Montefiore Medical Center/Albert Einstein College of Medicine, Division of Prosthodontics, Department of Dentistry, Bronx, NY 10467, USA.
J Prosthodont. 2011 Jul;20(5):348-54. doi: 10.1111/j.1532-849X.2011.00714.x. Epub 2011 May 17.
To investigate the effects of internally connected engaging component position in screw-retained fixed cantilevered prostheses.
Twenty-one three-unit fixed dental prostheses (FDPs) were cast in high-palladium alloy in three groups. In group A, engaging components were incorporated into the units away from the cantilevered segment; proximal units received nonengaging components. In group B, these positions were reversed. Control specimens were fabricated using all nonengaging components. Specimens were attached to internally connected 3.5 (diameter) × 13 mm (length) implants, torqued to 32 Ncm, and embedded into epoxy resin. Specimens were tested in cyclic fatigue with a 2 Hz sine wave and 0.1 min/max load ratio. Load amplitude started at 1.8 N and increased by 1.8 N every 60 cycles until fracture. Log-rank statistic, ANOVA, Spearman's correlation, and LIFETEST procedures were used to evaluate level of statistical significance within the results.
In the control group, the mean number of cycles to fracture was 31,205 ± 2639. Mean axial force at fracture was 932 ± 78 N. In group A, these numbers were 38,160 ± 4292 and 1138 ± 128 N, and in group B, 31,810 ± 3408 and 949 ± 101 N. Statistical significance levels for number of cycles to fracture were: Control versus group A, p = 0.0117, and groups A versus B, p = 0.0156 (statistically significant). Control versus group B, p = 0.357 (not statistically significant). Log-rank statistic for the survival curves is greater than would be expected by chance; there was a statistically significant difference between survival curves (p = 0.012). The location and mode of failure were noteworthy (always in the abutment screw).
The position of the engaging component had significant effects on the results. Within the limitations of this investigation, it can be concluded that using an engaging abutment in a screw-retained fixed cantilevered FDP provides a mechanical advantage, and engaging the implant furthest from the cantilever when designing a screw-retained cantilever FDP increased resistance to fracture of the distal abutment screw.
研究螺丝固位式固定单端桥中内部连接的嵌合部件位置的影响。
将 21 个三单位固定义齿（FDP）铸造成高钯合金，分为三组。在 A 组中，嵌合部件被纳入远离悬臂段的单位；近位单位接收非嵌合部件。在 B 组中，这些位置相反。使用所有非嵌合部件制造对照标本。将标本附着到内部连接的 3.5（直径）×13mm（长度）种植体上，以 32Ncm 的扭矩拧紧，并嵌入到环氧树脂中。在循环疲劳试验中，使用 2Hz 正弦波和 0.1min/max 负载比对标本进行测试。负载幅度从 1.8N 开始，每隔 60 个循环增加 1.8N，直到断裂。对数秩检验、方差分析、Spearman 相关和 LIFETEST 程序用于评估结果中的统计显著性水平。
在对照组中，断裂的平均循环次数为 31205±2639。断裂时的平均轴向力为 932±78N。在 A 组中，这些数字分别为 38160±4292 和 1138±128N，在 B 组中，这些数字分别为 31810±3408 和 949±101N。断裂循环次数的统计显著性水平为：对照组与 A 组，p=0.0117，A 组与 B 组，p=0.0156（具有统计学意义）。对照组与 B 组，p=0.357（无统计学意义）。生存曲线的对数秩检验大于随机预期；生存曲线之间存在显著差异（p=0.012）。失效的位置和模式值得注意（总是在基牙螺丝上）。
嵌合部件的位置对结果有显著影响。在本研究的限制范围内，可以得出结论，在螺丝固位式固定单端桥中使用嵌合基牙提供了机械优势，并且在设计螺丝固位式悬臂 FDP 时，将最远离悬臂的种植体嵌合，可以增加远侧基牙螺丝断裂的抵抗力。
