中国组织工程研究 ›› 2019, Vol. 23 ›› Issue (22): 3488-3494.doi: 10.3969/j.issn.2095-4344.1275

• 组织工程口腔材料 tissue-engineered oral materials • 上一篇    下一篇

持续或间断应力载荷下正畸微种植体稳定性的组织形态学和生物力学评价

吴也可1,郜然然1,赵立星2 
  

  1. 1成都中医药大学附属医院,四川省成都市  610072;2四川大学华西口腔医学院,四川省成都市  610041
  • 收稿日期:2019-03-15
  • 通讯作者: 吴也可,成都中医药大学附属医院,四川省成都市 610072
  • 作者简介:吴也可,男,1987年生,四川省成都市人,博士,主治医师,主要从事口腔正畸学临床及基础的研究工作,以及中医药防治牙周疾病的研究。
  • 基金资助:

    国家自然科学基金(81500818),项目负责人:吴也可;国家自然科学基金(81873334),项目参与者:吴也可

Orthodontic micro-implant stability under continuous or intermittent loading: a histomorphometric and biomechanical evaluation

Wu Yeke1, Gao Ranran1, Zhao Lixing2
  

  1. 1Affiliated Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu 610072, Sichuan Province, China; 2West China School of Stomatology, Sichuan University, Chengdu 610041, Sichuan Province, China
  • Received:2019-03-15
  • Contact: Wu Yeke, Affiliated Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu 610072, Sichuan Province, China
  • About author:Wu Yeke, MD, Attending physician, Affiliated Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu 610072, Sichuan Province, China
  • Supported by:

    the National Natural Science Foundation of China, No. 81500818 and 81873334 (both to WYK)

摘要:

文章快速阅读:

 

文题释义:
骨整合:即显微镜下骨与种植体间的直接接触,是种植体生物学稳定性和临床成功率的决定因素。骨整合的程度主要由种植体设计、手术操作和应力载荷等多因素决定,其中应力载荷条件(力值、方向、周期等)日益受到研究者的广泛关注。
生物力学:是应用力学原理和方法对生物体中的力学问题定量研究的生物物理学分支。微种植体生物力学方面的信息对于临床医师设计更好的种植体至关重要。实验中通过拉拔试验测量了微种植体在不同愈合时间的生物力学特性,峰值拉拔力检测数据表明,微种植体在间断应力载荷下相比持续应力获得了更好的力学稳定性。
 
 
背景:在正畸治疗过程中,很多学者认为间断力相比持续力能获得同等甚至更大的牙移动疗效,并可减少牙根吸收等不良反应的发生,然而上述结论多来自体外细胞实验或临床个案观察,尚缺少设计科学合理、规模较大的动物实验。
目的:分析持续应力或两种模式间断应力载荷对正畸微种植体骨整合及生物稳定性的影响。
方法:取48只Beagle犬(四川大学实验动物中心提供),在下颌骨两侧第一磨牙和第二前磨牙的根间区域各植入1枚微种植体(每只犬共植入4枚微种植体),随机分4组:持续组每个加载周期连续加载应力,间断A组在每个加载周期的最后3 d中断应力,间断B组在每个加载周期的最后7 d中断应力,以未加力组为对照。应力加载方法与周期:通过结扎丝在同侧2个微种植体安装镍钛螺旋拉簧,实施加载力;设置1个加载周期为2周,共加载4个周期。加载2,4,6,8周后,获取各组下颌骨组织,进行显微CT、组织学观察和力学拉拔测试。实验方案经过四川大学实验动物伦理委员会批准。
结果与结论:①未加力组加载不同时间点的峰值拉拔力均高于持续组(P < 0.05),间断B组加载2,4,6周后的峰值拉拔力均高于持续组(P < 0.05),间断A组加载2周后的峰值拉拔力均高于持续组(P < 0.05);②显微CT显示相同加载时间点下,未加力组骨整合、骨体积分数、相交表面均高于持续组(P < 0.05);间断B组加载2,4,6,8周后的骨整合、骨体积分数高于持续组(P < 0.05),加载2,4,6周后的相交表面高于持续组(P < 0.05);间断A组加载2,4周后的骨整合高于持续组(P < 0.05),加载2,4,6周后的骨体积分数高于持续组(P < 0.05),加载2周的相交表面高于持续组(P < 0.05);③加载8周后,各组均可见骨重塑现象,骨重塑由好到差的排序依次为:未加力组、间断B组、间断A组、持续组;④结果表明,间断应力相比持续应力加载更有利于微种植体获得良好的稳定性,且7 d/7 d间断加载周期较11 d/3 d方案更能促进骨-微种植体结合。

关键词: 微种植体, 持续应力, 间断应力, 骨整合, 稳定性, 峰值拉拔力, 动物实验, 显微CT

Abstract:

BACKGROUND: During the orthodontic treatment process, many scholars believe that intermittent force can achieve the same or even greater effect of tooth movement than persistent force, and reduce the occurrence of root resorption and other adverse reactions. However, the above conclusions are mostly from in vitro cell experiments or clinical case study, and there is still a lack of scientifically designed and large-scale animal experiments.
OBJECTIVE: To evaluate the influence of continuous or intermittent force of two modes on osseointegration and biostability of orthodontic micro-implant.
METHODS: Forty-eight beagles (provided by Laboratory Animal Center of Sichuan University) were selected and mini-implants were implanted bilaterally in intraradicular zones of mandibular first molar and second premolar. The beagles were randomly allotted into four groups: loadings were delivered consecutively in continuous group, and pauses were given for the last 3 or 7 days of each reactivation period for intermittent group A and B, respectively. The group unloaded served as control. Loading protocol and period: loading force was applied by installing nickel-titanium closed coil springs on two mini-implants with ligating wires, and 2-week was set as a loading period, for 4 periods. After 2, 4, 6 and 8 weeks, the mandible tissues were obtained for micro-CT, histological observation and pull-out test. The study was approved by the Experimental Animal Ethics Committee of Sichuan University.
RESULTS AND CONCLUSION: (1) The values of peak load at extraction (Fmax) at various loading time points in the control group were higher than those in the continuous group (P < 0.05). Fmax of the intermittent group B was higher than that in the continuous group at week 2, 4 and 6 (P < 0.05); and the Fmax at week 2 in the intermittent group A was higher than the continuous group (P < 0.05). (2) At the same loading time point, the ossointegration, bone volume/tissue volume and intersection surface in the unloaded control were higher than those in the continuous group (P < 0.05). The ossointegration and bone volume/tissue volume in the intermittent group B at 2, 4, 6 and 8 weeks were higher than those in the continuous group (P < 0.05). At 2, 4 and 6 weeks, the intersection surface was higher than in the continuous group  (P < 0.05). The ossointegration in the intermittent group A at 2 and 4 weeks was higher than that in the continuous group (P < 0.05).The bone volume/tissue volume was higher than in the continuous group at 2, 4 and 6 weeks (P < 0.05). The intersection surface was higher than in the continuous group at 2 weeks (P < 0.05). (3) Bone remodeling was observed in all groups after 8 weeks of loading, and the bone remodeling was best in the unloaded control group, followed by intermittent groups B and A and poorest in the continuous group. (4) In summary, intermittent loading regimen is more favorable for obtaining stability than continuous force, and the 7-day/7-day loading cycle is more beneficial for bone-implant integration than the 11-day/3-day protocol.

Key words: mini-implants, continuous force, intermittent force, osseointegration, stability, peak pull-out, animal experiment, micro-CT

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