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Wear of an ion-releasing powder/liquid polymer resin in relation to that of glass-ionomer and conventional resin composites.

PURPOSE
To evaluate the wear in vitro of a new ion-releasing powder/liquid polymer resin in relation to that of glass-ionomer derivatives and conventional composites.


METHODS
Flat specimens (eight per material) of the ion-releasing powder/liquid polymer resin Cention N, five resin-modified glass-ionomer cements [ChemFil Rock, Equia Fil (with and without coating), Fuji II, Photac Fil, Riva], six conventional glass-ionomer cements (Fuji IX, Fuji IX GP, Ionofil Molar, Ketac Fil Plus, Ketac Molar, Ketac Universal), and two popular conventional resin composites (CeramX, Filtek Z350 XT) were processed and luted to aluminum holders. After storage in water at 37°C for 24 hours, the specimens were polished to 2,500 grit and subjected to the Ivoclar wear method, which mainly simulates attrition wear using a commercially available chewing simulator. A standardized stylus made of pressable ceramic (IPS Empress) hits flat specimens 120,000 times with a 5 kg weight and a lateral movement of 0.7 mm under constant exchange of water at different temperatures (5°C/55°C). The vertical loss was measured on plaster replicas with a laser scanner and 3D software. The Ivoclar wear method moderately correlates with clinical wear.


RESULTS
The mean vertical wear of the resin-modified glass-ionomer cements was statistically significantly higher, between 616±44 µm (Ionofil Molar) and 946±101 µm (Fuji IX GP) than that of the ion-releasing polymer resin Cention N (327±63 µm) (ANOVA post-hoc Tukey B, P< 0.01), which was in the same statistical group of the conventional resin CeramX (323±31 µm). Filtek Z350 XT showed significantly lower wear (221±19 µm) (ANOVA post-hoc Tukey B, P< 0.05). The materials ChemFil Rock (39±13 µm), Photac Fil (41±9 µm), and Fuji II (42±8 µm) had the lowest antagonist wear, while Ketac Fil Universal (143±37 µm) and CeramX (135±13 µm) had the highest antagonist wear. Antagonist wear for Cention N was somewhere in between (90±21 µm).


CLINICAL SIGNIFICANCE
For the restoration of posterior Class II and large Class I restorations, resin-based materials should be chosen over resin-modified or conventional glass-ionomer cements.