Accuracy of intraoral and extraoral digital data acquisition for dental restorations

The computer-aided design (CAD) and computer-aided manufacturing (CAM) process chain for dental restorations starts with taking an impression of the clinical situation. For this purpose, either extraoral digitization of gypsum models or intraoral digitization can be used. Despite the increasing use of dental digitizing systems, there are only few studies on their accuracy. Objective This study compared the accuracy of various intraoral and extraoral digitizing systems for dental CAD/CAM technology. Material and Methods An experimental setup for three-dimensional analysis based on 2 prepared ceramic master dies and their corresponding virtual CAD-models was used to assess the accuracy of 10 extraoral and 4 intraoral optical non-contact dental digitizing systems. Depending on the clinical procedure, 10 optical measurements of either 10 duplicate gypsum dies (extraoral digitizing) or directly of the ceramic master dies (intraoral digitizing) were made and compared with the corresponding CAD-models. Results The digitizing systems showed differences in accuracy. However, all topical systems were well within the benchmark of ±20 µm. These results apply to single tooth measurements. Conclusions Study results are limited, since only single teeth were used for comparison. The different preparations represent various angles and steep and parallel opposing tooth surfaces (incisors). For most digitizing systems, the latter are generally the most difficult to capture. Using CAD/CAM technologies, the preparation angles should not be too steep to reduce digitizing errors. Older systems might be limited to a certain height or taper of the prepared tooth, whereas newer systems (extraoral as well as intraoral digitization) do not have these limitations

Analysis of technologies for rapid prototyping of dental constructions

In the following article new technologies for the production of dental implants are presented. Using the best achievements of mechanical engineering, such as CAD/CAM and additive technologies, entirely new opportunities for increasing complexity, geometric accuracy, speed, and production efficiency of dental products are discovered

Dental Failure Analysis: The Need of a Comprehensive Failure Classification

For more than thirty percent of patients with implant-supported fixed dental prosthesis, various complications can be observed over five-years of function. In some cases, failure can be ascribed to mechanical reasons such as loosening of the retaining screws or fracture of the implant components. The paper evaluates three different failures of implant-supported prostheses. All cases were analyzed by optical and SEM microscopy to identify the failure modes and the possible failure causes. Improper design or errors in finishing operations or in assembly are identified as dental failure causes. A matrix classification is proposed to collect rupture cases of implant-supported prostheses

Advanced technology composite aircraft structures

Work performed during the 25th month on NAS1-18889, Advanced Technology Composite Aircraft Structures, is summarized. The main objective of this program is to develop an integrated technology and demonstrate a confidence level that permits the cost- and weight-effective use of advanced composite materials in primary structures of future aircraft with the emphasis on pressurized fuselages. The period from 1-31 May 1991 is covered

Loma Linda University Dentistry - Volume 25, Number 1

Content: 8 | Ronald Secor Departs9 | Introducing Euni Cho12 | New Positions: Jessica Kim & Bonnie Retamozo14 | Natural Crowns as Provisional Restorations19 | A Generation of Implant Dentistry24 | Nick Caplanis Elected President, American Academy of Implant Dentistry36 | LLUSD at ADA in New Orleanshttps://scholarsrepository.llu.edu/articulator/1006/thumbnail.jp

Production Engineering and Management

It is our pleasure to introduce the 8th edition of the International Conference on Production Engineering and anagement (PEM), an event that is the result of the joint effort of the OWL University of Applied Sciences and the University of Trieste. The conference has been established as an annual meeting under the Double Degree Master Program “Production Engineering and Management” by the two partner universities. This year the conference is hosted at the university campus in Lemgo, Germany. The main goal of the conference is to offer students, researchers and professionals in Germany, Italy and abroad, an opportunity to meet and exchange information, discuss experiences, specific practices and technical solutions for planning, design, and management of manufacturing and service systems and processes. As always, the conference is a platform aimed at presenting research projects, introducing young academics to the tradition of symposiums and promoting the exchange of ideas between the industry and the academy. This year’s special focus is on Supply Chain Design and Management in the context of Industry 4.0, which are currently major topics of discussion among experts and professionals. In fact, the features and problems of Industry 4.0 have been widely discussed in the last editions of the PEM conference, in which sustainability and efficiency also emerged as key factors. With the further study and development of Direct Digital Manufacturing technologies in connection with new Management Practices and Supply Chain Designs, the 8th edition of the PEM conference aims to offer new and interesting scientific contributions. The conference program includes 25 speeches organized in seven sessions. Two are specifically dedicated to “Direct Digital Manufacturing in the context of Industry 4.0”. The other sessions are covering areas of great interest and importance to the participants of the conference, which are related to the main focus: “Supply Chai n Design and Management”, “Industrial Engineering and Lean Management”, “Wood Processing Technologies and Furniture Production”, and “Management Practices and Methodologies”. The proceedings of the conference include the articles submitted and accepted after a careful double-blind refereeing process

Advanced Materials for Oral Application

This book consists of one editorial, 12 original research articles and two review papers from scientists across the world, with expertise in materials for dental application. The main subjects covered are: biomaterials and techniques for oral tissue engineering and regeneration; biomaterials for surgical reconstruction; CAD/CAM technologies and dedicated materials; novel restorative and endodontic materials and instruments

Puesta en marcha y procedimiento de verificación de impresora 3D de estereolitografía Form 1. Análisis comparativo de precisión

Entre las múltiples tecnologías de Fabricación Aditiva existentes, este trabajo está focalizado en la estereolitografía (SLA), más concretamente en la puesta en marcha y verificación de la impresora 3D Form 1, así como la comparación de dicha impresora con otra que utiliza un método distinto de Fabricación Aditiva. Se fabricarán diferentes versiones de las piezas patrón en diferentes condiciones, con el posterior análisis metrológico en una Máquina de Medición de Coordenadas. Con los datos obtenidos se realizará un estudio tanto de la precisión geométrica de la impresora como de la precisión dimensional. Finalmente, se realizará una comparativa de precisión de la impresora a estudio con una impresora que emplea otra tecnología, a través de la fabricación y la medición de una pieza patrón