Use of cellulose nanofibers as a denture immersing solution

Potential of pure cellulose nanofibers as a denture base material

A study was conducted to evaluate the basic mechanical properties of a pure cellulose nanofiber (CNF) material in comparison with a commercial denture base material (polymethylmethacrylate [PMMA] acrylic resin). The working hypothesis was that CNFs have potential for use as denture base materials. Pure CNF specimens fabricated under various conditions were examined. The flexural strength (FS) and flexural modulus (FM) of the specimens were measured using the three-point bending test, and the morphologies of the fractured surfaces were examined using scanning electron microscopy. Addition of tricalcium phosphate to dehydrate the CNFs did not improve their FS or FM. Conversely, substitution with methanol effectively improved the dehydration process and significantly affected the mechanical properties of the CNFs. As the degree of CNF defibration increased, the physical properties of the specimens improved significantly. However, addition of CNFs to PMMA liquid to create CNF-reinforced PMMA did not improve the mechanical properties. Pure CNF specimens fabricated under particular conditions had higher FS and FM values than the control, suggesting that CNFs have potential as a "petroleum-free" alternative to acrylic resin denture base materials. Pure CNF would be potentially useful as a denture base material, and presumably applicable to computer-aided design/manufacture (CAD/CAM).

Influence of several biodegradable components added to pure and nanosilver-doped PMMA bone cements on its biological and mechanical properties

Acrylic bone cements (BC) are wildly used in medicine. Despite favorable mechanical properties, processability and inject capability, BC lack bioactivity. To overcome this, we investigated the effects of selected biodegradable additives to create a partially-degradable BC and also we evaluated its combination with nanosilver (AgNp). We hypothesized that using above strategies it would be possible to obtain bioactive BC. The Cemex was used as the base material, modified at 2.5, 5 or 10 wt% with either cellulose, chitosan, magnesium, polydioxanone or tricalcium-phosphate. The resulted modified BC was examined for surface morphology, wettability, porosity, mechanical and nanomechanical properties and cytocompatibility. The composite BC doped with AgNp was also examined for its release and antibacterial properties. The results showed that it is possible to create modified cement and all studied modifiers increased its porosity. Applying the additives slightly decreased BC wettability and mechanical properties, but the positive effect of the additives was observed in nanomechanical research. The relatively poor cytocompatibility of modified BC was attributed to the unreacted monomer release, except for polydioxanone modification which increased cells viability. Furthermore, all additives facilitated AgNp release and increased BC antibacterial effectiveness. Our present studies suggest the optimal content of biodegradable component for BC is 5 wt%. At this content, an improvement in BC porosity is achieved without significant deterioration of BC physical and mechanical properties. Polydioxanone and cellulose seem to be the most promising additives that improve porosity and antibacterial properties of antibiotic or nanosilver-loaded BC. Partially-degradable BC may be a good strategy to improve their antibacterial effectiveness, but some caution is still required regarding their cytocompatibility. STATEMENT OF SIGNIFICANCE: The lack of bone cement bioactivity is the main limitation of its effectiveness in medicine. To overcome this, we have created composite cements with partially-degradable properties. We also modified these cements with nanosilver to provide antibacterial properties. We examined five various additives at three different contents to modify a selected bone cement. Our results broaden the knowledge about potential modifiers and properties of composite cements. We selected the optimal content and the most promising additives, and showed that the combination of these additives with nanosilver would increase cements` antibacterial effectiveness. Such modified cements may be a new solution for medical applications.