Jiang Ting, Ai Minoru
School of Stomatology, Peking University, Beijing, China, Tokyo Medical and Dental University, Tokyo, Japan.
J Oral Rehabil. 2002 Feb;29(2):201-8. doi: 10.1046/j.1365-2842.2002.00815.x.
Lower rigidly connected long span bridges supported by natural abutments or implants sometimes become loose, come off, or fracture after a period of usage. Many reasons have been discussed for these failures. However, few researchers have shown the influence of mandibular elastic deformation on the abutments, although this influence is likely to produce a distortion force between the abutment and prosthesis. Therefore, this study measured the elastic deformation of the human mandibular arch during clenching on pivots by using charge-coupled device (CCD) cameras and an image analysing system. When the subjects clenched on the canines (unilaterally or bilaterally) or bilateral second molars, no mandibular deformation was found; whereas when the subjects clenched on the unilateral second molars, the mandibular arch on the non-pivot side moved upward and inward and the straight line distances between the right and left measurement points decreased by 0.2 mm. The magnitude of deformation is smaller than the depressible limit of periodontal membrane. This suggests that the influence of mandibular deformation on the connected prosthesis is negligible in the case of the natural root supported long span bridge but should probably be considered in the case of the implant supported bridge.
由天然基牙或种植体支持的下部刚性连接的大跨度桥体在使用一段时间后有时会松动、脱落或折断。针对这些失败情况已经讨论了许多原因。然而，很少有研究人员展示下颌弹性变形对基牙的影响，尽管这种影响很可能在基牙与修复体之间产生一种扭曲力。因此，本研究通过使用电荷耦合器件（CCD）相机和图像分析系统，测量了人体下颌牙弓在枢轴点咬合时的弹性变形。当受试者单侧或双侧在尖牙处咬合或双侧在第二磨牙处咬合时，未发现下颌变形；而当受试者单侧在第二磨牙处咬合时，非枢轴侧的下颌牙弓向上向内移动，左右测量点之间的直线距离减小了0.2毫米。变形幅度小于牙周膜的可压缩极限。这表明，对于天然牙根支持的大跨度桥体，下颌变形对连接的修复体的影响可忽略不计，但对于种植体支持的桥体，可能应该予以考虑。
