Computerized Casts for Orthodontic Purpose Using Powder-Free Intraoral Scanners: Accuracy, Execution Time, and Patient Feedback

Abstract

Introduction. Intraoral scanners allow direct images of oral situation, with fewer steps than conventional impressions. The purpose of this study was to compare the accuracy of digital impressions, traditional impressions, and digitalization of full-arch gypsum models, to evaluate timing of different methods and finally to study perception of patients about conventional and digital impression techniques. Methods. Dental arches of fourteen patients were evaluated by alginate impression, titanium dioxide powder-free intraoral scanning (Trios, 3Shape), and digitalization obtained from gypsum models using the same scanner. Conventional and digital techniques were evaluated through measurements (lower and upper arch anteroposterior length, lower and upper intercanine distance, and lower and upper intermolar distance) with a caliber for analogic models and using a computer software for digital models (Ortho Analyzer, Great Lakes Orthodontics). In addition, chairside and processing times were recorded. Finally, each patient completed a VAS questionnaire to evaluate comfort. Statistical analyses were performed with ANOVA and Tukey tests for accuracy measurements and paired t-test for times and VAS scores. Significance was predetermined at P<0.05. Results. The measurements obtained with intraoral scanning, gypsum models after conventional impression, and digitalized gypsum models were not significantly different. Both chairside and processing times of digital scanning were shorter than the traditional method. VAS reporting patients comfort were significantly higher when evaluating digital impression. Conclusions. Intraoral scanners used for orthodontic applications provide useful data in clinical practice, comparable to conventional impression. This technology is more time efficient than traditional impression and comfortable for patients. Further evolution with more accurate and faster scanners could in future replace traditional impression methods.