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Photogrammetry and Conventional Impressions for Recording Implant Positions: A Comparative Laboratory Study
Author(s) -
Örtorp Anders,
Jemt Torsten,
Bäck Tomas
Publication year - 2005
Publication title -
clinical implant dentistry and related research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.338
H-Index - 85
eISSN - 1708-8208
pISSN - 1523-0899
DOI - 10.1111/j.1708-8208.2005.tb00046.x
Subject(s) - photogrammetry , impression , plaster casts , plotter , coordinate measuring machine , distortion (music) , implant , dental arch , materials science , computer science , orthodontics , biomedical engineering , computer graphics (images) , dentistry , engineering drawing , optics , physics , computer vision , medicine , engineering , surgery , amplifier , optoelectronics , cmos , world wide web
Background: The development of digitized techniques for manufacturing implant frameworks has made possible alternative “impression” techniques for recording implant positions. Purpose: The objective of the present study was to test the precision and accuracy of a three‐dimensional photogrammetric technique to record implant positions in vitro and to compare casts made with this technique with conventional casts fabricated with two conventional impression techniques. Materials and Methods: Twenty casts were fabricated from 10 polyether (Impregum™, ESPE Dental AG, Seefeld, Germany) impressions and 10 plaster (Kühns Abdrucksgips, Ernst Hirnischs GmbH, Goslar, Germany) impressions of one master model. The casts were measured in a coordinate measuring machine (Zeiss Prismo VAST, Oberkochen, Germany) and compared with the master model. Six separate three‐dimensional photographs of the master model were taken with a special camera. After the photographs were measured with an analytic plotter, results were analyzed and compared to the coordinates of the original model and casts. Results: A systematic pattern of distortion in the x‐axis was found for the two impression techniques. Expansion of the implant arch at the terminal implants ( p < .01) averaged 22 μm and 94 |im on photographs and plaster casts, respectively. Polyether casts contracted an average of 52 μm when compared with the master ( p < .01). In absolute figures, photogrammetry and the polyether technique reproduced the x‐axis and three‐dimensional parameters more accurately than the plaster technique did when cylinder center point distortion was compared ( p < .05 to p < .001). However, angular cylinder distortion in absolute figures was greater with the photographic technique than with either of the impression techniques ( p < .05‐p < .001). Conclusion: Photogrammetry is a valid option for recording implant positions and has a precision comparable to that of conventional impression techniques. At present, however, it is limited to framework fabrication techniques that are based on digital platforms.