Statement of problem

Angle-correcting options allow the use of screw-retained implant prostheses in situations where an implant has been placed with a facial inclination. However, manufacturers have different recommended torque values, and it is unclear whether the performance of these designs is equivalent to that of the traditional screw-retained crowns (SRCs) when subjected to cyclic loading forces.

Purpose

The purpose of this in vitro study was to compare torque differences between conventional straight-line screw access and angulated access SRCs before and after simulated functional loading.

Material and methods

Five groups consisting of 10 SRCs and implants were formed: Nobel Biocare zirconia crowns with 20-degree access channels (NB-20); Dynamic Abutment Solution zirconia crowns (DA-20) with 20-degree access channels; Core3dcentre angle correction zirconia crowns with 20-degree access channels (C3D-20); Nobel Biocare zirconia crowns with 0-degree access channels (NB-0); and gold alloy crowns cast to Nobel Biocare Gold-Adapt abutments (GA-0). Each specimen underwent thermocycling before cyclic loading. A preload torque based on the manufacturer’s recommendation was applied to each crown placed on an implant. Reverse torque measurements were obtained for each specimen before cyclic loading. Each implant-abutment assembly was then cyclic loaded at 0 to 100 N at 10 Hz for 1 million cycles. Reverse torque measurements were obtained after cyclic loading and the percentage difference calculated.

Results

No significant percentage torque loss differences were observed between the 0-degree and 20-degree SRCs after cyclic loading. No significant differences were seen among the angulated access channel crowns. DA-20 and C3D-20 specimens had significantly higher torque loss compared with the NB-0 group. The C3D-20 group reported the largest percentage torque loss (34.5%) among the angulated access screw channel groups. The GA-0 group reported the largest percentage torque loss of all the groups (35.9%). No crown mobility or other complications were observed in any of the groups after cyclic loading.

Conclusions

Angulated access channel crowns performed comparably with conventional straight-line screw access SRCs with regard to percentage torque values after cyclic loading. Angulated access channel crowns with lower manufacturer recommended torque values had higher percentage torque differences.

中文翻译：

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基台螺钉扭矩随直的和成角度的螺钉通道而变化

问题陈述

角度校正选项允许在植入物以面部倾斜放置的情况下使用螺钉固定的植入物假体。但是，制造商具有不同的推荐扭矩值，并且尚不清楚这些设计在承受周期性载荷时的性能是否等同于传统的螺丝固定式表冠（SRC）。

目的

这项体外研究的目的是比较模拟功能载荷前后常规直线螺钉通道和成角度通道SRC之间的扭矩差异。

材料与方法

形成了由10个SRC和植入物组成的五组：具有20度进入通道（NB-20）的Nobel Biocare氧化锆牙冠；带有20度通道的动态基台解决方案氧化锆冠（DA-20）；具有20度通道的Core3dcentre角校正氧化锆冠（C3D-20）; 带有0度进入通道（NB-0）的Nobel Biocare氧化锆王冠；以及铸造到Nobel Biocare黄金适配基台（GA-0）的金合金冠。在循环加载之前，每个样品都要进行热循环。将基于制造商建议的预紧扭矩施加到放置在植入物上的每个牙冠上。在循环加载之前，对每个样品都获得了反向扭矩测量值。然后，将每个植入物-基台组件以10 Hz的频率在0到100 N下循环加载1百万个周期。

结果

在循环加载后，0度和20度SRC之间没有观察到明显的百分比扭矩损失差异。在成角度的通道槽顶之间没有发现显着差异。与NB-0组相比，DA-20和C3D-20标本的扭矩损失明显更高。C3D-20组报告了成角度的通道螺钉通道组中最大的扭矩损失百分比（34.5％）。GA-0组报告了所有组中最大的扭矩损失百分比（35.9％）。在循环加载后的任何一组中均未观察到冠脉活动性或其他并发症。

结论

就循环载荷后的百分比扭矩值而言，成角度的通道槽冠与传统的直线螺钉通道SRC的性能相当。制造商建议的扭矩值较低的弯形通道顶冠具有较高的百分比扭矩差。