Early and Long-term Wear of Conventional and Resin-modified Glass Ionomers

Abstract

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.

Shear bond strengths of three glass ionomer cements to enamel and dentine

“…This may be due to the low resistance to early wear, and the formation of glass ionomer matrix (20). Therefore, part of the glass ionomer remained adhered to the tooth structures, while part was broken at the interface GIC-tooth.…”

Fatigue of Restorative Materials

“…At extremely high volume fractions, there may be an element of increased brittleness, leading to more rapid crack propagation. Studies showed that the resin-modified glass ionomers exhibit poor wear characteristics, with conventional glass ionomers being subject to high early wear, apparently as a result of subsurface fatigue phenomena (de Gee et al, 1996).…”

Comparison between one-step self-etch adhesive and along with additional hydrophobic layer in the retention of giomer at non-carious cervical lesion

“…22 Furthermore, loss of restoration may also occur due to contamination at any step of the bonding process that can adversely impact the longevity of the restoration and hamper its clinical success. 23 Furthermore, 4 restorations in Group A and 3 in Group B were partially lost at 15 months which was replaced by re-application of giomer. A careful examination of these restorations revealed that these restorations were replaced due to chipping of the materials.…”