Recent Update on Applications of Quaternary Ammonium Silane as an Antibacterial Biomaterial: A Novel Drug Delivery Approach in Dentistry

Multifunctional Dental Adhesives Formulated with Silane-Coated Magnetic Fe3O4@m-SiO2 Core-Shell Particles to Counteract Adhesive Interfacial Breakdown

The process of bonding to dentin is complex and dynamic, greatly impacting the longevity of dental restorations. The tooth/dental material interface is degraded by bacterial acids, matrix metalloproteinases (MMPs), and hydrolysis. As a result, bonded dental restorations face reduced longevity due to adhesive interfacial breakdown, leading to leakage, tooth pain, recurrent caries, and costly restoration replacements. To address this issue, we synthesized and characterized a multifunctional magnetic platform, CHX@SiQuac@Fe3O4@m-SiO2, to provide several beneficial functions. The platform comprises Fe3O4 microparticles and chlorhexidine (CHX) encapsulated within mesoporous silica, which was silanized by an antibacterial quaternary ammonium silane (SiQuac). This platform simultaneously targets bacterial inhibition, stability of the hybrid layer, and enhanced filler infiltration by magnetic motion. Comprehensive experiments include X-ray diffraction, FT-IR, VSM, EDS, N2 adsorption-desorption (BET), transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, and UV-vis spectroscopy. Then, CHX@SiQuac@Fe3O4@m-SiO2 was incorporated into an experimental adhesive resin for dental bonding restorations, followed by immediate and long-term antibacterial assessment, cytotoxicity evaluation, and mechanical and bonding performance. The results confirmed the multifunctional nature of CHX@SiQuac@Fe3O4@m-SiO2. This work outlined a roadmap for (1) designing and tuning an adhesive formulation containing the new platform CHX@SiQuac@Fe3O4@m-SiO2; (2) assessing microtensile bond strength to dentin using a clinically relevant model of simulated hydrostatic pulpal pressure; and (3) investigating the antibacterial outcome performance of the particles when embedded into the formulated adhesives over time. The results showed that at 4 wt % of CHX@SiQuac@Fe3O4@m-SiO2-doped adhesive under the guided magnetic field, the bond strength increased by 28%. CHX@SiQuac@Fe3O4@m-SiO2 enhanced dentin adhesion in the magnetic guide bonding process without altering adhesive properties or causing cytotoxicity. This finding presents a promising method for strengthening the tooth/dental material interface's stability and extending the bonded restorations' lifespan.

Current appraises of therapeutic applications of nanocurcumin: A novel drug delivery approach for biomaterials in dentistry

Curcumin is a natural herb and polyphenol that is obtained from the medicinal plant Curcuma longa. It's anti-bacterial, anti-inflammatory, anti-cancer, anti-mutagenic, antioxidant and antifungal properties can be leveraged to treat a myriad of oral and systemic diseases. However, natural curcumin has weak solubility, limited bioavailability and undergoes rapid degradation, which severely limits its therapeutic potential. To overcome these drawbacks, nanocurcumin (nCur) formulations have been developed for improved biomaterial delivery and enhanced treatment outcomes. This novel biomaterial holds tremendous promise for the treatment of various oral diseases, the majority of which are caused by dental biofilm. These include dental caries, periodontal disease, root canal infection and peri-implant diseases, as well as other non-biofilm mediated oral diseases such as oral cancer and oral lichen planus. A number of in-vitro studies have demonstrated the antibacterial efficacy of nCur in various formulations against common oral pathogens such as S. mutans, P. gingivalis and E. faecalis, which are strongly associated with dental caries, periodontitis and root canal infection, respectively. In addition, some clinical studies were suggestive of the notion that nCur can indeed enhance the clinical outcomes of oral diseases such as periodontitis and oral lichen planus, but the level of evidence was very low due to the small number of studies and the methodological limitations of the available studies. The versatility of nCur to treat a diverse range of oral diseases augurs well for its future in dentistry, as reflected by rapid pace in which studies pertaining to this topic are published in the scientific literature. In order to keep abreast of the latest development of nCur in dentistry, this narrative review was undertaken. The aim of this narrative review is to provide a contemporaneous update of the chemistry, properties, mechanism of action, and scientific evidence behind the usage of nCur in dentistry.

