The purpose of this study was to develop and report upon a methodology for a non-linear capacity 3D modeling finite element analysis evaluating the loading behavior of different partial denture designs. A 3D finite element model using human CT data was constructed. An original material constant conversion program was implemented in the data simulation of non-linear tissue behavior. The finite element method material properties of residual ridge mucosa were found to have seven material constants and six conversion points of stress values. Periodontal tissues were found to have three constants, and two conversion points. Three magnetic attachment partial denture designs with different bracing elements were evaluated. Technical procedures for finite element model simulation of nonlinear tissue behavior properties evaluating the oral behavior of prosthetic device designs are reported for prosthodontic testing. The use of horizontal cross-arch bracing positively impacts upon the comparative stability of the partial denture designs tested.

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抄 録 症例の概要：患者は 43 歳男性．上顎全部床義歯不適合による咀嚼困難を主訴に来院．下顎両側臼歯部には歯 槽骨吸収と咬合平面の不整が観察され，顔貌から咬合高径の低下が疑われた．下顎両側臼歯部には歯内治療後， 残根上義歯を製作し，上顎全部床義歯と下顎残根上義歯を暫間義歯として咬合面再形成を行い，最終補綴装置 にて機能回復を行った． 考察：上下顎暫間義歯にて咬合面再形成を行い，適正な咬合平面，咬合高径を獲得できたことが，咀嚼機能改 善の要因と考えられる． 結論：下顎両側臼歯部咬合平面の不整と咬合高径低下を伴う上顎全部床義歯不適合症例に対して，暫間義歯を 用いた適切な咬合面再形成を行うことにより機能回復が可能であった． キーワード 暫間義歯，咬合面再形成，咬合平面，咬合高径ABSTRACT Patient: A 43-year-old patient complained of masticatory disturbance caused by the instability of a maxillary complete denture. The patient had a lower occlusal vertical dimension evident in the facial appearance, and alveolar bone resorption in the bilateral mandibular molars was confirmed. After endodontic treatment of the bilateral mandibular molars, recovery of the occlusal plane and occlusal vertical dimension was attained through occlusal reconstruction of the temporary dentures, mandibular overlay prosthesis, and the current maxillary complete denture. Based on the temporary dentures, recovery of the occlusal function was attained via a definitive prosthesis. Discussion: Acquisition of the appropriate occlusal plane and occlusal vertical dimension through the occlusal reconstruction of temporary dentures improved masticatory function. Conclusion: In cases of instability of maxillary complete denture caused by occlusal plane disorder and lower occlusal vertical dimension, the recovery of function via occlusal reconstruction of temporary dentures results in a good prognosis.

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Patient: The patient was a 50-year-old female who complained of masticatory and esthetic disturbance. The patient first visited AGU Hospital in 1993. Her remaining teeth showed many different types of clinical deterioration. These remaining teeth were used as the abutment teeth of the partial dentures. Magnetic attachments were selected for the prosthesis in order to maximize retention. Twenty years have passed since this treatment; the follow-up is reported here. Discussion: Because of the lowered load point on the abutment teeth through the introduction of a magnetic attachment system and the resulting improvement in the crown-root ratio of the teeth, abutment tooth mobility was improved. Consequently, the long-term prognosis has remained stable. Conclusion: Based on the stable long-term prognosis, we believe that this application of the magnetic attachment system for RPD has been successful.