Calcium chloride-enriched calcium aluminate cement promotes in vitro osteogenesis.

AIM: To evaluate the effects of 2.8% or 10% calcium chloride (CaCl2 ) in calcium aluminate cement (CAC) with either bismuth oxide (Bi2 O3 ) or zinc oxide (ZnO) as radiopacifiers on the progression of osteogenic cell cultures. METHODOLOGY: Rat calvaria-derived cells were grown on Thermanox® coverslips for 24 h and exposed to samples of (i) CACb: with 2.8% CaCl2 and 25% Bi2 O3 ; (ii) CACb+: with 10% CaCl2 and 25% Bi2 O3 ; (iii) CACz: with 2.8% CaCl2 and 25% ZnO; or (iv) CACz+: with 10% CaCl2 and 25% ZnO, placed on inserts. Nonexposed cultures served as the control. Calcium and phosphorus contents in culture media were quantified. The effects of the cements on cell apoptosis, cell viability and acquisition of the osteogenic cell phenotype were evaluated. Data were compared by Kruskal-Wallis test (α = 5%). RESULTS: CACb+ promoted the highest levels of calcium in the culture media; CACz+, the lowest levels of phosphorus (P < 0.05). CACz+ and CACb increased cell apoptosis (P < 0.05). CACb reduced cell viability (P < 0.05) and the expression of the osteoblastic phenotype. CACz+ and CACb+ promoted greater cell differentiation and matrix mineralization compared to CACz and CACb (P < 0.05). CONCLUSION: For CAC with the lower CaCl2 content, the use of Bi2 O3 was detrimental for osteoblastic cell survival and differentiation compared to ZnO, while CAC with the higher CaCl2 content supported the acquisition of the osteogenic cell phenotype in vitro regardless of the radiopacifier used. Thus, CAC with 10% CaCl2 would potentially promote bone repair in the context of endodontic therapies.

Dental discoloration caused by bismuth oxide in MTA in the presence of sodium hypochlorite.

OBJECTIVES: The aim of this research was to analyse the dental discolouration caused by mineral trioxide aggregate (MTA) induced by bismuth oxide and also assess the colour stability of other dental cements. MATERIALS AND METHODS: Bismuth oxide, calcium tungstate and zirconium oxide were placed in contact with sodium hypochlorite for 24 h after which they were dried and photographed. Phase analyses were performed by X-ray diffraction (XRD) of radiopacifiers before and after immersion in sodium hypochlorite. Furthermore, teeth previously immersed in water or sodium hypochlorite were filled with MTA Angelus, Portland cement (PC), PC with 20 % zirconium oxide, PC with 20 % calcium tungstate and Biodentine. Teeth were immersed for 28 days in Hank's balanced salt solution after which they were sectioned and characterized using scanning electron microscopy (SEM) with energy-dispersive mapping and stereomicroscopy. RESULTS: Bismuth oxide in contact with sodium hypochlorite exhibited a change in colour from light yellow to dark brown. XRD analysis demonstrated peaks for radiopacifier and sodium chloride in samples immersed in sodium hypochlorite. The SEM images of the dentine to material interface showed alteration in material microstructure for MTA Angelus and Biodentine with depletion in calcium content in the material. The energy-dispersive maps showed migration of radiopacifier and silicon in dentine. CONCLUSIONS: MTA Angelus in contact with a tooth previously immersed in sodium hypochlorite resulted in colour alteration at the cement/dentine interface. CLINICAL RELEVANCE: MTA Angelus should not be used after irrigation with sodium hypochlorite as this will result in tooth discoloration.

Avaliação da reação tecidual e da radiopacidade do cimento Portland acrescido de diferentes concentrações de óxido de bismuto: estudo em tecido subcutâneo de ratos / Radiopacity and rat subcutaneous tissue response to Portland cement containing different concentrations of bismuth oxide

A radiopacidade e a resposta tecidual do cimento Portland (CP) acrescido de óxido de bismuto (OB) nas concentrações de 0, 15, 20, 30 e 50%, determinadas em peso, foram avaliadas. Para a análise da radiopacidade, foi seguida a norma ISO 6876/2001. A densidade radiográfica foi mensurada em milímetros de alumínio (mmAl) e a análise estatística realizada utilizando-se os testes de ANOVA e Tukey-Kramer (p<0,05). Para a análise da resposta tecidual foram selecionados 81 ratos albinos e cada um recebeu como implante, na região dorsal, dois tubos de polietileno preenchidos com os cimentos experimentais. Os ratos foram mortos após 15, 30 e 60 dias. Na análise microscópica foram avaliados dois parâmetros: células inflamatórias e fenômeno reparatório. Os escores foram determinados e submetidos à análise estatística, utilizando-se os testes não paramétricos de Kruskal-Wallis e Dunn (p<0,05). Os resultados demonstraram que os valores representativos da radiopacidade aumentaram, gradativamente, de acordo com a concentração de óxido de bismuto. A significância estatística foi verificada entre o CP/50%OB e os demais cimentos avaliados, e entre o CP puro e o CP/30%OB (p<0,05). A radiopacidade apresentada pelo CP puro foi abaixo do mínimo (3 mmAl) recomendado pelas normas nº 57 da ADA e da ISO 6876/2001. Na análise da resposta tecidual, em relação à intensidade do infiltrado inflamatório, ocorreu diminuição de 15 para 30 dias e de 15 para 60 dias, com significância estatística (p<0,05), apenas para o grupo II nos dois intervalos de tempos. Com referência ao fenômeno reparatório ocorreu, em geral, para todos os grupos aumento do tecido fibrocelular, do período de 15 para o de 60 dias. Os resultados obtidos permitiram concluir que 15 a 20% de óxido de bismuto é suficiente para proporcionar ao CP a radiopacidade mínima recomendada pelas normas ADA e ISO. A diminuição do infiltrado inflamatório associada ao aumento do tecido fibrocelular, fundamentam a ausência de citotoxicidade...

