Effect of coffe and a cola-based soft drink on the color stability of bleached bovine incisors considering the time elapsed after bleaching

There is no consensus about the waiting time necessary for the patient to start consuming beverages containing colorants again after bleaching. Objective: To evaluate the influence of beverages with coloring agents on bleached bovine incisors considering the time elapsed after bleaching. Materials and methods: Sixty bovine incisors were bleached with 35% hydrogen peroxide for in-office use (Whiteness HP Max) and divided into 10 groups. The color was evaluated with a spectrophotometer (Spectro Shade MICRO) before and after bleaching, employing the CIE-Lab system. After bleaching, the teeth were exposed for 5 min to coffee or cola-based soft drink (CBSD) at different periods after bleaching: 10 min, 1 h, 24 h, 48 h, and 72 h. Color (∆E) and lightness (∆L) variations were obtained from the CIE-Lab coordinates. Data were subjected to two-way ANOVA and Tukey HSD tests (p<0.05). Results: Significant differences were observed between groups for both the ∆L and ∆E values (p<0.001). All specimens presented a decrease in brightness (negative ∆L). The highest ∆E values were observed for teeth stained with a CBSD at 10 min and 1 h (4.12 and 4.16, respectively). Teeth pigmented with coffee presented ∆E values below 3.3 units for all evaluation times. Conclusion: The exposure to coffee after bleaching causes less color changes than the exposure to a CBSD regardless of the time after bleaching. .

Glyceollins, a novel class of soybean phytoalexins, inhibit SCF-induced melanogenesis through attenuation of SCF/c-kit downstream signaling pathways

The anti-melanogenesis effect of glyceollins was examined by melanin synthesis, tyrosinase activity assay in zebrafish embryos and in B16F10 melanoma cells. When developing zebrafish embryos were treated with glyceollins, pigmentation of the embryos, melanin synthesis and tyrosinase activity were all decreased compared with control zebrafish embryos. In situ expression of a pigment cell-specific gene, Sox10, was dramatically decreased by glyceollin treatment in the neural tubes of the trunk region of the embryos. Stem cell factor (SCF)/c-kit signaling pathways as well as expression of microphthalmia-associated transcription factor (MITF) were determined by western blot analysis. Glyceollins inhibited melanin synthesis, as well as the expression and activity of tyrosinase induced by SCF, in a dose-dependent manner in B16F10 melanoma cells. Pretreatment of B16F10 cells with glyceollins dose-dependently inhibited SCF-induced c-kit and Akt phosphorylation. Glyceollins significantly impaired the expression and activity of MITF. An additional inhibitory function of glyceollins was to effectively downregulate intracellular cyclic AMP levels stimulated by SCF in B16F10 cells. Glyceollins have a depigmentation/whitening activity in vitro and in vivo, and that this effect may be due to the inhibition of SCF-induced c-kit and tyrosinase activity through the blockade of downstream signaling pathway.

Efeito de uma solução para bochecho contendo 0, 12% de clorexidina na atividade inibitória de placa e na pigmentação extrínseca dental e da língua / Effect of a mouthwash containing 0.12% of chlorhexidine on plaque inhibition and dental and tongue extrinsic staining

A pigmentação de dentes e língua associada ao uso de soluções de clorexedina é um dos efeitos adversos que mais desencoraja o seu uso por tempo prolongado. O objetivo deste estudo foi analisar o efeito da solução para bochecho contendo 0,12% de clorexidina, 0,05% de cetilpiridínio e 0,05% de fluoreto de sódio, na atividade antiplaca e formação da pigmentação extrínseca dental e da língua. Participaram do estudo 48 voluntários, com idade média de 22,3 anos. O design do estudo foi duplo-cego, randomizado, placebo-controlado. Os participantes foram alocados em três grupos e receberam as seguintes soluções: Grupo 1 - solução teste (Noplak Max); Grupo 2 - solução de clorexedina a 0,12%; Grupo 3 - placebo. Foi utilizado um modelo de pigmentação induzida por dieta cromogênica, e a área e intensidade de pigmentação foram analisadas através de fotografias digitais. Os resultados apontaram uma diferença na área coberta por placa aproximadamente 25% menor nos Grupos 1 e 2. O Grupo 1 apresentou maior área livre de pigmentação e menos superfícies com pigmentação leve/moderada (p<0,05). Nenhum indivíduo do Grupo 1 apresentou superfície com pigmentação

Dental and tongue staining associated with the use of chlorhexidine is one of the adverse which discourages it´s long-term use the most. The aim of this study was to analyze the effect of a solution containing 0.12% chlorhexidine , 0.05% cetylpyridinium and 0,05% sodium fluoride on the anti-plaque activity and extrinsic dental and tongue staining. 48 dental students volunteered for the study, with a mean of 22.3 years of age. The design of the study was double-blind, randomized, placebo-controlled. The participants were allocated in three groups, and received the following solutions: Group 1 - Test solution (Noplak Max); Group 2 - solution of chlorhexidine 0.12%; Group 3 - Placebo solution. A forced staining model was applied using a highly cromogenic diet. The results of inhibitory plaque formation activity showed approximately 25% less covered area in Group 1 and 2. Group 1 showed more staining-free areas and a less areas with light/moderate staining, when compared with the other groups ( p<0,05). None of the individuals in Group 1 showed intense dental or tongue staining, whereas 25% ( 4/16) of the individuals of Group 2 showed this type of dental staining, and 6% (1/16) of intense tongue staining. The results of this study showed that the tested solution (Noplak Max) was effective in plaque formation inhibition, showing a higher percentage of staining-free surfaces, and a lower staining potential than the other solutions.

