Abstract

BACKGROUND: TiNi shape memory alloy (TiNi-SMA) distractor can be buried completely, there is no time delay and it is different from other distractors previously used. Therefore, it is necessary to reevaluate the osteogenetic time and quality.
OBJECTIVE: To investigate the quality of the alveolar ridge augmented by TiNi-SMA distractor by bone mineral density (BMD) and biodynamics tests of new-formed bone.
DESIGN: Randomized controlled observation.
SETTING: Department of Stomatology of General Hospital of Chinese PLA.
MATERIALS: Twelve healthy adult male mongrel canines (ranged from 21 to 26 kg) were provided and bred by Medical Experimental Animal Center of General Hospital of Chinese PLA. All the animals were accorded with the requirements of the quarantine and animal ethnics. Self-made distractors were used in the study. XR-36 Dual Energy X-Ray Absorptiometry (Norland, USA) and 858 Mini Bionix Ⅱ Biomaterial Testing Machine (MTS, USA) were used in the study.
METHODS: The experiments were performed at the Medical Experimental Animal Center of General Hospital of Chinese PLA from July 2000 to May 2004. The animals were grouped into group Ⅰ(3 months group) and group Ⅱ (6 months group) randomly with 6 animals in each group. The left mandible was used as experimental side and the right was used as control side. The canines were killed after anaesthesia at 3 or 6 months later in both groups. After the mandible samples were cut, the BMD of three points in the distraction gap, above the distraction gap and below the distraction gap were measured by dual energy X-ray. Compressive biomechanics test was performed in the middle of the distraction area of the experimental side and the corresponding area of the control side to detect compressive stress and the modulus of elasticity.
MAIN OUTCOME MEASURES: ①BMD of the distraction area of the experimental side and the control side in the group Ⅰ and group Ⅱ. ②Compressive strength and modulus of elasticity of the mandibles of the experimental side and the control side.
RESULTS: All of the 12 experimental canines were included in the final analysis, no drop-out. BMD determination: BMD was lower in above the distraction gap of the mandibles of the experimental side than in the control side in the group Ⅰ (t=-2.898，P < 0.05). There was no significant difference in BMD between both sides in the group Ⅱ (P > 0.05). Compressive biomechanics test: Compressive stress and the modulus of elasticity of the mandibles on the experimental side were lower than on the control side in the group Ⅰ (t =-3.274，-3.534, P < 0.05). All indexes increased by some degree in the group Ⅱ compared to the group Ⅰ (P > 0.05).
CONCLUSION: The new bone is strong enough for later repair such as implantation after distraction osteogenesis using TiNi-SMA distractor.

1Department of Stomatology, 309 Clinical Division of General Hospital of Chinese PLA, Bei-jing 100091, China; 2Department of Stomatology, General Hospital of ChinesePLA, Beijing 100835, China

Xie Min☆, Doctor, Associate chief physician, Depart-ment of Stomatology, 309 Clinical Division of General Hospital of Chinese PLA, Beijing 100091, China
Xiemem2001@
hotmail.com

Supported by: the National Natural Science Foundation of China, No. 30171017*; the Natural Science Foundation of Bei-jing City, No. 7042058*

Received:2007-10-30 Accepted:2008-02-04 (07-50-10-5939/YWY)

Xie M, Hu M, Liu HC, Yao J, Zhou HZ.Bone mineral density and biome-chanics test after distraction osteo-genesis using TiNi-shape memory alloy distractor. Zhongguo Zuzhi Gongcheng Yanjiu yu Linchuang Kangfu 2008;12(17):3385-
3388(China)

[www.zglckf.com/
zglckf/ejournal/
upfiles/08-17/
17k-3385(ps).pdf]

钛镍记忆合金牵张成骨的骨密度及生物力学测试**☆

摘要
背景：钛镍记忆合金牵张器采用保留舌侧部分骨皮质的截骨方式，没有间歇期，与以往其他牵张器方法有所不同，因此对该方法成骨时间及质量都需要进行重新评价。
目的：通过对新生骨密度和生物力学测试观察钛镍记忆合金牵张器牵张成骨效果。
设计：随机对照观察。
单位：解放军总医院口腔科。
材料：选用雄性健康成年杂种犬12只，体质量21~26 kg，由解放军总医院医学实验动物中心提供并饲养。实验过程中对动物的处置符合动物伦理学标准。实验用牵张器为自行研制。XR－36型双能X线骨密度仪为美国Norland公司生产。858 Mini Bionix II型生物材料实验机为美国MTS公司生产。
方法：实验于2000-07/2004-05在解放军总医院医学实验动物中心完成。①采用统计软件随机法将实验犬分为牵张3个月组和牵张6个月组，每组各6只。两组实验犬左侧下颌骨均为实验侧，右侧下颌骨为自身对照侧。②牵张3个月组和牵张6个月组分别于牵张完成后3，6个月麻醉后处死实验犬，切取下颌骨标本，对牵张间隙上方、牵张间隙及牵张间隙下方进行双能X线骨密度测量，同时切取实验侧牵张侧区域中段及对照侧相应部位进行压缩生物力学测试，计算抗压强度、弹性模量。
主要观察指标：①牵张3个月组和牵张6个月组实验犬牵张侧及对照侧下颌骨密度测量结果。②实验侧牵张侧区域中段及对照侧相应部位抗压强度、弹性模量。
结果：纳入实验犬12只，12只均进入结果分析，无脱落。①下颌骨密度测量结果：牵张3个月组实验犬下颌骨牵张侧牵张间隙上方骨密度低于对照侧，差异有显著性意义(t=-2.898，P < 0.05)。牵张6个月组实验犬两侧各区域间的骨密度差异均无显著性意义(P > 0.05)。②压缩生物力学检测结果：牵张3个月组实验犬下颌骨牵张侧抗压强度、弹性模量均低于对照侧，差异有显著性意义（t=-3.274，-3.534, P < 0.05）。牵张6个月组实验犬两指标较牵张3个月组均有增加，差异无统计学意义（P > 0.05）。
结论：使用全埋置的钛镍记忆合金牵张器牵张成的新骨有足够的强度和质量，可以进行种植等后期修复。
关键词：牙槽突； 牵引器； 骨密度； 生物力学

谢 旻1，胡 敏2，刘洪臣2，姚 军2，周宏志2
1解放军总医院第三○九临床部口腔科，北京市 100091；2解放军总医院口腔科，北京市 100835
谢 旻☆，男，1971年生，河南省新乡市人，汉族，博士，副主任医师，2004年解放军军医进修学院毕业，主要从事口腔软硬组织修复研究。
国家自然科学基金资助项目（30171017）*；北京市自然科学基金资助项目（7042058）*

中图分类号: R318 文献标识码: A 文章编号: 1673-8225(2008)17-03385-04
谢旻，胡敏，刘洪臣，姚军，周宏志.钛镍记忆合金牵张成骨的骨密度及生物力学测试[J].中国组织工程研究与临床康复，2008，12(17):3385-3388
[www.zglckf.com/zglckf/ejournal/upfiles/08-17/17k-3385(ps).pdf]
（Edited by Zhang Sh/Qiu Y/Wang L）