Micromotion and dynamic fatigue properties of the dental implant–abutment interface

doi:10.1067/mpr.2001.112796

The Journal of Prosthetic Dentistry

Volume 85, Issue 1, January 2001, Pages 47-52

Presented at the American Academy of Fixed Prosthodontics Annual Meeting, Chicago, Ill., February 1998.

https://doi.org/10.1067/mpr.2001.112796 Get rights and content

Abstract

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 × 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. (J Prosthet Dent 2001;85:47-52.)

Section snippets

Material and methods

This study used a measure of joint opening to evaluate the dynamic fatigue of the screw joint interface as a function of 3 different screw preloads. Five identical frameworks were fabricated by duplicating a milled aluminum template in acrylic resin. A hexed gold alloy UCLA-type cylinder (Cat. No. GUCH1, 3i Implant Innovations, West Palm Beach, Fla.) was incorporated into each pattern. Acrylic resin patterns (GC Pattern Resin, G-C Dental Industrial Corp, Tokyo, Japan) were individually sprued

Results

Strain gauge calibration data before and after each test sequence demonstrated a linear response (r² = 0.9826 to 0.9986). A paired t test of the calibration slopes demonstrated a stable gauge response over the range of variables evaluated in this study (P=.0825, t=1.871, df=14). Therefore, an average of the calibration slopes before and after testing was calculated and used as the conversion factor for each of the 15 test sequences. This factor converted the millivolt output from the strain

Discussion

The innovative and unique measurement method used in this study allowed quantitative measurement of the stability of the joint interface over time. The positioning of the liquid metal strain gauge at a distance away from the screw joint avoided any alteration to the interface. The measurement of 9 to 17 μm mean micromotion demonstrated the sensitivity of the measurement technique.

Although the results of this study suggest that a preload as low as 16 N·cm may provide acceptable joint performance

Conclusions

Under the parameters of this study and from the resulting data collected, the following conclusions were drawn concerning micromotion at the dental implant–abutment interface:

The micromotion of the implant–abutment–abutment screw interface remained constant through 100,000 cycles for the 16, 32, and 48 N·cm preload groups, thus indicating that no fatigue of the screw joint interface occurred.
Dental implant screw joints utilizing screws that were undertightened (inadequate preload) exhibited

Supplementary Files

Acknowledgements

We gratefully acknowledge Todd Fridrich, CDT, for his dental laboratory support and Anneliese Heiner, PhD, for her expertise with the MTS universal testing machine.

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^☆: Based on a thesis submitted in partial fulfillment of the requirements for the Master of Science degree in Prosthodontics in the Graduate College of The University of Iowa.

^☆☆: Supported in part by a Stanley D. Tylman Research Grant, 3i Implant Innovations, and The University of Iowa College of Dentistry.

^★: ^aAssistant Professor, Division of Prosthodontics, School of Dentistry, The University of Western Ontario.

^★★: ^bProfessor, Department Executive, and Graduate Director, Department of Prosthodontics, College of Dentistry, The University of Iowa.

^♢: ^cAssociate Professor, Dows Institute for Dental Research and Department of Prosthodontics, College of Dentistry, The University of Iowa.

^♢♢: Reprint requests to: Dr David G. Gratton Division of Prosthodontics School of Dentistry The University of Western Ontario London, Ontario N6A 5C1 CANADA Fax: (519)661-3416 E-mail: [email protected]

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Micromotion and dynamic fatigue properties of the dental implant–abutment interface☆,☆☆,★,★★,♢,♢♢

Abstract

Section snippets

Material and methods

Results

Discussion

Conclusions

Supplementary Files

Acknowledgements

J Prosthet Dent

J Dent

J Prosthet Dent

J Prosthet Dent

J Prosthet Dent

J Prosthet Dent

J Prosthet Dent

3-year followup study of early single implant restorations ad modum Branemark

Int J Periodontics Restorative Dent

Effect of preload torque on the ultimate tensile strength of implant prosthetic retaining screws

Implant Dent

Osseointegrated implants for single tooth replacement: a 1-year report from a multicenter prospective study

Int J Oral Maxillofac Implants

Osseointegrated implants for single-tooth replacement: progress report from a multicenter prospective study after 3 years

Int J Oral Maxillofac Implants

The role of screws in implant systems

Int J Oral Maxillofac Implants

Mandibular deformation in subjects with osseointegrated implants

Int J Oral Maxillofac Implants

Torque generated by handheld screwdrivers and mechanical torquing devices for osseointegrated implants

Int J Oral Maxillofac Implants