Dental bonding technology and materials have been used widely in dentistry because of their excellent properties. The development of novel bonding technology and materials is constantly being performed to improve the effect of dental bonding restorations. Observation and analysis of the dental bonding interface is one of the most important methods for laboratory evaluation of bonding efficiency. This paper aims to review the methods of observation and analysis of dental bonding interfaces to provide a reference for the selection of evaluation methods in dental bonding research. The features of 6 methods, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM), Raman spectroscopy (RS), optical coherence tomography (OCT) and atomic force microscopy (AFM), were described and summarized. Among these methods, SEM and TEM are used most often in the analysis of fine structures; CLSM and OCT are used for the acquisition of characteristic image signals, such as microleakage and exogenous and endogenous fluorescence; and RS and AFM can test chemical composition and mechanical properties.

Microbial infections affect people worldwide. Quaternary ammonium salts serve antibacterial, antifungal, antiviral, anti-matrix metalloproteinase and polymerization functions. While the modification of biomaterials with quaternary ammonium salts cannot affect the physical or chemical properties of the biomaterials, this process can confer them with stable biological activity. Currently, quaternary ammonium salts are widely used in the development of functional orthopedic materials, sutures, dressings and dental materials, and the idea of modifying biomedical materials with quaternary ammonium salts has become the most promising, e.g., for preparing antimicrobial biomaterials. Recent studies have found that quaternary ammonium salt-modified antimicrobial monomers are cytotoxic. Therefore, it is of great significance to explore the cytotoxic mechanism of quaternary ammonium salt-modified antimicrobial monomers and determine possible cytoprotective measures for improving the biological safety of these antimicrobial resin-based materials and expanding their clinical applications. In addition, further validation of the clinical efficacy of these biomaterials is particularly important for accurately evaluating the clinical prospects of these biomaterials. Based on a literature review, this paper summarizes the applications and toxicity of biomedical materials modified with quaternary ammonium salts.

Stable and bioactive material–tissue interface (MTF) basically determines the clinical applications of biomaterials in wound healing, sustained drug release, and tissue engineering. Although many inorganic nanomaterials have been widely explored to enhance the stability and bioactivity of polymer-based biomaterials, most are still restricted by their stability and biocompatibility. Here we demonstrate the enhanced bioactivity and stability of polymer-matrix bio-composite through coupling multiscale material–tissue interfacial interactions with atomically thin TiO₂ nanosheets. Resin modified with TiO₂ nanosheets displays improved mechanical properties, hydrophilicity, and stability. Also, we confirm that this resin can effectively stimulate the adhesion, proliferation, and differentiation into osteogenic and odontogenic lineages of human dental pulp stem cells using in vitro cell–resin interface model. TiO₂ nanosheets can also enhance the interaction between demineralized dentinal collagen and resin. Our results suggest an approach to effectively up-regulate the stability and bioactivity of MTFs by designing biocompatible materials at the sub-nanoscale.