Clinical wear of overdenture ball attachments after 1, 3 and 8 years.

OBJECTIVES

Implant-supported overdentures have become the treatment of choice in restoring complete edentulism, but the types of attachment to assure durable retention are a subject of debate. Ball attachments were reported as a simple treatment, but wear of components was responsible for a decrease in retention. The aim of this retrospective study was to measure the wear of the ball abutment or patrix after three different periods of clinical wear.

MATERIAL AND METHODS

Sixty-nine specimens of three groups of patrix that were in use for a mean of 12.3 months (group A), 39 months (group B) and 95.6 months (group C) were retrieved from 35 patients and measured on a coordinate measuring machine equipped with a touch trigger probe. Ten unused ball abutments were added as a control (group D). The patrix diameters and any deviation from circularity in different axes were measured.

RESULTS

The diameters of groups A, B and C were significantly different from that of group D (control). No statistically significant differences were found between diameter and circularity variations between groups B and C. The maximal amount of diameter reduction was limited to approximately 30 μm, and 90% of diameter loss at the equator due to wear was reached in group B.

CONCLUSION

One, 3 and 8 years of clinical wear reduced significantly the diameters of the ball abutments tested, and the maximal amount of wear was reached after 3 years of clinical use.