In vivo changes in roughness of resin-modified glass ionomer materials.

Objectives: The clinical changes in roughness of resin-modified glass ionomer materials is relatively unknown. This study examined the in vivo wear of these materials using surface roughness as an indicator of wear patterns.

Methods: Ten patients with four cervical abrasion lesions each were selected. The four cavities in each patient were restored with Fuji II LC (GC Corp., Japan), Vitremer (3M Dental, USA), Photac-Fil (ESPE, Germany) and Fuji Cap II (GC Corp., Japan). After light-curing, the restorations were polished and left uncoated. Silicone impressions were made of the surface of each restoration after polishing, and then at 3 monthly intervals up to 24 mon after restoration placement. Gold-coated resin replicas were made from the impressions for surface wear evaluation. Quantitative assessment of wear was performed by measuring surface roughness with a confocal microscope for topographical reconstruction of the specimen surface. The effect of material at each time period was analyzed using the Kruskal-Wallis test with exact non-parametric inference. Rugosity, as determined by the center line average, was determined by image analysis. SEM images of the same surfaces provided the qualitative analysis.

Results: All restorations showed a cyclic distribution of rugosity with time as demonstrated by lowess plots. There were significant differences between materials at 6, 9 and 18 mon. The rugosity curves appeared to converge at 24 mon.

Significance: It was concluded that the in vivo surface changes in roughness of resin-modified glass ionomer materials is cyclic in nature over the first 2 y.