Pedodontics and Orthodontics Department, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
Braz Oral Res. 2011 Sep-Oct;25(5):427-32. doi: 10.1590/s1806-83242011000500009.
Primary stability is absence of mobility in the bone bed after mini-implant placement and depends on bone quality among other factors. Bone quality is a subjective term frequently considered as bone density. The aim of this preliminary study was to evaluate bone density in two bovine pelvic regions and verify the primary stability of miniscrews inserted into them. Forty bone blocks were extracted from bovine pelvic bones, 20 from iliac and 20 from pubic bone, all of them containing cortical bone about 1 mm thick. Half of the sections extracted from each bone were designated for histological evaluation of bone density (trabecular bone area - TBA) and the other half for bone mineral density (BMD) evaluation by means of central dual-energy X-ray absorptiometry (DEXA). Then, twenty self-drilling miniscrews (INP®, São Paulo, Brazil) 1.4 mm in diameter and 6 mm long were inserted into the bone blocks used for BMD evaluation. Peak implant insertion torque (IT) and pull-out strength (PS) were used for primary stability evaluation. It was found that iliac and pubic bones present different bone densities, iliac bone being less dense considering BMD and TBA values (P > 0.05). However, the miniscrew primary stability was not different when varying the bone type (P < 0.05). IT and PS were not influenced by these differences in bone density when cortical thickness was about 1 mm thick.
初级稳定性是指微型种植体植入后在骨床内无活动度，取决于骨质量等因素。骨质量是一个主观术语，常被认为是骨密度。本初步研究旨在评估两个牛骨盆区域的骨密度，并验证植入其中的微型螺钉的初级稳定性。从牛骨盆骨中提取了 40 块骨块，20 块来自髂骨，20 块来自耻骨，所有骨块都包含约 1 毫米厚的皮质骨。从每个骨块提取的一半部分用于评估骨密度的组织学（骨小梁面积-TBA），另一半部分用于通过中央双能 X 射线吸收法（DEXA）评估骨矿物质密度（BMD）。然后，将 20 个自攻微型螺钉（INP®，巴西圣保罗）插入用于 BMD 评估的骨块中，直径为 1.4 毫米，长 6 毫米。峰值种植体插入扭矩（IT）和拔出强度（PS）用于评估初级稳定性。发现髂骨和耻骨具有不同的骨密度，考虑到 BMD 和 TBA 值，髂骨的密度较低（P>0.05）。然而，当改变骨类型时，微型螺钉的初级稳定性没有差异（P<0.05）。当皮质厚度约为 1 毫米时，IT 和 PS 不受这些骨密度差异的影响。
