Faculdade de Medicina Dentária, Universidade do Porto, Porto, Portugal.
J Esthet Restor Dent. 2022 Dec;34(8):1147-1155. doi: 10.1111/jerd.12959. Epub 2022 Sep 2.
The prosthetic screw fixes the prostheses to the implants. Upon osteointegration, the untightening of the prosthetic screw is the most common problem in oral rehabilitation with implants.
To study the deformation of the implant retaining hexagonal screw head.
This investigation used two methods for evaluating the screw head's area of deformation (mm ): a stereoscopic microscopy and micro computed tomography (microCT). For stereoscopic microscopy, 16 titanium alloy (T) and 16 titanium gold-plated alloy (G) screws of the Zimmer Biomet™ brand were used, divided into eight groups: group 0 (control group), groups T1 and G1 (screws tightened 10 times to 20 Ncm), the groups T2 and G2 (screws tightened 20 times to 20 Ncm) and the groups T3 and G3 (screws tightened 10 times to 30 Ncm). In the study with microCT, one screw was randomly chosen from each of the groups described above to perform the scanning by microCT.
When comparing the type of screw material using stereoscopic microscopy, no statistically significant differences were found (p > 0.05). Contrarily, different number of successive grips and different torque value showed statistically significant differences in the head section of the retaining screws (p < 0.05). The observation by microCT showed the torque applied is crucial to the head deformation in titanium screws. In gold-plated screws the successive tightening appears to be pivotal.
Titanium and gold screws tend to behave similarly. By increasing the tightening cycles and the torque values of protocols greater levels of deformations can be expected. In general, microCT data showed better results for gold-plated titanium alloy.
To control severe screw head deformation and the impossibility of untightening the implant's restoration, clinicians should avoid extreme torque values and prevent surpassing 10 tightening cycles.
种植体上的修复体通过修复螺丝固定。在骨整合后，种植体修复中最常见的问题是修复螺丝松动。
研究种植体固位六角螺丝头的变形。
本研究采用两种方法评估螺丝头变形面积（mm）：立体显微镜和微计算机断层扫描（microCT）。立体显微镜检查中，使用了 16 个 Zimmer Biomet 品牌的钛合金（T）和 16 个镀金钛合金（G）螺丝，分为 8 组：第 0 组（对照组）、第 T1 和 G1 组（拧紧 10 次至 20 Ncm）、第 T2 和 G2 组（拧紧 20 次至 20 Ncm）以及第 T3 和 G3 组（拧紧 10 次至 30 Ncm）。在 microCT 研究中，从上述每组中随机选择一个螺丝进行 microCT 扫描。
使用立体显微镜比较螺丝材料类型时，未发现统计学差异（p>0.05）。相反，不同数量的连续夹持和不同的扭矩值对固位螺丝头部有统计学差异（p<0.05）。microCT 观察表明，施加的扭矩对钛螺丝头部变形至关重要。镀金螺丝中，连续拧紧似乎是关键。
钛和镀金螺丝的行为趋于相似。通过增加紧固周期和扭矩值，可以预期更高水平的变形。一般来说，microCT 数据显示镀金钛合金的结果更好。
为了控制严重的螺丝头变形和无法松动种植体修复体，临床医生应避免极端扭矩值，并防止超过 10 次拧紧周期。
