Optical impression method to measure three-dimensional position and orientation of dental implants using an optical tracker

Objectives: The aim of this study was to devise an optical impression method that could make impressions of dental implants accurately and rapidly. Materials and methods: Four paper markers (4 × 3 mm, 8 × 6 mm, 16 × 12 mm, and 24 × 18 mm) and one titanium marker (8 × 6 mm) were prepared to determine the measuring accuracy of the three-dimensional optical tracker. For a proposed and conventional impression taking method, we compared the reproduction accuracies of the positions and orientations of dental implants and the times to obtain impressions. Finally, we fabricated computer-aided designing (CAD)/computer-aided manufacturing (CAM) superstructure frameworks to determine the adaptation accuracy. Results: The 8 × 6-mm titanium marker was optimal among the prepared markers. Dental implants made by the proposed and conventional impression taking methods had measurement errors of 71 ± 31 μm and 32 ± 18 μm, respectively. The proposed method took a significantly shorter time to obtain an impression than did the conventional method. The connection between the CAD/CAM superstructure frameworks and four implant analogs had uplifts of 55 ± 10 μm, 94 ± 35 μm, 2 ± 1 μm, and 66 ± 3 μm. Conclusion: Our proposed method and fabricated titanium markers enabled us to measure the positions and orientations of dental implants both accurately and rapidly. We then used the reproducible measurement results for the positions and orientations of the dental implants to fabricate CAD/CAM superstructure frameworks within an acceptable accuracy range. © 2012 John Wiley & Sons A/S.This is the pre-peer reviewed version of the following article: Ono S., Yamaguchi S., Kusumoto N., et al. Optical impression method to measure three-dimensional position and orientation of dental implants using an optical tracker. Clinical Oral Implants Research 24, 1117 (2013), which has been published in final form at https://doi.org/10.1111/j.1600-0501.2012.02519.x.. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving

Three-Dimensional Cell and Tissue Patterning in a Strained Fibrin Gel System

Techniques developed for the in vitro reproduction of three-dimensional (3D) biomimetic tissue will be valuable for investigating changes in cell function in tissues and for fabricating cell/matrix composites for applications in tissue engineering techniques. In this study, we show that the simple application of a continuous strain to a fibrin gel facilitates the development of fibril alignment and bundle-like structures in the fibrin gel in the direction of the applied strain. Myoblasts cultured in this gel also exhibited well-aligned cell patterning in a direction parallel to the direction of the strain. Interestingly, the direction of cell proliferation was identical to that of cell alignment. Finally, the oriented cells formed linear groups that were aligned parallel to the direction of the strain and replicated the native skeletal muscle cell patterning. In addition, vein endothelial cells formed a linear, aligned vessel-like structure in this system. Thus, the system enables the in vitro reproduction of 3D aligned cell sets replicating biological tissue patterns

Original computer aided support system for safe and accurate implant placement—Collaboration with an university originated venture company

An original implant surgery support system with computer simulation to determine the position of implant placement and fabrication of a surgical guide that helps in bone drilling was developed by collaboration of Osaka University Faculty of Dentistry and Dental Prostheses Fabrication Company. A virtual reality haptic device that gives the sense of touch was used for simulation and a surgical template was fabricated by CAD/CAM method. A patented technology enabled to remove artifact due to metallic prostheses by replacing the damaged teeth of CT image by precise 3D measured image of dental cast. Surgical guide was designed using haptic device and fabricated including bone model by a computer-aided rapid prototyping modeling machine with a UV-cured acrylic-based resin material. Two clinical cases with implant placement on the three lower molars by flap operation using bone supported surgical guide and flapless operation with teeth supported surgical guide and immediate loading with provisional prostheses prepared beforehand are introduced. The present simulation and drilling support using the surgical guide may help to perform safe and accurate implant surgery

Development of a multi-layered virtual tooth model for the haptic dental training system

A virtual reality (VR) haptic dental training system could be a promising tool for future dental education. One major challenge is to develop a virtual tooth model which similarly reflected a real tooth having multiple layers with different mechanical hardness in each layer. The multi-layered virtual tooth model was successfully constructed in our virtual system. The constructed model allows us to feel tooth cutting which is similar to that with a real tooth. Through a cutting experiment by using the real tooth, a spring coefficient and a damping coefficient of a dental hard tissue were determined 0.8 N/mm and 1.79 Nsec/mm respectively. The feedback force smoothly altered when crossing the border of regions having different mechanical hardnesses. The constructed model introduced in this study could be a promising tool for acquiring dental hand skills in a virtual learning system.Yoshida Y., Yamaguchi S., Kawamoto Y., et al. Development of a multi-layered virtual tooth model for the haptic dental training system. Dental Materials Journal 30, 1 (2011); https://doi.org/10.4012/dmj.2010-082