Evaluation of intraoral digital impressions for obtaining gingival contour in the esthetic zone: accuracy outcomes

Objectives To assess the accuracy of intraoral digital impressions for gingival contour captured in the esthetic zone in vivo. Material and methods Five participants with full upper dentition were recruited. For each participant, three scans were taken using two intraoral scanning (IOS) systems (3Shape TRIOS Color, TRC; CEREC Omnicam, OC) respectively; three conventional impressions (CIs) were taken using vinyl polysiloxane materials. The CIs of all participants were casted and then digitized with a model scanner (IScan D103i, Imetric). Precision was evaluated by superimposing three repeated STL datasets per participant within each group and calculating the (90th - 10th)percentile/2 values. The CIs were the reference for evaluating the level of system error of the two IOS systems from the true value. Digital models from CI and each IOS group were superimposed and (mean positive deviation-mean negative deviation)/2[mean negative deviation, mean positive deviation] were calculated to assess trueness level of the two IOS systems. Results For the soft tissue acquisition, precision results of each group were 45.10 ± 12.54 μm in TRC, 66.04 ± 13.46 μm in OC, and 63.66 ± 17.19 in CI (TRC vs OC, p < 0.001; TRC vs CI, p = 0.001; OC vs CI, p = 0.66). Trueness results were 80.12 ± 8.69[− 112.10 ± 9.88, 48.13 ± 13.79] μm in TRC and 82.70 ± 8.85[− 121.41 ± 15.40, 43.98 ± 11.86] μm ( p > 0.05). Conclusions In dentate situations, the two tested IOS systems achieved a clinically satisfying accuracy for capturing gingival contour in anterior maxilla, with a comparable or superior precision to the CI. TRC achieved a similar trueness and a higher precision level compared with OC. Clinical relevance Intraoral digital impressions could be a recommended method for recording 3-dimensional gingival contour in the esthetic zone.