Effects of light-curing time on the cytotoxicity of a restorative composite resin on odontoblast-like cells

This in vitro study evaluated the cytotoxicity of an experimental restorative composite resin subjected to different light-curing regimens. METHODS: Forty round-shaped specimens were prepared and randomly assigned to four experimental groups (n=10), as follows: in Group 1, no light-curing; in Groups 2, 3 and 4, the composite resin specimens were light-cured for 20, 40 or 60 s, respectively. In Group 5, filter paper discs soaked in 5 µL PBS were used as negative controls. The resin specimens and paper discs were placed in wells of 24-well plates in which the odontoblast-like cells MDPC-23 (30,000 cells/cm²) were plated and incubated in a humidified incubator with 5% CO2 and 95% air at 37ºC for 72 h. The cytotoxicity was evaluated by the cell metabolism (MTT assay) and cell morphology (SEM). The data were analyzed statistically by Kruskal-Wallis and Mann-Whitney tests (p<0.05). RESULTS: In G1, cell metabolism decreased by 86.2%, indicating a severe cytotoxicity of the non-light-cured composite resin. On the other hand, cell metabolism decreased by only 13.3% and 13.5% in G2 and G3, respectively. No cytotoxic effects were observed in G4 and G5. In G1, only a few round-shaped cells with short processes on their cytoplasmic membrane were observed. In the other experimental groups as well as in control group, a number of spindle-shaped cells with long cytoplasmic processes were found. CONCLUSION: Regardless of the photoactivation time used in the present investigation, the experimental composite resin presented mild to no toxic effects to the odontoblast-like MDPC-23 cells. However, intense cytotoxic effects occurred when no light-curing was performed.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Toxicity of chlorhexidine on odontoblast-like cells

Chlorhexidine gluconate (CHX) is recommended for a number of clinical procedures and it has been pointed out as a potential cavity cleanser to be applied before adhesive restoration of dental cavities. OBJECTIVE: As CHX may diffuse through the dentinal tubules to reach a monolayer of odontoblasts that underlies the dentin substrate, this study evaluated the cytotoxic effects of different concentrations of CHX on cultured odontoblast-like cells (MDPC-23). MATERIAL AND METHODS: Cells were cultured and exposed to CHX solutions at concentrations of 0.06%, 0.12%, 0.2%, 1% and 2%. Pure culture medium (&#945;-MEM) and 3% hydrogen peroxide were used as negative and positive control, respectively. After exposing the cultured cells to the controls and CHX solutions for 60 s, 2 h or 60 s with a 24-h recovery period, cell metabolism (MTT assay) and total protein concentration were evaluated. Cell morphology was assessed under scanning electron microscopy. CHX had a dose-dependent toxic effect on the MDPC-23 cells. RESULTS: Statistically significant difference was observed when the cells were exposed to CHX in all periods (

