Effect of aging on mechanical and antibacterial properties of fluorinated graphene reinforced glass ionomer: In vitro study.

OBJECTIVES: This study: 1) aims to test the mechanical and antibacterial properties of fluorinated graphene strengthened glass ionomer materials (FG/GICs); 2) aims to investigate the effects of thermo-cycling on (FG/GICs). MATERIALS AND METHODS: Fluorinated graphene (FG) with bright white color was prepared from fluorinated graphite (SIGMA Aldrich), using modified Hummer's method, to be added to conventional glass ionomer cements (GICs). In addition to a control group (group 1), experimentally modified GICs were prepared by adding FG to the conventional glass ionomer powder with three different weight ratios; (group 2, 1 wt %; group 3, 2.5 wt %; and group 4, 5 wt %) using mechanical blending method. Experimental groups of the specimens (n = 240) were divided, for each concentration (n = 120) half of the specimens were subjected to thermo-cycling. Hardness, compressive strength, and antibacterial activity of (FG/GICs) were measured with and without thermo-cycling. Compressive strength was measured by a universal testing machine, hardness was measured using a Vickers micro-hardness tester, and antibacterial effects against staphylococcus aureus and streptococcus mutans were tested by the pellicle sticking method. For statistical analysis, numerical data were explored for normality and variance homogeneity using Shapiro-Wilk and Leven's tests respectively. RESULTS: The prepared (FG/GICs) showed an increase in hardness in group 4 (p < 0.001). Groups 3 and 4 gave the highest compressive strength values with no significant difference between them (p < 0.001). Groups 2, 3, and 4 showed improved antibacterial activity with no statistical difference between them (p > 0.001). Results after thermo-cycling showed significantly decreased hardness, and compressive strength values (p < 0.001), however, the results of antibacterial activity against streptococcus mutans showed no statistical difference after thermo-cycling (group 2, p = 0.05; group 3, p = 0.18; group 4, p = 0.26). The same results were observed for antibacterial activity against staphylococcus aureus (p = 0.92, p = 0.14, and p = 0.48 respectively). CONCLUSION: FG can be considered a promising additive to GICs to promote its anti-cariogenic effects, however, these antibacterial effects are only useful in the short term, as aging adversely affected their mechanical properties. The 2.5 wt % FG/GICs is suggested to be the most encouraging, as after aging, it represented the highest compressive strength among all groups, while its hardness values were at least comparable to that of conventional glass ionomer. CLINICAL SIGNIFICANCE: FG/GICs can be considered an anti-cariogenic restoration in temporary restorative interventions, as in certain cases in deciduous teeth where considerable esthetics may be required, especially those with difficult moisture control, where neither resin composite restorations nor amalgam restorations will be indicated. It can also be used for patients with high caries index or in atraumatic restorative treatment (ART) in low-income countries.

Evaluation of the pH, calcium ion release, and antibacterial effect of a premixed bioceramic endodontic sealer.

This study sought to compare a bioceramic sealer (TotalFill) and a calcium hydroxide (Ca[OH]2) sealer (Sealapex) in terms of their pH, calcium ion (Ca²âº) release, and antibacterial effect against Enterococcus faecalis bacteria. For the pH and Ca²âº release tests, 20 polyethylene tubes (10 mm in height and 1 mm in internal diameter) were filled with the appropriate sealer (n = 10 per sealer), immersed in glass flasks each containing 10 mL of deionized water, and stored in an incubator at 37°C. The water was changed after 1, 7, 28, and 90 days. At each water change, the eluates were measured with an advanced electrochemistry meter to determine the pH and with a flame atomic absorption spectrometer to determine the Ca²âº release. The antibacterial effect was measured using the turbidimetry-based direct contact test in which the wells of a microtiter plate were coated with a thin, even layer of freshly prepared sealer (10 wells per sealer), which was allowed to set before application of a suspension of E faecalis. Control wells were obtained by placing an identical bacterial suspension in 10 uncoated wells. The optical density of the sealer and control groups was measured immediately and 1, 3, and 7 days after sealer preparation. Data were analyzed for normality with the Shapiro-Wilk and Kolmogorov-Smirnov tests. Two-way analysis of variance (ANOVA), Student t test, and 1-way ANOVA with Tukey post hoc tests were all utilized with a significance level of P < 0.05. TotalFill maintained significantly higher pH and Ca²âº release levels than Sealapex at all evaluation times (P < 0.05). Both sealers demonstrated significantly greater antibacterial effect (lower optical density) than the control group; however, TotalFill resulted in significantly lower optical density values than Sealapex (P < 0.05). TotalFill bioceramic sealer demonstrated superior Ca(OH)2-related properties compared to Sealapex Ca(OH)2 sealer.

