Color stability of dental enamel bleached with violet LED associated with or without Low concentration peroxide gels.

BACKGROUND: This study aimed to evaluate the in vitro color of dental enamel bleached with the violet LED, associated with or without low-concentration of peroxide; analyzed in two time intervals: 24 h later and 6 months after the treatment. METHODS: Ninety fragments of bovine teeth (6 × 6 mm and 3 mm thick) were randomly divided into 6 groups according to bleaching treatment: NB - no bleaching, VL - Violet LED, HP- 7.5 % hydrogen peroxide, HP + VL - 7.5 % hydrogen peroxide + violet LED, CP - 22 % carbamide peroxide, CP + VL - 22 % carbamide peroxide + violet LED. The color change was analyzed by using a spectrophotometer, at time intervals of 24 h and 6 months after performing the bleaching techniques (n = 12). Scanning electron microscopy (SEM) was performed to verify the enamel surface morphology after treatment (n = 3). RESULTS: The color change data were analyzed using ANOVA and a post-hoc Tukey tests (α = 0.05). The VL group showed chromatic changes after 24 h of treatment, however the groups submitted to bleaching gel treatments associated with or without violet LED (CP + VL, CP, HP, HP + VL) showed the highest color change values at all time intervals analyzed, with color stability after 6 months of treatment for the CP + VL group. Scanning electron microscopy analysis showed the greatest change in enamel surface for Groups CP and HP. CONCLUSIONS: It could be concluded that violet LED had immediate bleaching effect without promoting significant changes in enamel morphology, however the association with carbamide peroxide 22 % showed color stability and greater bleaching efficacy than the use of violet LED alone, after 6 months.

Cross-infection control in clinical training: Development of a device for storing a composite resin in restorative dentistry.

This study presented a biosafety device for the hygienic storage of composite resin during restorative procedures in teaching clinics, RESTAURASAFE, and to compare the color stability, surface hardness, and degree of conversion of the composite resin made with the proposed device to those of conventionally made resins. Esthet-X HD composite was manipulated directly from the syringe, fractionated doses, dappen dish or RESTAURASAFE. Disc-shaped specimens were immersed in artificial saliva and coffee for 60 days and the color stability and the Vickers surface hardness were evaluated during 60 days. Degree of conversion was assessed after immersing specimens in saliva (baseline). The surface morphology analysis of composite resin has taken by scanning electron microscopy (SEM). The data were evaluated statistically by repeated measures ANOVA (α=.05). No difference of color stability was observed for saliva and coffee regardless of storing devices. The resin manipulated directly from the syringe presented lower hardness, and fractionated doses presented lower degree of conversion than the RESTAURASAFE. SEM analysis showed that after artificial aging in coffee for 60 days, the specimens prepared with fractionated doses of resin displayed the fewest changes in surface morphology, followed by those prepared with the RESTAURASAFE. We conclude that RESTAURASAFE allows to obtain similar color stability, higher hardness, and degree of conversion of the composite in comparison to the other storing devices.

Influence of light curing units and fluoride mouthrinse on morphological surface and color stability of a nanofilled composite resin.

Composite resin is a dental material susceptible to color change over time which limits the longevity of restorations made with this material. The influence of light curing units and different fluoride mouthrinses on superficial morphology and color stability of a nanofilled composite resin was evaluated. Specimens (N = 150) were prepared and polished. The experimental groups were divided according to the type of light source (halogen and LED) and immersion media (artificial saliva, 0.05% sodium fluoride solution-manipulated, Fluordent Reach, Oral B, Fluorgard). Specimens remained in artificial saliva for 24-h baseline. For 60 days, they were immersed in solutions for 1 min. Color readout was taken at baseline and after 60 days of immersion. Surface morphology was analyzed by Scanning Electron Microscopy (SEM) after 60 days of immersion. Color change data were submitted to two-way Analysis of Variance and Tukey tests (α = 0.05). Surface morphology was qualitatively analyzed. The factor light source presented no significant variability (P = 0.281), the immersion media, significant variability (P < 0.001) and interaction between factors, no significant variability (P = 0.050). According to SEM observations, no difference was noted in the surface of the specimens polymerized by different light sources, irrespective of the immersion medium. It was concluded that the light source did not influence the color stability of composite, irrespective of the immersion media, and among the fluoride solutions analyzed, Fluorgard was the one that promoted the greatest color change, however, this was not clinically perceptible. The immersion media did not influence the morphology of the studied resin.

Roughness and morphology of composites: influence of type of material, fluoride solution, and time.

