Wear testing of composite, gold, porcelain, and enamel opposing a removable cobalt-chromium partial denture alloy.
OBJECTIVE
Eighty percent of all removable partial denture (RPD) frameworks are fabricated from cobalt-chromium (Co-Cr) alloys. The advantages of this material include low density and high modulus of elasticity, hardness, and strength. Hardness is of particular concern when related to excessive wear of natural teeth or restorative materials. The purpose of this study was to compare the differences in localized wear among enamel, composite, gold, and porcelain by a Co-Cr alloy RPD.


METHODS
Thirty-two polished specimens were prepared and positioned in an acrylic-filled custom fixture for testing. Upon optical examination, the highly polished surfaces of the specimens were scratch-free. They were mounted into a water bath fixture and subjected to 250,000 cycles in a wear simulator equipped with a conical Co-Cr stylus specially fabricated to produce localized wear. A posttest was generated, and the profiles were fitted and evaluated using software. The total volume loss and depth of the wear facet on each specimen were analyzed using ANOVA and Fisher's PLSD test.


RESULTS
Volume loss (mm3) was as follows: composite, 0.110; gold, 0.021; enamel, 0.008; porcelain, 0.006. The maximum depths (microm) were: composite, 92; gold, 22; enamel, 13; porcelain, 17. Resin composite had significantly higher values (p < 0.0001) of volumetric loss and maximum depth than the other materials. No significant differences were detected among volumetric loss and maximum depth values for gold, enamel, and porcelain.


CONCLUSIONS
Significant differences for mean wear volume loss and maximum depth were found between composite and gold, enamel, and porcelain. Enamel proved to be wear resistant to the Co-Cr alloy.


CONCLUSIONS
porcelain and gold appear to be good options for occlusal surfaces opposing a Co-Cr alloy; however, the test composite was not found to be a recommended option.
Advanced Prosthodontics Program, University of Texas, Houston Dental Branch, Houston, TX 77030, USA.
Johanna V
JV
Alarcon
Robert L
RL
Engelmeier
John M
JM
Powers
Peter T
PT
Triolo
D002858:Chromium Alloys; D003188:Composite Resins / Q000737:chemistry; D003743:Dental Enamel; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry; D019554:Dental Restoration Wear; D003799:Dental Stress Analysis; D003779:Denture Design; D003832:Denture, Partial, Removable; D006047:Gold Alloys / Q000737:chemistry; D006244:Hardness; D008422:Materials Testing
D002858:Chromium Alloys; D003188:Composite Resins; D003764:Dental Materials; D006047:Gold Alloys; D003776:Dental Porcelain