Optimizing post-space drying: insights from an in vitro study using standardized three-dimensional-printed models

Objectives: This study aimed to evaluate the efficiency of four post-space drying methods using standardized three-dimensional (3D)-printed resin tooth specimens, with emphasis on clinical implications for adhesive post retention. Methods: Maxillary central incisor models with post spaces of three diameters (1.4, 1.7, 2.0 mm) and three lengths (6.0, 9.0, 12.0 mm) were digitally designed and 3D-printed. A total of 81 specimens (n = 9 per post-space condition) were evaluated. Four drying methods were tested: air-syringe (AS), post-air-blow (PAB), paper-point (PP), and root-canal suction (RCS). Remaining moisture amount and content were quantified gravimetrically and analyzed using two-way and oneway analysis of variance with Tukey honestly significant difference (α = 0.05). Results: Drying performance depended on both geometry and technique. AS consistently left greater remaining moisture, whereas PP and RCS showed stable, efficient drying. PAB was generally effective but technique-sensitive in long, narrow geometries. Conclusions: Standardized 3D-printed models enabled reproducible evaluation of post-space drying and revealed clinically relevant limitations of commonly used methods. Selecting drying protocols tailored to post-space geometry may reduce residual moisture prior to adhesive cementing.