Er:YAG Laser Physical Etching and Ultra-High-Molecular-Weight Cross-Linked Sodium Polyacrylate Chemical Etching for a Reliable Dentin Dry Bonding.

Dentin bond interface stability is the key issue of dental adhesion in present clinical dentistry. The concept of selective extrafibrillar demineralization has opened a new way to maintain intrafibrillar minerals to prevent interface degradation. Here, using ultra-high-molecular-weight sodium polyacrylate [Carbopol (Carbo) > 40 kDa] as a calcium chelator, we challenge this concept and propose a protocol for reliable dentin dry bonding. The results of high-resolution transmission electron microscopy revealed periodic bands of 67 nm dentin collagen fibrils after Carbo etching, and the hydroxyproline concentration increasing with prolonged chelating time denied the concept of extrafibrillar demineralization. The results that wet and dry bonding with Carbo-based demineralization produced a weaker bond strength than the traditional phosphoric acid wet adhesion suggested that the Carbo-based demineralization is an unreliable adhesion strategy. A novel protocol of Er:YAG laser physical etching followed by Carbo chemical etching for dentin adhesion revealed that a micro-/nano-level rough, rigid, and non-collagen exposed dentin surface was produced, the micro-tensile bond strength was maintained after aging under dry and wet bonding modes, and in situ zymography and nanoleakage within the hybrid layers presented lower signals after aging. Cell culture in vitro and a rabbit deep dentin adhesion model in vivo proved that this protocol is safe and biocompatible. Taken together, the concept of extrafibrillar demineralization is limited and insufficient to use in the clinic. The strategy of Er:YAG laser physical etching followed by Carbo chemical etching for dentin adhesion produces a bonding effect with reliability, durability, and safety.

Oxidized Dopamine Acrylamide Primer to Achieve Durable Resin-Dentin Bonding.

The durability of the resin-dentin bonding interface is a key issue in clinical esthetic dentistry. Inspired by the extraordinary bioadhesive properties of marine mussels in a wet environment, we designed and synthetized N-2-(3,4-dihydroxylphenyl) acrylamide (DAA) according to the functional domain of mussel adhesive proteins. DAA's properties of collagen cross-linking, collagenase inhibition, inducing collagen mineralization in vitro, and as a novel prime monomer for clinical dentin adhesion use, its optimal parameters, and effect on the adhesive longevity and the bonding interface's integrity and mineralization, were evaluated in vitro and in vivo. The results showed that oxide DAA can inhibit the activity of collagenase and cross collagen fibers to improve the anti-enzymatic hydrolysis of collagen fibers and induce intrafibrillar and interfibrillar collagen mineralization. As a primer used in the etch-rinse tooth adhesive system, oxide DAA can improve the durability and integrity of the bonding interface by anti-degradation and mineralization of the exposed collagen matrix. Oxidized DAA (OX-DAA) is a promising primer for improving dentin durability; using 5% OX-DAA ethanol solution and treating the etched dentin surface for 30 s is the optimal choice when used as a primer in the etch-rinse tooth adhesive system.

Fabrication of Multilayered Biofunctional Material with an Enamel-like Structure.

The oral cavity is an environment with diverse bacteria; thus, antibacterial materials are crucial for treating and preventing dental diseases. There is a high demand for materials with an enamel-like architecture because of the high failure rate of dental restorations, due to the physical differences between dental materials and enamel. However, recreating the distinctive apatite composition and hierarchical architecture of enamel is challenging. The aim of this study was to synthesize a novel material with an enamel-like structure and antibacterial ability. We established a non-cell biomimetic method of evaporation-based bottom-up self-assembly combined with a layer-by-layer technique and introduced an antibacterial agent (graphene oxide) to fabricate a biofunctional material with an enamel-like architecture and antibacterial ability. Specifically, enamel-like graphene oxide-hydroxyapatite crystals, formed on a customized mineralization template, were assembled into an enamel-like prismatic structure with a highly organized orientation preferentially along the c-axis through evaporation-based bottom-up self-assembly. With the aid of layer-by-layer absorption, we then fabricated a bulk macroscopic multilayered biofunctional material with a hierarchical enamel-like architecture. This enamel-inspired biomaterial could effectively resolve the problem in dental restoration and brings new prospects for the synthesis of other enamel-inspired biomaterials.

