Effect of carbamide peroxide-based bleaching agents containing fluoride or calcium on tensile strength of human enamel

OBJECTIVE: The aim of this study was to evaluate the effects of carbamide peroxide-based bleaching agents (CPG) containing fluoride (CF) or calcium (CCa) on the ultimate tensile strength of enamel (UTS). METHOD: A "cube-like" resin composite structure was built-up on the occlusal surface of twenty-two sound third molars to facilitate specimen preparation for the micro-tensile test. The restored teeth were serially sectioned in buccal-lingual direction in slices with approximate 0.7 mm thickness. Each slice was trimmed with a fine diamond bur to reduce the buccal, internal slope enamel of the cusps to a dumb-bell shape with a cross-sectional area at the "neck" of less than 0.5 mm². The samples were randomly divided into 12 groups (n=11). The control groups were not submitted to the bleaching regimen. Specimens were treated with 10% CPG gel or with 10% CPG formulations containing CF (0.2% and 0.5%) or CCa (0.05% and 0.2%). Bleached groups received the application of the 10% CPGs for 6 hours/day at 37º C, during 14 consecutive days and were stored in artificial saliva (AS) or 100% relative humidity (RH) among each application. After bleaching, specimens were tested with the microtensile method at 0.5 mm/min. Data were analyzed by two-way ANOVA and Tukey test (5%). RESULTS: No significant difference was observed between groups stored in AS or RH. Specimens treated with CF or CCa presented similar UTS as unbleached control groups. CONCLUSION: Either 10% CPG formulations containing CF or CCa can preserve the UTS after bleaching regimen.OBJETIVO: O propósito deste estudo foi avaliar os efeitos de agents clareadores à base de peróxido de carbamida (CPG) contendo fluoreto (CF) e cálcio (CCa) na resistência à tração do esmalte (UTS). MÉTODO: Um bloco de resina composta foi confeccionada na superfície oclusal de vinte e dois terceiros molars hígidos para facilitar a preparação dos espécimes para o teste de micro-tração. Os dentes restaurados foram seccionados com disco diamantado no sentido vestíbulo-lingual em fatias de aproximadamente 0,7 mm de espessura. Com uma ponta diamantada, foi realizada uma constrição na região de esmalte da vertente oclusal interna. Os espécimes apresentaram aproximadamente 0,5 mm² de área na secção transversal da região de constrição e foram divididos em 12 grupos (n=11). Os grupos controles não foram submetidos ao regime clareador e os experimentais foram tratados com gel de CPG 10% ou com formulações de CPG 10% contendo CF (0,2% e 0,5%) ou CCa (0,05% e 0,2%). Os grupos clareadores receberam a aplicação dos CPGs por 6 horas/dia a 37ºC, durante 14 dias consecutivos e foram armazenados em saliva artificial (AS) ou em umidade relativa 100% (RH), entre as aplicações do gel clareador. Após o clareamento, os espécimes foram testados através do método de micro-tração (0,5 mm/min). Os dados foram analisados pela ANOVA (2 fatores) e teste Tukey (5%). RESULTADOS: Nenhuma diferença foi observada entre os grupos armazenados em AS ou RH. Os espécimes tratados com CPG com CF ou Cca apresentaram similar UTS aos grupos controles não clareados. CONCLUSÃO: Ambos CPGs 10% CF or CCa não alteraram a UTS após o tratamento clareador

Effect of a carbamide peroxide bleaching gel containing calcium or fluoride on human enamel surface microhardness

