The role of remineralizing and anticaries agents in caries management

Theranostic gold-in-gold cage nanoparticles enable photothermal ablation and photoacoustic imaging in biofilm-associated infection models

Biofilms are structured communities of microbial cells embedded in a self-produced matrix of extracellular polymeric substances. Biofilms are associated with many health issues in humans, including chronic wound infections and tooth decay. Current antimicrobials are often incapable of disrupting the polymeric biofilm matrix and reaching the bacteria within. Alternative approaches are needed. Here, we described a complex structure of a dextran-coated gold-in-gold cage nanoparticle that enabled photoacoustic and photothermal properties for biofilm detection and treatment. Activation of these nanoparticles with a near infrared laser could selectively detect and kill biofilm bacteria with precise spatial control and in a short timeframe. We observed a strong biocidal effect against both Streptococcus mutans and Staphylococcus aureus biofilms in mouse models of oral plaque and wound infections, respectively. These effects were over 100 times greater than those seen with chlorhexidine, a conventional antimicrobial agent. Moreover, this approach did not adversely affect surrounding tissues. We concluded that photothermal ablation using theranostic nanoparticles is a rapid, precise, and nontoxic method to detect and treat biofilm-associated infections.

Theranostic gold in a gold cage nanoparticle for photothermal ablation and photoacoustic imaging of skin and oral infections

Biofilms are structured communities of microbial cells embedded in a self-produced matrix of extracellular polymeric substances. Biofilms are associated with many health issues in humans, including chronic wound infections and tooth decay. Current antimicrobials are often incapable of disrupting the polymeric biofilm matrix and reaching the bacteria within. Alternative approaches are needed. Here, we describe a unique structure of dextran coated gold in a gold cage nanoparticle that enables photoacoustic and photothermal properties for biofilm detection and treatment. Activation of these nanoparticles with a near infrared laser can selectively detect and kill biofilm bacteria with precise spatial control and in a short timeframe. We observe a strong biocidal effect against both Streptococcus mutans and Staphylococcus aureus biofilms in mouse models of oral plaque and wound infections respectively. These effects were over 100 times greater than that seen with chlorhexidine, a conventional antimicrobial agent. Moreover, this approach did not adversely affect surrounding tissues. We conclude that photothermal ablation using theranostic nanoparticles is a rapid, precise, and non-toxic method to detect and treat biofilm-associated infections.

The Use of Toothpastes Containing Different Formulations of Fluoride and Bioglass on Bleached Enamel

To investigate the application of toothpaste either containing calcium sodium phospho-silicate bioglass (NovaMin) or calcium fluorosilicate bioglass (BioMinF) on the surface mineral composition and morphology of enamel after bleaching procedure. Methods: Thirty extracted noncarious human teeth were allocated into five groups (n = 6). Group 1: Bleaching using 40% hydrogen peroxide (HP) and fluoridated toothpaste containing bioactive glass (1450 ppm fluoride). Group 2: Bleaching using 40%HP and toothpaste containing calcium fluorosilicate bioglass (540 ppm fluoride). Group 3: Bleaching using 40%HP and fluoridated toothpaste (1450 ppm fluoride). Group 4: Bleaching alone using 40%HP. Group 5: Negative control with distilled water alone. The surface morphology was evaluated using Scanning Electron Microscope (SEM) and Scanning Probe Microscope (SPM). The concentration of elements as atomic percentages were determined by X-ray Photoelectron Spectroscopy (XPS) and Energy-Dispersive X-ray Spectroscopy (EDS). Results: This laboratory-based study reported that SPM and SEM detected minor changes on the surfaces of all toothpaste-treated enamel samples (Groups 1-3) after 45 days. Bioactive glass deposits were observed on enamel surfaces in Groups 1 and 2, whilst the bleaching-alone samples (Group 4) had rough enamel surfaces. XPS reported that toothpaste containing calcium fluorosilicate bioglass (Group 2) had a high atomic% of calcium and phosphate, whilst silicon values were high in the toothpaste containing bioactive glass and 1450 ppm fluoride (Group 1) after bleaching procedure when compared to other groups (p < 0.05). In addition, EDS detected the highest %F in Groups 1, 2 and 5. Conclusions: Within the limitations of this laboratory-based study, there was no significant decrease in the Ca%, P% values and surface properties of enamel after the bleaching procedure following the use of different formulations of toothpastes for a period of 45 days. However, the Ca% and P% values were significantly high for the toothpaste containing calcium fluorosilicate bioglass (BioMinF) on the bleached enamel. Clinical relevance: The bleaching process can provide optimum aesthetic outcomes, but the effect of peroxides on hard tissues is still in question. Toothpastes containing different formulations of fluoride and bioactive glass might have the potential to prevent mineral loss on bleached enamel. However, further laboratory-based studies and controlled double-blind randomised clinical trials are required to interpret the effects of toothpastes with different fluoride and bioactive glass formulations on enamel surfaces following bleaching procedures.