Efficacy of the dual-action GA-KR12 peptide for remineralising initial enamel caries: an in vitro study.

OBJECTIVE: To investigate the antibiofilm and remineralising effects of the dual-action peptide GA-KR12 on artificial enamel caries. MATERIALS AND METHODS: Enamel blocks with artificial caries were treated with sterilised deionised water as control or GA-KR12. The blocks underwent biochemical cycling with Streptococcus mutans for 3 weeks. The architecture, viability, and growth kinetics of the biofilm were determined, respectively, by scanning electron microscopy (SEM), confocal laser scanning microscopy, and quantitative (culture colony-forming units, CFUs). The mineral loss, calcium-to-phosphorus ratio, surface morphology, and crystal characteristics of the enamel surface were determined, respectively, using micro-computed tomography, energy dispersive spectroscopy, SEM, and X-ray diffraction (XRD). RESULTS: SEM showed confluent growth of S. mutans in the control group but not in the GA-KR12-treated group. The dead-to-live ratios of the control and GA-KR12-treated groups were 0.42 ± 0.05 and 0.81 ± 0.08, respectively (p < 0.001). The log CFUs of the control and GA-KR12-treated groups were 8.15 ± 0.32 and 6.70 ± 0.49, respectively (p < 0.001). The mineral losses of the control and GA-KR12-treated groups were 1.39 ± 0.09 gcm-3 and 1.19 ± 0.05 gcm-3, respectively (p < 0.001). The calcium-to-phosphorus molar ratios of the control and GA-KR12-treated groups were 1.47 ± 0.03 and 1.57 ± 0.02, respectively (p < 0.001). A uniformly remineralised prismatic pattern on enamel blocks was observed in the GA-KR12-treated but not in the control group. The hydroxyapatite in the GA-KR12-treated group was better crystallised than that in the control group. CONCLUSION: The dual-action peptide GA-KR12 inhibited the growth of S. mutans biofilm and promoted the remineralisation of enamel caries. CLINICAL RELEVANCE: GA-KR12 potentially is applicable for managing enamel caries.

An enamel-inspired bioactive material with multiscale structure and antibacterial adhesion property.

Conventional dental materials lack of the hierarchical architecture of enamel that exhibits excellent intrinsic-extrinsic mechanical properties. Moreover, restorative failures frequently occur due to physical and chemical mismatch between artificial materials and native dental hard tissue followed by recurrent caries which is caused by sugar-fermenting, acidogenic bacteria invasion of the defective cite. In order to resolve the limitations of the conventional dental materials, the aim of this study was to establish a non-cell-based biomimetic strategy to fabricate a novel bioactive material with enamel-like structure and antibacterial adhesion property. The evaporation-based, bottom-up and self-assembly method with layer-by-layer technique were used to form a large-area fluorapatite crystal layer containing antibacterial components. The multilayered structure was constructed by hydrothermal growth of the fluorapatite crystal layer and highly conformal adsorption to the crystal surface of a polyelectrolyte matrix film. Characterization and mechanical assessment demonstrated that the synthesized bioactive material resembled the native enamel in chemical components, mechanical properties and crystallographic structure. Antibacterial and cytocompatibility evaluation demonstrated that this material had the antibacterial adhesion property and biocompatibility. In combination with the molecular dynamics simulations to reveal the effects of variables on the crystallization mechanism, this study brings new prospects for the synthesis of enamel-inspired materials.

Occluding dentin tubules with monetite paste in vitro.

OBJECTIVES: This study was performed to evaluate the occlusion of monetite paste on dentine tubule and provide a new potential method for treating dentine hypersensitivity. METHODS: Calcium oxide, strontium chloride, and polyethylene glycol phosphate were mixed in a certain proportion and ground in a planetary ball mill. The reaction was carried out by adjusting the pH to obtain monetite and hydroxyapatite paste. The morphological characteristics of the paste were observed through scanning electron microscope (SEM). The structure and composition were analyzed through X-ray diffraction (XRD) and Fourier transform infrared spectrometer (FTIR). The extracted third molar was selected to undergo demineralization to establish the in vitro study model of dentin hypersensitivity. The samples were randomly divided into four groups: blank control group (treated with distilled water), casein peptide phosphate-amorphic calcium phosphate (CPP-ACP) group, monetite paste group, and hydroxyapatite paste group. Each group was used to scrub the dentin surface with the corresponding materials for 7 days. The morphological characteristics of the dentin surface and section were observed through SEM, the microhardness of the dentin before and after mineralization was analyzed with a microhardness tester, and the composition of the deposits on the surface of the mineralized samples was examined through XRD. RESULTS: XRD and FTIR showed that the composition of the paste was mainly monetite, and the composition of hydroxyapatite paste was mainly composed of hydroxyapatite. SEM revealed that the size of the crystal particles of the synthesized paste was tens to hundreds of nanometers. Monetite and hydroxyapatite paste could produce a thicker mineralization layer on the dentin surface, and the mineralization of the dentin tubules of monetite was deeper than that of hydroxyapatite paste. The microhardness of the monetite paste group was significantly less than those of the hydroxyapatite paste groups (P<0.05). CONCLUSIONS: Monetite paste could effectively block the exposed dentin tubules and be used for treating dentin hypersensitivity.

