The effect of different implant-abutment types and heights on screw loosening in cases with increased crown height space.

Objectives: The stability of the abutment screw is pivotal for successful implant-supported restorations, yet screw loosening remains a common complication, leading to compromised function and potential implant failure. This study aims to evaluate the effect of different implant-abutment types and heights on screw loosening in cases with increased crown height space (CHS).
Materials and Methods: In this in vitro study, a total of 64 abutments in eight distinct groups based on their type and height were evaluated. These groups included stock, cast, and milled abutments with heights of 4 mm (groups S4, C4, and M4), 7 mm (groups S7, C7, and M7), and 10 mm (groups C10 and M10). Removal torque loss (RTL) was assessed both before and after subjecting the abutments to dynamic cyclic loading. Additionally, the differences between initial RTL and RTL following cyclic loading were analyzed for each group (p < .05).
Results: The C10 group demonstrated the highest RTL, whereas the S4 group exhibited the lowest initial RTL percentage (p < .05). Furthermore, the study established significant variations in RTL percentages and the discrepancies between initial and postcyclic loading RTL across different abutment groups (p < .05). Additionally, both abutment types and heights were found to significantly influence the RTL percentage (p < .05).
Conclusion: The type and height of the implant abutment affected screw loosening, and in an increased CHS of 12 mm, using a stock abutment with a postheight of 4 mm can be effective in minimizing screw loosening.
(© 2024 The Authors. Clinical and Experimental Dental Research published by John Wiley & Sons Ltd.)