Reeh E S, Ross G K
Minnesota Dental Research Center for Biomaterials and Biomechanics, University of Minnesota, School of Dentistry, Minneapolis 55455, USA.
Dent Mater. 1994 Jul;10(4):247-52. doi: 10.1016/0109-5641(94)90069-8.
This study was conducted to determine the impact of composite veneer procedures on the functional properties of incisors.
Ten extracted human maxillary central incisors were mounted in pairs in a nylon ring. One strain gauge was bonded along the long axis of each tooth on the center of the lingual surface. Each pair formed half of a Wheatstone bridge circuit and was wired to eliminate all but the voltage resulting from experimentally applied procedures. The teeth were ramp-loaded to 50 N near the incisal edge on the lingual surface. Loading was performed on the unaltered teeth, teeth with preparations and restored teeth. Two-dimensional finite element (FE) models were generated to evaluate each test condition. Relative stiffness, compared with the unaltered tooth, was calculated from measurements with the strain gauge steps and from the FE models.
A relative stiffness value of unity represents recovery of stiffness to the level of the unaltered tooth. Both methods of evaluation demonstrated a decrease in mean relative stiffness with each subsequent reduction in tooth structure. The composite restoration increased its mean relative stiffness compared to its corresponding preparation but never to the level of the unaltered tooth. Across all procedures, the two-dimensional FE model correlated well in both direction and magnitude with the experimental strain gauge method (R = 0.83).
A resin composite veneer does not restore the stiffness to the level of an unaltered tooth.
本研究旨在确定复合贴面修复程序对中切牙功能特性的影响。
将十颗拔除的人类上颌中切牙成对安装在尼龙环中。在每颗牙齿舌面中心沿长轴粘贴一个应变片。每对牙齿构成惠斯通电桥电路的一半，并进行布线以消除除实验施加程序产生的电压之外的所有电压。在舌面切缘附近对牙齿施加斜坡加载至50 N。对未处理的牙齿、有预备体的牙齿和修复后的牙齿进行加载。生成二维有限元（FE）模型以评估每种测试条件。与未处理的牙齿相比，相对刚度通过应变片测量步骤和FE模型计算得出。
相对刚度值为1表示刚度恢复到未处理牙齿的水平。两种评估方法均表明，随着牙齿结构的每次后续减少，平均相对刚度都会降低。与相应的预备体相比，复合修复体增加了其平均相对刚度，但从未达到未处理牙齿的水平。在所有程序中，二维FE模型在方向和大小上与实验应变片方法的相关性都很好（R = 0.83）。
树脂复合贴面不能将刚度恢复到未处理牙齿的水平。