Synergistic effects of graphene quantum dots and carbodiimide in promoting resin-dentin bond durability.

OBJECTIVE: Resin-based dental adhesion is mostly utilized in minimally invasive operative dentistry. However, improving the durability and stability of resin-dentin bond interfaces remain a challenge. Graphene quantum dots (GQDs) reinforced by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) were introduced to modify the resin-dentin bond interfaces, thereby promoting their durability and stability. METHODS: GQDs, EDC, and EDC+GQDs groups were designed to evaluate the effects of GQDs and EDC on collagenase activity, the interaction of GQDs with collagen, and the resin-dentin interface. First, the effects of GQDs and EDC on collagenase activity was evaluated by Collagenase (EC 3.4.24.3) reacting with its substrate. The interaction of GQDs and EDC with collagen were evaluated by cross-linking degree analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, attenuated total reflection Fourier transform infrared spectroscopy and enzymatic hydrolysis. Second, the acid-etched and rinse adhesive system was used to evaluate the resin-dentin bond on the basis of microtensile bond strength, in situ zymography and fluorescence confocal laser scanning microscopy. RESULTS: GQDs could inhibit collagenase activity. GQDs with the aid of EDC could cross-link collagen via covalent bonds and improve the anti-enzymatic hydrolysis of collagen. In the resin-dentin adhesion model, the µTBS of the EDC+GQDs group was significantly higher than the other control groups after thermocycling. The addition of EDC to GQDs could inhibit matrix metalloproteinase activity and promote the integrity of the bonding interfaces after thermocycling. SIGNIFICANCE: This study presents a novel strategy to modify the resin-dentin interface and provides a new application for GQDs. This strategy has the potential to improve the durability of resin-based restoration in dentistry.

A Dopamine Acrylamide Molecule for Promoting Collagen Biomimetic Mineralization and Regulating Crystal Growth Direction.

The reconstruction of the intra/interfibrillar mineralized collagen microstructure is extremely important in biomaterial science and regeneration medicine. However, certain problems, such as low efficiency and long period of mineralization, are apparent, and the mechanism of interfibrillar mineralization is often neglected in the present literature. Thus, we propose a novel model of biomimetic collagen mineralization that uses molecules with the dual function of cross-linking collagen and regulating collagen mineralization to construct the intrafibrillar and interfibrillar collagen mineralization of the structure of mineralized collagen hard tissues. In the present study completed in vitro, N-2-(3,4-dihydroxyphenyl) acrylamide (DAA) is used to bind and cross-link collagen molecules and further stabilize the self-assembled collagen fibers. The DAA-collagen complex provides more affinity with calcium and phosphate ions, which can reduce the calcium phosphate/collagen interfacial energy to promote hydroxyapatite (HA) nucleation and accelerate the rate of collagen fiber mineralization. Besides inducing intrafibrillar mineralization, the DAA-collagen complex mineralization template can realize interfibrillar mineralization with the c-axis of the HA crystal on the surface of collagen fibers and between fibers that are parallel to the long axis of collagen fibers. The DAA-collagen complex, as a new type of mineralization template, may provide a new collagen mineralization strategy to produce a mineralized scaffold material for tissue engineering or develop bone-like materials.

Remineralising dentine caries using an artificial antimicrobial peptide: An in vitro study.

