Biomedical subjects

Matts Andersson

Publications and source records attributed to Matts Andersson.

6 recordsLinked to original sources

PubMed2006

A three-dimensional evaluation of a laser scanner and a touch-probe scanner.

STATEMENT OF PROBLEM: The fit of a dental restoration depends on quality throughout the entire manufacturing process. There is difficulty in assessing the surface topography of an object with a complex form, such as teeth, since there is no exact reference form. PURPOSE: The purpose of this study was to determine the repeatability and relative accuracy of 2 dental surface digitization devices. A computer-aided design (CAD) technique was used for evaluation to calculate and present the deviations 3-dimensionally. MATERIAL AND METHODS: Ten dies of teeth prepared for complete crowns were fabricated in presintered yttria-stabilized tetragonal zirconia (Y-TZP). The surfaces were digitized 3 times each with an optical or mechanical digitizer. The number of points in the point clouds from each reading were calculated and used as the CAD reference model (CRM). Alignments were performed by registration software that works by minimizing a distance criterion. In color-difference maps, the distribution of the discrepancies between the surfaces in the CRM and the 3-dimensional surface models was identified and located. RESULTS: The repeatability of both scanners was within 10 microm, based on SD and absolute mean values. The qualitative evaluation resulted in an even distribution of the deviations in the optical digitizer, whereas the dominating part of the surfaces in the mechanical digitizer showed no deviations. The relative accuracy of the 2 surface digitization devices was within +/- 6 microm, based on median values. CONCLUSION: The repeatability of the optical digitizer was comparable with the mechanical digitization device, and the relative accuracy was similar.

Computer-Aided Design↗

PubMed2005

Health risks and occupational exposure to volatile anaesthetics--a review with a systematic approach.

AIMS AND OBJECTIVES: To provide practicing nurse anaesthetists with evidence based knowledge as to whether they are at risk handling volatile anaesthetics by answering the question: What are the health risks threatening health care personnel occupationally exposed to volatile anaesthetics? BACKGROUND: The interpretations of results from specific scientific studies vary and preliminary research results indicate that occupational exposure to volatile anaesthetics affects the health of operating room personnel. DESIGN: Review of scientific literature with a systematic approach. METHOD: The review included a systematic search in three major databases, a screening process of abstracts/articles followed by a quality assessment of the included studies. The screening process and the quality assessment were done independently by the six reviewers and followed specific protocols. RESULTS: A systematic search of The Cochrane Library, MedLine and CINAHL resulted in a screening of 413 abstracts of which 31 articles were assessed for quality, all done independently by the reviewers. Finally, the reviewers agreed upon how to interpret the results of the assessed articles. CONCLUSIONS: The 31 articles assessed covered areas such as genotoxic effects, neurobehavioural effects, immunology, and general health effects. In the scientific literature reviewed there is no evidence of occupational exposure to volatile anaesthetics either being associated with health risks or being harmless. Studies indicating a potential health risk are all investigating circumstances ignorant of modern environmental regulations and/or with no scavenging equipment. RELEVANCE TO CLINICAL PRACTICE: Although no answer has been given, this review illuminates the methodological difficulties encountered in designing studies. The result of this review further stresses the need for scientific knowledge in this area and enhances the extensive use of scavenging equipment.

Anesthetics, Inhalation↗

PubMed2005

A computed tomographic scan-derived customized surgical template and fixed prosthesis for flapless surgery and immediate loading of implants in fully edentulous maxillae: a prospective multicenter study.

BACKGROUND: Based on three-dimensional implant planning software for computed tomographic (CT) scan data, customized surgical templates and final dental prostheses could be designed to ensure high precision transfer of the implant treatment planning to the operative field and an immediate rigid splinting of the installed implants, respectively. PURPOSE: The aim of the present study was to (1) evaluate a concept including a treatment planning procedure based on CT scan images and a prefabricated fixed prosthetic reconstruction for immediate function in upper jaws using a flapless surgical technique and (2) validate the universality of this concept in a prospective multicenter clinical study. MATERIALS AND METHODS: Twenty-seven consecutive patients with edentulous maxillae were included. Treatments were performed according to the Teeth-in-an-Hour concept (Nobel Biocare AB, Göteborg, Sweden), which includes a CT scan-derived customized surgical template for flapless surgery and a prefabricated prosthetic suprastructure. RESULTS: All patients received their final prosthetic restoration immediately after implant placement, that is, both the surgery and the prosthesis insertion were completed within approximately 1 hour. In the 24 patients followed for 1 year, all prostheses and individual implants were recorded as stable. CONCLUSION: The present prospective multicenter study indicates that the prefabrication, on the basis of models derived from three-dimensional oral implant planning software, of both surgical templates for flapless surgery and dental prostheses for immediate loading is a very reliable treatment option. It is evident that the same approach could be used for staged surgery and in partial edentulism.