This study evaluated the effect of fluoride solutions on surface roughness and morphology of composites in the short and long term. Specimens were randomly assigned to experimental groups (n=5) according to type of composite (nanofilled, microhybrid, microfilled) and immersion media (artificial saliva, 0.05% sodium fluoride solution, Fluordent Reach, Oral-B, and Fluorgard). Roughness was evaluated at time intervals: T 0 after 24 h in artificial saliva (baseline); T 60 after being in assigned immersion media for 1 min daily over 60 days; and T final after artificial aging (20,000 thermal cycles, 1,200,000 mechanical loading cycles, and continuous immersion for 1,825 min). Surface morphology was qualitatively analyzed by scanning electron microscopy (SEM) at T 60 and T final. Roughness data were submitted to analysis of variance for mixed repeated measures, Sidak, and Tukey tests at α=0.05. Micro-filled resin showed the highest roughness values. Fluoride solutions had no influence on roughness. Higher roughness values were observed after artificial aging. In SEM observations after the artificial aging, the specimens showed surface degradation, irrespective of immersion medium or type of composite. Nano-filled resin showed higher loss of resin matrix and protrusion of filler particles. Roughness was not influenced by fluoride solutions; however, it is material dependent and increases over time.

Effects of immersion media and repolishing on color stability and superficial morphology of nanofilled composite resin.

This study evaluated the influence of fluoride mouth rinses and repolishing on the superficial morphology and color stability of nanofilled resin. About 150 specimens were prepared and polished using aluminum oxide discs for 15 s with a pressure of 2 kg. The experimental groups were divided according to the immersion medium (artificial saliva, 0.5% sodium fluoride, Fluordent Reach, Oral B, Fluorgard) and repolishing procedure (without and with). The specimens were continuously immersed for 1 week. Thereafter, half of each sample was repolished. A color reading was performed after 24 h of immersion in the artificial saliva baseline, after continuous immersion, and after repolishing. The superficial morphology was examined using scanning electron microscopy (SEM) in a qualitative way. Color change (∆E) data were submitted to a mixed analysis of variance using a Shapiro-Wilk test (p>0.05 for the different immersion media) and Sidak's test (p<0.05 for the differences between groups). In the interaction between the repolishing and the immersion media, Fluorgard showed a statistical difference between the ∆E values with and without repolishing (p<0.0001). On the SEM observations, both Fluordent Reach and Fluorgard caused degradation of the superficial resinous matrix of the composite after continuous immersion. This matrix was removed after repolishing.

Chemical and morphological features of nanofilled composite resin: influence of finishing and polishing procedures and fluoride solutions.

This study evaluated the influence of finishing and polishing procedures and different fluoride solutions on superficial morphology and chemistry of the nanofilled composite resin Supreme XT (3M) through the EDX analysis and SEM evaluation. Circular specimens (n = 30) of 10 mm diameter and 2 mm thickness were prepared, with half of the sample assays finished and polished with Super-Snap® sandpaper. The experimental groups were divided according to the presence or absence of finishing and polishing and solutions (artificial saliva, 0.05% of manipulated sodium fluoride solution, Fluordent Reach, Oral B, Fluorgard). Specimens were immersed in each respective solution for 1 min per day, during 60 days and stored in artificial saliva at 37 ± 1°C between immersion periods. Topography and chemical analysis was qualitative. It was observed that specimens submitted to finishing and polishing procedures had lower superficial degradation. Fluoride solutions promoted superficial alterations on specimens, being the highest degradation obtained with Fluordent Reach. It can be concluded that finishing and polishing procedures and the immersion media influence the superficial morphology of composite resin tested; the Fluordent Reach was the fluoride solution that most affected the material's surface.

Chemical and morphological features of dental composite resin: influence of light curing units and immersion media.

AIMS: The study evaluated the influence of light curing units and immersion media on superficial morphology and chemistry of the nanofilled composite resin Supreme XT (3M) through the EDX analysis and SEM evaluation. Light curing units with different power densities and mode of application used were XL 3000 (480 mW/cm(2)), Jet Lite 4000 Plus (1230mW/cm(2)), and Ultralume Led 5 (790 mW/cm(2)) and immersion media were artificial saliva, Coke((R)), tea and coffee, totaling 12 experimental groups. Specimens (10 mm x 2 mm) were immersed in each respective solution for 5 min, three times a day, during 60 days and stored in artificial saliva at 37 degrees C +/- 1 degrees C between immersion periods. Topography and chemical analysis was qualitative. FINDINGS: Groups immersed in artificial saliva, showed homogeneous degradation of matrix and deposition of calcium at the material surface. Regarding coffee, there was a reasonable chemical degradation with loss of load particles and deposition of ions. For tea, superficial degradation occurred in specific areas with deposition of calcium, carbon, potassium and phosphorus. For Coke((R)), excessive matrix degradation and loss of load particles with deposition of calcium, sodium, and potassium. CONCLUSION: Light curing units did not influence the superficial morphology of composite resin tested, but the immersion beverages did. Coke((R)) affected material's surface more than did the other tested drinks.