Effect of friction coefficient on Akers clasp retention

Statement of problem. Retentive force control of clasp retainers is one of the most essential factors for the successful function of removable partial dentures. However, it is not yet known how the friction coefficients differ among restored abutments and clasp materials, and how the friction coeffi...

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Bibliographic Details
Published in:	The Journal of prosthetic dentistry 1997-07, Vol.78 (1), p.22-27
Main Authors:	Sato, Yuuji, Abe, Yasuhiko, Yuasa, Yoshitaka, Akagawa, Yasumasa
Format:	Article
Language:	eng
Subjects:	Analysis of Variance Chromium Alloys - chemistry Dental Abutments Dental Alloys - chemistry Dental Clasps Dental Enamel - physiology Dental Materials - chemistry Dental Polishing Dentistry Denture Design Denture Retention Denture, Partial, Removable Friction Gold Alloys - chemistry Humans Linear Models Palladium - chemistry Saliva - physiology Stress, Mechanical Surface Properties Water
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Summary:	Statement of problem. Retentive force control of clasp retainers is one of the most essential factors for the successful function of removable partial dentures. However, it is not yet known how the friction coefficients differ among restored abutments and clasp materials, and how the friction coefficients affect the retention of clasps. Purpose. The purposes of this study were to clarify the friction coefficients among restored abutments and clasp materials and to estimate the effect of friction coefficients on the retention of clasps. Material and methods. The coefficients of static friction between three clasp materials (type IV gold, high Pd, and cobalt-chromium [Co-Cr] alloys) of two surface treatments (polished and sandblasted) and four abutment materials (human enamel, porcelain, type IV gold, and high Pd alloys) were evaluated under three conditions (dry, wet with water, and wet with saliva), and theoretically, the effect of the friction coefficients on clasp retention was estimated. Results. The friction coefficients under various conditions ranged from 0.08 (polished Co-Cr clasp on type IV abutment in dry condition) to 0.37 (sandblasted Co-Cr clasp on high Pd abutment in dry condition). The theoretical estimation clarified that the retentive force of the clasp was linear to the friction coefficient. Conclusion. The retentive force increased linearly with increasing friction coefficient between abutment material and clasp material according to the newly developed formula. This study suggested that clasp designs should be changed depending on abutment materials.(J Prosthet Dent 1997;78:22-7.)
ISSN:	0022-3913 1097-6841