A Novel Abutment Screw Head Design with an Integrated Retrieval Feature: An In Vitro Study

Background/Objectives: This study aimed to present the design of a novel abutment screw head featuring an integrated retrieval mechanism and to evaluate the retrievability of four prototype designs. Methods: In this in vitro mechanical study, the modified screws were produced by replicating the macrogeometry of the Brånemark and Klockner VEGA abutment screws and incorporating a secondary screw chamber below the original one, with a 1.0 mm or 0.9 mm hexagonal design. Sixty screws were manufactured, fifteen for each group: BC0.9, BC1.0, KC0.9, and KC1.0. Retrieval success and the relationship between peak tightening and loosening torque were evaluated (α = 0.05). Results: All screws tolerated tightening at a torque 20% above the manufacturer's recommendation. Most specimens from BC0.9 and KC0.9 failed during loosening, while all specimens in BC1.0 and KC1.0 were successfully retrieved. Regarding peak tightening torque and the loosening-to-tightening ratio, neither prototype exhibited a statistically significant correlation. BC1.0 demonstrated a statistically significant positive correlation between peak tightening torque and peak loosening torque, whereas KC1.0 showed a weaker relationship; detailed correlation coefficients and p-values are reported in the Results. Conclusions: Under the in vitro conditions tested, the prosthetic screw incorporating a 1.0 mm secondary retrieval head demonstrated reliable retrieval performance, supporting its potential as a simple retrieval system. These findings represent a proof-of-concept and require further mechanical and clinical investigation before clinical application.