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 vi vo wear of these materials using surface roughness as an indicator of wear patterns. Methods. Ten patients with four cervical abrasion lesio ns 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-cur ing, the restorations were polished and left uncoated. Silicone impres sions were made of the surface of each restoration after polishing, an d then at 3 monthly intervals up to 24 mon after restoration placement . Gold-coated resin replicas were made from the impressions for surfac e wear evaluation. Quantitative assessment of wear was performed by me asuring surface roughness with a confocal microscope for topographical reconstruction of the specimen surface. The effect of material at eac h time period was analyzed using the Kruskal-Wallis test with exact no n-parametric inference. Rugosity, as determined by the center line ave rage, was determined by image analysis. SEM images of the same surface s 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 an d 18 mon. The rugosity curves appeared to converge at 24 mon.Significa nce. It was concluded that the in vivo surface changes in roughness of resin-modified glass ionomer materials is cyclic in nature over the f irst 2 y.