Showing papers by "Sandro Barone published in 2015"

A Novel Methodology for the Creation of Customized Eruption Guidance Appliances

Abstract: Within the orthodontic field, malocclusion problems are usually treated by using different types of appliances. In particular, Eruption Guidance Appliances (EGAs) are recommended for early orthodontic treatment or prevention of malocclusion problems. The traditional approach with EGAs is based on the use of standard prefabricated appliances. Experts in the orthodontic field believe that the customization of the EGAs would strongly enhance the results of malocclusion treatments.This paper presents an innovative methodology for the design and manufacturing of fully customized EGAs. The methodology is based on an extensive integration between traditional orthodontic procedures with advanced computer aided design processes. The methodology moves from the digitalization of the plaster models obtained by optical scanning techniques. The patient morphology is then exploited, under dental practitioner supervision, for the design of the appliance geometry through CAD modeling tools. Medical guided assessment is required throughout the most of the data elaboration processes, in order to design the EGAs accordingly to the patient’s clinical conditions. Low-pressure injection molds for the physical manufacturing of the appliances are then 3D printed by using rapid prototyping techniques. The proposed methodology allows the production of patient customized appliances guaranteeing low cost manufacturing and high quality standards, similar to those typically obtained by in series productions. Moreover, the presented approach offers a high integration level with numerical and finite element methods, which can be used for evaluating the stress applied on the EGA, thus allowing the reinforcement of the appliance prior its manufacturing.Copyright © 2015 by ASME

Three-Dimensional Tooth Segmentation by Integrating Multiple Ray-Sum Images From CBCT Data

Abstract: The reconstruction of tooth anatomies is of utmost importance when dental implant surgeries and/or orthodontic corrections must be planned. In the last few years, cone beam CT (CBCT) has gained popularity in dentistry for 3D imaging of jawbones and teeth. However, within CBCT data sets, each tooth is defined by a region, which cannot be easily separated from surrounding tissues (i.e., bone tissue) by only considering pixel’s grey-intensity values. For this reason, some enhancement is usually necessary in order to properly segment tooth geometries.In this paper, a semi-automatic approach to reconstruct individual 3D tooth anatomies by processing CBCT-scan data is presented. The methodology is based on the creation of a minimal number of 2D “local ray-sum” images by adding the absorption values of adjacent voxels along the most significant views for each tooth. The knowledge of the specific anatomical patient morphology drives the selection of these significant projection directions. The reconstructed “ray-sum” images greatly enhance the clearness of the root contours, which can then be interactively traced by dentists. A set of meaningful 2D tooth contours is consequently obtained and used to automatically extract a cubic spline curve for each transverse slice, thus approximating the overall 3D tooth profile.The effectiveness of the methodology has been evaluated by comparing the results obtained for the reconstruction of anterior teeth with those obtained by using classical segmentation tools provided within commercial software.Copyright © 2015 by ASME

Multi-Sensor Reverse Engineering Technique for the Acquisition of Centrifugal Pump Impellers

Abstract: The geometrical reconstruction of centrifugal pump impellers is a strategic activity for many manufacturing industries. In particular, the digitalization of internal hydraulic shapes represents the most critical task due to the difficulties in accessing the internal parts of impeller disks.In this paper, an automatic approach to digitize the internal shape of impellers is presented. The methodology is based on the integration of optical and probing methods in order to combine the advantages of both technologies. The developed approach uses an optically tracked hand-held probe designed to digitize, point-by-point, the whole surface of blades. The tracking system is based on a passive device, composed of two stereo cameras, which is used to accurately locate a specific plate, rigidly connected to a probe. The proposed methodology has been validated by experimental tests on primitive surfaces as plane, cylinders and spheres. Nonetheless, the robustness and flexibility of the developed technique has allowed the whole reconstruction of industrial impellers through the acquisition of hundreds of points in few minutes.Copyright © 2015 by ASME