Evaluation of the influence of gingival retraction width on the optical impression of the subgingival region using a 3D printed abutment tooth model

This study aimed to evaluate the conditions for the finish line position and gingival retraction width that allow for taking optical impressions using three-dimensional (3D) printed models. Taking an impression using an intraoral scanner (IOS) is widely performed in fabricating crown prostheses. Measuring the subgingival finish line using an IOS is difficult; to obtain optical impressions of the subgingival finish line, the gingival retraction has been recommended. However, no study has evaluated the amount of gingival retraction width and the depth of the finish line. In this study, the measurement limits of the subgingival finish line using an IOS and models fabricated by a 3D printer were investigated. The results of this study revealed that TRIOS3 could not measure the finish line when the gingival retraction width was <0.25 mm, and the finish line was located >0.50 mm below the gingival margin.