Surface Characteristics of Aesthetic Restorative Materials - an SEM Study

Objective: To determine the degree of surface roughness of glass-ionomer cements (GICs) and polyacid-modified resin composite (PAMRC) after polishing and immersion in various foodstuffs. Methods: Three tooth-coloured restorative materials were used: a PAMRC (F2000, 3M/ESPE), a conventional GIC (Fuji IX, GC) and a resin-modified GIC (Fuji II LC, GC). Disk-shaped specimens were prepared and tested with either a matrix finish or polished using wet silicon carbide papers up to 2000 grit. All specimens were immersed in 37°C-distilled water for 1 week, followed by three different foodstuffs (red wine, coffee, and tea) for a further 2 weeks. Replicas of specimens were prepared, gold sputter-coated and examined using a Scanning Electron Microscope. Results: The polished specimens of F2000 showed many microcracks at low magnification similar to the matrix finish specimens, but at high magnification the polished specimens had eroded surfaces with missing and protruding particles, whereas the matrix finish specimens had a relatively smooth surface. The surface-polished specimens of Fuji II LC in distilled water were considerably rougher than the matrix-finish specimens, with large voids and protruding filler particles. Water-stored polished specimens of Fuji IX presented slightly rougher surfaces with numerous pores and voids in comparison with matrix finish specimens. Effects of foodstuffs on Fuji II LC and F2000 were not noticeable. Coffee and tea markedly affected the surface roughness of Fuji IX, with some loss of integrity, large voids, missing and protruding of filler particles and consequently greater surface roughness in comparison with control groups. Conclusion: All specimens had the smoothest surface when they were cured against a plastics strip, and all materials had rougher surface after polishing. None of the foodstuffs produced perceptible roughness in RM-GIC and PAMRC. Conventional GIC, both matrix finish and polished samples, became noticeably rougher after exposure to coffee and tea.