Effect of Mechanical Cycling on Screw Torque in External Hexagon Implants with and without Platform Switching

This in vitro study evaluated the effect of mechanical cycling on the torque of retaining screw in external hexagon implants with platform switching (PS), regular platform (RP) and wide platform (WP). A total of 30 specimens were equally divided into 3 groups: PS, PR and WP. Each specimen was prepared with implants: 3.75 x 10 mm for RP group and 5.0x10 mm for PS and WP groups and its respective abutment with 32 Ncm torque. All groups were subjected to 106 cycles with 100 N (corresponding to about 40 months of chewing). The results were obtained with the reverse torque of each specimen and data were evaluated using ANOVA and Tukey test (p<0.05). The PS group showed statistically significant difference in screw removal torque (30.06±5.42) compared with RP (23.75±2.76) and WP (21.32±3.53) (p<0.05) groups; the RP and WP groups showed no statistically significant difference between them. It was concluded that the PS group showed higher reverse torque value, suggesting lower susceptibility of the abutment screw loosening.

本体外实验探究了机械循环载荷对三类外六角种植体固位螺钉扭矩的影响，三类种植体分别为平台切换（platform switching, PS）、常规平台（regular platform, RP）及宽平台（wide platform, WP）。本研究共制备30份标本，均分为PS、RP及WP三组。每组标本均配套对应规格的植入体与基台：RP组使用3.75×10 mm规格植入体，PS组与WP组使用5.0×10 mm规格植入体，初始扭矩均设置为32 Ncm。所有组别均接受10^6次循环载荷，载荷力为100 N（等效于约40个月的咀嚼负荷）。通过测定所有标本的反向扭矩获取实验数据，并采用方差分析（ANOVA）与Tukey检验进行统计学分析，检验水准设定为p<0.05。结果显示，PS组的螺钉拆卸扭矩为30.06±5.42，与RP组（23.75±2.76）及WP组（21.32±3.53）相比，组间差异具有统计学意义（p<0.05）；RP组与WP组之间未发现显著统计学差异。本研究结论表明，PS组的反向扭矩值更高，提示其基台螺钉松动的风险更低。