Influence of storage regime prior to abrasion on surface topography of restorative materials
ABSTRACT This investigation was carried out to evaluate the effect of storage conditions prior to brushing simulation on surface texture of restorative materials. One resin-modified glass ionomer (Fuji II LC Improved/GC Corp.), one polyacid-modified composite resin (Dyract AP/Denstply), one microfill composite (Durafill VS/Kulzer), and one hybrid (Filtek-Z250/3M) composite were tested. Forty-five standardized cylindrical specimens of each material were made and randomly divided into three groups according to their subsequent storage conditions: distilled deionized water, artificial saliva, or pH-cycling regime. After 24 h, the experimental units were finished and polished and the surface roughness was measured to obtain Ra baseline values (Bv). Samples were subjected to their assigned storage regime and brushed afterwards. By the end of 10 repetitions of this protocol, final surface roughness readings (Fv) were taken. The analysis of covariance (alpha = 0.05), considering the covariate Bv showed a significant interaction between restorative material and storage condition (p(value) = 0.0002). Tukey's test revealed that the pH-cycling model provided a significantly lower surface roughness for Fuji II LC and Dyract AP than did the other media. For both composites no significant difference among storage regimes was detected. Under a condition simulating dynamic variation in pH prior to abrasion, the resultant surface texture may be either smoothed down or unchanged, depending on the restorative material, when compared to the effect provided by artificial saliva and distilled deionized water.
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ABSTRACT: The knowledge about the potential adverse effects of radiotherapy compared to dental composites is a useful information for the clinician's decision regarding adoption of repairs or replacement of dental restorations during oral cancer treatment. This study evaluated the effects of irradiation on microhardness and surface roughness of a microfilled and a packable composite resin. The microfilled composite resin demonstrated significantly lower microhardness and a smoother surface compared to the packable composite resin (p < 0.05). Although irradiation significantly reduced the microhardness for both composite resins (P < 0.05), increasing the x-ray doses did not cause an additional significant decrease in surface hardness (P > 0.05). Meanwhile, irradiation did not produce a significantly rougher surface (P > 0.05), but specimens submitted to abrasion exhibited a significant increase in surface roughness for both composite resins (P < 0.05). It was concluded that while irradiation can adversely affect the hardness of tested composite resins, it does not interfere with surface roughness.General dentistry 59(4):e168-72.
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ABSTRACT: The aim of this study was to evaluate the wear of resin-based materials caused by the association of abrasive and corrosive processes. Twenty specimens were prepared for each material, cast in epoxy in acrylic rings, polished, and profiled with an MTS 3D Profiler. Antagonists were made from deciduous molars. Specimens were distributed into eight groups (n = 10), according to the material (Filtek Supreme, Point 4, Dyract AP, and Fuji II LC) and the type of slurry (neutral and acidic), and then cycled 100,000 times in the OHSU oral wear simulator. The specimens were cleaned and reprofiled. Volume loss and maximum depth were determined. ANOVA and Tukey's test were used for data analysis (p < 0.05). The area of the wear facet on the antagonist was also measured. Composites displayed less wear than the compomer and the resin-modified glass ionomer. Significant differences also were found for cusp wear, with a significant positive correlation shown between cusp and material wear. The acidic slurry significantly increased the wear of the materials compared to the neutral slurry. Exposure to acidic slurry accelerated the wear of resin-based materials.Journal of Biomedical Materials Research Part B Applied Biomaterials 07/2006; 78(1):105-14. DOI:10.1002/jbm.b.30461 · 2.33 Impact Factor
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ABSTRACT: To evaluate the effects of Streptococcus mutans biofilm/restorative materials interaction on surface roughness, hardness and morphology of materials tested. Empress 2 (E2), Filtek Supreme (FS), Vitremer (V) and Ketac Molar Easymix (KM) were tested. Twenty-five disks of each material were made and divided into three storage groups: (1) 100% relative humidity (n=5); (2) growth medium (BHI and 1% sucrose) (n=5); (3) S. mutans biofilm-growth medium (n=15). Before storage, hardness measurements were immediately obtained from group 1 specimens. After 30 days of storage, the specimens were cleaned in order to obtain the surface roughness and hardness values, besides morphology analysis by scanning electron microscopy. The surface roughness and hardness values obtained from E2 and FS specimens did not present statistically significant differences among the groups 1, 2 and 3 and between immediate and 30-day-old specimens of each material. However, group 3 specimens of V and KM showed statistically significant higher surface roughness means than other groups. Group 1 specimens of V and KM also showed higher hardness values than the immediate values. Group 3 specimens of V presented decreased hardness values compared with other groups. The scanning electron micrographs showed an increase in surface degradation from group 1 to group 3 for FS, V and KM. Thirty-day-old biofilm promotes a negative effect on the surface morphology of FS, V and KM, on the surface roughness of V and KM and on the hardness of V.Journal of Dentistry 08/2008; 36(10):833-9. DOI:10.1016/j.jdent.2008.06.002 · 2.84 Impact Factor