Dental plaque-inspired versatile nanosystem for caries prevention and tooth restoration

Dental caries is one of the most prevalent human diseases resulting from tooth demineralization caused by acid production of bacteria plaque. It remains challenges for current practice to specifically identify, intervene and interrupt the development of caries while restoring defects. In this study, inspired by natural dental plaque, a stimuli-responsive multidrug delivery system (PMs@NaF-SAP) has been developed to prevent tooth decay and promote enamel restoration. Classic spherical core-shell structures of micelles dual-loaded with antibacterial and restorative agents are self-assembled into bacteria-responsive multidrug delivery system based on the pH-cleavable boronate ester bond, followed by conjugation with salivary-acquired peptide (SAP) to endow the nanoparticle with strong adhesion to tooth enamel. The constructed PMs@NaF-SAP specifically adheres to tooth, identifies cariogenic conditions and intelligently releases drugs at acidic pH, thereby providing antibacterial adhesion and cariogenic biofilm resistance, and restoring the microarchitecture and mechanical properties of demineralized teeth. Topical treatment with PMs@NaF-SAP effectively diminishes the onset and severity of caries without impacting oral microbiota diversity or surrounding mucosal tissues. These findings demonstrate this novel nanotherapy has potential as a promising biomedical application for caries prevention and tooth defect restoration while resisting biofilm-associated diseases in a controlled manner activated by pathological bacteria.

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Nanomaterials can adhere to tooth and target acidic biofilms specifically.

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Application of caries prevention and tooth defect restoration.

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Guidance for the innovation of the existing post-defect restoration strategies.

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The multidrug delivery system exerts antibacterial and restorative abilities on demand.

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Bacteria-responsive system resists biofilm-associated diseases in a controlled manner.

Remineralization Potential of a Combination of Chitosan with Nanohydroxyapatite and a Self-assembling Peptide with Nanohydroxyapatite: An In Vitro Study

AIM

This study explores the demineralizing potential of the combination of chitosan with nanohydroxyapatite (n-HA) and self-assembling peptides with n-HA.

MATERIALS AND METHODS

A total of 66 first premolar teeth of similar dimensions extracted for orthodontic purposes were collected for this study. These were then demineralized and randomly divided into the following three groups (n = 22): (i) Control group, (ii) n-HA + Chitosan (HAC), and (iii) self-assembling peptide + n-HA (SP-HA). The samples in each group were brushed every 24 hours with the respective agent. The specimens were stored in Fusayama Meyer's artificial saliva at room temperature and the solution was replenished daily. Mineral content (Ca, P) and surface morphology of the specimens was analyzed, using scanning electron microscopy and energy dispersion X-ray spectroscopy (SEM-EDAX), before demineralization, at 15 days of remineralization and 30 days of remineralization. A two-way analysis of variance (ANOVA) test followed by Tukey's honest significant difference (HSD) post hoc analysis was used to compare the mean elemental composition of the different groups (p < 0.05).

RESULTS

There was no significant difference in the calcium (Ca) and phosphate (P) weight percentage between the different groups at the baseline and after demineralization. The Ca and P weight percentages of all three groups after remineralization for 15 and 30 days showed no significant difference from the baseline or after demineralization. The surface morphology after 15 days of remineralization therapy showed decreased surface porosity and increased mineral deposition in the HAC group than the HP-SA group. Surface morphology after 30 days of remineralization showed a more homogenous and smoother surface in the HAC group than the HP-SA group.

CONCLUSION

From the results of this study, it can be concluded that the combination of chitosan with n-HA and self-assembling peptides with n-HA can be considered effective demineralizing agents.

CLINICAL SIGNIFICANCE

Considering the non-invasive nature of remineralization therapy understanding the effectiveness of different agents is of utmost importance. The demineralizing properties of chitosan, n-HA and self-assembling peptides make their combinations ideal for studying their effectiveness in treating white spot lesions.

