- 作者：Tabea V. Fl¨¹gge ; Stefan Schlager ; Katja Nelson ; Susanne Nahles ; Marc C. Metzger
- 刊名：American Journal of Orthodontics and Dentofacial Orthopedics
- 出版年：2013
- 出版时间：September, 2013
- 年：2013
- 卷：144
- 期：3
- 页码：471-478
- 全文大小：1401 K
Introduction
Digital impression devices are used alternatively to conventional impression techniques and materials. The aims of this study were to evaluate the precision of digital intraoral scanning under clinical conditions (iTero; Align Technologies, San Jose, Calif) and to compare it with the precision of extraoral digitization.Methods
One patient received 10 full-arch intraoral scans with the iTero and conventional impressions with a polyether impression material (Impregum Penta; 3M ESPE, Seefeld, Germany). Stone cast models manufactured from the impressions were digitized 10 times with an extraoral scanner (D250;?3Shape, Copenhagen, Denmark) and 10 times with the iTero. Virtual models provided by each method were roughly aligned, and the model edges were trimmed with cutting planes to create common borders (Rapidform XOR; Inus Technologies, Seoul, Korea). A second model alignment was then performed along the closest distances of the surfaces (Artec Studio software; Artec Group, Luxembourg, Luxembourg). To assess precision, deviations between corresponding models were compared. Repeated intraoral scanning was evaluated in group 1, repeated extraoral model scanning with the iTero was assessed in group 2, and?repeated model scanning with the D250 was assessed in group 3. Deviations between models were measured and expressed as maximums, means, medians, and root mean square errors for quantitative?analysis. Color-coded displays of the deviations allowed qualitative visualization of the deviations.
Results
The greatest deviations and therefore the lowest precision were in group 1, with mean deviations of 50 ¦Ìm, median deviations of 37 ¦Ìm, and root mean square errors of 73 ¦Ìm. Group 2 showed a higher precision, with mean deviations of 25 ¦Ìm, median deviations of 18 ¦Ìm, and root mean square errors of 51 ¦Ìm. Scanning with the D250 had the highest precision, with mean deviations of 10 ¦Ìm, median deviations of 5?¦Ìm, and root mean square errors of 20 ¦Ìm. Intraoral and extraoral scanning with the iTero resulted in deviations at the facial surfaces of the anterior teeth and the buccal molar surfaces.
Conclusions
Scanning with the iTero is less accurate than scanning with the D250. Intraoral scanning with the iTero is less accurate than model scanning with the iTero, suggesting that the intraoral conditions (saliva, limited spacing) contribute to the inaccuracy of a scan. For treatment planning and manufacturing of tooth-supported appliances, virtual models created with the iTero can be used. An extended scanning protocol could improve the scanning results in some regions.