Hábitos tabágicos : conhecimentos e consumo dos adolescentes

Enquadramento: No adolescente ocorrem metamorfoses físicas, psicológicas, comportamentais e sociais, sentindo-se mais autónomo, integrado e independente. Reproduzindo o mundo dos adultos, espelha no grupo de pares hábitos de consumo de substâncias psicoativas, mormente o tabaco, amplamente aceite como a causa principal de morbilidade e de mortalidade evitável no mundo, com consequências diretas e indiretas na saúde, a curto e longo prazo. Objetivos: Identificar as variáveis sociodemográficas e de contexto familiar; estimar o impacto das variáveis de contexto escolar e estilos de vida; analisar a relação entre as variáveis psicológicas (autoestima, autoconceito); identificar as atitudes que influem os conhecimentos e o consumo de tabaco. Métodos: Estudo quantitativo, descritivo, correlacional, analítico e transversal, numa amostra de 971 adolescentes, aplicou-se o questionário sociodemográfico, de contexto escolar e estilos de vida; a Escala de Autoestima de Rosenberg (Romano, Negreiro & Martins, 2007); o Inventário Clínico de Autoconceito (Vaz Serra, 1984) e a Escala do Consumo de Tabaco (Precioso, 2007). Resultados: Os 971 inquiridos são adolescentes entre os 14 e 21 anos, 43.4% têm idade inferior a 17 anos, são maioritariamente rapazes (50.8%), residem predominantemente em meio rural (66.4%) e coabitam com os pais (77.3%). Cerca de 39.0% frequentam o 10.º ano, revelam bom autoconceito (45.3%) e elevada autoestima (47.4%). A maioria (62.0%) é ou já foi consumidora de tabaco (63.0% raparigas vs 60.6% rapazes); fumaram o primeiro cigarro, em média, aos 13,8 anos, sendo os rapazes mais precoces (≤ 13 anos) que as raparigas ( ≥15 anos). O primeiro cigarro foi obtido na escola (35.5% raparigas vs rapazes 39.1%), principal local de oferta (56.8%) e a compra ocorreu na tabacaria ou no café (60.0%). Dos inquiridos, 17,7% (13.0% raparigas vs 22.0% rapazes) são fumadores diários, consumindo até sete cigarros (60.9% rapazes vs 58.3% raparigas). Como razão principal para fumar o primeiro cigarro, 74.3% apontam “Querer saber como era”. Conclusão: O tabagismo é um fenómeno complexo e globalizante com repercussões tanto na saúde individual dos fumadores como na saúde pública, pelo que permanece a urgência de implementação de políticas de educação para a saúde, com ações de sensibilização, prevenção e promoção de mudanças comportamentais e atitudinais, preditoras de estilos de vida saudável.ABSTRACT Framework: During adolescence, the teenager suffers metamorphosis at a physical, psychological, behavioral and social level, therefore feeling more autonomous, integrated and independent. While mimicking adult behavior among its peers, he/she tends to engage in the consumption of psychoactive substances, namely tobacco, widely accepted as the leading cause of morbidity as well as mortality avoidable worldwide, with both direct and indirect consequences in short and long term health. Goals: Identify the sociodemographic and familiar context variables; assess the impact of the school context and lifestyle variables; analyze the relation between the psychological variables (self-esteem, self-concept) and identify the attitudes, which influences the knowledge as well as the tobacco consumption. Methods: Quantitative, correlational, analytical and transversal study, within a sample of 971 adolescents was applied the sociodemographic questionnaire of school context and lifestyle; Self-Esteem Rosenberg Scale (Romano, Negreiro & Martins, 2007); Self-Concept Clinical Inventory (Vaz Serra, 1984) and the Tobacco Consumption Scale (Precioso, 2007). Results: The 971 inquired were adolescents from 14 to 21 years old, 43.3% were under 17 years old, mainly males (50.8%), living in the countryside (66.4%) with their parents (77.3%). About 39.0% are in the 10th grade, reveal good self-concept (45.3%) and high selfesteem (47.4%). The majority (62.0%) is or has been a tobacco consumer (63.0% girls vs 60.6% boys); they smoked their first cigarette with an average age of 13.8 years old, whilst male are more premature (≤13 years old) than female (≥15 years old). Their first smoke was in school (35.5% girls vs 39.1% boys), which is the main place of offering (56.8%) and they buy them in tobacco or coffee shops (60.0%) From the surveyed, 17.7% (13.0% girls vs 22.0% boys) are daily smokers, some smoking up to 7 cigarettes per day. The main reason to smoke their first cigarette is “Wishing to know how it felt like” (74.3%). Conclusion: Smoking is both a complex and global phenomenon with repercussions not only in individual health, but also in public health. The urgency to implement politics for health education, through awareness raising actions, prevention and promotion of behavioral changes as well as attitude, predictive of a healthy lifestyle

Transdentinal cytotoxic effects of different concentrations of chlorhexidine gel applied on acid-conditioned dentin substrate

It has been demonstrated that chlorhexidine digluconate (CHX) is capable of eliminating bacteria that may remain lodged in dentin after mechanical caries removal. In addition, the use of CHX on acid-etched dentin before adhesive system application delays the resin-dentin interface degradation, maintaining the integrity of the adhesive restorations. Despite these advantages of using CHX in restorative dentistry, when applied on dentin, this chemical agent may diffuse across dentinal tubules to cause toxic effects to the pulp cells. The aim of this study was to evaluate the transdentinal cytotoxic effects caused by different concentrations of CHX gels applied on acid-conditioned dentin substrate. Dentin discs (0.2-mm and 0.5-mm thick) were cut from human third molars and mounted in artificial pulp chambers. Odontoblast-like MDPC-23 cells (50,000 cells/cm(2)) were seeded on the pulpal side of the discs, and the carbon polymer gel (natrosol) with different CHX concentrations (0.12, 0.2, 1, and 2%), 35% phosphoric acid, or pure natrosol were applied on the occlusal side of the discs, forming six treatment groups (n = 10 discs/thickness). The dentin discs in the control group (it = 10 discs/thickness) did not receive any treatment. In each group, cell metabolism was analyzed by the methyltetrazolium assay (n = 8/thickness), and cell morphology was assessed by scanning electron microscopy (n = 2/thickness). Statistical analysis showed that CHX gels had a dose-dependent toxic effect on the odontoblast-like cells. Cell metabolism decreased by 12.8, 14.6, 18.3, 26, 13.7, and 10.5% for the 0.5-mm-thick dentin discs and 23, 26.3, 28.1, 34.5, 22.5, and 19.4% for the 0.2-mm-thick dentin discs treated with 0.12% CHX, 0.2% CHX, 1% CHX, 2% CHX, H(3)PO(4), and pure natrosol, respectively. According to the experimental conditions of the current investigation, it may be concluded that the application of natrosol gel with different concentrations of CHX on acid-conditioned dentin causes mild transdentinal cytotoxic effects to the MDPC-23 cells in a dose-dependent manner. Dentin acted as a biological barrier against CHX diffusion, and this effect was directly related to dentin thickness. (C) 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 92B: 40-47, 2010Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Protective Effect Of Sodium Ascorbate On Mdpc-23 Odontoblast-like Cells Exposed To A Bleaching Agent.

