Analysis of retention and wear of ball attachments
Katia Wolf1, Klaus Ludwig, Heike Hartfil
1Department of Prosthodontics, Propaedeutics, and Dental Materials, School of Dentistry, Christian-Albrechts University, Kiel, Germany. kwolf@proth.uni-kiel.de
Objective:
To evaluate the retention and the wear of different prefabricated precision ball attachments consecutively during long-term use.
Method And Materials:
Six commercially available ball attachment systems were selected. The balls were attached to stylized implants fixed in metal casts. The matrices were fixed in a stylized unilaterally removable partial denture (RPD). Using a chewing simulator with 8 units, 50,000 joining and separating cycles of the matrices were performed. After each joining movement, an eccentric load of 100 N was applied to the RPD at a distance of 12 mm from the ball attachment. The retention forces were measured at intervals.
Results:
Initially, median retentive forces varied between 8.2 N and 14.0 N. During the test, patterns in retention changes were identified. At the end of the test, one group with a matrix using precious alloy lamellae and a titanium ball showed significantly higher median retention forces (10.4 N) than the other ball attachments (1.0 N to 3.7 N). Also, the wear of the ball attachments varied considerably.
Conclusion:
Within the limitations of this study, the material combination of a precious gold alloy matrix and a titanium ball seems to be favorable for long-term retention.
Related Concept Videos
Collar Bearings
Bearings: Problem Solving
Abrasion Resistance of Concrete
One such test is the revolving disc test, where three plates...
Residual Stresses in Circular Shafts
Journal Bearings
To better understand the concept of journal bearings, consider a rope winch with dry or...
Design of Transmission Shafts - Stress Analysis