OBJECTIVE: To investigate the antibacterial and remineralising effects of a novel dual-action antimicrobial peptide, GA-KR12, on artificial dentine caries. METHODS: Human dentine blocks with artificial carious lesions were allocated to two groups - Group 1: dentine blocks treated with the novel antimicrobial peptide GA-KR12 twice daily; Group 2: dentine blocks received water as the negative control. Two groups underwent Streptococcus mutan biofilm-remineralisation cycles at 37 °C for 7 days. The morphology, viability and growth kinetics of the S. mutans biofilm were evaluated by scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and colony-forming unit (CFU) counting, respectively. The dentine blocks' lesion depths and mineral loss, changes in chemical structure, dentine surface morphology and crystal characteristics were determined using micro-computed tomography, Fourier transform infrared (FTIR), SEM and X-ray diffraction (XRD), respectively. RESULTS: The surface of the dentine blocks in Group 1 was partially covered by S. mutans with damaged cell structure. Group 2 showed affluent growth of S. mutans covering the dentine surface when compared to Group 1. The dead-to-live ratio of Group 1 and Group 2 were 0.78 ± 0.01 and 0.47 ± 0.08, respectively (p < 0.001). The Log CFUs of Group 1 and Group 2 were 7.14 ± 0.30 and 8.24 ± 0.20, respectively (p < 0.001). The lesion depths of Group 1 and Group 2 were 109 ± 1 µm and 135 ± 3 µm, respectively (p < 0.001). The mineral loss of Group 1 and Group 2 were 0.59 ± 0.08 gHApcm-3 and 0.81 ± 0.07 gHApcm-3, respectively (p < 0.001). FTIR showed the amide I-to-hydrogen phosphate (HPO42-) ratios of Group 1 and Group 2 were 0.25 ± 0.05 and 0.39 ± 0.05 (p < 0.001), respectively. SEM images showed Group 1 had less exposed dentine collagen fibres than Group 2. The XRD revealed that the hydroxyapatite in Group 1 was well crystalised. CONCLUSION: This study demonstrated that the novel antimicrobial peptide GA-KR12 inhibited the growth of S. mutans biofilm and enhanced the remineralisation of artificial dentine caries.

A Novel Strategy for Caries Management: Constructing an Antibiofouling and Mineralizing Dual-Bioactive Tooth Surface.

Existing single-functional agents against dental caries are inadequate in antibacterial performance or mineralization balance. This problem can be resolved through a novel strategy, namely, the construction of an antibiofouling and mineralizing dual-bioactive tooth surface by grafting a dentotropic moiety to an antimicrobial peptide. The constructed bioactive peptide can strongly adsorb onto the tooth surface and has beneficial functions in a myriad of ways. It inhibits cariogenic bacteria Streptococcus mutans adhesion, kills planktonic S. mutans, and destroys the S. mutans biofilm on the tooth surface. It also protects teeth from demineralization in acidic environments, and induces self-healing regeneration in the remineralization environment. Molecular dynamics simulations elucidate the main adsorption mechanism that the positively charged amino acid residues in the bioactive peptide bind to phosphate groups on the tooth surface, and the main mineralization mechanism that the negative charges on the outermost layer of the bioactive peptide repel acetic acid ions and attract calcium ions as nucleation sites for remineralization. This study suggests that this in-house synthesized dual-bioactive peptide is a promising functional agent to prevent dental caries, and is effective in inducing in situ self-healing remineralization for the treatment of decayed teeth.

A novel dual-action antimicrobial peptide for caries management.

OBJECTIVES: To develop a novel dual-action peptide with antimicrobial and mineralising properties. METHODS: A novel peptide, namely GA-KR12, was synthesised through grafting gallic acid to KR12. The secondary structure of GA-KR12 was evaluated by circular dichroism spectroscopy. The stability was evaluated by high-performance liquid chromatography. The cytotoxicity was evaluated by a mitochondrial dehydrogenase activity assay. The antimicrobial properties against common cariogenic species were evaluated by minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC). The morphology of cariogenic species was analysed by transmission electron microscope (TEM). To assess the mineralising effect of GA-KR12 on enamel, the lesion depths, mineral loss, surface morphology, calcium-to-phosphorus ratio and crystal characteristics were determined using micro-computed tomography, scanning electron microscopy (SEM) and energy dispersive spectroscopy X-ray diffraction, respectively. RESULTS: GA-KR12 did not exhibit cytotoxicity against HGF. Around 82% of the GA-KR12 remained in human saliva at 37°C for 1 h. The MIC and MBC/MFC against the tested species were 10-320 µM and 20-1,280 µM, respectively. GA-KR12 induced remarkable morphological defects in the tested species. The enamel treated with GA-KR12 had smaller lesion depths (p < 0.001), less mineral loss (p < 0.001) and higher calcium-to-phosphorus molar ratios (p < 0.001) than those in the enamel treated with water. SEM showed a well-organised prism pattern in enamel treated with GA-KR12. X-ray diffraction revealed that the hydroxyapatite on the enamel treated with GA-KR12 was better crystalised. CONCLUSIONS: This study developed a biocompatible and stable peptide which inhibited the growth of cariogenic species and mineralised the enamel caries. CLINICAL SIGNIFICANCE: The novel dual-action peptide, GA-KR12, is potential applicable in the management of caries.

