Methods: A total of 100 crowns were evaluated for this study, 50 conventional and 50 digital impressions were taken for single unit posterior crowns. The teeth must have opposing contact and at least one proximal contact. The digital impressions were performed using the iTero 3D intraoral scanner from Cadent Inc. The conventional impressions were done using Aquasil (Dentsply) or Impregum (3M ESPE) impression material in a disposable tray. Stone models were fabricated from the conventional impressions; plastic models were milled from plastic blocks from the digital impressions. The plastic blocks were manufactured at Cadent Inc. in New Jersey. All crowns for these models were fabricated at California Dental Arts, a dental laboratory in Cupertino, CA. Prior to cementation the following protocol was followed; proximal contacts, intaglio surfaces, margins, occlusion and esthetics. The time required for all necessary adjustments was monitored. The student t-test was used at a 95% confidence interval to analyze the resulting data.
Results: The average adjustment times for conventional versus digital impressions were 72 (±38) min and 56 (±31) min respectively. Statistical analysis revealed a significant difference between the two average adjustment times, with p= 0.018.
Conclusions: A time savings of 22% on crown adjustments prior to cementation can be achieved when using the digital impression system iTero versus the conventional impression method.