The aim of the study was to evaluate the radiopacity and subcutaneous tissue response of Portland cement (PC) with different concentrations of bismuth oxide (BO). PC was mixed with 0, 15, 20, 30 and 50% of BO determined in weight. The radiopacity was performed according to the ISO 6876/2001 standard for dental root canal sealing materials Statistical analysis was performed using ANOVA and Tukey-Kramer tests (p<0.05). For biocompatibility test, eighty-one albino rats (Rattus norvegicus) were selected. Two subcutaneous pockets were created in animal dorsum and polyethylene tubes filled with the cements were implanted. The rats were sacrificed at 15, 30 and 60 days after implantation. Histological evaluations were classified according to inflammatory response and repair process and scores were established. Statistical analysis was performed using the Kruskal-Wallis and Dunn tests (p<0.05). The results showed that there were statistical differences in radiopacity among PC with 50% of BO and all the other evaluated concentrations (p<0.05). Also, there was statistical difference between PC with 30% of BO and PC without BO (p<0.05). No statistical differences were found for inflammatory response in all the evaluated groups in each period (p>0.05). For repair process evaluation was observed a significant increase in fiber cellular tissue through the periods for all the groups (p<0.05). The tests suggested that 15 to 20% of BO added to PC attended ISO requirements for radiopacity. For biological response, there were decreases in the inflammatory response associated with an increase in the repair process, suggesting the lack of toxicity of BO added to PC.

Comportamento biológico, físico e químico do cimento Portland associado a diferentes radiopacificadores / Biological, physical and chemical comportament of the Portland sealer associated with differents radiopacifying agents

Objetivo do presente estudo foi avaliar algumas propriedades físicas, químicas, comportamento biológico em tecido subcutâneo de ratos e caracterísitcas superficiais do cimento Portland (CP) associado a diferentes radiopacificadores (óxido de bismuto (OB), tungstato de cálcio (TC) e óxido de zircônio (OZ). As propriedades físicas analisadas foram radiopacidade, tempo de presa, solubilidade e características superficiais, enquanto que às químicas foram pH e liberação de ions cálcio, e a biocompatibilidade foi analisada in vivo em tecido subcutâneo de rato. A metodologia para a realização das propriedades físicas, foram as recomendadas pela ISO 6876/2001 e n.57 ADA/2000, com pequena modificação para o tempo de presa que além da agulha com peso de l00g foi utilizado também agulha com peso de 453,6 para determinação do tempo de presa final conforme norma da ASTM. As características superficiais foram realizadas em microscopia eletrônica de varredura. Para o pH e liberação de íons cálcio, os materiais foram acondicionados em dente de acrílico com cavidades retrógradas e imersos em 15 mL de água MilliQ. Nos períodos de 3, 24, 72 e 168 horas os dentes eram trocados de frasco e mensurou-se seu pH por meio de pHmetro e cálcio com uso de espectrofotômetro de absorção atômica da água que o material estava imerso. Para a biocompatibilidade os materiais foram colocados em tubos de polietileno e implantados no dorso de 15 ratos, que foram mortos após 7, 15 e 30 dias da implantação. Os dados foram comparados estatisitcamente pelo teste de Kruskal-Wallis e Miller ou ANOVA e tukey, dependendo da normalidade ou não dos dados, sendo empregado nível de significância foi de 5%. Os resultados mostraram diferença significante (P<0,05) para o tempo de presa inicial entre todos os materiais, enquanto que no tempo de presa final só não ocorreu diferença (P>0,05) entre o óxido de bismuto e tungstato de cálcio...

The aims of this study were to evaluate some physicochemical properties, subcutaneous tissue response and scanning electron microscope surface characteristics related to Portland cementassociated with the following radiopacifiersagents: bismuth oxide (BO), calcium tungstate (CT) and zirconium oxide (ZO). The physical properties evaluated were: radiopacity, setting time, solubility and scanning electron microscope study of the cements surface. The chemical properties evaluated were: pH and calcium íon release. The biocompatibility test was performed in subcutaneous tissue of rats. For the study of the physical properties, the methodologies ISO 6876/2001 e n.57 ADA/2000SO with slight variations for the setting time test were used. For the setting time test the 100g needle was used. Determination of the final setting time was performed also using the 453,6g needle according to the ASTM criteria. The surface characteristics were studied using scanning electron microscopy. For the pH and calcium ion release tests, the samples were inserted into root-end cavities prepared in acrylic teeth. Immediately, after being filled, all specimens were immersed in 15 mL of Milli-Q water. Evaluations were performed at periods of 3 hours, 24 hours, 72 hours, and 168 hours for assessment of the pH and calcium ion release. After each measurement, the specimens were moved to new tubes containing fresh MiIIi-Q water. The measurements were carried out using a pH meter. The calcium ions release was measured using an atomic absorption spectrophotometer equipped with a calcium-specific hollow cathode lamp. To evaluate the biocompatibility polyethylene tubes were filled with the samples and implanted into the subcutaneous tissue of 15 rats. The biological response was evaluated at 7, 15 and 30 days. The data was statistically compared using the kruskal-wlilis and Miller test or by using the ANOVA-Tukey test, according to the presence or absence of normal distribution...