Clinical Comparative Study for Validation of Digital Impression Reliability with the Gypsum Check: A Simple and Fast Way to Evaluate the Trueness and Accuracy of Implant-Supported Rehabilitation

Despite many advantages, digital impressions, when compared to the conventional one, produce contrasting results and their complete substitution is still under debate. This comparative study aims to test a way to perform a clinical evaluation of digital impression Accuracy and Trueness with a gypsum check. After calculating the Trueness, Precision, and Accuracy of the digital impressions, a gypsum check was fabricated and screwed on implant abutments. The impression was not considered reliable if the gypsum check fractured during the insertion. The gypsum check test was correlated to a cut-off of 100 µm Trueness. Mean Trueness was 151.19 ± 37.23 µm of the first optical impression and 125.47 ± 41.90 µm of the second optical impression. The Precision mean was 39.76 ± 10.89 µm. The mean Accuracy percentage was 98.69 ± 0.29%. The gypsum checks fractured 10 times on 42 tests, and in any case, the Trueness value was above the 100 µm cut off, with a p = 0.001. A gypsum check screwed onto an implant abutment could be considered a way to perform clinical measurement of Trueness, allowing the clinician to understand if the Trueness value is higher or lower than 100 µm and reflecting the reliability of digital impressions.