The effect of adding ytterbium trifluoride on the radiopacity, compressive strength, setting time and bioactivity of biodentine: an in vitro study / Efeito da adição de trifluoreto de itérbio na radiopacidade, resistência à compressão, tempo de presa e bioatividade da biodentina: estudo in vitro

Objective: This study aimed to evaluate the radiopacity, compressive strength, setting time and bioactivity of Biodentine after modification with Ytterbium Tri-Fluoride (YbF3) in three different concentrations. Material and Methods: Radiopacity was determined using the equivalence in millimeters of aluminum (mm Al) from digital radiographs. Compressive strength was evaluated using a universal testing machine. The initial and final setting times were evaluated using Gillmore needle. The bioactive potential was evaluated using the environmental scanning electron microscope (ESEM) connected with Energy Dispersive X-ray analysis (EDX) and X-ray Diffractometer (XRD) at three different time intervals. pH was measured using a pH-meter. Data were analyzed using one-way ANOVA followed by Tukey's post hoc tests (P≤ 0.05). Results: Radiopacity of Biodentine with 2.5%, 5% and 7.5% YbF3 was significantly higher than unmodified Biodentine (P ≤ 0.05). Unmodified Biodentine showed the highest mean compressive strength values compared to all other groups (p≤ 0.05). The addition of YbF3 to Biodentine has extended the final setting time except for the 2.5% YbF3 group that showed no significant difference compared to the control. All groups showed an alkaline pH at 28 days, ESEM coupled with EDX analysis showed evidence of dense globules of calcium phosphate on the surface indicating enhancement of bioactivity. Conclusion: 2.5% YbF3 can be a promising radiopacifying agent to Biodentine with improvement in radiopacity, bioactive potential and maintaining the setting time and compressive strength at acceptable level as indicated by the ISO standards (AU)

Objetivo: O estudo buscou avaliar a radiopacidade, resistência à compressão, tempo de presa e bioatividade da Biodentina modificada por Trifluoreto de itérbio (YbF3). Materiais e Métodos: YbF3 foi incorporado ao pó de Biodentina e dividido em 4 grupos (X0, X1, X2 e X3) de acordo com a concentração de YbF3; 0%, 2.5%, 5% e 7.5% do peso, respectivamente. Os espécimes foram preparados para cada experimento com um total de 40 espécimes para cada teste (n=10 por grupo). A radiopacidade foi determinada através do uso equivalente em milímetros de alumínio. A resistência a compressão foi avaliada através do uso de uma máquina de teste universal. O tempo inicial e final foi avaliado através de uma agulha de Gillmore. O potencial bioativo foi avaliado através do Microscópio Eletrônico de Varredura (ESEM), conectado com a análise de espectroscopia de raios X por energia dispersiva (EDX) e difração de raio X (DRX). O pH foi mensurado através do uso de um pHmetro. Os dados foram analisados pelo ANOVA seguido do Test Tukey. Resultados: A radiopacidade nos grupos X1, X2 e X3 foi significantemente maior do que no grupo X0. O grupo X0 mostrou a maior resistência à compressão comparado com os outros grupos. A adição de YbF3 a Biodentina excedeu o tempo final exceto pelo grupo X1, que não apresentou diferença estatística significante quando comparado com o grupo X0. Todos os grupos apresentaram um pH alcalino com 28 dias. ESEM com análise EDX mostrou evidência de densos glóbulos de fosfato de cálcio na superfície, indicando uma melhora na bioatividade. Conclusão: 2.5% YbF3 é um promissor radiopacificador para Biodentina, que aumentou a radiopacidade e potencial bioativo enquanto manteve o tempo definido e a resistência à compressão em níveis aceitáveis como indica a norma ISO.(AU)