基牙不同牙周状况下球帽附着体义齿支持组织的应力分析

目的探讨基牙牙周组织不同程度吸收对球帽附着体义齿支持组织VonMises等效应力的影响。方法分别建立基牙牙周组织正常、吸收1／4、吸收1／3、吸收1／2的球帽附着体义齿模型，采用垂直向加载力300N，分析支持组织的VonMises等效应力变化。结果随着基牙牙周组织的吸收基牙应力集中区逐渐扩大，以根尖区扩大较明显，第二前磨牙颈部出现高应力区，最大VonMises等效应力分别为25．6962MPa、27．2047MPa、34．4062MPa、47．3841MPa；牙周膜根尖应力集中区也逐渐扩大；而缺牙区牙槽嵴的应力变化较小。结论基牙牙周组织吸收小于1／3时，支持组织应力逐渐增加，采取相应的措施减小验力，仍可使用球帽附着体义齿修复。吸收1／2时支持组织高应力区应力变化显著，对于此情况不建议采用球帽附着体义齿修复。

Stress Analysis of Bail - cap Attachment Denture Supporting Tissue with Different Abutment Periodontal Quantities

Objective To investigate the influence of varying degrees of abutment periodontal tissue absorption on the Von Mises equivalent stress of ball - cap attachment denture supporting tissue. Methods Ball - cap attachment denture models of normal, 1/4,1/3 and 1/2 ab- sorbexl periodontal tissues were built,respectlvely. The change of the Von Mises equivalent stress of supporting tissue was analyzed by emplo- ying a vertical loading force of 300N. Results With the absorption of abutment periodontal tissue, the stress concentration area and the api- cal periodontal ligment stress concentration.area were gradually expandod,particularly in the apical region. Smaller changes took place in the alveolar ridge stress in the edentulous region. A high stress area was found in the neck of the second premolar. The high Von Mises equiva- lent stresses were 25. 6962 MPa,27. 2047MPa,34. 4062MPa and 47. 3841 MPa, respectively. Conclusions The stress of supporting tissue increases gradually while the absorbed abutment periodontal tissue is less than 1/3 ball -cap attachment denture. Corresponding measures are taken to reduce the force of the teeth,and a ball -cap attachment denture can still be used to repair it. The high stress area of 1/2 ab- sorbed supporting tissue changes markedly. For this rcason,it is suggested that a ball -cap attachment denture should not be used to repair it.