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Published on: February 10, 2014
Micromotion and dynamic fatigue properties of the dental implant-abutment interface
D G Gratton1, S A Aquilino, C M Stanford
1School of Dentistry, The University of Western Ontario, London, Ontario, Canada. dgratton@julian.uwo.ca
Statement Of Problem:
Clinical loading may result in micromotion and metal fatigue in apparently stable implant screw joints. This micromotion may contribute to tissue inflammation and prosthesis failure.
Purpose:
This study investigated dental implant screw joint micromotion and dynamic fatigue as a function of varied preload torque applied to abutment screws when tested under simulated clinical loading.
Material And Methods:
Fifteen noble alloy single-tooth implant restorations, each containing a hexed UCLA-style gold cylinder, were randomly assigned to 3 preload groups (16, 32, and 48 N.cm). Each group consisted of 5 implants (each 3.75 x 15 mm) and 5 square gold alloy abutment screws. A mechanical testing machine applied a compressive cyclic sine wave load between 20 and 130 N at 6 Hz to a contact point on each implant crown. A liquid metal strain gauge recorded the micromotion of the screw joint interface after 100, 500, 1,000, 5,000, 10,000, 50,000, and 100,000 cycles. Baseline data at 0 N.cm were collected before the application of the specified preload torque.
Results:
The 16 N.cm group exhibited greater micromotion (P<.001) than both the 32 and 48 N.cm groups at all cycle intervals (2-way ANOVA, Tukey HSD). Micromotion of the implant-abutment interface remained constant (P=.99) for each of the preload groups through 105 cycles.
Conclusion:
Under the loading parameters of this study, no measurable fatigue of the implant-abutment interface occurred. However, dental implant screw joints tightened to lower preload values exhibited significantly greater micromotion at the implant-abutment interface.