Graphene Oxide-Copper Nanocomposites Suppress Cariogenic Streptococcus mutans Biofilm Formation

Introduction

Dental caries is a biofilm-dependent disease that largely relies on the ability of Streptococcus mutans to synthesize exopolysaccharide matrix. Graphene oxide-based metal nanomaterials, as the derivatives of graphene, are potent agents against pathogens by their impressive antibacterial and anti-biofilm biofunctions. Previously, we fabricated the novel graphene oxide-copper nanocomposites (GO-Cu), maintaining a long-term release of copper nanoparticles. Here, the biofunctionalization of GO-Cu nanocomposites against cariogenic S. mutans is investigated.

Methods

Growth curve observation and colony forming units counting were applied to detect the antibacterial effect of GO-Cu nanocomposites on S. mutans. Scanning electron microscopy and the crystal violet assay were used to detect nanocomposite effects on biofilm forming ability. The production and distribution of exopolysaccharides within biofilm was analyzed and the expression of genes required for biofilm formation was explored. Moreover, the regulatory landscape of GO-Cu nanocomposites on S. mutans pathogenicity was probed.

Results

It has been found that GO-Gu nanocomposites were antibacterial to S. mutans and 10 μg/mL GO-Cu nanocomposites could inhibit the bacteria bioactivity instead of killing them. The biomass of S. mutans biofilm was significantly reduced when treated with 10 μg/mL GO-Cu nanocomposites. Also, 10 μg/mL GO-Cu nanocomposites could alter the biofilm architecture and impair exopolysaccharides production and distribution, and dysregulated the expression of exopolysaccharide-associated genes.

Conclusion

In all, we found low-dose GO-Cu nanocomposites could disrupt exopolysaccharide matrix assembly and further impair optimal biofilm development with minimal cytotoxicity. Therefore, GO-Cu nanocomposites can open up a new avenue for the development of alternative anti-caries biomaterials.

Caries Management by Risk Assessment vs. Traditional Preventive Strategies: Effect on Oral Health Behaviors and Caries Diagnoses: A Retrospective Case-Control Observational Design

Results showed patients who had undergone Caries Management by Risk Assessment (CAMBRA) had statistically significant lower plaque scores and improved their oral self-care behaviors. This study supports existing evidence that the use of caries management by risk assessment appears to offer a preventive approach to oral health care delivery.

A Comparison of Four Caries Risk Assessment Methods

Introduction: Caries risk assessment (CRA) is essential as the basis for successful management of dental caries. Of the many published CRA tools, four well-known ones are CAMBRA, Cariogram, American Dental Association (ADA), and American Academy of Pediatric Dentistry (AAPD) CRAs. The predictive accuracy of CAMBRA and Cariogram CRA tools have been examined in clinical outcomes studies in thousands of patients and the tools are widely used all over the world. The purpose of the present paper is three-fold, namely (1) to briefly review, compare and contrast these four CRA methods, (2) to provide a concise method for CRA introducing a quantitative component to the CAMBRA forms (CAMBRA 123), and (3) to guide the choice of CRA methods that will support caries management decisions. Comparison of Caries Risk Assessment Methods: In the present evaluation, the above-mentioned four CRA methods for ages 0-6 years and 6 years-adult were compared using 26 hypothetical patients (13 per age group). Comparison results show that Cariogram and CAMBRA categorized patients into identical risk categories. Each of the ADA and AAPD tools gave different results than CAMBRA and Cariogram in several comparison examples. CAMBRA 123 gave the same caries risk level results as the Cariogram and the CAMBRA methods for all hypothetical patients for both age groups. Conclusions: Both the Cariogram and the CAMBRA CRA methods are equally useful for identifying the future risk of dental caries. CAMBRA 123 shows promise as an easy-to-use quantitative method for CRA in clinical practice. The health care providers will be the ones to decide which CRA method will allow them to establish individualized, successful caries management therapies and how to combine these for the best care of their patients.

Remineralization of dentine tubules induced by phosphate-terminated PAMAM dendrimers

Various sealants have been developed to treat the exposure of dentinal tubules (DTs) and further dental hypersensitivity. Herein, the phosphate-terminated fourth generation polyamidoamine dendrimers (PAMAM-PO₃H₂) was successfully synthesized. Six duplicates of demineralized dentin and type I collagen matrix were incubated in artificial saliva solution with or without PAMAM-PO₃H₂ treatment at 37 °C for 2 weeks, respectively. The artificial saliva solution was replaced every day. These regenerated crystals on the surface of dentin and collagen matrix were confirmed to be hydroxyapatite (HAp). The approach thus demonstrates that PAMAM-PO₃H₂ can offer an efficient therapy for seal DTs in clinical dentistry.