The multifaceted roles of antimicrobial peptides in oral diseases.

Antimicrobial peptides are naturally occurring protein molecules with antibacterial, antiviral and/or antifungal activity. Some antimicrobial peptides kill microorganisms through direct binding with negatively charged microbial surfaces. This action disrupts the cytoplasmic membrane and leads to the leakage of the cytoplasm. In addition, they are involved in the innate immune response. Antimicrobial peptides play an important role in oral health, as natural antimicrobial peptides are the first line of host defence in response to microbial infection. The level of natural antimicrobial peptides increases during severe disease conditions and play a role in promoting the healing of oral tissues. However, they are insufficient for eliminating pathogenic micro-organisms. The variability of the oral environment can markedly reduce the effect of natural antimicrobial peptides. Thus, researchers are developing synthetic antimicrobial peptides with promising stability and biocompatibility. Synthetic antimicrobial peptides are a potential alternative to traditional antimicrobial therapy. Pertinent to oral diseases, the deregulation of antimicrobial peptides is involved in the pathogenesis of dental caries, periodontal disease, mucosal disease and oral cancer, where they can kill pathogenic microorganisms, promote tissue healing, serve as biomarkers and inhibit tumor cells. This narrative review provides an overview of the multifaceted roles of antimicrobial peptides in oral diseases.

Antimicrobial peptides for the prevention and treatment of dental caries: A concise review.

The objective of this study was to perform a comprehensive review of the use of antimicrobial peptides for the prevention and treatment of dental caries. The study included publications in the English language that addressed the use of antimicrobial peptides in the prevention and treatment of caries. These publications were also searchable on PubMed, Web of Science, Embase, Scopus, the Collection of Anti-Microbial Peptides and the Antimicrobial Peptide Database. A total of 3,436 publications were identified, and 67 publications were included. Eight publications reported seven natural human antimicrobial peptides as bactericidal to Streptococcus mutans. Fifty-nine publications reported 43 synthetic antimicrobial peptides developed to mimic natural antimicrobial peptides, fusing peptides with functional sequences and implementing new designs. The 43 synthetic antimicrobial peptides were effective against Streptococcus mutans, and nine peptides specifically targeted Streptococcus mutans. Ten antimicrobial peptides had an affinity for hydroxyapatite to prevent bacterial adhesion. Six antimicrobial peptides were also antifungal. Four antimicrobial peptides promoted remineralisation or prevented the demineralisation of teeth by binding calcium to hydroxyapatite. In conclusion, this study identified 67 works in the literature that reported seven natural and 43 synthetic antimicrobial peptides for the prevention and treatment of caries. Most of the antimicrobial peptides were bactericidal, and some prevented bacterial adhesion. A few antimicrobial peptides displayed remineralising properties with hydroxyapatite.

Anti-Biofouling Coatings on the Tooth Surface and Hydroxyapatite.

Dental plaque is one type of biofouling on the tooth surface that consists of a diverse population of microorganisms and extracellular matrix and causes oral diseases and even systematic diseases. Numerous studies have focused on preventing bacteria and proteins on tooth surfaces, especially with anti-biofouling coatings. Anti-biofouling coatings can be stable and sustainable over the long term on the tooth surface in the complex oral environment. In this review, numerous anti-biofouling coatings on the tooth surface and hydroxyapatite (as the main component of dental hard tissue) were summarized based on their mechanisms, which include three major strategies: antiprotein and antibacterial adhesion through chemical modification, contact killing through the modification of antimicrobial agents, and antibacterial agent release. The first strategy of coatings can resist the adsorption of proteins and bacteria. However, these coatings use passive strategies and cannot kill bacteria. The second strategy can interact with the cell membrane of bacteria to cause bacterial death. Due to the possibility of delivering a high antibacterial agent concentration locally, the third strategy is recommended and will be the trend of local drug use in dentistry in the future.

