Soft tissue replication in single unit implant impressions-A three dimensional clinical study

Objective Comparison of soft tissue replication between conventional and digital impressions for definitive single unit implant rehabilitation in the esthetic zone. Materials and Methods Six patients were recruited according to inclusion criteria for this cross-over pilot study and submitted to a conventional silicone implant impression with customized coping and a digital impression with an intraoral scanner. Stereolithography files obtained from the same patient were superimposed with appropriate software and trueness evaluated between methods at predetermined locations (56 in hard and soft tissues and 18 in the emergence profile, per patient). Results were presented as mean root mean square (RMS) +/- 95% confidence interval and effect size calculated with Hedges' g +/- 95%. Mann-Whitney and Kruskal-Wallis were performed when appropriate and alpha was set at .05. Results Trueness between methods equated to 51.08[45.68;56.47] mu m and 60.46[52.29;68.62] mu m in hard and soft tissues, respectively. Soft tissue replication by intraoral scanner acquisition corresponded to a statistically significant RMS of 243.89[209.15;278.63] mu m equating to a Hedges' g of 1.52[1.22;1.82] which corresponded to a large effect size. Conclusions The proposed method could be considered for soft tissues assessment and the results suggest that intraoral impression techniques produce statistically significant changes in peri-implant soft tissue replication, although below the clinically detectable threshold. Clinical Significance The proposed technique allows for the 3D determination of peri-implant tissues changes in digital models with higher sensitivity than visual techniques, thus presenting itself as a promising alternative in clinical studies and that the use of an intraoral scanner obtained significant differences in the soft tissue emergence profile replication when compared with the gold standard.