Fernanda de Carvalho Panzeri Pires-de-Souza

Effect of staining solutions and repolishing on color stability of direct composites

Objectives The purpose of this study was to assess the color change of three types of composite resins exposed to coffee and cola drink, and the effect of repolishing on the color stability of these composites after staining. Materials and Methods Fifteen specimens (15 mm diameter and 2 mm thick) were fabricated from microhybrid (Esthet-X; Dentsply and Filtek Z-250; 3M ESPE) and high-density hybrid (Surefil; Dentsply) composites, and were finished and polished with aluminum oxide discs (Sof-Lex; 3M ESPE). Color of the specimens was measured according to the CIE L*a*b* system in a reflection spectrophotometer (PCB 6807; BYK Gardner). After baseline color measurements, 5 specimens of each resin were immersed in different staining solutions for 15 days: G1 - distilled water (control), G2 - coffee, G3 - cola soft drink. Afterwards, new color measurement was performed and the specimens were repolished and submitted to new color reading. Color stability was determined by the difference (∆) between the coordinates L*, a*, and b* obtained from the specimens before and after immersion into the solutions and after repolishing. Results There was no statistically significant difference (ANOVA, Tukeys test; p>0.05) among the ∆ values for the different types of composites after staining or repolishing. For all composite resins, coffee promoted more color change (∆>3.3) than distilled water and the cola soft drink. After repolishing, the ∆ values of the specimens immersed in coffee decreased to clinically acceptable values (∆<3.3), but remained significantly higher than those of the other groups. Conclusions No significant difference was found among composite resins or between color values before and after repolishing of specimens immersed in distilled water and cola. Immersing specimens in coffee caused greater color change in all types of composite resins tested in this study and repolishing contributed to decrease staining to clinically acceptable ∆ values.

Color stability of composites subjected to accelerated aging after curing using either a halogen or a light emitting diode source

The purpose of this study was to evaluate, in vitro, the color stability of three composite resins of two different shades (A3 and C3) cured with either a quartz tungsten halogen (QTH) or a light emitting diode (LED) source. Forty specimens (20 x 2 mm) were prepared for each composite (Tetric Ceram, Heliomolar and Esthet-X), being 20 for each shade. In each group, 10 specimens were light-cured using the QTH unit and 10 with the LED source. The shade of the materials was evaluated before and after submitting the specimens to artificial accelerated aging (4 h UV-B/4 h condensing vapor), using a reflection spectrophotometer. deltaE means were calculated and analyzed statistically by 2-way ANOVA and Tukeys test at 5% significance level. Both A3 and C3 shades of Esthet-X composite resin showed the lowest color change when cured with the QTH light, while Tetric C3 cured with the QTH light showed the highest color change.

Color stability of dental ceramics submitted to artificial accelerated aging after repeated firings

STATEMENT OF PROBLEM Color stability is an important factor to ensure the long-term clinical success of ceramic restorations. There is a lack of information on how color is affected by fabrication procedures, such as the number of firings. PURPOSE The purpose of this study was to evaluate the effects that the number of firings and type of substrate have on the color stability of dental ceramic submitted to artificial accelerated aging. MATERIAL AND METHODS Sixty specimens were fabricated: 30 metal ceramic (Verabond II + IPS d.SIGN) and 30 all-ceramic (IPS d.SIGN). Specimens were divided into 3 groups (n=10), and submitted to 2, 3, or 4 firings (+/-900 degrees C), respectively, according to the manufacturers instructions. Color readings were obtained with a spectrophotometer before and after artificial accelerated aging, and L*, a*, and b* coordinates and total color variation (Delta E) were analyzed (2-way ANOVA, Bonferroni, alpha=05). RESULTS For metal ceramic specimens, differences for the L* coordinates were significant (P<.05) only for the group submitted to 3 firings. With respect to the all-ceramic specimens, smaller L* coordinates were obtained for greater a* and b* coordinates, indicating that the greater the number of firings, the darker and more reddish/yellowish the specimen. All Delta E values, for all groups, were below 1.0. All-ceramic specimens submitted to 3 and 4 firings presented Delta E means differing statistically (P<.05) from those of the metal ceramic group. CONCLUSIONS The type of substrate and number of firings affected the color stability of the ceramic material tested. Artificial accelerated aging did not produce perceptible color stability changes (Delta E<1.0).