To evaluate the cytotoxic effects of a bleaching agent composed of 0.01% carbamide peroxide (CP; 2.21mug/ml H(2)O(2)) on the MDPC-23 odontoblastic cell line, and to determine whether sodium ascorbate (SA) is capable of reducing, or even eliminating, the toxic effects caused by this bleaching agent. The cells were seeded in wells and incubated for 48 hours. CP and SA were dissolved in a culture medium (DMEM) in order to obtain experimental extracts. Six groups of cells (n=10) were treated as follows: G1: no treatment (control); G2: 0.25 mM SA/60 min; G3: 0.5 mM SA/60 min; G4: 0.25 mM SA+0.01% CP/60 min; G5: 0.5 mM SA+0.01% CP/60 min; and G6: 0.01% CP/60 min. The cell metabolism was evaluated by MTT assay, and the cell morphology was assessed by scanning electron microscopy. The data obtained were analyzed by 2-way ANOVA and post-hoc Tukey's test (alpha=5%). THE PERCENTAGES OF CELL METABOLISM WERE AS FOLLOWS: G1 (control)=100%; G2=110.06%, G3=108.57%, G4=90.35%, G5=97.63%, and G6=66.88%. Group 6 presented a statistically lower cell metabolism than did the other groups, and the cells that remained on the substrate exhibited changes in their morphology. SA decreased the cytotoxic effects caused by CP, demonstrating its protective effect against the toxic components of this dental product. It was concluded that CP gel has cytopathic effects on MDPC-23 odontoblastic cells, even at low concentrations such as 0.01%. SA at 0.25 mM, and that 0.5 mM is able to protect these cultured cells against the cytotoxic effects of CP.4238-4

Cytotoxicity of resin-based light-cured liners

Purpose: To evaluate the cytotoxic effects of resin-based light-cured liners on culture of pulp cells. Methods: Discs measuring 4 mill in diameter and 2 mm thick were fabricated from TheraCal (TCMTA), Vitrebond (VIT), and Ultrablend Plus (UBP). These specimens were immersed in serum-free culture medium (DMEM) for 24 hours or 7 days to produce the extracts. After incubating the pulp cells for 72 hours, the extracts were applied on the cells and the cytotoxic effects were determined based on the cell metabolism (MTT), total protein expression and cell morphology (SEM). In the control group, fresh DMEM was used. Data from MTT analysis and protein expression were submitted to Kruskal-Wallis and Mann-Whitney tests at the preset level of significance of 5%. Results: When in contact with the 24-hour extract, TCMTA, VIT, and UBP decreased the cell metabolism by 31.5%, 73.5% and 71.0%, respectively. The total protein expressed by the cells in contact with VIT and UBP was lower than TCMTA and DMEM (Mann-Whitney, P< 0.05). When in contact with the 7-day extract, TCMTA, VIT, and UBP decreased the metabolic activity by 45.9%, 77.1% and 64.4%, respectively. All the liners expressed statistically lower amounts of proteins when compared to the control. A reduction in the number of cells was observed for all liners. The remaining cells from TCMTA group resembled those from the control group while for VIT and UBP the cells presented significant morphological alterations. (Ani J Dent 2009;22:137-142).Bisco and the Brazilian Research Foundadion Conselho Nacional para o Desenvolvimento Cientifico e Tecnologico - CNPq[476137/2006-3]Bisco and the Brazilian Research Foundadion Conselho Nacional para o Desenvolvimento Cientifico e Tecnologico - CNPq[301029/2007-5