RESUMEN
OBJECTIVES: We are introducing novel glass-ionomer cement (GIC) dually-modified with chitosan (CH) in the liquid phase and titanium-dioxide nano-powder (TiO2 /NP) in the powder phase. The aim was to investigate the effect of this dual-modification on the antibacterial properties against S. mutans biofilms and on the bulk and surface mechanical properties. METHODS: Commercially available powder/liquid restorative GIC was used in this study. The GIC specimens were modified with 3% (w/w) TiO2 /NP, 10% (v/v) CH solution, or dually-modified with TiO2 /CH. The non-modified GIC was used as a control. The biofilms formations were characterized by SEM, live/dead assay using confocal-microscopy, colony-forming unit counts, and MTS assay. The bulk and surface mechanical properties were characterized in terms of flexural and compressive strengths and surface hardness, respectively. RESULTS: With the dual-modification, a significant improvement in the antibacterial properties was found both qualitatively and quantitatively. The synergetic effect of the dual-modification was also reflected on the enhancement of the flexural and compressive strengths. However, no difference was found in surface hardness. CONCLUSIONS: The modification of GIC powder with TiO2 /NP showed to be more effective in enhancing the mechanical properties. However, the enhancement in the antibacterial properties was more evident with CH incorporation in GIC liquid. CLINICAL SIGNIFICANCE: This study introduced novel glass ionomer cement dually-modified with TiO2 NP and chitosan with superior mechanical and antibacterial properties for potential applications in restorative and preventive dentistry. The modification of GIC powder with TiO2 NP showed to be more effective in enhancing the mechanical properties. However, the enhancement in the antibacterial properties was more evident with CH incorporation in GIC liquid. Although of the promising synergetic effect of the dual-modification of GIC with TiO2 NP/CH, further clinically-related studies are recommended. (J Esthet Restor Dent 29:146-156, 2017).
Asunto(s)
Quitosano/química , Restauración Dental Permanente , Cementos de Ionómero Vítreo/química , Nanotecnología , Polvos , Titanio/química , Biopelículas , Ensayo de Materiales , Microscopía Confocal , Microscopía Electrónica de RastreoRESUMEN
OBJECTIVES: The aim is to investigate the effect of modifying the liquid phase of a conventional glass ionomer restorative material with different chitosan volume contents on the antibacterial properties and adhesion to dentin. METHODS: The liquids of commercially available restorative glass ionomer cements (GIC) were modified with chitosan (CH) solutions at different volume contents (5%, 10%, 25%, and 50%). The GIC powders were mixed with the unmodified and the CH-modified liquids at the desired powder/liquid (P/L) ratio. For the characterization of the antibacterial properties, Streptococcus mutans biofilms were formed on GIC discs and characterized by scanning electron microscope (SEM), confocal microscopy, colony forming unit (CFU) count, and cell viability assay (MTS). The unmodified and CH-modified GICs were bonded to dentin surfaces and the micro-tensile bond strength (µTBs) was evaluated and the interface was investigated by SEM. RESULTS: Modification with CH solutions enhanced the antibacterial properties against S. mutans in terms of resistance to biofilm formation, CFU count, and MTS assay. Generally, significant improvement in the antibacterial properties was found with the increase in the CH volume content. Modification with 25% and 50% CH adversely affected the µTBs with predominant cohesive failure in the GIC. However, no difference was found between the control and the 5% and 10% CH-modified specimens. CONCLUSION: Incorporation of acidic solutions of chitosan in the polyacrylic acid liquid of GIC at v/v ratios of 5-10% improved the antibacterial properties of conventional glass ionomer cement against S. mutans without adversely affecting its bonding to dentin surface.