Wear of ceramic and titanium ball attachments in subjects with an implant-retained overdenture: a controlled clinical trial.
BACKGROUND
Loss of retention of implant-retained overdentures due to wear of the patrix or matrix of the attachment system is a common clinical problem.


OBJECTIVE
The purpose of this controlled clinical trial was to compare the wear of ceramic and titanium ball attachments and their corresponding gold matrices after 1 year of clinical function in subjects with implant-retained mandibular overdentures.


METHODS
Forty subjects who had been treated with a 2-implant-retained overdenture received either 2 ruby ball attachments (20 subjects) or 2 titanium ball attachments (20 subjects). The diameter of the ball attachments and the thickness of the matrix were measured optically before insertion and after 1 year of clinical function. Differences among groups were then compared with the Wilcoxon rank sum test (α=.05). To estimate any correlation between clinical parameters and wear, the Spearman rank test was used.


RESULTS
There was no significant difference (P=.73) in the median wear of ball attachments for the titanium group (5.3 μm; median 1.3 μm) and for the ceramic group (1.3 μm; median 1.3 μm). In the ceramic group, a fracture rate of 30% was observed. The mean wear of the matrices in the titanium group was 3.1 μm (median 6.8 μm) and in the ceramic group 2.1 μm (median 3.4 μm), P=.01. No correlation was found between ball attachment wear and matrix insert wear (Spearman rank test). Wear of matrices was weakly correlated with an increase in divergence between implant axes in the sagittal plane (P=-.28 and P=.021). Ball attachment wear was associated with an increase in divergence between matrix axes in the sagittal plane (P=-.34 and P=.047).


CONCLUSIONS
Matrices on ceramic ball attachments showed less wear than those placed on titanium ball attachments. However, the use of ruby ball attachments cannot be recommended because of a high fracture rate.
Clinic for Reconstructive Dentistry and Temporomandibular Disorders, Dental School, University of Basel, Switzerland. mail@zahnarzt-basel.ch
Adrian E
AE
Büttel
Heinz
H
Lüthy
Pedram
P
Sendi
Carlo P
CP
Marinello
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000537:Aluminum Oxide / Q000737:chemistry; D002012:Bruxism / Q000503:physiopathology; D002516:Ceramics / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D003766:Dental Occlusion; D003768:Dental Occlusion, Centric; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D019554:Dental Restoration Wear; D003779:Denture Design; D003781:Denture Retention / Q000295:instrumentation*; D003828:Denture, Overlay; D005260:Female; D005500:Follow-Up Studies; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D008297:Male; D008422:Materials Testing; D008875:Middle Aged; D055096:Optical Devices; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
D003764:Dental Materials; D006047:Gold Alloys; D014025:Titanium; D000537:Aluminum Oxide