Castaño F J, Troulis M J, Glowacki J, Kaban L B, Yates K E
Skeletal Biology Research Center and Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, Harvard School of Dental Medicine, Boston 02129, USA.
J Oral Maxillofac Surg. 2001 Mar;59(3):302-7. doi: 10.1053/joms.2001.21000.
Long-term success of distraction osteogenesis depends on the ability of the surrounding soft tissues to tolerate distraction forces and to adapt to the resulting increase in skeletal length and volume. The hypothesis tested in this study was that mandibular elongation by distraction induces myocyte proliferation.
Unilateral mandibular angle osteotomies were performed in 16 Yucatan minipigs. The hemimandibles were lengthened using semiburied distraction devices (Synthes Maxillofacial, Paoli, PA) with 0-day latency, 1, 2, or 4 mm/d distraction rates, and a neutral fixation period of twice the gap size in days. In 2 additional animals, the dissection and osteotomies were performed, and distraction devices were placed without activation (sham control). At the end of neutral fixation, tissues were taken from masseter muscle overlying the osteotomy and the equivalent region on the unoperated side (contralateral control). Proliferation of myocytes was estimated using immunohistochemical localization with antibodies against proliferating cell nuclear antigen (PCNA).
Muscle overlying the distracted mandible showed 6-fold more PCNA-positive myocytes (16.8% +/- 11.3%) than the contralateral control side (2.8% +/- 1.1%, P < .0001). In the 2 sham-control animals, there was a low index of PCNA-positive myocytes on both the osteotomy (2%, 5%) and the contralateral sides (1%, 2%).
The results of this study suggest that distraction of the porcine mandible by the protocol described induces myocyte proliferation in the masseter muscle. A proliferative response may contribute to improved long-term stability of mandibular expansion by distraction osteogenesis.
牵张成骨的长期成功取决于周围软组织耐受牵张力并适应骨骼长度和体积增加的能力。本研究检验的假设是牵张诱导下颌骨延长会引起肌细胞增殖。
对16只尤卡坦小型猪进行单侧下颌角截骨术。使用半埋式牵张装置（Synthes颌面公司，宾夕法尼亚州波利）延长半侧下颌骨，延迟期为0天，牵张速率为每天1、2或4毫米，中立固定期为间隙大小（以天为单位）的两倍。另外2只动物进行解剖和截骨术，放置牵张装置但不激活（假手术对照）。在中立固定结束时，从截骨部位上方的咬肌以及未手术侧（对侧对照）的相应区域取材。使用抗增殖细胞核抗原（PCNA）抗体通过免疫组织化学定位评估肌细胞增殖情况。
牵张侧下颌骨上方的肌肉中PCNA阳性肌细胞数量（16.8%±11.3%）比对侧对照侧（2.8%±1.1%，P<.0001）多6倍。在2只假手术对照动物中，截骨侧（2%，5%）和对侧（1%，2%）的PCNA阳性肌细胞指数均较低。
本研究结果表明，按照所述方案牵张猪下颌骨会诱导咬肌中的肌细胞增殖。增殖反应可能有助于通过牵张成骨改善下颌骨扩张的长期稳定性。