This in vitro study evaluated the surface microhardness of human enamel submitted to bleaching with 10% carbamide peroxide (CP) containing calcium or fluoride. Ninety-eight dental blocks (5 x 5 mm²) with polished enamel surfaces were randomly assigned to 7 treatment groups (n=14), as follows: without bleaching and storage in artificial saliva (control); 10% CP; 10% CP + 0.05% calcium; 10% CP + 0.1% calcium; 10% CP + 0.2% calcium; 10% CP + 0.2% fluoride; and 10% CP + 0.5% fluoride. During 14 days, enamel surfaces were daily exposed to a 6-h bleaching regimen followed by storage in artificial saliva. Surface microhardness was measured before (baseline), during (7th day), immediately after bleaching (14th day) and 1 week post bleaching. Data were analyzed by two-way ANOVA and Tukey's test (p<0.05). All treatments reduced SM significantly during the bleaching cycle (7th day), immediately after bleaching (14th day) and 1 week post bleaching, compared to baseline and to the unbleached control group. In conclusion, in spite of the addition of calcium and fluoride, all bleaching treatments affected the enamel surface microhardness.Este estudo in vitro avaliou microdureza superficial do esmalte após o clareamento com peróxido de carbamida a 10% (PC) contendo cálcio ou flúor. Noventa e oito blocos dentais (5 x 5 mm²) com a superfície do esmalte polido foram divididos em sete grupos experimentais (n=14): sem clareamento e armazenado em saliva artificial; 10% (PC); (3) 10% PC + 0,05% cálcio; 10% PC + 0,1% cálcio; 10% PC + 0,2% cálcio; 10% PC + 0,2% flúor; e 10% PC + 0,5% flúor. Os géis clareadores foram aplicados por 6 h durante 14 dias e após cada dia de tratamento, os espécimes foram armazenados em saliva artificial. A microdureza superficial foi mensurada antes (baseline), durante (7º dia), imediatamente após o clareamento (14º dia) e 1 semana após o fim do tratamento clareador. Os dados foram analisados pela ANOVA (2 fatores) e teste de Tukey (p<0.05). Os tratamentos clareadores reduziram significativamente a microdureza durante (7º dia), imediatamente após o clareamento (14º dia) e 1 semana após o seu término, quando comparados aos valores iniciais (baseline) e aos do grupo controle. Os achados deste estudo sugerem que, a despeito da adição de cálcio e flúor, todos os géis clareadores afetaram a microdureza superficial do esmalte.103106Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Prognostic value of the immunohistochemical expression of vascular endothelial growth factors in malignant salivary gland neoplasms:a systematic review and meta-analysis

The immunohistochemical expression of vascular endothelial growth factor is a prognostic marker in several cancer types. In salivary gland tumors, the association between vascular endothelial growth factor and prognosis remains unclear. The purpose of this study was to perform a systematic review and meta-analysis to assess whether the immunohistochemical expression of vascular endothelial growth factor in patients with salivary gland neoplasms presents prognostic value. Immunohistochemical studies assessing the predictive value of vascular endothelial growth factor in salivary gland neoplasms were systematically reviewed using PubMed, Scopus, Embase, Cochrane Library, and Web of Science databases. It was assessed any survival rates. The fixed-effect model with an adjusted hazard ratio (HR) and 95% confidence intervals (95% CI) as effect measures were performed in the meta-analysis. The Quality in Prognosis Studies (QUIPS) tool was used to assess the quality of the included studies, and the evidence quality was assessed by the Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) system. The immunohistochemical overexpression of vascular endothelial growth factor in patients with salivary gland neoplasms was associated with shortened survival (HR=5.37, 95% CI: 2.67-10.83, P = 0.00001). In addition, the presence of vascular endothelial growth factor was tightly associated with tumor size, lymph node metastasis, clinical stage, perineural invasion, vascular invasion, poor local control of the disease, and recurrence. The immunohistochemical overexpression of vascular endothelial growth factor in patients with salivary gland neoplasms has prognostic value and was associated with decreased survival time. However, more primary well-designed studies are necessary to increase the level of evidence

The importance of fluoride dentifrices to the current dental caries prevalence in Brazil

