, 大学院・歯学研究科, 助教授 (00005109)
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| Project Period (FY) |
2002 – 2004
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| Keywords | openbite / intrusion of molars / orthodontic anchorplate / skeletal stability / occlusal force / masticatory muscle activity / mandibular movement / neuromuscular adaptation |
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| Research Abstract |
The Skeletal Anchorage System (SAS) was newly developed for tooth movements in orthodontic treatment. It consists of titanium miniplates which are temporarily implanted in the basal bones as stationary anchorages. Although distalization and intrusion of teeth have been extremely difficult by traditional mechanotherapies, those are more easily achieved by SAS. With SAS, anterior open bite can be improved by the counterclockwise rotation of the mandible, accompanied by the intrusion of molars. However, it has been unknown about the influences of changing the vertical dimension by orthodontic intrusion of molars on masticatory muscle activities and dentoskeletal adaptations. In this paper, we introduced an outline of SAS and evaluated morphological and functional changes produced during the Implant-Orthodontics treatment with SAS in the anterior openbite patients. The dentoskeletal morphology was assessed through lateral cephalograms taken before and after treatment. Occlusal contact area
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, occlusal pressure, bite force, masticatory efficiency, levels of electromyogram (EMG) activity in some of the muscles of mastication, and chewing movement by mandibular kinesiograph (MKG) were measured on all subjects. The results in patients with anterior openbite were compared with those in controls with normal occlusion. Cephalometric evaluation revealed intrusion of upper and lower posterior teeth, counterclockwise rotation of the mandible and a significant decrease of anterior facial height (vertical occlusal dimension) during treatment. Before treatment, the openbite patients had masticatory efficiency, bite force and occlusal contact area significantly less than those of controls. The patients' masticatory muscle activity was relatively low during clenching and chewing. After treatment, masticatory efficiency, bite force and occlusal contact area increased, but they were still significantly lower than the control subject level. The masticatory muscles were working harmoniously, and their activity was much higher. The results of this study suggest that in openbite patients, function of the masticatory system is impaired and orthodontic correction by intrusion of molars with SAS improves both the morphological and functional deficits. A larger sample is needed to confirm these findings. Less
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