Dentine tubule occlusion effect of hydrolyzed casein in a bioactive glass-based dental desensitizing gel.

OBJECTIVES: The effectiveness of three different groups of polyethylene glycol (PEG)-based gels containing powders on dentin hypersensitivity (DH) treatment were assessed and compared with Actimins® as commercial reference group. METHODS: Hydroxyapatite nanorods (nHA) and sol-gel-derived 45S5 bioglass (SGD 45S5) powders were synthesized through hydrothermal and sol-gel methods, respectively. First, 25 demineralized dentin disks were divided into five groups. Then, the prepared gels based on 45S5 bioglass with and without hydrolyzed casein (HC) as experimental, nHA gel and Actimins® as positive and commercial reference groups were applied twice a day on disks by a micro applicator. To mimic the oral environment, treated disks were immersed in artificial saliva in a water bath at 37 °C for 7 days. However, in the negative control group, no agent was applied on the samples. FE-SEM, EDS, AFM, and XRD were performed to assess tubule occlusion. One-way ANOVA test was used for statistical analysis and p*<0.05 was set as the significance level. RESULTS: The nHA with an average aspect ratio of 2.77 and the SGD 45S5 powders with a polygonal morphology and the average size of 48.64±11.38 µm were synthesized. After treatment, tubule occlusion in HC-SGD 45S5 and nHA gels were shown to be higher than other groups. The root mean square roughness (Rrms) of the above-mentioned gels showed to be 121.54±9.25 nm, and 312.6 ± 9 nm, respectively. CONCLUSION: The nHA containing group exhibited the highest tubule occlusion efficiency (i.e., tubule diameter of 0.92±0.32 µm) with a superior mineral precipitation. HC as a novel material demonstrates to be potentially beneficial in DH treatment. CLINICAL SIGNIFICANCE: DH as a common issue may be reduced or eliminated by occlusion of patent dentinal tubules. There are various types of desensitizing agents capable of controlling the DH by the occlusion of patent dentinal tubules. The desensitizing gels developed in this study showed to be promising for clinical and home-use applications.

Characterization and antibacterial performance of electrodeposited chitosan-vancomycin composite coatings for prevention of implant-associated infections.

Orthopaedic implant-associated infections are one of the most serious complications in orthopaedic surgery and a major cause of implant failure. In the present work, drug-eluting coatings based on chitosan containing various amounts of vancomycin were prepared by a cathodic electrophoretic deposition process on titanium foils. A three-step release mechanism of the antibiotic from the films in a phosphate-buffered saline solution was noticed. At the early stage, physical encapsulation of the drug in the hydrogel network controlled the release rate. At the late stage, however, in vitro degradation/deattachment of chitosan was responsible for the controlled release. Cytotoxicity evaluation of the drug-eluting coatings via culturing in human osteosarcoma cells (MG-63 osteoblast-like cell line) showed no adverse effect on the biocompatibility. Antibacterial tests against Gram-positive Staphylococcus aureus also demonstrated that the infection risk of titanium foils was significantly reduced due to the antibiotic release. Additionally, in vitro electrochemical corrosion studies by polarization technique revealed that the corrosion current density was significantly lower for the titanium foils with drug-eluting coatings compared to that of uncoated titanium.

Recent progress in inorganic and composite coatings with bactericidal capability for orthopaedic applications.

This review covers the most recent developments of inorganic and organic-inorganic composite coatings for orthopedic implants, providing the interface with living tissue and with potential for drug delivery to combat infections. Conventional systemic delivery of drugs is an inefficient procedure that may cause toxicity and may require a patient's hospitalization for monitoring. Local delivery of antibiotics and other bioactive molecules maximizes their effect where they are required, reduces potential systemic toxicity and increases timeliness and cost efficiency. In addition, local delivery has broad applications in combating infection-related diseases. Polymeric coatings may present some disadvantages. These disadvantages include limited chemical stability, local inflammatory reactions, uncontrolled drug-release kinetics, late thrombosis and restenosis. As a result, embedding of bioactive compounds and biomolecules within inorganic coatings (bioceramics, bioactive glasses) is attracting significant attention. Recently nanoceramics have attracted interest because surface nanostructuring allows for improved cellular adhesion, enhances osteoblast proliferation and differentiation, and increases biomineralization. Organic-inorganic composite coatings, which combine biopolymers and bioactive ceramics that mimick bone structure to induce biomineralization, with the addition of biomolecules, represent alternative systems and ideal materials for "smart" implants. In this review, emphasis is placed on materials and processing techniques developed to advance the therapeutic use of biomolecules-eluting coatings, based on nanostructured ceramics. One part of this report is dedicated to inorganic and composite coatings with antibacterial functionality. FROM THE CLINICAL EDITOR: Inorganic and composite nanotechnology-based coating methods have recently been developed for orthopedic applications, with the main goal to provide bactericide and other enhanced properties, which may result in reduced need for pharmaceutical interventions and overall more cost effective orthopedic procedures. This review discusses key aspects of the above developments.