Introduction: Traditionally, digital models have been made from alginate impressions, which are either scanned directly or poured in plaster and then scanned. The development of chairside oral scanners now allows direct intraoral scanning of the dentition, but questions remain regarding the accuracy of full-arch digital models acquired using this technology, the time required for such scanning, and patient acceptance. These factors will be critical in determining the acceptance of direct scanning technology in the orthodontic setting. Materials and Methods: Fifteen consecutive patients had full-arch digital models acquired using a chairside oral scanner (Lava COS; 3M ESPE, St. Paul, MN, USA) and conventional alginate impressions, which were then digitized using a computed tomography scanner (OrthoProof, Albuquerque, NM, USA). The time required to perform the procedures was recorded to the closest second. Each patient was given a questionnaire to assess model acquisition preference. For each digital model pair, the individual arches were globally superimposed utilizing best-fit surface-based registration. Discrepancies in individual tooth position between models were computed using eModel 9.0 software (GeoDigm, Falcon Heights, MN, USA). A Bland-Altman comparison was performed on each discrepancy measurement. Time differences were tested for statistical significance using a Student's t-test. For all tests, P<0.05 was considered significant. Results: When compared to digital models made from alginate impressions, those made from intraoral scans were not significantly different. The chairside time required to perform impressions was significantly shorter (7m, 35s +/- 0m, 26s) than that required for COS scans (20m, 27s +/- 3m, 6s). When the time required for disinfection and packaging of the impressions was included, the time requirement did not differ significantly from the scan time. While 73.33% of patients preferred conventional impressions because they were "easier" and/or "faster," 26.67% preferred the intraoral scan because it was "more comfortable." Conclusions: Despite the high relative accuracy of intraoral scans, traditional alginate impressions are still the preferred model acquisition method with respect to chairside time and patient acceptance. As digital technologies evolve to increase efficiency and patient acceptance, direct scanning technology may become more accepted by the orthodontic community.
University of Minnesota M.S. thesis. November 2013. Major: Dentistry. Advisors: Thorsten Thorsten and Brent Larson. 1 computer file (PDF); v, 54 pages.
McCarthy, Shawn D..
Clinical use of a direct chairside oral scanner: an assessment of accuracy, time, and patient preference.
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