Restorative Sciences, Baylor College of Dentistry, Texas A&M Health Science Center, Dallas, TX 75246, USA.
Am J Orthod Dentofacial Orthop. 2012 Jul;142(1):32-44. doi: 10.1016/j.ajodo.2012.01.016.
The primary aim of this study was to better understand how bone adapts to forces applied to miniscrew implants. A secondary aim was to determine whether the direction of force applied to miniscrew implants has an effect on bone surrounding the miniscrew implants.
A randomized split-mouth design, applied to 6 skeletally mature male foxhound dogs, was used to compare miniscrew implants loaded for 9 weeks with 200 or 600 g to unloaded control miniscrew implants. By using microcomputed tomography, with an isotropic resolution of 6 μm, bone volume fractions (bone volume/total volume) were calculated for bone around the entire miniscrew implant surface. Bone volume fractions were calculated for bone 6 to 24, 24 to 42, and 42 to 60 μm from the miniscrew implant surface. For each loaded miniscrew implant, the bone volume fraction was also calculated for 2 compression and 2 noncompression zones.
The 6 to 24-μm layer showed a significantly lower (P <0.05) bone volume fraction than did the 24 to 42-μm and the 42 to 60-μm layers, which were not significantly different. The bone volume fractions of cortical bone surrounding the apical aspects of the unloaded miniscrew implants were significantly greater (P <0.05) than the bone volume fractions of cortical bone surrounding the loaded miniscrew implants. In contrast, the bone volume fractions of noncortical bone surrounding loaded miniscrew implants were significantly greater (P <0.05) than the bone volume fractions of bone surrounding the unloaded miniscrew implants. Miniscrew implants loaded with 200 g showed significantly greater (P <0.05) amounts of noncortical bone volume fractions than did miniscrew implants loaded with 600 g. With both 200 and 600 g, zones under compression had significantly greater bone volume fractions than did the noncompression zones.
The application of force, the amount of force applied, and the direction of force all have significant effects on the amounts of bone produced around miniscrew implants.
本研究的主要目的是更好地了解骨骼如何适应施加在微型螺钉植入物上的力。次要目的是确定施加在微型螺钉植入物上的力的方向是否会影响微型螺钉植入物周围的骨骼。
本研究采用随机分侧设计，应用于 6 只骨骼成熟的雄性猎狐犬，比较了加载 9 周 200 克和 600 克的微型螺钉植入物与未加载的对照微型螺钉植入物。通过使用分辨率为 6 μm 的各向同性微计算机断层扫描，计算了整个微型螺钉植入物表面周围的骨体积分数（骨体积/总体积）。计算了距微型螺钉植入物表面 6 至 24 μm、24 至 42 μm 和 42 至 60 μm 处的骨体积分数。对于每个加载的微型螺钉植入物，还计算了 2 个压缩区和 2 个非压缩区的骨体积分数。
6 至 24 μm 层的骨体积分数明显低于（P <0.05）24 至 42 μm 层和 42 至 60 μm 层，而这两层之间没有显著差异。未加载微型螺钉植入物根尖区皮质骨的骨体积分数明显大于（P <0.05）加载微型螺钉植入物的皮质骨骨体积分数。相比之下，加载微型螺钉植入物周围的非皮质骨骨体积分数明显大于（P <0.05）未加载微型螺钉植入物周围的骨体积分数。加载 200 g 的微型螺钉植入物的非皮质骨体积分数明显大于（P <0.05）加载 600 g 的微型螺钉植入物。对于 200 和 600 g，受压区的骨体积分数明显大于非受压区。
力的应用、施加的力的大小以及力的方向都对微型螺钉植入物周围骨的生成量有显著影响。
