Rechargeable adhesive with calcium phosphate nanoparticles inhibited long-term dentin demineralization in a biofilm-challenged environment

Hagfish-inspired hydrogel for root caries: A multifunctional approach including immediate protection, antimicrobial phototherapy, and remineralization

Root caries is the main cause of oral pain and tooth loss in the elderly. Protecting root lesions from environmental disturbances, resisting pathogens, and facilitating remineralization over time are essential for addressing root caries, but are challenging due to the irregular root surface and the complex oral environment. Hagfish secretes slime when facing danger, which converts into gels upon contact with seawater, suffocating the predators. Inspired by hagfish's defense mechanism, a fluid-hydrogel conversion strategy is proposed to establish a mechanical self-regulating multifunctional platform for root caries treatment. The fluid system (silk fibroin-tannic acid-black phosphorene-urea, ST-BP-U), in which urea disrupts the hydrogen bonds between silk fibroin and tannic acid, can easily spread on the irregular root surface and permeate into dentinal tubules. Upon contact with the surrounding water, urea diffuses, prompting the hydrogel re-formation and creating intimate attachments with micromechanical inlay locks. Meanwhile, BP increases the crosslinking of the re-formed hydrogel network, resulting in reinforced cohesion for robust wet adhesion to the tooth root. This process establishes a structured platform for effective antimicrobial phototherapy and dentin remineralization promotion. This water-responsive fluid-hydrogel conversion system adapts to the irregular root surface in the dynamic wet environment, holding promise for addressing root caries. STATEMENT OF SIGNIFICANCE: Root caries bring a heavy burden to the aging society, but the irregular root surface and dynamic moist oral environment always hinder non-surgical therapeutic effects. Here, we propose a water-responsive fluid-hydrogel conversion strategy aimed at mechanical self-regulation on the irregular and wet root interface to construct a functional structural platform. The liquid system (ST-BP-U) that prebreak intermolecular hydrogen bonds can easily spread on irregular surfaces and dentin tubules. When encountering water, hydrogen bonds re-form, and BP increases the crosslinking of the hydrogel formed in situ. Based on this firm wet-adhesion platform, it provides powerful phototherapy effects and promotes dentin remineralization. This fluid-hydrogel conversion system turns the disadvantages of wet environment into advantages, offering a promising strategy for root caries.

Efficacy of silver diamine fluoride (SDF) in arresting dentin caries against inter-kingdom biofilms of Streptococcus mutans and Candida albicans

OBJECTIVES

To compare, in vitro, the efficacy of three proprietary silver diamine fluoride (SDF) products in mitigating progression of dentinal caries induced by an inter-kingdom, dual-species, bacterial-yeast biofilm.

METHODS

Human dentin blocks were demineralized to create artificial caries lesions and randomized into three SDF test groups: Saforide, Topamine, T-SDF, and an aqueous control (n = 26 per group). After application of foregoing SDF variants, the blocks were incubated with Streptococcus mutans and Candida albicans for 24 h for biofilm development, and subsequently subjected to a microbe-induced, pH-cycling process for 7 days, to mimic the oral eco-system. The biofilm cell viability and surface topography were assessed by colony-forming units (CFUs) and scanning electron microscopy respectively. The lesion depth and mineral density were evaluated by micro-computer tomography. SDF precipitate and matrix-to-mineral ratio were evaluated by X-ray diffraction and Fourier transform infrared spectroscopy, respectively. Standard, accepted methodology was used for all these evaluations and procedures.

RESULTS

After pH cycling, the SDF groups demonstrated comparable inhibition of the biofilm relative to the control. the log CFU of S. mutans for Saforide, Topamine, T-SDF, and control were 6.69±0.73, 6.48±0.56, 6.63±0.66, and 8.01±0.45, respectively. For C. albicans, the log CFU were 4.86±0.44, 4.72±0.53, 4.92±0.29, and 5.60±0.27, respectively. The log CFU of S. mutans and C. albicans in the SDF groups were significantly lower than the control group (p<0.001). Further, the lesion depth decreased by approximately 14.79±7.00% in the SDF groups, while it increased by 11.07±8.61% in the control (p<0.001), and the mineral density increased by 16.36±4.58% in the SDF group, as opposed to a 5.59±2.64% reduction in the control (p<0.001) implying their caries mitigating effect. These findings were corroborated by SEM images of the lesions.

CONCLUSION

SDF significantly mitigated dentin caries due to an assault by a polymicrobial plaque biofilm whilst arresting mineral loss and lesion growth. There was no difference in the caries-arresting efficacy of the compared SDF variants.

New generation of orthodontic devices and materials with bioactive capacities to improve enamel demineralization

OBJECTIVE

The article reviewed novel orthodontic devices and materials with bioactive capacities in recent years and elaborated on their properties, aiming to provide guidance and reference for future scientific research and clinical applications.

DATA, SOURCES AND STUDY SELECTION

Researches on remineralization, protein repellent, antimicrobial activity and multifunctional novel bioactive orthodontic devices and materials were included. The search of articles was carried out in Web of Science, PubMed, Medline and Scopus.

