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A prospective 5-year study of two cast framework alloys for fixed implant-supported mandibular prostheses
William M Murphy1, Elias G Absi, Max C Gregory
1Department of Prosthetic Dentistry, Dental School, University of Wales College of Medicine, Cardiff, United Kingdom.
Purpose:
A longitudinal 5-year clinical investigation was carried out to compare screw-retained frameworks constructed from two alloys with different mechanical properties, either gold or silver-palladium, supported in the mandible by the Astra Tech implant system.
Materials And Methods:
Twenty-six edentulous patients with mandibular implants were divided into two groups: group A was provided with Chicago IV gold alloy superstructures, and group B was provided with Palliag M silver-palladium alloy superstructures. The surgical procedures for placing the mandibular bone implants and the prosthodontic and laboratory techniques for constructing the prostheses were carried out according to standard, well-documented practices. All patients wore conventional maxillary complete dentures. The integrity of prostheses and health of supporting tissues were compared over a 5-year period.
Results:
Both materials had similar accuracy of fit and resistance to functional stress, although silver-palladium was technique sensitive and necessitated meticulous laboratory practice to achieve accuracy of casting. Clinical performance of both prostheses was similar, and radiographic assessment showed no statistically significant differences in periimplant bone changes.
Conclusion:
There were no differences in clinical performance and radiographic changes between the two materials. Therefore, silver-palladium alloy may be considered a suitable low-cost substitute for gold alloy for fixed implant-supported prostheses.