Biocompatibility of New Calcium Aluminate Cement (EndoBinder)

INTRODUCTION The purpose of this study was to evaluate the biocompatibility of calcium aluminate cement (EndoBinder) in subcutaneous tissue of rats. METHODS Fifteen rats, weighing 300 g, were separated into 3 groups (n = 5) in accordance with the time of death (7, 21, 42 days). Two incisions were made in the dorsal subcutaneous tissue of each rat in which were implanted 2 polyethylene tubes filled with the test materials, EndoBinder (EB) and Grey MTA (GMTA). The external tube walls were considered the negative control group (CG). After 7, 21, and 42 days, animals were killed, obtaining 5 samples per group, at each time interval of analysis. RESULTS From the morphologic and morphometric analyses by using a score of (0-3) (50, 100, and 400×), results showed absence of inflammatory reaction (0) for EB after 42 days. However, for GMTA, a slight inflammatory reaction (1) was observed after 42 days, which means the persistence of a chronic inflammatory process. When compared with CG, tissue reaction ranging from discrete (1-7 days) to absent (0-42 days) was observed. CONCLUSIONS EndoBinder presented satisfactory tissue reaction; it was biocompatible when tested in subcutaneous tissue of rats.

Color stability, surface roughness and microhardness of composites submitted to mouthrinsing action

Objective The purpose of this study was to evaluate the effect of mouth rinse solutions on color stability, surface roughness and microhardness of two composite resins. Material and Methods Fifty test specimens of each composite (Filtek Z250 and Z350; 3M ESPE) were made using a teflon matrix (12x2 mm). Color, surface roughness and Knoop microhardness baseline measurements of each specimen were made and specimens (n=10) were immersed in 5 mouth rinse solutions: G1: distilled water (control), G2: Plax Classic, G3: Plax alcohol-free; G4: Periogard, and G5: Listerine. Final measurements of color, roughness and microhardness were performed and the results submitted to statistical analysis (2-way ANOVA, Bonferronis test; p<0.05). Results The most significant color change was observed for Z250 when immersed in Listerine (p<0.05). Z350 showed greater color change when immersed in Plax alcohol-free (p<0.05), but with no significant difference for Listerine (p>0.05). With regard to roughness, both composites showed significant changes when immersed in Listerine in comparison with Plax alcohol-free (p<0.05). Microhardness of Z350 was shown to be significantly changed when the composite was immersed in Plax alcohol-free (p<0.05). Conclusion Composite changes depended on the material itself rather than the mouth rinse solution used.

Radiopacity Evaluation of Calcium Aluminate Cement Containing Different Radiopacifying Agents

INTRODUCTION The aim of this study was to evaluate the radiopacity of calcium aluminate cement (EndoBinder) with 3 different radiopacifiers (bismuth oxide, zinc oxide, or zirconium oxide) in comparison with gray mineral trioxide aggregate (GMTA), white MTA, and dental structures (enamel and dentin). METHODS Eighteen test specimens of each cement with thicknesses of 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mm (n = 3) were made by using a stainless steel matrix and were adapted to a standardizing device (8 × 7 cm) with a graduated aluminum stepwedge varying from 2.0-16.0 mm in thickness. To compare the radiopacity of the cements with that of dental structures, slices of first molars with a thickness increasing from 0.5-3.0 mm were obtained and placed on the standardizing device. One occlusal radiograph for each tested cement was taken, with exposure time of 0.1 seconds and focus-film distance of 20 cm. Films were processed in an automatic device, and the mean radiopacity values were obtained by using a photodensitometer. RESULTS Mean values showed that the thicker the specimen was, the greater was its radiopacity. Only EndoBinder + bismuth oxide (EBBO) and GMTA demonstrated radiopacity values greater than 3.0 mm of the aluminum scale for all thicknesses. When zinc oxide was used as radiopacifier agent, EndoBinder only reached the desired radiopacity with a thickness of 2.0 mm, and with zirconium oxide it was 2.5 mm. CONCLUSIONS Bismuth oxide was the most efficient radiopacifier for EndoBinder, providing adequate radiopacity in all studied thicknesses, as recommended by ISO 6876, being similar to GMTA.

Color stability of silorane-based composites submitted to accelerated artificial ageing-An in situ study

OBJECTIVES To assess the in situ color stability, surface and the tooth/restoration interface degradation of a silorane-based composite (P90, 3M ESPE) after accelerated artificial ageing (AAA), in comparison with other dimethacrylate monomer-based composites (Z250/Z350, 3M ESPE and Esthet-X, Dentsply). METHODS Class V cavities (25 mm(2) × 2 mm deep) were prepared in 48 bovine incisors, which were randomly allocated into 4 groups of 12 specimens each, according to the type of restorative material used. After polishing, 10 specimens were submitted to initial color readings (Easyshade, Vita) and 2 to analysis by scanning electronic microscopy (SEM). Afterwards, the teeth were submitted to AAA for 384 h, which corresponds to 1 year of clinical use, after which new color readings and microscopic images were obtained. The values obtained for the color analysis were submitted to statistical analysis (1-way ANOVA, Tukey, p<0.05). RESULTS With regard to color stability, it was verified that all the composites showed color alteration above the clinically acceptable levels (ΔE ≥ 3.3), and that the silorane-based composite showed higher ΔE (18.6), with a statistically significant difference in comparison with the other composites (p<0.05). The SEM images showed small alterations for the dimethacrylate-based composites after AAA and extensive degradation for the silorane-based composite with a rupture at the interface between the matrix/particle. CONCLUSION It may be concluded that the silorane-based composite underwent greater alteration with regard to color stability and greater surface and tooth/restoration interface degradation after AAA.

