Ana Carolina Botta

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 Sidaks 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.

Antibacterial activity of glass ionomer cement modified by zinc oxide nanoparticles: Garcia et al.

This study evaluated the antibacterial activity of zinc oxide nanoparticles incorporated into self‐cured glass ionomer cement (GIC) and light‐cured resin‐reinforced GIC on Streptococcus mutans biofilm. The GICs, Fuji II (GC America) and Fuji II LC (GC America), were incorporated with nanoparticles at concentrations of 0%, 1%, and 2% by weight, and the biofilm maturation time was one and seven days. Circular specimens of each GIC type were prepared. The antibacterial activity was evaluated by determining the number of colony forming units of S. mutans strain per milliliter. Morphology of the biofilm was analyzed by scanning electron microscopy (SEM). The data obtained for each GIC were analyzed by two‐way ANOVA (α = 5%). For chemically activated GIC, no significant difference was observed in relation to the time of biofilm maturation (p = 0.744), concentration of nanoparticles (p = 0.966), and their interaction (p = 0.800). The results from analysis of GIC modified by light‐polymerized resin showed that only of the maturing time significantly affected the number of adhered cells on the biofilm (p = 0.034, F = 4.778). The more mature the biofilm, higher the number of cells. SEM analysis showed no change in cell morphology in relation to the type of GIC, maturation time, and nanoparticles concentration. We conclude that the inclusion of zinc oxide nanoparticles at concentrations of 1% and 2% by weight into the GICs evaluated here, did not promote their antimicrobial activity against S. mutans.

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. Microsc. Res. Tech. 77:941–946, 2014.

Validity and reliability of the Disabilities of Arm, Shoulder, and Hand scale in dental students: A transnational study

ABSTRACT This study aimed to evaluate the validity and reliability of the Disabilities of Arm, Shoulder, and Hand (DASH) scale in Brazilian and American dental students and assess the influence of demographic variables on disability in them. A cross-sectional observational study was conducted with a nonprobabilistic sample. The sample was composed of students of both genders from the School of Dentistry of Araraquara, State University of São Paulo (UNESP) (n = 288), and students from Stony Brook University, New York, NY, USA (n = 149). The disabilities of the upper limbs were estimated using the DASH scale. The samples were characterized by collecting information on gender, academic year, and sports and work activities. The refined bifactorial model presented goodness-of-fit indices for both countries. There was a significant effect of the variables gender and academic year for the Brazilian sample and the variable sports practices for the American sample. The refined bifactorial model was valid and reliable for the Brazilian and American populations. In this model, the removal of item 17 for the Brazilian sample and items 3, 13, and 23 for the American sample was necessary. Demographic variables such as gender, academic year, and sports practice contributed significantly to the level of disability in the study populations.