Behavioural and hematological responses of Cyprinus carpio exposed to mercurial chloride.

The static bioassay experiments were conducted to study the hematological and behavioural responses of Cyprinus carpio after exposure to mercuric chloride. Three different concentrations i.e. 0.5, 1.0 and 1.5 ppm of mercuric chloride (HgCl2) were used for 8, 16, 24, 48, 72, 96 and 124 hrs for evaluating behavioural responses. Hematological responses were assessed after 60 days exposure to 0.1 ppm of HgCl2. The changes in body colour, movement, sluggishness or activeness, disbalance etc. constituted the observations on behavioural responses. Hematological parameters included total erythrocyte (TEC) and leukocyte (TLC) counts and hemoglobin (Hb) levels. Body colour had changed in all groups after 48 hours. The fish exposed to 0.5 ppm HgCl2 did not show any abnormal activity except colour change throughout the experiment. Though no sign of distress was observed initially in groups exposed to 1.0 and 1.5 ppm HgCl2 but abnormal posturing, disbalance and sluggishness became apparent after 72 hrs and all specimens of 1.5 ppm group had died within 124 hours. TEC and Hb levels decreased whereas TLC increased in both male and female specimens of C. carpio after exposure to 0.1 ppm HgCl2 for 60 days. These observations indicated that mercurial toxicity even at low levels, caused adverse effects on body colour, behavioural responses and hematological parameters like TEC, TLC and hemoglobin levels in C. carpio.

Effect of glyphosate toxicity on growth, pigment and alkaline phosphatase activity in cyanobacterium Anabaena doliolum: a role of inorganic phosphate in glyphosate tolerance.

Response of glyphosate toxicity on photoautotrophic cyanobacterium A. doliolum and its mutant strain was investigated. Chlorophyll a content of both the wild type and mutant strain in the presence of glyphosate (N-phosphonomethyl glycine) initially showed an increasing trend when supplemented with Pi and a declining tendency under the Pi-starved condition. The results suggested that both the wild type and mutant strains were more sensitive to glyphosate in the absence of phosphate. Alkaline phosphatase activity of wild type strain in the presence of Pi, enhanced in response to addition of glyphosate (40 microg/ml), but the activity remained unaltered by addition of glyphosate in the Pi-starved cells, whereas the alkaline phosphatase activity in the mutant strain under both Pi-starved as well as unstarved conditions was stimulated (approximately 5.4 and 3.1-fold, respectively) by addition of glyphosate. The results on alkaline phosphatase activity indicated a glyphosate-induced depletion in the phosphate content of the cells, particularly in the mutant strain, as evident from the stimulated activity of alkaline phosphatase. It is suggested that enzyme activity in the Pi-starved wild type cells may not be influenced any further by glyphosate, as cellular phosphate reserve might not be available for further depletion.

Late afternoon administration of melatonin is prosomatotrophic and exerts androgen independent effects on erythropoiesis in male house sparrow Passer domesticus.

In the third week of September 1989, birds were purchased locally and acclimated to their housing conditions in a room fully exposed to natural day length (average: 11.96 hr) and temperature (26 degrees +/- 2 degrees C) for 2 weeks. Birds were in the regressive phase of their annual gonadal cycle. In the first experiment 24 birds were selected randomly and were divided into 3 groups of 8 birds each. Initial body weight and bill color score were recorded. The birds of group-I and group-II were injected daily with 5 and 10 micrograms of melatonin in 0.1 ml of vehicle, respectively. The birds of group-III were injected with vehicle only and treated as control. Injections were given daily between 1700 and 1730 hrs over a period of 10 days. At the termination of the experiment, the birds were weighed, sacrificed, bill color scored, blood collected and immediately processed to determine the number of erythrocytes and hemoglobin concentration. The mean body weight loss amounted to 9.6% in vehicle-treated house sparrow. Birds receiving low and high doses of melatonin maintained their initial body weight. Melatonin significantly accelerated the rate of bleaching of bill color. Results clearly indicate that in house sparrow, melatonin produces prosomatotrophic and antigonadotrophic effects. The low dose of melatonin stimulated erythropoiesis significantly. In the second experiment, melatonin nullified the castration-induced decline in the number of circulating red cells. This clearly suggests that the influence of melatonin on erythropoietic machinery appears to be independent of testicular hormone(s).