Applications of Bioactive Strontium Compounds in Dentistry.

Divalent cations have captured the interest of researchers in biomedical and dental fields due to their beneficial effects on bone formation. These metallic elements are similar to trace elements found in human bone. Strontium is a divalent cation commonly found in various biomaterials. Since strontium has a radius similar to calcium, it has been used to replace calcium in many calcium-containing biomaterials. Strontium has the ability to inhibit bone resorption and increase bone deposition, making it useful in the treatment of osteoporosis. Strontium has also been used as a radiopacifier in dentistry and has been incorporated into a variety of dental materials to improve their radiopacity. Furthermore, strontium has been shown to improve the antimicrobial and mechanical properties of dental materials, promote enamel remineralization, alleviate dentin hypersensitivity, and enhance dentin regeneration. The objective of this review is to provide a comprehensive review of the applications of strontium in dentistry.

Enhancing the Physical, Antimicrobial, and Osteo/Odontogenic Properties of a Sol-Gel-Derived Tricalcium Silicate by Graphene Oxide for Vital Pulp Therapies.

OBJECTIVES: This study developed a sol-gel tricalcium silicate/graphene oxide (TCS-GO) composite and examined its physicochemical properties, antimicrobial activity, and osteo/odontogenic effect on dental pulp stem cells. METHODS: Tricalcium silicate was synthesized and combined with graphene oxide at three different concentrations, namely 0.02%, 0.04%, and 0.08% w/w, while tricalcium silicate and mineral trioxide aggregate served as controls. The setting time, compressive strength, pH, and calcium ion release of the composites were evaluated, as well as antimicrobial properties against Streptococcus mutans and Lactobacillus acidophilus. Additionally, the viability of dental pulp stem cells; apatite forming ability; and the gene expression of Alkaline phosphatase, Dentin sialophosphoprotein, and Runt-related transcription factor 2 were assessed. RESULTS: TCS-GO (0.08%) showed a significantly shorter setting time and higher compressive strength when compared to MTA (p < 0.05). Additionally, tricalcium silicate and TCS-GO groups showed a higher release of Ca ions than MTA, with no significant difference in pH values among the different groups. TCS-GO (0.08%) also demonstrated a significantly stronger antimicrobial effect against Lactobacillus acidophilus compared to MTA (p < 0.05). ALP expression was higher in TCS-GO (0.08%) than MTA on days 3 and 7, while DSPP expression was higher in TCS-GO (0.08%) than MTA on day 3 but reversed on day 7. There was no significant difference in RUNX2 expression between TCS-GO (0.08%) and MTA on days 3 and 7. CONCLUSIONS: The TCS-GO (0.08%) composite demonstrated superior physicochemical characteristics and antimicrobial properties compared to MTA. Moreover, the early upregulation of ALP and DSPP markers in TCS-GO (0.08%) indicates that it has the potential to promote and enhance the osteo/odontogenic differentiation of DPSCs.

Trans-Cinnamaldehyde Eluting Porous Silicon Microparticles Mitigate Cariogenic Biofilms.

Dental caries, a preventable disease, is caused by highly-adherent, acid-producing biofilms composed of bacteria and yeasts. Current caries-preventive approaches are ineffective in controlling biofilm development. Recent studies demonstrate definite advantages in using natural compounds such as trans-cinnamaldehyde in thwarting biofilm assembly, and yet, the remarkable difficulty in delivering such hydrophobic bioactive molecules prevents further development. To address this critical challenge, we have developed an innovative platform composed of components with a proven track record of safety. We fabricated and thoroughly characterised porous silicon (pSi) microparticles to carry and deliver the natural phenyl propanoid trans-cinnamaldehyde (TC). We investigated its effects on preventing the development of cross-kingdom biofilms (Streptococcus mutans and Candida albicans), typical of dental caries found in children. The prepared pSi microparticles were roughly cubic in structure with 70-75% porosity, to which the TC (pSi-TC) was loaded with about 45% efficiency. The pSi-TC particles exhibited a controlled release of the cargo over a 14-day period. Notably, pSi-TC significantly inhibited biofilms, specifically downregulating the glucan synthesis pathways, leading to reduced adhesion to the substrate. Acid production, a vital virulent trait for caries development, was also hindered by pSi-TC. This pioneering study highlights the potential to develop the novel pSi-TC as a dental caries-preventive material.

Biofilm inhibition in oral pathogens by nanodiamonds.

Complex microbial communities, e.g., biofilms residing in our oral cavity, have recognized clinical significance, as they are typically the main cause for infections. Particularly, they show high resistance to conventional antibiotics, and alternatives including nanotechnology are being intensively explored nowadays to provide more efficient therapeutics. Diamond nanoparticles, namely, nanodiamonds (NDs) with many promising physico-chemical properties, have been demonstrated to work as an effective antibacterial agent against planktonic cells (free-floating state). However, little is known about the behaviors of NDs against biofilms (sessile state). In this study, we uncovered their role in inhibiting biofilm formation and their disrupting effect on preformed biofilms in several selected orally and systemically important organisms. The current findings will advance the mechanistic understanding of NDs on oral pathogens and might accelerate corresponding clinical translation.

A curcumin-sophorolipid nanocomplex inhibits Candida albicans filamentation and biofilm development.

Candida albicans is an opportunistic fungal pathogen that is highly resistant to contemporary antifungals, due to their biofilm lifestyle. The ability of C. albicans to invade human tissues is due to its filamentation. Therefore, inhibition of biofilms and filamentation of the yeast are high value targets to develop the next-generation antifungals. Curcumin (CU) is a natural polyphenol with excellent pharmacological attributes, but limitations such as poor solubility, acid, and enzyme tolerance have impeded its practical utility. Sophorolipids (SL) are biologically-derived surfactants that serve as efficient carriers of hydrophobic molecules such as curcumin into biofilms. Here, we synthesised a curcumin-sophorolipid nanocomplex (CUSL), and comprehensively evaluated its effects on C. albicans biofilms and filamentation. Our results demonstrated that sub-inhibitory concentration of CUSL (9.37 µg/mL) significantly inhibited fungal adhesion to substrates, and subsequent biofilm development, maturation, and filamentation. This effect was associated with significant downregulation of a select group of biofilm, adhesins, and hyphal regulatory genes. In conclusion, the curcumin-sophorolipid nanocomplex is a potent inhibitor of the two major virulence attributes of C. albicans, biofilm formation and filamentation, thus highlighting its promise as a putative anti-fungal agent with biofilm penetrative potential.