3D printing vs. conventional wax patterns: a comparative in vitro study on retention of RPD framework

Removable partial dentures (RPDs) are widely used in prosthodontic rehabilitation, where retention is crucial for function, comfort, and patient satisfaction. Conventional wax-up techniques for fabricating RPD frameworks are prone to inaccuracies due to manual errors. Advances in digital dentistry and 3D printing have introduced alternative fabrication methods, potentially enhancing fit and retention. This study aimed to evaluate and compare the retention of cobalt-chromium RPD frameworks fabricated using conventional wax patterns and 3D-printed castable resin pattern. An in vitro experimental design was employed using prefabricated typodont models of mandibular Kennedy Class I and maxillary Kennedy Class II modification 2. A total of 120 casts (60 per arch) were divided equally into conventional (CT) and 3D-printed (3DPT) groups. Frameworks were fabricated following standardized protocols. Retention was measured using an electronic vertical pull device, and statistical analysis included paired t tests and Wilcoxon signed-rank tests, depending on data distribution. 3D-printed RPD frameworks demonstrated significantly higher retention compared to conventional ones. For mandibular models, mean retention values were 4.82 N (3DPT) vs. 3.86 N (CT) (p < 0.001, r = 0.87). For maxillary models, mean retention was 49.67 N (3DPT) vs. 40.92 N (CT) (p < 0.001, Cohen's dz = 4.20). Within the limitations of this in vitro study, RPD frameworks fabricated from 3D-printed castable resin pattern exhibited superior retention compared to those made with conventional wax patterns. These findings support the integration of digital workflows in removable prosthodontics, highlighting the potential of 3D printing to enhance clinical outcomes.