LAUSR

OBJECTIVE To assess the clinical and laboratory time efficiency and quality of outcomes for posterior single implant crowns by means of a model-free digital workflow using digital impressions immediately after implant placement. METHODS Forty patients missing a single posterior tooth received implant therapy. For within-subject comparison, digital impressions were taken immediately after implant placement and conventional impressions after implant healing. Two monolithic zirconia crowns were fabricated using a laboratory-based CAD-CAM system. One crown was produced from the immediate digital impression and a model-free digital workflow (test group), and the second crown was produced from the conventional impression and a hybrid workflow (control group). Clinical and laboratory time was recorded. Quality of outcomes was evaluated double-blinded. A paired-sample t test was applied for statistical analysis. RESULTS The total mean chairside time (impression and delivery) was 23.2 min (95%CI 22.2, 24.3) in the test group and 25.7 min (95%CI 24.4, 26.9) in the control group (p = 0.013). Significantly less laboratory time was needed in the model-free digital workflow (13.6 min, 95%CI 11.5, 15.6) as compared to the model-based hybrid workflow (29.9 min, 95%CI 25.7, 34.2) (p < 0.05). At crown delivery, 4/40 (test) and 12/40 (control) had no need of chairside adjustments, and 6/40 (test) and 5/40 (control) implant crowns were in need of additional laboratory interventions. CONCLUSION The fabrication of posterior single implant crowns using digital impressions taken immediately after implant placement and a model-free, laboratory-based digital workflow was more time efficient and resulted in similar quality of outcomes as a hybrid workflow using conventional impressions.