1. Computer aided analysis of digitized dental stone replicas by dental CAD/CAM technology
- Author
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Matts Andersson, Gunilla Sandborgh-Englund, Anna Persson, and Agneta Odén
- Subjects
Cuspid ,Engineering drawing ,Scanner ,business.product_category ,Materials science ,Siloxanes ,Surface Properties ,Calcium Sulfate ,Image Processing, Computer-Assisted ,Humans ,Bicuspid ,Yttrium ,General Materials Science ,General Dentistry ,Orthodontics ,Reproducibility ,Crowns ,biology ,Dental Impression Materials ,Reproducibility of Results ,Repeatability ,biology.organism_classification ,Dental Porcelain ,Molar ,Models, Dental ,Incisor ,Dental stone ,Dental Prosthesis Design ,Mechanics of Materials ,Computer-aided ,Computer-Aided Design ,Die (manufacturing) ,Dental impression material ,Polyvinyls ,Zirconium ,Procera ,business ,Software - Abstract
Objectives. To determine the reproducibility of digitized dental stone replicas compared to the master model and the reliability of the computer aided analysis. Methods. Four master dies, prepared for complete crowns were fabricated in presintered yttria-stabilized tetragonal zirconia (Y-TZP). Eight vinyl polysiloxane impressions (PROVIL novo; Heraeus Kulzer) were taken of each die and stone replicas were poured in type IV stone (Vel-Mix Stone; Kerr). The master dies and the stone replicas were digitized in a touch-probe scanner (Procera ® Forte; Nobel Biocare AB), to create triangulated surface-models. The point-cloud from the first of the repeated digitizations of each master die was used as CAD-reference-models (CRM). Discrepancies between the points in the triangulated surfacemodels and the corresponding CRM were measured by a matching-software (CopyCAD 6.504 SP2; Delcam Plc). The distribution of the discrepancies was analyzed and presented in colordifference-maps. Results. The precision of the measuring method, presented as the repeatability coefficient, ranged between 7 and 16m (entire surface), whereas the analysis of the stone replicas revealed a precision (repeatability coefficient) ranging from 19 to 26m. The accuracy of the replica to master (the mean discrepancy) ranged from 0.5 to 2.0m (95% confidence interval 1.5–2.9m). Significance. The greatest precision of the measurement was seen in the jacket surface of the die. The size of the stone replicas varied and the repeatability coefficient was on average 15m (2–25m) greater for the replica-to-master alignment than the repeated digitizations of the master.
- Published
- 2008
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