Wilmes Benedict, Su Yu-Yu, Sadigh Lilian, Drescher Dieter
Poliklinik für Kieferorthopädie, Heinrich Heine Universität Düsseldorf, Moorenstrasse 5, Düsseldorf, Germany.
J Orofac Orthop. 2008 Jan;69(1):51-8. doi: 10.1007/s00056-008-0726-5.
The use of mini-implants for skeletal anchorage has greatly broadened the therapeutic spectrum in orthodontics over the last few years. The alveolar ridge is the most frequent insertion site, which however is associated with tooth injury, a risk not to be underestimated. The objective of this study was to examine the quantitative parameters of pre-drilling and implant insertion in association with the degree of a root contact.
Eleven lower jaw bones of adult pigs were prepared and embedded in resin. At 320 sites in the toothbearing alveolar ridge a 1.3 mm pre-drilling was carried out up to the complete implant length. The vertical force exerted against the pre-drilling upon penetration of the different bone layers and at a root contact was measured at a drift-speed of 0.5 mm/s. Dual Top screws (1.6 x 8 mm) were then inserted into the prepared implant sites, the insertion torques were measured, and recorded as a function of the rotation angle. After explantation, we prepared histological slides from the level of the implant's maximum diameter. The implant's contact with cortical and cancellous bone and to the roots was measured and correlated to vertical pre-drilling forces and insertion torques.
Vertical pre-drilling forces and insertion torques of orthodontic mini-implants varied in relation to the type of tissue penetrated and the degree of root contact. The insertion torques ranged from 32 to 345 Nmm and pre-drilling forces up to 6 N overall.
Root contact can be recognized during pre-drilling by a distinct increase in resistance, and during mini-implant insertion by higher torques.
在过去几年中，使用微型种植体进行骨骼锚固极大地拓宽了正畸治疗的范围。牙槽嵴是最常见的植入部位，然而这与牙齿损伤相关，这种风险不容小觑。本研究的目的是研究预钻孔和种植体植入的定量参数与牙根接触程度的关系。
准备11块成年猪的下颌骨并嵌入树脂中。在含牙牙槽嵴的320个部位进行1.3毫米的预钻孔，深度达到种植体的全长。以0.5毫米/秒的漂移速度测量在穿透不同骨层以及与牙根接触时施加在预钻孔上的垂直力。然后将双头顶丝（1.6×8毫米）插入准备好的种植部位，测量插入扭矩，并记录为旋转角度的函数。取出后，从种植体最大直径水平制备组织学切片。测量种植体与皮质骨、松质骨以及牙根的接触情况，并将其与垂直预钻孔力和插入扭矩相关联。
正畸微型种植体的垂直预钻孔力和插入扭矩因穿透的组织类型和牙根接触程度而异。插入扭矩范围为32至345牛毫米，预钻孔力总体上高达6牛。
在预钻孔过程中，通过阻力的明显增加可识别牙根接触，在微型种植体植入过程中，通过较高的扭矩可识别牙根接触。
