Comparison of Marginal Fit and Mechanical Performance of Three-unit Implant-supported Fixed Dental Prostheses...

To compare the marginal fit and mechanical performance of three-unit implant-supported fixed dental prostheses (ISFDPs) fabricated using fully digital and conventional workflows.

Three-unit ISFDP specimens in this study simulated the restoration of three consecu-tively missing teeth in the mandibular posterior region. Twenty-four specimens were divided into three groups: the zirconia fully digital (ZFD) group received zirconia ISFDPs fabricated using a fully digital workflow; the polyetherketoneketone fully digital (PFD) group received polyetherketoneketone (PEKK) ISFDPs fabricated using a fully digital workflow; and the zir-conia control (ZC) group received zirconia ISFDPs fabricated using a conventional workflow. Marginal gaps between restorations and abutments during passive and active fit were meas-ured, and initial screw loosening torque values of restorations were recorded. After undergoing 1,200,000 cycles of vertical loading, the restorations were reassessed for marginal gaps and loosening torque values.

Marginal fit under passive and active fit in the ZFD group showed no significant dif-ference in relation to the ZC group. Marginal gaps in the PFD group (134.39 ± 41.13 µm) under passive fit were significantly larger than in the ZFD group, and decreased significantly under active fit (22.28 ± 10.45 µm). No significant difference in marginal fit was observed before and after cyclic loading in all groups. No significant difference was found in loosening torque change between the ZFD and ZC groups, whereas the change in the PFD group (median -2.13%, Q25 -3.30%/Q75 0.28%) was significantly lower than in the ZC group (median -5.83%, Q25 -8.46%/Q75 -3.75%).

Three-unit ISFDPs fabricated using fully digital and conventional workflows exhibit similar marginal fit and mechanical performance. Additionally, PEKK ISFDPs demonstrate clinically acceptable marginal fit and mechanical performance.