Color stability, opacity and degree of conversion of pre-heated composites

OBJECTIVES To assess color stability and opacity associated with the degree of conversion of a pre-heated nanohybrid composite (Tetric N-Ceram, Ivoclar/Vivadent, Schaan, Liechtenstein). METHODS Twenty-seven specimens were prepared (n=9) using a Teflon matrix following storage of compules containing the composite at temperatures of 8°C, 25°C or 60°C. After photoactivation and polishing, baseline readings of six specimens were taken regarding their color and opacity (Spectrophotometer PCB 6807, Byk Gardner, Geretsried, Germany). Then, the specimens were submitted to artificial ageing for 384 h (C-UV, Adexim Comexim, São Paulo, SP, Brazil), after which the final readings were taken. Three specimens for each temperature were submitted to analysis of degree of conversion (Nicolet 380, Thermo Scientific, Waltham, MA, USA). The results were analysed by 1-way ANOVA/Tukey (p<0.05). RESULTS There was no significant difference in color stability and opacity variation amongst the temperatures evaluated. The composite pre-heated at 60°C had a higher degree of conversion (65.13%), with statistically significant difference compared to the other temperatures (p<0.05). CONCLUSIONS Composite pre-heating does not promote changes in the optical properties, despite the increase in the degree of conversion.

Effectiveness of a new toothbrush design versus a conventional tongue scraper in improving breath odor and reducing tongue microbiota.

For centuries, specific instruments or regular toothbrushes have routinely been used to remove tongue biofilm and improve breath odor. Toothbrushes with a tongue scraper on the back of their head have recently been introduced to the market. The present study compared the effectiveness of a manual toothbrush with this new design, i.e., possessing a tongue scraper, and a commercial tongue scraper in improving breath odor and reducing the aerobic and anaerobic microbiota of tongue surface. The evaluations occurred at 4 moments, when the participants (n=30) had their halitosis quantified with a halimeter and scored according to a 4-point scoring system corresponding to different levels of intensity. Saliva was collected for counts of aerobic and anaerobic microorganisms. Data were analyzed statistically by Friedmans test (p<0.05). When differences were detected, the Wilcoxon test adjusted for Bonferroni correction was used for multiple comparisons (group to group). The results confirmed the importance of mechanical cleaning of the tongue, since this procedure provided an improvement in halitosis and reduction of aerobe and anaerobe counts. Regarding the evaluated methods, the toothbrushs tongue scraper and conventional tongue scraper had a similar performance in terms of breath improvement and reduction of tongue microbiota, and may be indicated as effective methods for tongue cleaning.

Effect of cigarette smoke on color stability and surface roughness of dental composites

OBJECTIVE To evaluate the color stability and surface roughness of 3 dental composites subjected to cigarette smoke and brushing. METHODS Twenty specimens were prepared for each type of restorative material used: nanohybrid (Tetric N-Ceram); hybrid (Z250-3M ESPE) and silorane-based microhybrid (Filtek P90-3M ESPE), which were divided into 2 groups (n=10), according to the type of finishing/polishing received: Group 1 - papers with decreasing abrasive grit and Group 2 - polyester matrix (without polishing). After initial readouts of color (Easy Shade-VITA) and surface roughness (SJ-201P Mitutoyo), specimens were subjected to action of smoke from 20 cigarettes, (Marlboro Red-Philip Morris). After each cigarette, the samples were submitted to brushing in a standardised device. After this, final readouts were taken to calculate change in color (ΔE and ΔL) and roughness (ΔRa), which were statistically analysed (2-way ANOVA, Bonferroni, and Students-t tests respectively, p<0.05). RESULTS Tetric N-Ceram presented color change at clinically unacceptable levels (ΔE>3.3) when the polyester strip was used for finishing, a result differing (p<0.05) from those of the other composites, which presented no difference between them (p>0.05). Unpolished composites presented higher Ra values than those that were polished (p<0.05), with exception of the silorane based composite. CONCLUSION Absence of polishing increases cigarette capacity to stain composites and surface roughness of composites, with exception of the silorane based type.