The effect of silver diamine fluoride in preventing in vitro primary coronal caries under pH-cycling conditions

OBJECTIVES

This study investigated the ability of SDF, and its individual components, silver (Ag⁺) and fluoride (F^-) ions, in preventing enamel demineralization under pH-cycling conditions in the presence or absence of twice-daily fluoride application.

DESIGN

Polished human enamel specimens were assigned to five treatment groups (n = 36 per group): SDF (38 %); SDF followed by application of a saturated solution of potassium iodide (SDF + KI); silver nitrate (AgNO₃; silver control, 253,900 ppm Ag); potassium fluoride (KF; fluoride control, 44,800 ppm F); deionized water. Treatments were applied once. Specimens in each treatment group were divided into two subgroups (n = 18). During the subsequent 7-day pH-cycling phase, specimens were treated twice daily with either 275 ppm fluoride as sodium fluoride or deionized water, immediately before and after a 3-h cariogenic challenge with exposure to artificial saliva at all other times. Changes in color, Vickers surface microhardness (SMH), transverse microradiography (TMR) was calculated. Data were analyzed using two-way ANOVA.

RESULTS

In both models, SDF, SDF + KI and KF were superior in inhibiting demineralization compared to AgNO₃ and deionized water (p < 0.0001). There was no statistically significant difference between SDF, SDF + KI and KF with twice daily fluoride treatments (p > 0.8). However, KF was more effective in preventing demineralization than SDF and SDF + KI in the absence of fluoride treatments (p = 0.0002). KI did not affect the ability of SDF to prevent demineralization (p > 0.4).

CONCLUSION

SDF and SDF + KI appears to be an effective option in preventing primary coronal caries.

Hypersensitivity of teeth after orthodontic treatment in adolescence

Relevance. In adolescence, focal demineralization after orthodontic treatment is highly prevalent. This, in turn, leads to symptomatic hypersensitivity in the absence of other predisposing factors (recessions, exposure of cervical dentin, increased abrasion, etc.). Reviewed the mechanism for reducing hypersensitivity and remineralizing of calcium-sodium phosphosilicate, also the effectiveness of using a prophylactic toothpaste with this component in adolescents.

Materials and methods. A single-center, non-comparative open study was conducted to evaluate the  effectiveness of the Sensodyne Restoration and Protection toothpaste at the Department of Pediatric Dentistry and Orthodontics, USMU for 4 weeks. 22 adolescents aged 14-16 years with focal demineralization of enamel in the stain stage after completion of orthodontic treatment participated in the study.

Results. The use of toothpaste with calcium-sodium phosphosilicate after a month of use leads to a decrease in the hygiene index by 23.38%, a decrease in hypersensitivity according to the results of the Schiff air index by  56.94% (p ≤ 0.05), and a tendency to an increase in the level of mineralization and a decrease in areas of white  spot lesions.

Conclusions. Toothpaste with calcium-sodium phosphosilicate has a cleansing effect and reduces sensitivity and can be recommended for adolescents with focal demineralization against the background of orthodontic  treatment.

Anti-biofilm activity of a novel pit and fissure self-adhesive sealant modified with metallic monomers

Dental plaque is a biofilm composed of a complex oral microbial community. The accumulation of plaque in the pit and fissures of dental elements often leads to the development of tooth decay (dental caries). Here, potent anti-biofilm materials were developed by incorporating zinc methacrylates or di-n-butyl-dimethacrylate-tin into the light-curable sealant and their physical, mechanical, and biological properties were evaluated. The data revealed that 5% di-n-butyl-dimethacrylate-tin (SnM 5%) incorporated sealant showed strong anti-biofilm efficacy against various single-species (Streptococcus mutans or Streptococcus oralis or Candida albicans) and S. mutans-C. albicans cross-kingdom dual-species biofilms without either impairing the mechanical properties of the sealant or causing cytotoxicities against mouse fibroblasts. The findings indicate that the incorporation of SnM 5% in the experimental pit and fissure self-adhesive sealant may have the potential to be part of current chemotherapeutic strategies to prevent the formation of cariogenic oral biofilms that cause dental caries.

