【作者】 韶波；

【导师】 刘宝林； 孔亮；

【作者基本信息】 第四军医大学 ， 口腔临床医学， 2013， 博士

【摘要】 种植义齿因其可以长期稳定的行使功能和优于传统修复方式的美学效果，已得到越来越多的临床应用。然而，由于拔牙、牙周病、创伤、肿瘤等导致的牙槽嵴高度不足却可能引起种植体无法植入、修复美学缺陷，甚至治疗失败。这是目前临床急需解决的问题之一。在类似的病例中，通过牙槽嵴增高术可以重建理想的牙槽嵴高度，建立适合于种植体修复的环境。目前用于解决牙槽嵴高度不足的方法主要有onlay或sandwich骨移植技术、引导骨组织再生技术（GBR）及牙槽嵴牵张成骨（ADO）等。其中，ADO应用于实验和临床的首例报道出现于1996年。与其它方法相比较，ADO具有独特的优势，例如，软、硬组织可以同步升高，无需取骨，避免了取骨区损伤，与游离骨移植相比更小的骨吸收率等。然而，传统的ADO技术需要进行三次外科手术，分别是：牵张器植入，牵张器取出，牵张完成8-16周后进行的种植体植入。此后，仍需要再等待4-6个月，待种植体愈合后才能进行义齿修复。以上复杂的过程对于患者和医生均是难以接受的，所以目前急需一种更加简单有效的方法。因此，一种叫做牵张种植体（DI）的新设备应运而生，它同时将牵张成骨和种植体的功能集于一身，大大简化了治疗过程，缩短了治疗时间。虽然DI具有其独特的优势，但现有DI的复杂结构却限制了它的临床应用。首先，功能段（FP）是它行使功能的主要部分，但它的长度过短，难以承受强大的咬合力；其次，中心螺丝（DS、CS）在长期的受力过程中容易损伤甚至折断；再次，在可能出现的失败病例中，固定段（SP）难以取出。因此，为了让DI更适合临床应用的要求，我们将对它的结构进行优化设计，并通过实验加以验证。在本课题中，我们优化设计并制作了一种末端可吸收DI，并通过离体生物力学测试，及离体、在体动物牵张实验评价该DI的性能，利用X线片、CT、Micro-CT、组织切片等技术对其牵张成骨性能进行观察，以期实现“早期可靠牵张，远期最佳载力”。第一部分：末端可吸收DI的设计制作实验一：末端可吸收DI的设计及制作方法：分析现有DI存在的问题，针对这些问题进行外形结构及制作材料方面的优化改进，确定各部分的具体参数，并根据优化结果加工制作一种末端可吸收的DI。结果：找到了现有DI在外形结构、生物力学性能及从牵张器到种植体转化等各方面存在的问题，根据本课题组以前对DI生物力学结构进行优化的结果，并根据DI的应用目标提出了优化改进的方法，分别为：TP与SP的长度比R=8:2，DS直径D≥2mm，及使用可吸收材料制作SP段。依据以上优化改进方案，我们成功加工制作出了末端可吸收的DI。第一部分结论：1.对DI的外形、生物力学结构及牵张器到种植体的转化过程进行了分析，找到现有DI的不足，并进行了优化改进。2.根据优化结果R=8:2，D≥2mm，SP段可吸收，加工制作了一种末端可吸收DI。第二部分：离体实验实验二：末端可吸收DI的生物力学测试方法：将上述优化改进后的末端可吸收DI与普通种植体进行体外生物力学检测实验：周期荷载疲劳及轴向拔出实验。结果：轴向拔出实验，DI的最大拔出力为1114.13±75.52N，普通种植体的为1102.38±114.16N，二者在统计学上无差别（P>0.05）；周期荷载疲劳实验，经过240万次的连续加载（模拟10年咀嚼状态），所有DI与普通种植体均未发生疲劳损伤。实验三：末端可吸收DI的离体犬下颌骨牵张实验方法：;利用已建成的牙槽嵴高度不足犬模型，截取其下颌骨，模拟截骨、DI植入的手术过程，并在DI植入后进行牵张测试。结果：手术操作过程顺利，针对以往牵张成骨手术中的弊端，采用创新的手术方式，成功模拟了手术过程。术后成功将移动骨段牵起。第二部分结论：该末端可吸收DI的生物力学性能良好，牵张性能良好。第三部分：动物实验实验四：牙槽嵴高度不足动物模型的建立方法：拔除6只家犬双侧下颌全部前磨牙，修整牙槽嵴，3个月后，待其拔牙创骨质完全恢复，牙槽嵴高度不足的犬模型即建成。结果：自创的麻醉方式提高了手术效率及安全性。拔牙后3个月肉眼观察及X线片均显示牙槽嵴高度不足的犬模型建立成功。实验五：末端可吸收DI的植入及牵张成骨方法：将已成功建立的6只牙槽嵴高度不足犬模型作为实验动物，采用创新的前庭沟底黏骨膜切口及超声骨刀截骨，完成DI植入手术。植入完成后5天开始以1mm/2d的速度进行牵张成骨，共12天，牵高6mm。结果：使用创新术式成功完成DI植入术，并避免了以往同类手术的一些弊端；术后成功将牙槽嵴牵高6mm。实验六：末端可吸收DI牵张成骨效果的评价方法：分别对牵张完成后1月、2月及3月的实验犬进行大体、X线片、CT扫描、Micro-CT扫描及组织切片检查，对牙槽嵴高度不足犬模型牵张成骨的效果进行评价。结果：大体观察：所有DI均稳定，未出现松动、脱落，位置保持不变，移动骨段高度保持良好。X线片、CT扫描、Micro-CT扫描、硬组织切片结果均显示牵张区域在牵张完成后3个月内逐渐生成新骨，到3个月时新骨与周围自体骨已无明显区别。第三部分结论：1.创新的DI植入术，及优化后的DI能有效减小术区软硬组织的创伤，缩短手术时间，减小患者痛苦。并对术后移动骨段的安全及DI的稳定提供保障。2.动物实验结果证实该末端可吸收DI具有较为可靠的牵张成骨性能。更多还原

【Abstract】 Dental implantation has drawn attention for its long-term functional and estheticpreponderances, and has become one of the most common and efficient practice. However,the insufficient alveolar bone height resulted from tooth extraction, trauma, periodontaldisease, or tumor resections etc., makes the dental implantation difficult insertion, estheticdefects or even failure. The nature of this deficiency poses either structural or aestheticobstacles to successful dental prosthesis.In such cases, alveolar ridge augmentation was required to restore a favorable alveolarridge height and to create an appropriate environment for the placement of endosseousimplants. Many methods have been proposed to reconstruct the alveolar ridge, including onlay or sandwich bone graft, guided bone regeneration (GBR), and alveolar distractionosteogenesis (ADO). Among these methods, ADO has received considerable interest