Similar to that which occurred in most developed countries, dental caries have shown a significant decline in Brazil over the last two decades. Water fluoridation, expansion of preventive programs at schools, and especially, the widespread use of fluoride dentifrice are discussed as factors related to this reduction in caries. Data from epidemiological surveys and historical facts are presented to support the importance of fluoride dentifrices to the current caries prevalence in Brazil.Assim como observado na maioria dos países desenvolvidos, a prevalência de cárie dental no Brasil apresentou um declínio significativo nas últimas duas décadas. A fluoretação das águas de abastecimento público, a expansão de programas preventivos nas escolas e principalmente o uso abrangente de dentifrícios fluoretados no país são apresentados como fatores relacionados a essa redução de cárie. Dados de levantamentos epidemiológicos e fatos históricos são apresentados para corroborar a importância dos dentifrícios fluoretados na atual prevalência de cárie no Brasil16717

Epigenetic alterations in ameloblastomas : a literature review

Ameloblastoma is a locally aggressive tumor, originated from odontogenic epithelium, and affects the jawbones with an elevated recurrence rate. The molecular mechanisms involved with the pathogenesis of this tumor remain undetermined. This review aimed t

Alkali-soluble Fluoride Deposition On Enamel After Professional Application Of Topical Fluoride In Vitro.

Since the efficacy of topical fluoride products is related to the fluoride (F) availability and its reactivity with enamel, this study was conducted. The F concentration of the following materials was verified: I- acidulated phosphate fluoride (APF) gel (1.23% F), II- APF foam (1.23% F) and III- Varnish (2.26% F). Forty blocks of bovine enamel were divided into 4 groups and treated according to the materials described, being one of them used as control. Loosely bound fluoride (''CaF2'') was determined on enamel after extraction with 1.0M KOH and analyzed by ion-selective electrode. Total F concentration found in gel was 12,642, in foam 12,755 and in varnish 23,183 mg F/g. All products formed statistically higher amounts of ''CaF2'' on enamel compared to the control group (p 0.05). Thus, ''CaF2'' formation was not proportional to the total F content in the products, suggesting that the pH and the vehicle used are more important.1218-2

Formação de flúor fracamente ligado ao esmalte após a aplicação tópica profissional de flúor in vitro

Since the efficacy of topical fluoride products is related to the fluoride (F) availability and its reactivity with enamel, this study was conducted. The F concentration of the following materials was verified: I- acidulated phosphate fluoride (APF) gel (1.23% F), II- APF foam (1.23% F) and III- Varnish (2.26% F). Forty blocks of bovine enamel were divided into 4 groups and treated according to the materials described, being one of them used as control. Loosely bound fluoride (''CaF2'') was determined on enamel after extraction with 1.0M KOH and analyzed by ion-selective electrode. Total F concentration found in gel was 12,642, in foam 12,755 and in varnish 23,183 mg F/g. All products formed statistically higher amounts of ''CaF2'' on enamel compared to the control group (p ; 0.05). Thus, ''CaF2'' formation was not proportional to the total F content in the products, suggesting that the pH and the vehicle used are more important.Considerando que a eficácia dos produtos para aplicação tópica profissional de flúor (géis, espumas e vernizes) está relacionada com a reatividade do flúor (F) com o esmalte e sendo esta dependente da disponibilidade do F em cada produto, este estudo foi conduzido. A concentração de F nos seguintes produtos foi estudada: I - Flúor Fosfato Acidulado (FFA) gel (1,23% F), II - FFA espuma (1,23% F) e III- Verniz fluoretado (2,26% F). Foram confeccionados 40 blocos de esmalte bovino, tratados de acordo com os grupos descritos, sendo um deles utilizado como controle. O F fracamente ligado (''CaF2'') ao esmalte foi determinado após a extração com 1.0 M KOH e analisado em eletrodo específico. A concentração de F encontrada no gel foi de 12.642, na espuma 12.755 e no verniz 23.183 mg F/g. Todos os produtos formaram uma quantidade significantemente maior de ''CaF2'' na superfície do esmalte, comparado ao grupo controle (p ; 0,05). Assim, a formação de ''CaF2'' na superfície do esmalte não foi proporcional ao conteúdo de F nos produtos, sugerindo que o pH e o veículo utilizado são mais importantes

Decreased dentin tubules density and reduced thickness of peritubular dentin in hyperbilirubinemia-related green teeth