Adult↗

PubMedDate not supplied

A custom template and definitive prosthesis allowing immediate implant loading in the maxilla: a clinical report.

PURPOSE: The purpose of the present investigation was to examine to what extent precision data from 3-dimensional planning software for oral implants can be transferred to the operative field by means of a drilling template, containing high-precision drilling sleeves, fitted on the jawbone. It was investigated whether this procedure would allow advance preparation of a fixed definitive prosthesis that could be placed at the completion of surgery. MATERIALS AND METHODS: This procedure was experimentally carried out in 2 cadavers and later in 8 consecutive human patients. RESULTS: The results indicated a nearly perfect match between the positions and axes of the placed implants and those planned. DISCUSSION: This procedure permitted the placement of a definitive fixed prosthesis with limited freedom of space between the abutments and the metallic cylinders incorporated into the prosthesis. CONCLUSION: These encouraging results of the Leuven information technology-based oral rehabilitation by means of implants (LITORIM) are presently being further investigated at the clinical level.

Cadaver↗

PubMedDate not supplied

All-ceramic crowns and preparation characteristics: a mathematic approach.

PURPOSE: The purpose of this investigation was to compare two mathematically calculated preparation parameters, ie, retentive capacity and finish line type, with a visual characterization based on a 3-D projection of the same prepared teeth on a PC screen. MATERIALS AND METHODS: Data from 400 teeth prepared for all-ceramic crowns recorded and manufactured by the Procera system, ie, 100 teeth each of types 11, 13, 14, and 16, were selected. Teeth were visually characterized for retentive capacity as good, acceptable, or insufficient, and type of finish line was characterized as deep chamfer, chamfer, or knife edge. For the mathematic calculations, data points located along vertical lines every 10 degrees around the tooth from finish line to occlusal/incisal midpoint were selected to calculate retentive area, defined as the part of the axial walls with an angle of less than 10 degrees to the preparation midline, and the area at the finish line with an angle of more than 45 degrees to the midline. RESULTS: Significant differences were found between the calculated size of surface areas for all types of prepared teeth visually characterized as having good retention and the two other categories (acceptable and insufficient). The difference between the latter two categories was not significant. Significant differences were also found between calculated surface areas for teeth visually characterized as having a deep chamfer and the two other finish line categories, ie, small chamfer and knife edge, but not between the latter two categories. CONCLUSION: The mathematic program allows a characterization of preparation parameters and may be further developed for use in prospective or retrospective studies of CAD/CAM restorations.

Algorithms↗

PubMedDate not supplied

Titanium dental copings prepared by a powder metallurgy method: a preliminary report.

PURPOSE: The purpose of this study was to determine if the Procera pressed-powder method can be used to fabricate titanium copings. MATERIALS AND METHODS: Commercially pure titanium powder was used to prepare the copings. The powder was pressed onto an enlarged tooth preparation die of aluminum using cold isostatic pressing. The outer shape of the coping was formed using a Procera milling machine, and the copings were vacuum sintered. RESULTS: Titanium copings could be prepared using this method. The density of the sintered copings reached 97% to 99%+ of theoretic density, and the copings showed ductile behavior after sintering. Enlarging the tooth preparation die to compensate for the sintering shrinkage could optimize the final size of the copings. CONCLUSION: Ductile and dense titanium dental copings can be produced with powder-metal processing using cold isostatic pressing, followed by milling and sintering to final shape. The forming technique has, if properly optimized, a potential of becoming a more cost-efficient production method than spark erosion.

Cold Temperature↗