Inhibition of dentine caries using fluoride solution with silver nanoparticles: An in vitro study.

OBJECTIVES: To investigate the remineralising and staining effects of sodium fluoride (NaF) with silver nanoparticles (AgNPs) on artificial dentine caries. METHODS: Human dentine blocks with artificial caries were divided into four groups. Group 1 received 5 % NaF (22,600 ppm fluoride) with 4000 ppm AgNPs; group 2 received 4000 ppm AgNPs; group 3 received 5 % NaF, group 4 received deionised water (negative control). All groups underwent three biochemical cycles. Each cycle included Streptococcus mutans biofilm challenge and remineralisation process. The lesion depth, mineral-organic content, surface morphology and crystal characteristics of dentine blocks were evaluated using micro-computed tomography, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction. Colour change of dentine blocks was assessed using spectrophotometry. RESULTS: The mean lesion depths of groups 1-4 were 151.13 ± 29.13 µm, 172.38 ± 23.44 µm, 190.41 ± 32.81 µm and 221.24 ± 27.91 µm, respectively. The hydrogen phosphate-to-amide I ratios of groups 1-4 were 5.98 ± 0.36, 3.86 ± 0.56, 4.00 ± 0.67 and 2.53 ± 0.40, respectively. There was no significant interaction effect between AgNPs and NaF. SEM showed less exposure of dentine collagen fibres in group 1 when compared to other groups. X-ray diffraction revealed presence of silver chloride and metallic silver in group 1 and 2. There was no significant difference in colour change among the four groups (p = 0.74). CONCLUSIONS: NaF solution with AgNPs can remineralise dentine caries without staining. CLINICAL SIGNIFICANCE: Sodium fluoride solutions that include silver nanoparticles have potential uses in the management of caries.

Using metagenomic analysis to assess the effectiveness of oral health promotion interventions in reducing risk for pneumonia among patients with stroke in acute phase: study protocol for a randomized controlled trial.

BACKGROUND: The prevalence of pneumonia complicating stroke in acute phase has a poor prognosis and higher risk for death. Oral opportunistic pathogens have been reported to be associated with pneumonia among people with compromised health. Oral health promotion is effective in reducing dental plaque among patients with stroke, which is considered as reservoirs for oral opportunistic pathogens. This study evaluates the effectiveness of oral health promotions in reducing the prevalence of pneumonia via its effects on composition and relative abundance of oral opportunistic pathogens. METHODS/DESIGN: This study is a randomized, single-blind, parallel trial of 6 months duration. The study is being conducted at one of the largest medical teaching hospitals in Hefei, China. A total of 166 patients with stroke and free from any post-stroke complication will be recruited. After enrollment, patients will be randomized to one of the following groups: (1) oral hygiene instruction (OHI) or (2) OHI, 6-month use of powered tooth brushing, and 0.2% chlorhexidine gluconate mouth rinse (10 ml twice daily). The primary outcome is the prevalence of pneumonia complicating stroke. Patients will be monitored closely for any occurrence of pneumonia over the entire period of this trial. Oral rinse samples will be collected at baseline and multiple follow-up reviews (3, 5, 7 days, and 1, 3, 6 months after baseline). Next-generation sequencing will be employed to detect composition and relative abundances of the microorganism in the oral rinse samples. Questionnaire interviews and clinical oral examinations will be conducted at baseline and 1, 3, and 6 months after baseline. DISCUSSION: The findings of this trial will provide evidence whether oral health promotion intervention is effective in reducing the prevalence of pneumonia complicating stroke via its effect on the oral microbiome. The analysis of the outcomes of this trial is empowered by metagenomic analysis at 16S rRNA level, which is more sensitive and comprehensive to help us detect how oral health promotion inventions affect the oral microbiome in terms of its composition, relative abundance, and interactions between species, which all may contribute to the occurrence of pneumonia complicating stroke. TRIAL REGISTRATION: ClinicalTrials.gov NCT04095780 . Registered on 19 September 2019.

