Department of Prosthodontics, Dental School, Ludwig-Maximilian-University Munich, Germany.
Clinic of Preventive Dentistry, Periodontology and Cariology, Center of Dental Medicine, University of Zurich, Switzerland.
J Prosthodont. 2018 Feb;27(2):162-168. doi: 10.1111/jopr.12482. Epub 2016 Apr 1.
To investigate the retention loads of differently fabricated secondary telescopic polyetheretherketone (PEEK) crowns on cobalt-chromium primary crowns with different tapers.
Cobalt-chromium primary crowns with 0°, 1°, and 2° tapers were constructed, milled, and sintered. Corresponding secondary crowns were fabricated by milling, pressing from pellets, and pressing from granules. For these nine test groups, the pull-off tests of each crown combination were performed 20 times, and the retention loads were measured (Zwick 1445, 50 mm/min). Data were analyzed using linear regression, covariance analysis, mixed models, Kruskal-Wallis, and Mann-Whitney U-test, together with the Benferroni-Holm correction.
The mixed models covariance analysis reinforced stable retention load values (p = 0.162) for each single test sequence. There was no interaction between the groups and the separation cycles (p = 0.179). Milled secondary crowns with 0° showed the lowest mean retention load values compared to all tested groups (p = 0.003) followed by those pressed form pellets with 1°. Regarding the different tapers, no effect of manufacturing method on the results was observed within 1° and 2° groups (p = 0.540; p = 0.052); however, among the 0° groups, the milled ones showed significantly the lowest retention load values (p = 0.002). Among the manufacturing methods, both pressed groups showed no impact of taper on the retention load values (p > 0.324 and p > 0.123, respectively), whereas among the milled secondary crowns, the 0° taper showed significantly lower retention load values than the 1° and 2° taper (p < 0.002).
Based on these results, telescopic crowns made of PEEK seem to show stable retention load values for each test sequence; however, data with thermo-mechanical aging are still required. In addition, further developments in CAD/CAM manufacturing of PEEK materials for telescopic crowns are warranted, especially for 0°.
研究不同锥度钴铬基冠上不同制作的二次聚醚醚酮（PEEK）套筒冠的固位力。
制作 0°、1°和 2°锥度的钴铬基基牙，铣削、烧结。通过铣削、粒料压制和粒料压制成型制作相应的二次冠。对这 9 个实验组的每种冠组合进行 20 次拉脱试验，测量固位力（Zwick 1445，50mm/min）。采用线性回归、协方差分析、混合模型、Kruskal-Wallis 和 Mann-Whitney U 检验，结合 Benferroni-Holm 校正对数据进行分析。
混合模型协方差分析加强了各单组试验序列稳定的固位力值（p=0.162）。组间和分离循环之间没有相互作用（p=0.179）。与所有测试组相比，0°铣削成型的二次冠具有最低的平均固位力值（p=0.003），其次是 1°粒料压制成型的二次冠。关于不同的锥度，在 1°和 2°组内，制造方法对结果没有影响（p=0.540；p=0.052）；然而，在 0°组内，铣削成型的二次冠显示出明显较低的固位力值（p=0.002）。在制造方法中，两种压制成型的二次冠的锥度对固位力值均没有影响（p＞0.324 和 p＞0.123），而铣削成型的二次冠的 0°锥度的固位力值明显低于 1°和 2°锥度（p＜0.002）。
基于这些结果，聚醚醚酮制成的伸缩冠在每个试验序列中似乎表现出稳定的固位力值；然而，仍需要热机械老化的数据。此外，需要进一步开发 CAD/CAM 制造聚醚醚酮材料的伸缩冠，特别是 0°的。
