Department of Oral Implantology and prosthetics, Academic centre for dentistry Amsterdam, University of Amsterdam, Amsterdam, The Netherlands.
Int J Oral Maxillofac Implants. 2010 Mar-Apr;25(2):247-57.
The objectives of this study are to describe, in vitro, a novel technique to measure the misfit of digitally designed and manufactured implant-supported frameworks according to a new concept based on computer-guided surgery in combination with previously placed mini-implants. Also, the digitally created framework and an impression-based milled structure were compared using strain gauge measurements.
Acrylic resin and plaster models were prepared to represent the edentulous mandible. After insertion of three mini-implants in the acrylic resin model, a cone-beam computed tomographic scan was performed. The data were imported to planning software, where six implants were virtually inserted. A drill guide and titanium framework were designed and milled using a fully digital computer-aided design/computer-assisted machining protocol. Six implants were inserted using the drill guide attached to the mini-implants. After an impression was made of the acrylic resin model with six implants, the second model (plaster model) was prepared. A second milled titanium structure was fabricated following optical scanning of the acrylic resin model. Strain gauge measurements were done on both structures attached to both models. To validate the results, a high-accuracy industrial optical scanning system was used to capture all connection geometry and the measurements were compared.
The accuracy of the digital superstructures was 19, 22, and 10 Microm with standard deviations (SD) of 19.2 (17.9), 21.5 (28.3), and 10.3 (10.1) Microm for the x-, y-, and z-axes, respectively. For the impression-based superstructure the measured misfit was 11, 20, and 17 Microm, with SD 11.8 (10.5), 19.7 (11.7), and 16.7 (8.2) Microm for the x-, y-, and z-axes, respectively.
The misfit of the digitally designed and produced superstructure on the digitally planned and inserted implants was clinically insignificant.
本研究的目的是描述一种新的技术，即根据基于计算机引导手术与之前植入的微型种植体相结合的新概念，体外测量数字化设计和制造的种植体支持框架的不匹配程度。此外，还通过应变计测量比较了数字化创建的框架和基于印模的铣削结构。
制备丙烯酸树脂和石膏模型以代表无牙下颌。在丙烯酸树脂模型中插入三个微型种植体后，进行锥形束计算机断层扫描。将数据导入规划软件，在该软件中虚拟插入六个种植体。使用全数字化计算机辅助设计/计算机辅助制造协议设计和铣削钻头导向器和钛框架。使用连接到微型种植体的钻头导向器插入六个种植体。在丙烯酸树脂模型中植入六个种植体后制取印模，然后制备第二个模型（石膏模型）。通过对丙烯酸树脂模型进行光学扫描后，制作第二个铣削钛结构。对连接到两个模型的两个结构进行应变计测量。为了验证结果，使用高精度工业光学扫描系统捕获所有连接几何形状并进行比较测量。
数字上部结构的精度为 19、22 和 10 微米，标准偏差（SD）分别为 19.2（17.9）、21.5（28.3）和 10.3（10.1）微米，用于 x、y 和 z 轴。对于基于印模的上部结构，测量的不匹配为 11、20 和 17 微米，SD 分别为 11.8（10.5）、19.7（11.7）和 16.7（8.2）微米，用于 x、y 和 z 轴。
数字化设计和生产的上部结构在数字化规划和植入的种植体上的不匹配程度在临床可忽略不计。
