Effect of alcoholic beverages on surface roughness and microhardness of dental composites.

The aim of this study was to evaluate the microhardness and surface roughness of composite resins immersed in alcoholic beverages. Three composite resins were used: Durafill (Heraeus Kulzer), Z250 (3M-ESPE) and Z350 XT (3M-ESPE). The inital surface roughness and microhardness were measured. The samples were divided into four groups (n=30): G1-artificial saliva; G2-beer; G3-vodka; G4-whisky. The samples were immersed in the beverages 3× a day for 15 min and 30 days. The surface roughness and microhardness assays were repeated after immersion period. The data were statistically analyzed by two-way ANOVA and Tukey-HSD test (p<0.05). Surface roughness increased for all composite resins immersed in beer and whisky. Microhardness of all groups decreased after immersion in alcoholic beverages. The effect of these beverages on dental composites is depended upon the chemical composition, immersion time, alcohol content and pH of solutions.

Evaluation of the Surface Roughness and Microleakage of Dental Composites Exposed to Different Beverages.

AIM: The purpose of this study was to determine the effect of different solutions cola soft drink (CSD) and coffee on roughness and microleakage of composite resin restorations. MATERIALS AND METHODS: Sixty bovine incisors were prepared and restored using Filtek Z350 XT (3M/ESPE) nanoparticulate resin. The samples were divided into three groups (n = 20): A (control)-Immersion in artificial saliva (14 days); B: Immersion in coffee (14 days), for 15 minutes (3x/day) and C: Immersion in CSD for 14 days (3x/day). Then the samples were analyzed for microleakage (dye penetration) and surface roughness (atomic force microscope). The one-way analysis of variance (ANOVA) was applied to assess the surface roughness and microleakage. The Tukey's test was set at 0.05. RESULTS: Group A (roughness-GAR) presented significantly the lowest average surface roughness. Group C (microleakage-GCM) showed significantly the highest average microleakage. CONCLUSION: It was concluded that CSD and coffee change the surface roughness and increase the microleakage of restorations. CLINICAL SIGNIFICANCE: Nowadays there is a high consumption of artificially sweetened soft drinks, sports drinks, high-energy beverages and coffee products by people that cause problems in composite resin restorations.

Effect of the insertion and polymerization technique in composite resin restorations: analysis of marginal gap by atomic force microscopy.

This in vitro study evaluated the marginal gap at the composite tooth/resin interface in class V cavities under the influence of two insertion techniques and a curing system by means of atomic force microscopy (AFM). Forty enamel and dentin cavities were prepared on the buccal surface in bovine teeth with quadratic forms measuring 2 mm × 2 mm and depth of 1.5 mm. The teeth were then divided into four groups: group A, 10 cavities were restored in one increment, light cured by halogen light; group B, 10 cavities filled with bulk filling, light cured by the light emitting diodes (LED); group C, 10 cavities were restored by the incremental technique, light cured by halogen light; group D, 10 cavities were restored by the incremental technique, light cured by the LED. The teeth underwent the polishing procedure and were analyzed by AFM for tooth/restoration interface evaluation. The data were compared between groups using the nonparametric Kruskall-Wallis and Mann-Whitney tests (p < 0.05). The results showed a statistically significant difference between groups A and B and groups A and C. It was concluded that no insertion and polymerization technique was able to completely seal the cavity.

Evaluation of surface roughness of microhybrid and nanofilled composites after pH-cycling and simulated toothbrushing.

AIM: This study evaluated the surface roughness patterns of two resin-based composite restorative materials, a microhybrid (Filtek Z250, 3M ESPE) and a nanofilled (Filtek Supreme, 3M ESPE), subjected to a regimen that simulated dynamic pH-cycling and toothbrushing. METHODS AND MATERIALS: Twelve standardized cylindrical specimens of each resin-based composite material were prepared, finished, and mechanically polished. The experimental units were submitted to a pH-cycling regimen followed by 50,000 toothbrushing cycles, after which the surface roughness was measured using an atomic force microscope (AFM). AFM surface roughness was evaluated at three intervals: (1) immediately after specimen preparation (baseline), (2) after pH-cycling, and (3) after simulated toothbrushing. The results were then analyzed using a split-plot design and followed by linear regression and a Tukey's test at a significance level of p<0.05. RESULTS: The results obtained indicated that simulated toothbrushing provoked a remarkable increase in surface roughness for both types of composite resins tested (p=0.0031). However, pH-cycling did not alter the surface of the composite under the conditions of this experiment. CONCLUSION: Based on the results obtained, it was concluded that simulated toothbrushing was capable of increasing the surface roughness of the microhybrid (Filtek Z250) and the nanofilled (Filtek Supreme) composites tested. CLINICAL SIGNIFICANCE: Surface roughness of nanofilled and microhybrid composites is significantly increased after toothbrushing, although pH-cycling, as tested in this study, does not appear to affect the morphology of either composite material.

Atomic force microscopy of removal of dentin smear layers.

The regular periodontal practice of scaling and root planing produces a smear layer on the root surface that is detrimental to the readhesion of tissues during subsequent regeneration therapy. Although it has been demonstrated that gels containing the chelating agent ethylenediaminetetraacetic acid (EDTA) can assist in the removal of this contaminating layer, no quantitative method is yet available by which to evaluate the efficiency of the treatment. In this article, the power of atomic force microscopy (AFM) as a technique for monitoring and mapping the surfaces of dentinal roots is demonstrated. Roughness parameters of teeth that had been scaled and root planed were determined from AFM images acquired both before and after treatment with EDTA. The results confirmed that EDTA is an efficient cleaning agent and that dentinal samples free from a smear layer are significantly rougher than the same samples covered by a contaminating layer. AFM analysis is superior to alternative methods involving scanning electron microscopy because the same sample section can be analyzed many times, thus permitting it to be used as both the control and the treatment surface.