RESUMEN
The aim of this study was to evaluate the maximum amount of chlorhexidine (CHX) that could be incorporated to self-adhesive resin cements to add antibacterial effect without affecting the physical properties. The CHX was incorporated into a commercial self-adhesive resin cement at mass fractions of 0.5-15 wt%, and the CHX-release profile, antibacterial effect, flexural and bond strengths of experimental cements were evaluated. Increasing the CHX content from 5 to 15 wt% resulted in a higher released concentration of CHX. In agar diffusion tests, experimental cements containing 5, 10, and 15 wt% CHX produced inhibition zones against oral bacteria. In flexural strength and shear bond strength to dentin, no significant reduction was observed with the incorporation of 5 wt% CHX. This in vitro study suggests that the addition of 5 wt% CHX yielded an antibacterial self-adhesive cement and had no adverse effect on the flexural and shear bond strengths.
Asunto(s)
Recubrimiento Dental Adhesivo , Cementos de Resina , Agar/análisis , Agar/farmacología , Antibacterianos/farmacología , Clorhexidina/química , Clorhexidina/farmacología , Recubrimiento Dental Adhesivo/métodos , Cementos Dentales/farmacología , Dentina/química , Ensayo de Materiales , Cementos de Resina/químicaRESUMEN
The aim of this study was to investigate a failure criterion to predict flexural strengths of composite resins (CR) by three-dimensional finite element analysis (3D-FEA). Models of flexural strength for test specimens of CR and rods comprising a three-point loading were designed. Calculation of Young's moduli and Poisson's ratios of CR were conducted using a modified McGee-McCullough model. Using the experimental CR, flexural strengths were measured by three-point bending tests with crosshead speed 1.0 mm/min and compared with the values determined by in silico analysis. The flexural strengths of experimental CR calculated using the maximum principal strain significantly correlated with those obtained in silico amongst the four types of failure criteria applied. The in silico analytical model established in this study was found to be effective to predict the flexural strengths of CR incorporating various silica filler contents by maximum principal strain.
Asunto(s)
Resinas Compuestas/química , Diseño Asistido por Computadora , Materiales Dentales/química , Simulación por Computador , Análisis del Estrés Dental , Módulo de Elasticidad , Análisis de Elementos Finitos , Ensayo de Materiales , Estrés MecánicoRESUMEN
OBJECTIVE: Development of high strength dental composites with adhesive, antibacterial and re-mineralizing potential. MATERIALS: Urethane and triethylene glycol dimethacrylates were combined with HEMA (10 or 20wt%) and 2MP (2 or 10wt%), antibacterial chlorhexidine (2.5wt%) and chemical cure initiators. Reactive mono/tri calcium phosphate (CP) mixed with silica/silicon carbide nanoparticles (S) (CP:S weight ratio 1:2 or 2:1) was added (50wt%). RESULTS: Decreasing CP/S ratio and HEMA content reduced monomer conversion at 15min from 93 to 63%. Conversely, decreasing CP/S increased initial "dry" compressive (137-203MPa) and flexural (79-116MPa) strength. With high HEMA content, these decreased by â¼15-20MPa upon 24h water storage. With low HEMA content, average decline was <8MPa due to reduced water sorption. Early water sorption induced mass increase, volume expansion, mono calcium phosphate dissolution and chlorhexidine release, were proportional to the initial calcium phosphate content. Furthermore, they increased â¼1.5 fold upon raising HEMA wt%. These diffusion controlled processes and strength decline slowed after 24h as phosphates reaction bound water within the materials. Increasing 2MP concentration reduced calcium release but did not affect strength. Formulations with high CP/S indicated greater antibacterial activity in agar diffusion and in vitro biofilm tests. SIGNIFICANCE: New material use beneath a conventional composite could potentially reduce high failure rates associated with residual caries and bacterial microleakage.
Asunto(s)
Antibacterianos/química , Fosfatos de Calcio/química , Compuestos Inorgánicos de Carbono/química , Clorhexidina/química , Resinas Compuestas/síntesis química , Metacrilatos/química , Compuestos de Silicona/química , Actinomyces/efectos de los fármacos , Antibacterianos/farmacología , Fosfatos de Calcio/farmacología , Células Cultivadas , Clorhexidina/farmacología , Resinas Compuestas/farmacología , Fuerza Compresiva , Lacticaseibacillus casei/efectos de los fármacos , Nanopartículas/química , Espectroscopía Infrarroja por Transformada de Fourier , Streptococcus mutans/efectos de los fármacos , Difracción de Rayos XRESUMEN
Light curable methacrylate dental monomers containing reactive calcium phosphate filler (monocalcium phosphate monohydrate (MCPM) with particle diameter of 29 or 90microm) and beta-tricalcium phosphate (beta-TCP) at 1:1 weight ratio in a powder:liquid ratio (PLR) of 1:1 or 3:1 and chlorhexidine diacetate (0 or 5 wt.%), were investigated. Upon light exposure, approximately 90% monomer conversion was gained irrespective of the formulation. Increasing the PLR promoted water sorption by the set material, induced expansion and enhanced calcium, phosphate and chlorhexidine release. Concomitantly, a decline in compressive and biaxial flexural strengths occurred. With a reduction in MCPM particle diameter, however, calcium and phosphate release was reduced and less deterioration in strength observed. After 24h, the remaining MCPM had reacted with water and beta-TCP, forming, within the set materials, brushite of lower solubility. This provided a novel means to control water sorption, component release and strength properties. Measurable chlorhexidine release was observed for 6weeks. Both diffusion rate and total percentage of chlorhexidine release decreased with lowering PLR or by adding buffer to the storage solutions. Higher chlorhexidine release was associated with reduced bacterial growth on agar plates and in a biofilm fermenter. In cell growth media, brushite and hydroxyapatite crystals precipitated on the composite material surfaces. Cells spread on both these crystals and the exposed polymer composite surfaces, indicating their cell compatibility. These formulations could be suitable antibacterial, biocompatible and remineralizing dental adhesives/liners.