Faculty of Odontology, UFR of Odontology, Paris 7 University, France.
J Prosthet Dent. 2012 Mar;107(3):191-8. doi: 10.1016/S0022-3913(12)60055-9.
Matrices of unsplinted attachment systems are generally reported to be the weak component of implant overdentures, often requiring frequent maintenance. Clinical wear results in reduced retention of the prosthesis, requiring activation or renewal of the matrix to restore the initial level of retention.
The purpose of this retrospective study was to measure the wear of the matrix of a ball attachment after various periods of clinical wear.
Seventy specimens of 3 groups of matrices of ball attachments that had been in use for mean periods of 12.3 months (1Y group, n=26), 39.0 months (3Y group, n=28) and 95.6 months (8Y group, n=16) were retrieved from 35 patients (2 specimens per patient) and measured on a coordinate measuring machine equipped with a touch trigger probe. Ten unused matrices were used as controls (CTRL group). The external and internal matrix diameters and deviations from circularity were measured. For the various time periods, the decreases in matrix thickness were calculated and compared with controls. Kruskal-Wallis 1-way ANOVA by ranks, followed by the Mann-Whitney post hoc tests, were conducted to test for differences in median values among groups (α =.05).
For the internal upper diameter of the matrices tested, the Kruskal-Wallis and Mann-Whitney tests revealed significant differences for the 3 groups compared to the controls. For group 1Y, a significant difference (P<.001) of the internal upper diameter was found compared to the CTRL group. Compared to the controls, the nonparametric analyses for groups 3Y and 8Y showed significant differences for the internal upper diameter (P<.001) and deviations from circularity (P<.001). For groups 1Y, 3Y and 8Y, matrix thickness losses were 07, 47 and 70 μm, respectively.
Within the limitations of this study, it was observed that one year of clinical wear had limited effect on the ball attachment matrices. Three to 8 years of clinical use resulted in a significant decrease of matrix thickness, especially at the tip of the retentive lamellae.
未夹板式附着体系统的基质通常被认为是种植覆盖义齿的薄弱部件，往往需要频繁维护。临床使用导致义齿的固位力降低，需要激活或更新基质以恢复初始的固位力。
本回顾性研究的目的是测量球附着体的基质在不同临床使用时间后的磨损情况。
从 35 名患者（每名患者 2 个样本）中取出 3 组球附着体基质的 70 个样本，使用时间分别为 12.3 个月（1Y 组，n=26）、39.0 个月（3Y 组，n=28）和 95.6 个月（8Y 组，n=16）。使用坐标测量机和触针探头对样本进行测量。10 个未使用的基质作为对照组（CTRL 组）。测量了基质的外部和内部直径以及圆度偏差。计算了各个时间段基质厚度的减少量，并与对照组进行比较。采用 Kruskal-Wallis 1 路方差分析（等级），然后进行 Mann-Whitney 事后检验，检验组间中位数的差异（α=0.05）。
对于所测试的基质内部上直径，Kruskal-Wallis 和 Mann-Whitney 检验显示 3 组与对照组相比有显著差异。对于 1Y 组，与 CTRL 组相比，内部上直径有显著差异（P<.001）。与对照组相比，3Y 和 8Y 组的非参数分析显示内部上直径（P<.001）和圆度偏差（P<.001）有显著差异。对于 1Y、3Y 和 8Y 组，基质厚度损失分别为 0.7μm、4.7μm 和 7.0μm。
在本研究的限制范围内，观察到临床使用 1 年对球附着体基质的影响有限。3 至 8 年的临床使用导致基质厚度显著减少，特别是在保持瓣的尖端。
