Structural design of a cartesian coordinate tooth-arrangement robot
Aiming to the problem of time-consuming and low precision of the traditional tooth-arrangement methods, a conception of a professional and miniature Cartesian coordinate type robot for tooth-arrangement was put forward in this paper. Based on the analysis of tooth-arrangement process, the design scheme of tooth-arrangement robot were determined. We also build the whole three-dimensional model of Cartesian coordinate type robot of tooth-arrangement after functional analysis of every function module of tooth-arrangement robot. Finally, the kinematics simulation analysis of robot model using ADAMS is performed, and the results indicates that it is feasible and practical to realize the scheme design and structural design of Cartesian coordinate tooth-arrangement robot.
Custom denture fabrication with new abrasive computer tomography and rapid prototyping technologies
Fixed partial denture produced by conventional method is greatly relied on the skill and experience of dental technician. Its quality and accuracy depends mostly on the technician's subjective judgment. In addition, the manual process involves many procedures which require a long time to complete. Most important, it does not preserve any quantitative information for future retrieval. In this paper, a new device for scanning denture images and reconstructing 3D digital information of dental model by abrasive computer tomography (ACT) was designed in-house and proposed. The fixed partial denture was then produced by the rapid prototyping (RP) and computer numerical control (CNC) machining methods based on ACT scanned digital information. A force feedback sculptor (FreeForm system, Sensible Technologies Inc., USA) accompany with 3D touch technology was applied to modify the morphology or the design of denture. It enables the dentist to perform digital manipulation of denture profile with real-time and user-friendly human interactive operation without relying on CAD/CAM technician or dental technician. In this article, the comparison of conventional manual operation and digital manufacture using both RP and CNC machining technologies for denture production was presented. In addition, a digital custom denture manufacturing protocol integrating proposed computer abrasive teeth profile scanning, computer-aided denture design, 3D touchable force feedback feature modification and advanced denture manufacturing techniques were suggested. These proposed methods provide a solid evidence that digital design and manufacturing technologies may become a new avenue for custom-made denture design, analysis, and production in 21st century.
A mathematic-geometric model to calculate variation in mandibular arch form.
A mathematic-geometric model was used to evaluate the variation of mandibular dental arch length with respect to the incisor inclination, but without modifying the intercanine width. In analytical terms, the equations of the curves representing the lower dental arch, before and after incisor inclination of 1 mm and of 1 degree, with controlled and uncontrolled tipping, were studied. The length of the mandibular dental arch changed in the parabolic arch form by 1.51 mm for each millimetre of incisor inclination with respect to the occlusal functional plane, by 0.54 mm for each degree of controlled tipping and by 0.43 mm for each degree of uncontrolled tipping. In the elliptical arch form (e = 0.78), it changed by 1.21, 0.43, and 0.34 mm, respectively, in the hyperbolic form by 1.61, 0.57, and 0.46 mm, in the circular form by 1.21, 0.43, and 0.34 mm, and in the catenary form by 2.07, 0.74, and 0.59 mm. The results show that by changing the arch form without modifying the dimension of the dental arch, different arch lengths can be gained for each millimetre of proclination. In addition, by controlled tipping an inter-incisive arch one-fifth longer than by uncontrolled tipping can be obtained. It would be advisable in orthodontic treatment planning to evaluate the type of dental arch, since the space available or the space required changes depending on the arch form and on the orthodontic tooth movement.