CONCLUSIONS

The new generation of orthodontic devices and materials with bioactive capacities has broad application prospects. However, most of the current studies are limited to in vitro studies and cannot explore the true effects of various bioactive devices and materials applied in oral environments. More research, especially in vivo researches, is needed to assist in clinical application.

CLINICAL SIGNIFICANCE

Enamel demineralization (ED) is a common complication in orthodontic treatments. Prolonged ED can lead to dental caries, impacting both the aesthetics and health of teeth. It is of great significance to develop antibacterial orthodontic devices and materials that can inhibit bacterial accumulation and prevent ED. However, materials with only preventive effect may fall short of addressing actual needs. Hence, the development of novel bioactive orthodontic materials with remineralizing abilities is imperative. The article reviewed the recent advancements in bioactive orthodontic devices and materials, offering guidance and serving as a reference for future scientific research and clinical applications.

Synergistic effect of ion-releasing fillers on the remineralization and mechanical properties of resin-dentin bonding interfaces

In modern restorative dentistry, adhesive resin materials are vital for achieving minimally invasive, esthetic, and tooth-preserving restorations. However, exposed collagen fibers are found in the hybrid layer of the resin-dentin bonding interface due to incomplete resin penetration. As a result, the hybrid layer is susceptible to attack by internal and external factors such as hydrolysis and enzymatic degradation, and the durability of dentin bonding remains limited. Therefore, efforts have been made to improve the stability of the resin-dentin interface and achieve long-term clinical success. New ion-releasing adhesive resin materials are synthesized by introducing remineralizing ions such as calcium and phosphorus, which continuously release mineral ions into the bonding interface in resin-bonded restorations to achieve dentin biomimetic remineralization and improve bond durability. As an adhesive resin material capable of biomimetic mineralization, maintaining excellent bond strength and restoring the mechanical properties of demineralized dentin is the key to its function. This paper reviews whether ion-releasing dental adhesive materials can maintain the mechanical properties of the resin-dentin bonding interface by supplementing the various active ingredients required for dentin remineralization from three aspects: phosphate, silicate, and bioactive glass.

Developing Bioactive Dental Resins for Restorative Dentistry

Despite its reputation as the most widely used restorative dental material currently, resin-based materials have acknowledged shortcomings. As most systematic survival studies of resin composites and dental adhesives indicate, secondary caries is the foremost reason for resin-based restoration failure and life span reduction. In subjects with high caries risk, the microbial community dominated by acidogenic and acid-tolerant bacteria triggers acid-induced deterioration of the bonding interface and/or bulk material and mineral loss around the restorations. In addition, resin-based materials undergo biodegradation in the oral cavity. As a result, the past decades have seen exponential growth in developing restorative dental materials for antimicrobial applications addressing secondary caries prevention and progression. Currently, the main challenge of bioactive resin development is the identification of efficient and safe anticaries agents that are detrimental free to final material properties and show satisfactory long-term performance and favorable clinical translation. This review centers on the continuous efforts to formulate novel bioactive resins employing 1 or multiple agents to enhance the antibiofilm efficacy or achieve multiple functionalities, such as remineralization and antimicrobial activity antidegradation. We present a comprehensive synthesis of the constraints and challenges encountered in the formulation process, the clinical performance-related prerequisites, the materials' intended applicability, and the current advancements in clinical implementation. Moreover, we identify crucial vulnerabilities that arise during the development of dental materials, including particle aggregation, alterations in color, susceptibility to hydrolysis, and loss of physicomechanical core properties of the targeted materials.

Metronidazole and Ketoprofen-Loaded Mesoporous Magnesium Carbonate for Rapid Treatment of Acute Periodontitis In Vitro

In the clinical pharmacological treatment of acute periodontitis, local periodontal administration is expected to be preferable to systemic administration. However, the action of the active medicine component is hindered and diminished by the limitation of drug solubility, which does not provide timely relief of the enormous pain being suffered by patients. This study aimed to develop a mesoporous magnesium carbonate (MMC) medicine loading system consisting of MMC, metronidazole (MET), and ketoprofen (KET), which was noted as MET-KET@MMC. A solvent evaporation process was utilized to load MET and KET in MMC. Scanning electron microscopy, nitrogen sorption, thermogravimetric analysis, and X-ray diffraction were performed on the MET-KET@MMC. The rapid drug release properties were also investigated through the drug release curve. The rapid antiseptic property against Porphyromonas gingivalis (P. gingivalis) and the rapid anti-inflammatory property (within 1 min) were analyzed in vitro. The cytotoxicity of MET-KET@MMC was tested in direct contact with human gingival cells and human oral keratinocytes. Crystallizations of MET and KET were completely suppressed in MMC. As compared to crystalline MET and KET, MMC induced higher apparent solubility and rapid drug release, resulting in 8.76 times and 3.43 times higher release percentages of the drugs, respectively. Over 70.11% of MET and 85.97% of KET were released from MMC within 1 min, resisting bacteria and reducing inflammation. MET-KET@MMC nanoparticles enhanced the solubility of drugs and possess rapid antimicrobial and anti-inflammatory properties. The MET-KET@MMC is a promising candidate for the pharmacotherapy of acute periodontitis with drugs, highlighting a significant clinical potential of MMC-based immediate drug release systems.