Rotational Stability of Non-Engaging Abutments: Influence of Positioning Guide Thickness and Definitive Prosthesis...

To evaluate tightening-stage-dependent rotational behavior of non-engaging abutments according to delivery method, focusing on positioning guides and cement space configuration.

Non-engaging prefabricated abutments were delivered using positioning guides of varying thicknesses or definitive prostheses fabricated with different cement space. Angular deviation was measured after initial hand tightening and subsequent tightening stages. Positional changes across tightening stages were compared among groups to assess positional reproducibility and stability.

When positioning guides were used, angular displacement was observed after initial hand tightening; however, no significant additional displacement occurred during subsequent torque application, indicating maintenance of positional reproducibility. Guide thickness did not significantly influence rotational stability. In contrast, definitive prosthesis-assisted delivery demonstrated tightening-stage-dependent rotational behavior that varied with cement space. With a conventional cement space, angular deviation remained comparable to that observed with positioning guides, whereas increased cement space resulted in progressive angular displacement during tightening. Across all groups, rotational stability was more associated with interfacial space control than with material stiffness.

Within the limitations of this study, the rotational behavior of non-engaging abutments was influenced by the delivery method and interfacial space configuration. Positioning guides promoted reproducible seating, whereas increased cement space during definitive prosthesis-assisted delivery compromised rotational stability.