Gragg K L, Shugars D A, Bader J D, Elter J R, White B A
Department of Orthodontics, Center for Health Services Research, School of Dentistry, The University of North Carolina, Chapel Hill 27599-7450, USA.
J Dent Res. 2001 Nov;80(11):2021-4. doi: 10.1177/00220345010800111401.
Bounded edentulous spaces (BES)-a missing posterior tooth with intact adjacent teeth-are thought to lead to arch collapse resulting from the movement of adjacent teeth. To determine the rate of change in distance between teeth adjacent to a BES, we examined three successive measurable radiographs of 116 untreated posterior BES cases. The distance between the teeth (DBT) adjacent to the space was measured, and change in DBT (delta DBT) between pre-extraction and follow-up radiographs was calculated. We used linear spline regression to construct models for tooth movement and to identify factors associated with delta DBT. The mean delta DBT was < 1 mm during the first year post-extraction, and the DBT continued to decrease at a successively slower rate each following year. Overall and for each tooth type, the greatest rates of decrease in DBT were seen in the zero to two-year period. In a multivariable model, time since extraction and tooth type were significantly associated with delta DBT. These findings suggest that movement of teeth adjacent to a posterior BES after the first two years is usually gradual and minor within the time frame of this study.
局限性无牙间隙（BES）——一颗后牙缺失而相邻牙齿完好——被认为会因相邻牙齿的移动导致牙弓塌陷。为了确定与BES相邻牙齿之间距离的变化率，我们检查了116例未经治疗的后牙BES病例的三张连续可测量的X光片。测量了与间隙相邻牙齿之间的距离（DBT），并计算了拔牙前和随访X光片之间DBT的变化（δDBT）。我们使用线性样条回归构建牙齿移动模型，并确定与δDBT相关的因素。拔牙后第一年的平均δDBT小于1毫米，随后每年DBT继续以逐渐减慢的速度下降。总体而言，对于每种牙齿类型，DBT下降最快的是在零至两年期间。在多变量模型中，拔牙后的时间和牙齿类型与δDBT显著相关。这些发现表明，在本研究的时间范围内，后牙BES相邻牙齿在前两年后的移动通常是渐进的且较小。