It is stated anecdotally that patients with liver diseases in childhood who develop green teeth have increased risk for rampant caries, which may be secondary to changes in dental structure. The aim of this study was to test the hypothesis that hyperbilirubinemia affects the dentin morphology of green teeth. Sixteen primary teeth were prepared and divided into two groups (green teeth, n = 8 and control, n = 8), which were transversely fractured across the cervical third of the dental crowns; dentin was prepared and sputter-coated with gold, and examined under a scanning electron microscope. The mean density and mean diameter of dentin tubules, as well as the thickness of peritubular dentin, were compared. Hyperbilirubinemia was associated with a decrease in the density of the dentin tubules (p< .01) and the thickness of peritubular dentin of green teeth (p< .01). There was a correlation between childhood hyperbilirubinemia and changes in the dentin morphology, including a decrease in the density of the dentin tubules and a reduction in the thickness of peritubular dentin in green teeth

MicroRNA and protein profiles in invasive versus non-invasive oral tongue squamous cell carcinoma cells in vitro

Complex molecular pathways regulate cancer invasion. This study overviewed proteins and microRNAs (miRNAs) involved in oral tongue squamous cell carcinoma (OTSCC) invasion. The human highly aggressive OTSCC cell line HSC-3 was examined in a 3D organotypic human leiomyoma model. Non-invasive and invasive cells were laser-captured and protein expression was analyzed using mass spectrometry-based proteomics and miRNA expression by microarray. In functional studies the 3D invasion assay was replicated after silencing candidate miRNAs, miR-498 and miR-940, in invasive OTSCC cell lines (HSC-3 and SCC-15). Cell migration, proliferation and viability were also studied in the silenced cells. In HSC-3 cells, 67 proteins and 53 miRNAs showed significant fold-changes between non-invasive vs. invasive cells. Pathway enrichment analyses allocated "Focal adhesion" and "ECM-receptor interaction" as most important for invasion. Significantly, in HSC-3 cells, miR-498 silencing decreased the invasion area and miR-940 silencing reduced invasion area and depth. Viability, proliferation and migration weren't significantly affected. In SCC-15 cells, down-regulation of miR-498 significantly reduced invasion and migration. This study shows HSC-3 specific miRNA and protein expression in invasion, and suggests that miR-498 and miR-940 affect invasion in vitro, the process being more influenced by mir-940 silencing in aggressive HSC-3 cells than in the less invasive SCC-15.Peer reviewe

Generation of a Chinese Hamster Ovary Cell Line Producing Recombinant Human Glucocerebrosidase

Impaired activity of the lysosomal enzyme glucocerebrosidase (GCR) results in the inherited metabolic disorder known as Gaucher disease. Current treatment consists of enzyme replacement therapy by administration of exogenous GCR. Although effective, it is exceptionally expensive, and patients worldwide have a limited access to this medicine. In Brazil, the public healthcare system provides the drug free of charge for all Gaucher's patients, which reaches the order of $ 84million per year. However, the production of GCR by public institutions in Brazil would reduce significantly the therapy costs. Here, we describe a robust protocol for the generation of a cell line producing recombinant human GCR. The protein was expressed in CHO-DXB11 (dhfr(-)) cells after stable transfection and gene amplification with methotrexate. As expected, glycosylated GCR was detected by immunoblotting assay both as cell-associated (similar to 64 and 59 kDa) and secreted (63-69 kDa) form. Analysis of subclones allowed the selection of stable CHO cells producing a secreted functional enzyme, with a calculated productivity of 5.14 pg/cell/day for the highest producer. Although being laborious, traditionalmethods of screening high-producing recombinant cellsmay represent a valuable alternative to generate expensive biopharmaceuticals in countries with limited resources.FAPESP (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)CNPq (Conselho Nacional de Desenvolvimento Cientificoe Tecnologico)CNPQ(Conselho Nacional de Desenvolvimento Cientifico e Tecnologico)Fundacao ButantanFundacao Butanta