since1996, when the first experimental and clinical application of ADO was reportedrespectively. Compared with other methods, ADO has many advantages, such assimultaneous augmentation of hard and soft tissue, no bone harvesting, avoidance ofdonor site morbidity, and less bone resorption versus with free bone graft.However, the conventional procedure of ADO included three surgical steps: placementof a distractor, removal of the distractor, and insertion of one or more implants8~16weeks after the distraction. After the insertion, another4~6months of bone-implantosseointegeration were needed before the application of prostheses. All mentioned abovehad disappointed both the dentists and patients, and a new technique was needed urgentlyto simplified the surgery procedure. Thus, a new device named as Distraction Implant (DI),which could act as both a distracter and an implant, had shortened the whole treatmenttime obviously.Although DI had its special advantages, the complicated structure of previous DIlimited its clinical usage. Firstly, the coronal function portion was the main load bearingpart, but it was too short to support the occlusal force. Secondly, the central distractionscrew could be easily broken under long-time stress. Thirdly, it was difficult to take outthe apical support portion in case the implantation failure occurred. Thus, in order topromote the DIs’ clinical application, it was necessary to optimize the current DI and takea comprehensive evaluation.In this study，we aimed to examine the feasibility of a new optimized DI to correct theinsufficient alveolar height in adult mongrel dogs by X-ray, Micro-CT, histological, andbiomechanical evaluations.Part one: Design and manufacture of the new optimized DIExperiment one: Design and manufacture of the new optimized DIMethod： The problems of existing DI were found after analysis, and the optimizationof the structure and materials was done to solve these problems. After that the specificparameters of each part were determined, and the optimized DI was manufactured according to the optimization results.Results: We have found the problems of existing DI in structure, biomechanicalproperties and transformation from distracter to implant. After optimization of previouslyDI structure, and according to the aim of DI, the improvements were establishedrespectively: firstly, the length ratio of the TP: SP was8:2; secondly, the diameter of DS≥2mm; thirdly, manufacturing SP with absorbable materials. Finally, we have successfullyproduced an optimized DI.Conclusions of part one1.After optimization, the problems of previous DI were found, and improvements weremade.2. R=8:2and D≥2mm were the optimal choices. And according to these results, theoptimized DI was made.Part two：In vitro study of DIExperiment two: Biomechanical testing of the Optimized DIMethod：Comparative analysis of the in vitro biomechanical properties between theoptimized DI and normal implant were conducted: axial pull-out test and cyclic loadingfatigue test.Results: After in vitro biomechanical testing, the optimized DI and normal implantshad similar biomechanical properties. Test results: axial