Effect of a novel quaternary ammonium silane based cavity cleanser FiteBac 2% K21 QAS in comparison with other cavity disinfectants on the bond strength of resin-modified glass ionomer cement

Background

The application of cavity cleansers for cavity disinfection can be a crucial step in the longevity of restorations. The objective of the present study was to compare the effect of the application of a new quaternary ammonium silane (QAS)-based cavity cleanser (2% K21 QAS), with other commercially available cavity disinfectants on the bond strength of resin-modified glass ionomer cement (RMGIC).

Materials and Methods

The buccal surfaces of 40 extracted premolars were trimmed to obtain a flat dentinal surface and were randomly divided into four experimental groups depending on the cavity cleansers used before restoration. Group 1: 2% chlorhexidine (CHX), Group 2: QAS (FiteBac 2% K21 QAS), Group 3: silver diamine fluoride-potassium iodide (Riva Star, SDF-KI), and Group 4: 3% hydrogen peroxide (H2O2). Then, a predetermined dimension of RMGIC restoration was bonded to the treated dentin surfaces. Following this, each sample was tested for shear bond strength (SBS) using a universal testing machine at a crosshead speed of 0.5 mm/min.

Results

Among the experimental groups, SDF-KI has shown the highest mean SBS, followed by 2% K21 QAS, and 2% CHX, which have shown almost comparable results. The 3% H2O2 group has shown the lowest values.

Conclusion

According to the results of the present study, 2% K21 QAS has the potential to be used as an effective cavity cleanser before the placement of RMGIC restorations. Since its application does not affect the bond strength of restoration, it can be successfully used as an alternative to CHX and SDF-KI.

Cauterization of Narrow Root Canals Untouched by Instruments by High-Frequency Current

The mechanical removal of bacteria is fundamental to the treatment of infected root canals, but complete sterilization of biofilms tends not to extend to uninstrumented areas. However, during electrical conduction to a root canal filled with a conductor, the higher impedance where the root canal is narrower generates Joule heat that may result in a large temperature increase and sterilization. The effect of a high-frequency electric current on the wall of a simulated narrow root canal was investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). Simulated root canals, 0.1 mm in diameter, were prepared in dentine blocks. The root canal wall was treated with Plank-Rychlo solution for 5 min to create a decalcified layer. The simulated root canal was filled with either saline or NaClO, and 150 or 225 V at 520 kHz was applied for 0 s, 1 s, or 5 s. As the conduction time increased, and when the saline was replaced with NaClO, the proportion with a flat decalcified surface decreased, dentinal tubules and a lava-like morphology were significantly more evident on SEM (p < 0.01), and EDS showed significant decreases in carbon and oxygen and increases in calcium (p < 0.01). It was concluded that filling uninstrumented root canals with NaClO and using electrical conduction for 5 s could incinerate and eliminate the organic material of the root canal wall. The application of high-frequency electric current may lead to the cure of many cases of persistent apical periodontitis.

Hybrid Bio-Based Silicone Coatings with Anti-adhesive Properties

Hybrid polysiloxanes and polysilsesquioxanes grafted with naturally occurring bioactive phytochemicals: eugenol and linalool, were synthesized and investigated with regard to their structure and properties. The two series of materials, differing in the type of inorganic structure and the content of active groups, were coated onto the surface of glass plates, and their antibiofilm activities against bacteria Aeromonas hydrophila were assessed by luminometry and fluorescence microscopy. Bioactivity was correlated with specific properties of the hybrid coatings (chemical structure, surface free energy and adhesiveness). The functionalized polysilsesquioxanes exhibited the most favorable anti-adhesive effects. Cell adhesion after 6 days of incubation, expressed as RLU/cm², was significantly reduced (44 and 67 for, respectively, Z-E-100 and Z-L-100, compared to 517 for the control glass carrier). The surface stickiness of polysiloxane films deteriorated their anti-adhesion properties, despite the presence of a large amount of bioactive species.