Kondo Takayuki, Wakabayashi Noriyuki
Department of Removable Prosthodontics, School of Dentistry, Iwate Medical University, 1-3-27 Chuodori, Morioka, Iwate 020-8580, Japan.
J Dent. 2009 Jul;37(7):541-8. doi: 10.1016/j.jdent.2009.03.015. Epub 2009 Apr 19.
To test the hypothesis that loss of molar support causes increased stress and strain in the periodontal structures surrounding the premolars, and to assess the influence of denture use on stress distribution.
Subjects included female patients with unilateral and bilateral loss of mandibular molar teeth and controls with complete dentition (n=7 in each group). The subjects included had normal dentition mesial to the edentulous region and use of a lower free-end saddle removable partial denture. Occlusal contacts were registered in vivo, and a patient-specific finite element model was constructed for each subject based on morphological measurements of the diagnostic cast and radiographs. The maximum bite force on each tooth was then used to calculate the stress and strain on the cortical and the cancellous bone.
Mean maximum bite force and maximum principal stress and strain on periodontal tissues of the second premolars were significantly higher in the bilateral molar loss group than those in the other groups (p<0.05). The increase in stress could not be prevented by wearing dentures. The mean maximum stress and strain per bite force were relatively constant among the groups, indicating that the increased maximum stress and strain in the bilateral molar loss group was attributed to the higher maximum bite force.
The results suggest that the periodontium surrounding the most posteriorly located occluding premolars may become sensitive to bilateral loss of molar support when patients exhibit higher maximum bite forces.
验证磨牙支持丧失会导致前磨牙周围牙周结构应力和应变增加这一假设，并评估义齿使用对应力分布的影响。
受试者包括单侧和双侧下颌磨牙缺失的女性患者以及全口牙列完整的对照组（每组n = 7）。纳入的受试者在无牙区近中牙列正常，且使用下颌游离端鞍式可摘局部义齿。在体内记录咬合接触情况，并根据诊断模型和X线片的形态学测量为每个受试者构建特定患者的有限元模型。然后使用每颗牙齿上的最大咬合力来计算皮质骨和松质骨上的应力和应变。
双侧磨牙缺失组第二前磨牙牙周组织的平均最大咬合力、最大主应力和应变显著高于其他组（p<0.05）。佩戴义齿无法预防应力增加。每组中每咬合力的平均最大应力和应变相对恒定，表明双侧磨牙缺失组中最大应力和应变的增加归因于更高的最大咬合力。
结果表明，当患者表现出较高的最大咬合力时，最靠后的咬合前磨牙周围的牙周组织可能会对双侧磨牙支持丧失变得敏感。