pull-out test, maximum pulloutforce of DI was1106±75.22N, maximum pullout force of normal implant was1094±114.3N. There was no statistically difference between them. Fatigue test: after2,400,000continuous load (to simulate10years of chewing), all DIs and normal implants were notfailed.Experiment three: In vitro canine mandibular distraction test of the Optimized DIMethod：On a fresh alveolar defect canine mandible, the osteotomy and insertion of DIwere conducted, after that, the DI was distracted with FP.Results: The operating procedure was successful. And we used some innovativesurgical approach to avoid the drawbacks happened in the previous surgery. Thesimulation surgical procedure was successful, and FP promoted successfully. Conclusions of part two1. The biomechanical property of the optimized DI was as good as the normalimplant.2. The optimized DI had reliable distraction osteogenesis capability.Part three: in vivo animal experimentExperiment four: Establishment of insufficient alveolar height animal modelMethod:6dogs were involved in the experiment. All the mandible premolars wereextracted and an alveoloplasty was performed. After3months of bone healing, theinsufficient alveolar height animal models were built up.Results: The innovative anesthesia method improved the surgical efficiency and safety.3months after tooth extraction, visual observation and X-ray examination showed that theinsufficient alveolar height animal model was successfully established.Experiment five: The insertion of the optimized DI and distraction osteogenesisMethod： The6insufficient alveolar height dog models were involved in thisexperiment. A horizontal incision in the vestibule and ultrasonic osteotomy were used tocomplete the DI insertion. Five days after insertion the distraction osteogenesis wasconducted at a rate of1mm/2d, a total of12days,6mm.Results: Successfully completed the DI insertion with innovative use of surgicalmethods, and avoided some of the drawbacks of previous surgery; the alveolar ridge wassuccessful promoted6mm height.Experiment six: evaluation of bone regeneration of in vivo experimentMethod: One month,2months and3months after distraction, the dogs were examinedby X-ray, CT scanning, Micro-CT scanning and histological analysis, to evaluate the resultof distraction osteogenesis of the optimized DI.Results：The visual observation: none of the DIs was lost or loose during the healing,the height of the transport bone segment remained in position. X-ray, CT scanning,Micro-CT scanning, and hard tissue histological analysis showed new bone graduallyregenerated in the distraction gap3months after distraction. The new bone was noobvious difference compared with the native bone around, at3months after distraction. Conclusions of part three1. Innovation surgical methods of DI insertion, and optimized DI could effectivelyreduced the trauma of the hard and soft tissue, shortened operating time, reduced thesuffering of the patients, and provided protection to the transport bone segment and DIstability.2. The results of animal experiments confirmed that the optimized DI had reliablecapability of distraction osteogenesis.更多还原