Early and long-term wear of conventional and resin-modified glass ionomers.
Various studies have shown that glass ionomers are susceptible to brittle fracture and acid conditions and that they undergo long-term changes in their mechanical properties. Little information is available on how brittleness, acid susceptibility, and long-term changes are reflected in the wear characteristics of glass ionomers. The purpose of this study was to evaluate long-term changes in conventional glass ionomers, metal-reinforced glass ionomers (including a cermet), and (light-curing) resinmodified glass ionomers by wear experiments simulating the wear process in occlusal contact-free areas. The wear tests were conducted periodically over a period of one year. In addition, wear was determined after one year at a pH of 5 or 6, for assessment of acid susceptibility, and at a condition as found in the occlusal contact areas. All materials showed high early-wear rates which decreased significantly during the one-year test period. This long-term process may be related to a slow progression of the acid-base reaction extending over several months. At each stage, the resinmodified glass ionomers wore significantly faster than the acid-base setting glass ionomers. Most of these materials were not affected at a pH of 6.0, while at a pH of 5.0 only the conventional and the metal-reinforced glass ionomers showed increased wear. Direct contacts with the antagonist led to a significant increase in wear in comparison with contact-free wear, probably as a result of sub-surface fatigue phenomena. In view of the unfavorable wear characteristics of the resin-modified glass ionomers and the high early wear of the conventional glass ionomers, including the metal-reinforced glass ionomers, it was concluded that none of these materials can yet be recommended for use in high-stress-bearing situations.
de Gee
A J
AJ
Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam ACTA, The Netherlands.
van Duinen
R N
RN
Werner
A
A
Davidson
C L
CL
D000538:Aluminum Silicates; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate; D016722:Cermet Cements; D003188:Composite Resins; D003722:Dental Alloys; D019554:Dental Restoration Wear; D003793:Dental Restoration, Permanent / Q000379:methods*; D005899:Glass Ionomer Cements; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008298:Maleates; D008422:Materials Testing; D015999:Multivariate Analysis; D019279:Resin Cements; D012117:Resins, Synthetic
D000538:Aluminum Silicates; D016722:Cermet Cements; D003188:Composite Resins; D003722:Dental Alloys; D005899:Glass Ionomer Cements; D008298:Maleates; C081144:Photac-Fil; D019279:Resin Cements; D012117:Resins, Synthetic; C101939:Shofu High Dense; C084550:Vitremer; C065771:P50 composite resin; C084541:Fuji glass-ionomer lining cement; C033470:Dispersalloy; D017438:Bisphenol A-Glycidyl Methacrylate; C039733:Chemfil; C040964:Ketac-Fil