Dimensional Accuracy of Two-Step Impressions Measured on Scanned Casts in CAD.

Purpose: The purpose of the study was to find out how light-body impression material thickness influences the horizontal dimensional accuracy of casts examined on a scanned model. Materials and Methods: Customized manikin mandibles were used for impression taking with a dual-phase impression method. These mandibles were prepared in a way that allowed the control of light-bodied impression material thickness. First premolars were prepared for a full crown by supragingival chamfer on both sides in all mandibles. For the measurements, buccal and lingual reference points were made at the preparation margin. Impressions were taken at nine thickness levels and a control level (T-Total = 10; 0-1.2 mm), and the reference points' average distance was compared across thickness levels on both the left and right side. We carried out three measures for each specimen and used three specimens per thickness level. Total sample size was N = 180, creating a sizable database to understand the influence. Results: The results indicated that light-body impression material thickness had no influence on the horizontal dimension of a die measured on scanned dies in these specific circumstances. Conclusions: The thickness of light-body impression material in the dual-phase impression taking technique did not have a significant influence on the horizontal accuracy of scanned dies, which makes the technique safe and reliable for single crown restorations without having to take extra precautions for the thickness of light-body impression material.