Kaci Nadir, Hakem Karima, Laraba Safia, Benrekaa Nasser, Le Gall Michel
Department of Dentofacial Orthopaedics, Tizi-Ouzou Hospital Centre, Department of Dental Medicine, University of Mouloud Mammeri, 15000 Tizi-Ouzou, Algeria.
Department of Dentofacial Orthopaedics, Tizi-Ouzou Hospital Centre, Department of Dental Medicine, University of Mouloud Mammeri, 15000 Tizi-Ouzou, Algeria.
Int Orthod. 2018 Jun;16(2):246-257. doi: 10.1016/j.ortho.2018.03.021. Epub 2018 Apr 6.
The aim of this study was to identify the fracture resistance of grade 23 Titanium mini-implants recycled for orthodontic purposes and having stayed in the mouth during different periods of time.
A total of 52 hybrid-designed titanium mini-implants, threaded length L=8mm, self-drilling and self-taping were used in 32 patients presenting orthodontic anomalies which required the use of mini-implants. Two types of tests were performed: polarizing optical imagery to assess the surface characteristics of the mini-implants (polarizing optical microscopy) and (mechanical) torsional strength tests, more quantitative, in order to establish the breaking point of the mini-implants during their re-use.
For the mini-implants which had been in the mouth for a short period of time, (immediate removal or after two months of use), it must be noted that their surface characteristics revealed no defect at micron scale, the drilling head did not show any alteration, with a breaking point record of about 53Newton/cm (N/cm). In contrast, the mini-implants, which had stayed in the mouth for 12 and 14 months, showed surface alterations especially at the "screw-gingiva" interface and the rupture stress ranges from 42 to 39N/cm, respectively.
Our results show that the resistance to fracture of the re-used mini-implants is inversely proportional to the duration of stay in the mouth.
本研究的目的是确定回收用于正畸目的且在口腔中停留不同时间的23级钛微型种植体的抗断裂性。
在32例需要使用微型种植体的正畸异常患者中，共使用了52颗混合设计的钛微型种植体，螺纹长度L = 8mm，自钻自攻。进行了两种类型的测试：偏振光学成像以评估微型种植体的表面特征（偏振光学显微镜）和（机械）扭转强度测试，该测试更具定量性，以便确定微型种植体在重复使用期间的断裂点。
对于在口腔中停留时间较短的微型种植体（立即取出或使用两个月后），必须注意的是，其表面特征在微米尺度上未显示缺陷，钻头未显示任何改变，断裂点记录约为53牛顿/厘米（N/cm）。相比之下，在口腔中停留12个月和14个月的微型种植体，表面出现改变，尤其是在“螺钉 - 牙龈”界面处，断裂应力分别为42至39N/cm。
我们的结果表明，重复使用的微型种植体的抗断裂性与在口腔中的停留时间成反比。
