基于形状记忆聚合物的一体式个性化矫治器正畸机理及其实现技术研究

In orthodontics, straight arch wire techniques are mainly dependent on orthodontist's experience and needed complex clinic operations, and utilize general brackets and wire as dental braces to relaize tooth movement.On the other hand, the orthodontic technology of invisionalign has narrow indication and complex utilization on attachemnts.So under these conditions of both orthodontic methods, the required orthodintic force and moment are hardly quantified, certained,and dynamic controlled in the whole treatment procedure, and perosonalized orthodontic treatment based on patient's oral condition can not be realized too. From reviews on current clinical applications, more research work and innovational progress are needed to improve the accuracy and efficiency of orthodontics. Aiming at these problems, this project proposes a theory of unitary personalized orthodontic appliances, which unites the fixation structure and force loaded structure as a whole unit. With this novel idea, the orthodontic force will be under control by the force loaded element with shape memory polymer. Based on the research of biomechaniccal mechanism of tooth momvement and the research of force loaded mechanism of shape memory material deforamtion, the theorical system of unitary orthodontics will be constructed. The structure design of unitray appliances and the recostruction of oral cavitity model will be realized via medical image processing and digital design method. Then, construct thermal-mechanical model of shape memory polymer material and mathematical model among corrective force, stress in periodontal tissue, tooth movement, and periodontal tissue remodeling, so the corrective force can be quantified accurately as well as be controlled to release evenly and steadily in whole treatement procedure, and this procedure is simulated with finite element method to check the validity of the proposed models; And then regarding with the condition of patient's dentition and periodontal tissue, optimal treatment plan is designed to satisfy optimized stress distribution on periodtal tissue and realize precise tooth movement, and the special shape of personalized unitary appliance is acquired; To guarantee the optimal treatment plan to be realized in clinic, the appliance with pesonalized shape and navigation template for positioning are designed and fabricated through digital design and 3D printting technology. Finally, design and fabricate a appliance for simulation experiment and force measureing, and acquire the precise vaule and change of force and moment during treatment procedure, accompanying with animal experiments to check the validity of proposed methodolgy and improve the related mathematical models.

口腔正畸中，直丝弓矫治需要较多依赖医生经验和复杂临床操作,而无托槽隐形矫治适应症较窄，附件使用复杂，两种技术都很难对矫治力进行精确动态控制，治疗效率和质量有待提高。针对以上问题，本项目提出一种一体式个性化矫治思想，将牙冠固持单元和施力单元作为整体，利用具有形状记忆功能的聚合物施力单元实现正畸矫治力的自动控制；通过对牙齿移动的生物力学机理和形状记忆材料的变形施力机理进行研究，建立一体式矫治的理论体系；利用医学图像处理和数字化设计实现矫治器结构设计和口腔模型重建，在形状记忆材料热-力学模型以及矫治力-牙周应力-牙齿移动-牙周组织重建关系模型的基础上，进行有限元仿真和矫治方案优化，实现矫治力精确计算和可控释放；利用高分子材料合成与改性实现材料制备，通过两种材料一次成型的立体打印实现一体式矫治器制造；最后通过模拟口腔环境的仿真实验，结合动物实验，构建有效性评价模型验证并预估矫治器临床效果和适应症。

随着我国经济发展和生活水平的提高，人们对外貌和牙齿的要求越来越高，正畸美学和力学精确控制要求也不断提高。唇侧直丝弓矫治和无托槽隐形矫治都很难对治疗过程中的矫治力进行精确动态控制，治疗的效率和质量都有待提高。本项目针对唇侧正畸矫治中存在的美学以及力学方面的问题，提出利用新型形状记忆高分子材料-聚氨酯（Shape memory Polyurethane, SMPU）作为正畸矫治材料，初步构建了矫治力-牙周膜应力-牙齿移动的生物力学体系，以上颌尖牙为对象，使牙周膜应力作为精确调控指标的牙齿加力范围比现有数据缩小了80%；构建了SMPU的三维本构模型并进行了力学性能生物力学仿真，初步验证了3 mm纯SMPU弓丝能提供约50 g左右的回复力，基本可以用于牙齿初期排齐阶段；为了提高PU材料的力学性能，利用玻璃纤维（GF，Glass fiber）增加技术，使具有35%质量分数的GF增强型PU的弹性模量从纯SMPU的6.3 MPa增加到最大40.79 MPa, 3 mm的GF增强SMPU弓丝的力提高到110 g左右，力学性能显著改善，而且形状记忆性能得到了较好的保持，可以较好的适用于正畸矫治，但与金属弓丝的力学性能相比仍然存在提高的空间；搭建了基于六维力学传感器Nano17的正畸力检测平台，实现了弓丝初始力的量化检测；研究了基于石蜡的动态正畸模拟技术，利用石蜡构建了牙齿动态模拟模型，并实现了正畸力的动态测量；基于以上研究，初步构建了基于SMPU的一体式矫治器设计体系，通过有限元仿真和实验测试初步验证了其应用于正畸矫治的可行性；同时，本项目在医学模型三维重建、有限元建模与生物力学分析、医学数字化设计与医学3D打印技术等方面的研究成果向舌侧美学正畸、隐形矫治、数字化牙种植、牙齿根尖精确切除、下颌骨精确重建等方面进行了拓展研究，并成功实现临床应用。. 经过四年的研究，基本完成了项目的研究任务。本项目的研究成果，已经发表论文20篇，其中SCI收录11篇，EI收录1篇，一级学报一篇；申请发明专利10项，其中已授权7项；共培养硕士研究生6人；培养博士研究生1人，将于2018年6月毕业；相关成果获2016年浙江省技术发明二等奖一项（负责人排名第四）。