A Randomized Clinical Trial Comparing the Clinical Fit of CAD/CAM Monolithic Zirconia Fixed Dental Prostheses on Ti-Base Abutments Based on Digital or Conventional Impression Techniques: 1-Year Follow-up

Purpose: To compare the fit and clinical performance of screw-retained monolithic zirconia implant fixed dental prostheses (FDPs) fabricated based on either intraoral optical scanning (IOS) or conventional impressions. Materials and Methods: Patients with two posterior tissue-level implants (Regular Neck, Straumann) replacing two or three adjacent teeth were recruited. Impressions were taken with both IOS (True Definition Scanner, 3M Espe) and a conventional (polyether) pick-up impression. Double-blind randomization was performed after impression-taking, and patients were to receive an FDP based on either the digital or the conventional impression. The fit was evaluated, and the time required for adjustments was recorded. Additionally, survival and technical complication rates with a follow-up of 1 year were documented. Results: A total of 38 patients requiring 45 FDPs were included: 24 FDPs in the test (IOS) and 21 in the control (conventional) group. The average adjustment time was 6.92 minutes (SD: ± 10.84; range: 0 to 49) for digital vs 12.38 minutes (SD: ± 14.52, range: 0 to 54) for conventional impressions (P= .090). A proper fit (no adjustments) was achieved in 33.3% of the digital and 28.6% of the conventional group. Forty-two FDPs could be placed within the two planned appointments, and 3 FDPs exhibited an unacceptable fit and required an extra appointment. Eight technical complications occurred during the first year of function. The overall restoration survival rate was 100%. Conclusion: The clinical fit of CAD/CAM FDPs based on digital impressions is comparable to conventional impressions. Screw-retained monolithic zirconia FDPs on Ti-base abutments show low major complication and 100% survival rates in the short term. Int J Prosthodont 2021;34:733–743. doi: 10.11607/ijp.707