Constructing an Antibiofouling and Mineralizing Bioactive Tooth Surface to Protect against Decay and Promote Self-Healing.

Numerous methods have been investigated to manage dental caries, one of the top three diseases threatening human health as reported by the World Health Organization. An innovative strategy was proposed to prevent dental caries and achieve self-healing of the decayed tooth, and a novel bioactive peptide was designed and synthesized to construct an antibiofouling and mineralizing dual-bioactive tooth surface. Compared to its original endogenous peptide, the synthesized bioactive peptide showed statistically significantly higher binding affinity to the tooth surface, stronger suppression of demineralization, and a certain promotion of tooth remineralization. The abilities of the peptide to inhibit Streptococcus mutans (S. mutans) biofilm formation and S. mutans adhesion on the tooth surface were not affected after synthesis. Biocompatibility tests revealed the safety of the synthesized bioactive peptide. Interaction mechanisms between the synthesized bioactive peptide and tooth surface were also explained by molecular dynamic simulation analysis. In summary, the synthesized bioactive peptide could be applied safely to prevent dental caries and effectively induce in situ self-healing remineralization for treatment of the decayed tooth.

Effects of oligopeptide simulating DMP-1/mineral trioxide aggregate/agarose hydrogel biomimetic mineralisation model for the treatment of dentine hypersensitivity.

Dentine hypersensitivity (DH) occurs when dentine is exposed to stimuli from the oral environment due to a lack of enamel or cementum. The use of biomimetic mineralisation in occluding exposed dentinal tubules and regenerating enamel-like tissues on dentine surfaces is preferred for a long-lasting treatment. In this study, we established a biomimetic mineralisation model composed of oligopeptide stimulating dentine matrix protein 1 (DMP-1), mineral trioxide aggregate (MTA) and an agarose hydrogel biomimetic mineralisation model (AHBMM); the proposed model is thus referred to as DMP-1@MTA@AHBMM. The effectiveness of DMP-1@MTA@AHBMM for the management of DH was analysed with scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy and a microhardness test. The use of DMP-1@MTA@AHBMM on a demineralised dentine surface occluded the dentinal tubules and regenerated an enamel-like tissue containing well-defined fluoridated hydroxyapatite crystals on the dentine surface. The microhardness of the regenerated enamel-like tissue was greater than that of the demineralised dentine. Therefore, DMP-1@MTA@AHBMM can be a promising method for the management of DH.

Developing biocompatible silver nanoparticles using epigallocatechin gallate for dental use.

OBJECTIVE: To develop silver nanoparticles (AgNPs) using epigallocatechin gallate (EGCG) and evaluate its biocompatibility and inhibition effect on Streptococcus mutans biofilm growth. DESIGN: AgNPs were synthesized using EGCG as a reducing agent. Cytotoxicity was assessed using half-maximal inhibitory concentration (IC50) against human gingival fibroblast (HGF-1) and stem cells from human exfoliated deciduous teeth (SHED). Antibacterial properties were evaluated with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against S. mutans. Dentine blocks were treated with AgNPs, silver nitrate (AgNO3), or water before being incubated with S. mutans. The kinetics, morphology and viability of the biofilm at different time points were assessed by colony-forming units (CFUs), scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM), respectively. Lactic acid and polysaccharide production of the biofilm were also investigated. RESULTS: Spherical AgNPs with diameter 17 ± 7 nm were developed. The IC50 of AgNPs and AgNO3 against HGF-1 were 44.88 ± 11.39 µg/mL and 11.53 ± 6.96 µg/mL, respectively (p < 0.001), whereas those against SHED were 68.02 ± 24.48 µg/mL and 9.54 ± 6.63 µg/mL, respectively (p = 0.02). The MIC of AgNPs and AgNO3 were 32.22 ± 7.34 µg/mL and 48.89 ± 15.11 µg/mL, respectively (p = 0.01), whereas their MBC was 63.33 ± 11.73 µg/mL and 85.00 ± 20.77 µg/mL, respectively (p = 0.02). Log CFUs of the AgNPs group were the lowest among the groups (p < 0.001). SEM and CLSM found a confluent biofilm in AgNO3 and water groups but not in AgNPs group. Biofilms in AgNPs group was revealed with lowest level of acidic acid and polysaccharides production (p < 0.001). CONCLUSION: This study developed biocompatible AgNPs which inhibited the growth of a cariogenic biofilm.