New and Efficient Bioactive Glass Compositions for Controlling Endodontic Pathogens

Novel bioactive nanospheres show effective antibacterial effect against multiple endodontic pathogens

Aim

The current study evaluated the antibacterial activity of a newly developed quaternary ammonium polymethacrylate (QAPM)-containing bioactive glasses (BGs) via a two-step method by our group, namely BGs-HAEMB, and explored its cytotoxicity and biocompatibility.

Methods

The antibacterial effects of the BGs-HAEMB against planktonic bacteria, bacterial biofilm formation, and experimental root canal biofilms of persistent pathogens (Enterococcus faecalis, Streptococcus sanguis and Porphyromonas endodontalis) associated with endodontic infection were evaluated in vitro by agar diffusion tests, direct contact tests and live/dead staining. The cytotoxicity and biocompatibility of BGs-HAEMB were evaluated by CCK-8 assays in vitro and a skin implantation model in vivo.

Results

Compared to three clinically used endodontic sealers (Endofill, AH Plus, and iRoot SP), BGs-HAEMB exhibited the relatively strongest antibacterial effect against E. faecalis, S. sanguis and P. endodontalis after sitting for 14 and 28 days (P < 0.01). SEM images and CLSM images also showed that for each tested bacteria, BGs-HAEMB killed the most microorganism among all the experimental groups, regardless of treatment for 7 days or 28 days (P < 0.05). Besides, the BGs-HAEMB-treated groups showed a relatively low cytotoxicity (RGRs ranging from 88.6% to 102.9%) after 1, 3, and 7 days of exposure. Meanwhile, after 28 days of implantation, the inflammatory grade in BGs-HAEMB treated group was assessed as Grade I, in which the average numbers of inflammatory cells (6.7 ± 2.1) were less than 25.

Conclusions

BGs-HAEMB exerted a long-term and stable antibacterial effect. The remarkable biocompatibility of BGs-HAEMB in vitro and in vivo confirmed its possible clinical application as a potential alternative in the development of the next generation of endodontic sealers.

Nanoparticles and Their Antibacterial Application in Endodontics

Root canal treatment represents a significant challenge as current cleaning and disinfection methodologies fail to remove persistent bacterial biofilms within the intricate anatomical structures. Recently, the field of nanotechnology has emerged as a promising frontier with numerous biomedical applications. Among the most notable contributions of nanotechnology are nanoparticles, which possess antimicrobial, antifungal, and antiviral properties. Nanoparticles cause the destructuring of bacterial walls, increasing the permeability of the cell membrane, stimulating the generation of reactive oxygen species, and interrupting the replication of deoxyribonucleic acid through the controlled release of ions. Thus, they could revolutionize endodontics, obtaining superior results and guaranteeing a promising short- and long-term prognosis. Therefore, chitosan, silver, graphene, poly(lactic) co-glycolic acid, bioactive glass, mesoporous calcium silicate, hydroxyapatite, zirconia, glucose oxidase magnetic, copper, and zinc oxide nanoparticles in endodontic therapy have been investigated in the present review. The diversified antimicrobial mechanisms of action, the numerous applications, and the high degree of clinical safety could encourage the scientific community to adopt nanoparticles as potential drugs for the treatment of endodontic diseases, overcoming the limitations related to antibiotic resistance and eradication of the biofilm.

Sol-Gel Technologies to Obtain Advanced Bioceramics for Dental Therapeutics

The aim of this work is to review the application of bioceramic materials in the context of current regenerative dentistry therapies, focusing on the latest advances in the synthesis of advanced materials using the sol-gel methodology. Chemical synthesis, processing and therapeutic possibilities are discussed in a structured way, according to the three main types of ceramic materials used in regenerative dentistry: bioactive glasses and glass ceramics, calcium phosphates and calcium silicates. The morphology and chemical composition of these bioceramics play a crucial role in their biological properties and effectiveness in dental therapeutics. The goal is to understand their chemical, surface, mechanical and biological properties better and develop strategies to control their pore structure, shape, size and compositions. Over the past decades, bioceramic materials have provided excellent results in a wide variety of clinical applications related to hard tissue repair and regeneration. Characteristics, such as their similarity to the chemical composition of the mineral phase of bones and teeth, as well as the possibilities offered by the advances in nanotechnology, are driving the development of new biomimetic materials that are required in regenerative dentistry. The sol-gel technique is a method for producing synthetic bioceramics with high purity and homogeneity at the molecular scale and to control the surfaces, interfaces and porosity at the nanometric scale. The intrinsic nanoporosity of materials produced by the sol-gel technique correlates with the high specific surface area, reactivity and bioactivity of advanced bioceramics.