Cope J B, Yamashita J, Healy S, Dechow P C, Harper R P
TAMUS-Baylor College of Dentistry, Department of Orthodontics, Dallas, TX 75266-0677, USA.
J Oral Maxillofac Surg. 2000 Feb;58(2):171-8; discussion 178-9. doi: 10.1016/s0278-2391(00)90333-1.
Recent reports have demonstrated that device orientation is important during mandibular distraction osteogenesis. The purpose of this study was to evaluate the force level and strain patterns on the mandible during bilateral osteodistraction with devices oriented either parallel to the body of the mandible or parallel to the sagittal axis of distraction.
Five unembalmed human cadaver mandibles were placed in a specially designed apparatus for stabilization of the proximal segments during distraction. A force transducer was attached to the lateral aspect of the inferior ramus, and strain gauges were attached to the mandibular bone segments proximal and distal to the distraction device. Lateral force and bone strains were then measured at 5 and 10 mm of distraction. Osteodistraction proceeded first with the devices placed parallel to the mandibular body, then parallel to the axis of distraction.
Significantly greater lateral forces were seen when the devices were oriented parallel to the mandibular body. With this device orientation, increased tensile strains were seen at the labial symphysis and medial ramus, and increased compressive strains were found at the lingual symphysis and lateral ramus. However, when the devices were oriented parallel to the axis of distraction, the forces and strains were not detected.
The results suggest that device orientation has important biomechanical effects on lateral forces and strain patterns during mandibular osteodistraction.
近期报告表明，在下颌骨牵张成骨过程中，器械的方向很重要。本研究的目的是评估在下颌骨双侧骨牵张过程中，器械平行于下颌骨体或平行于牵张矢状轴时，下颌骨上的力水平和应变模式。
将五具未防腐处理的人类尸体下颌骨置于专门设计的器械中，以便在牵张过程中稳定近端节段。在下颌支外侧附着一个力传感器，并在牵张装置近端和远端的下颌骨节段上附着应变片。然后在牵张5毫米和10毫米时测量侧向力和骨应变。首先将器械平行于下颌骨体放置进行骨牵张，然后平行于牵张轴放置。
当器械平行于下颌骨体放置时，观察到明显更大的侧向力。在这种器械方向下，唇侧联合处和内侧下颌支出现拉伸应变增加，舌侧联合处和外侧下颌支出现压缩应变增加。然而，当器械平行于牵张轴放置时，未检测到力和应变。
结果表明，器械方向在下颌骨牵张成骨过程中对侧向力和应变模式具有重要的生物力学影响。