Application of Antibiotics/Antimicrobial Agents on Dental Caries

Dental caries is the most common oral disease. The bacteriological aetiology of dental caries promotes the use of antibiotics or antimicrobial agents to prevent this type of oral infectious disease. Antibiotics have been developed for more than 80 years since Fleming discovered penicillin in 1928, and systemic antibiotics have been used to treat dental caries for a long time. However, new types of antimicrobial agents have been developed to fight against dental caries. The purpose of this review is to focus on the application of systemic antibiotics and other antimicrobial agents with respect to their clinical use to date, including the history of their development, and their side effects, uses, structure types, and molecular mechanisms to promote a better understanding of the importance of microbial interactions in dental plaque and combinational treatments.

Therapeutic Strategies Targeting Cariogenic Biofilm Microenvironment

Cariogenic biofilms are highly structured microbial communities embedded in an extracellular matrix, a multifunctional scaffold that is essential for the existence of the biofilm lifestyle and full expression of virulence. The extracellular matrix provides the physical and biological properties that enhance biofilm adhesion and cohesion, as well as create a diffusion-modulating milieu, protecting the resident microbes and facilitating the formation of localized acidic pH niches. These biochemical properties pose significant challenges for the development of effective antibiofilm therapeutics to control dental caries. Conventional approaches focusing solely on antimicrobial activity or enhancing remineralization may not achieve maximal efficacy within the complex biofilm microenvironment. Recent approaches disrupting the biofilm microbial community and the microenvironment have emerged, including specific targeting of cariogenic pathogens, modulation of biofilm pH, and synergistic combination of bacterial killing and matrix degradation. Furthermore, new "smart" nanotechnologies that trigger drug release or activation in response to acidic pH are being developed that could enhance the efficacy of current and prospective chemical modalities. Therapeutic strategies that can locally disrupt the pathogenic niche by targeting the biofilm structure and its microenvironment to eliminate the embedded microorganism and facilitate the action of remineralizing agents may lead to enhanced and precise anticaries approaches.

Topical ferumoxytol nanoparticles disrupt biofilms and prevent tooth decay in vivo via intrinsic catalytic activity

Ferumoxytol is a nanoparticle formulation approved by the U.S. Food and Drug Administration for systemic use to treat iron deficiency. Here, we show that, in addition, ferumoxytol disrupts intractable oral biofilms and prevents tooth decay (dental caries) via intrinsic peroxidase-like activity. Ferumoxytol binds within the biofilm ultrastructure and generates free radicals from hydrogen peroxide (H₂O₂), causing in situ bacterial death via cell membrane disruption and extracellular polymeric substances matrix degradation. In combination with low concentrations of H₂O₂, ferumoxytol inhibits biofilm accumulation on natural teeth in a human-derived ex vivo biofilm model, and prevents acid damage of the mineralized tissue. Topical oral treatment with ferumoxytol and H₂O₂ suppresses the development of dental caries in vivo, preventing the onset of severe tooth decay (cavities) in a rodent model of the disease. Microbiome and histological analyses show no adverse effects on oral microbiota diversity, and gingival and mucosal tissues. Our results reveal a new biomedical application for ferumoxytol as topical treatment of a prevalent and costly biofilm-induced oral disease.

Ferumoxytol is a nanoparticle formulation approved for systemic use to treat iron deficiency. Liu et al. show that topical use of ferumoxytol, in combination with low concentrations of H₂O₂, disrupts intractable oral biofilms and prevents tooth decay in vitro and in an animal model.

Seal or Varnish? A randomised controlled trial to determine the relative cost and effectiveness of pit and fissure sealant and fluoride varnish in preventing dental decay

BACKGROUND

Fissure sealant (FS) and fluoride varnish (FV) have been shown to be effective in preventing dental caries when tested against a no-treatment control. However, the relative clinical effectiveness and cost-effectiveness of these interventions is unknown.

OBJECTIVE

To compare the clinical effectiveness and cost-effectiveness of FS and FV in preventing dental caries in first permanent molars (FPMs) in 6- and 7-year-olds and to determine their acceptability.

DESIGN

A randomised controlled allocation-blinded clinical trial with two parallel arms.

SETTING

A targeted population programme using mobile dental clinics (MDCs) in schools located in areas of high social and economic deprivation in South Wales.

PARTICIPANTS

In total, 1016 children were randomised, but one parent subsequently withdrew permission and so the analysis was based on 1015 children. The randomisation of participants was stratified by school and balanced for sex and primary dentition baseline caries levels using minimisation in a 1 : 1 ratio for treatments. A random component was added to the minimisation algorithm, such that it was not completely deterministic. Of the participants, 514 were randomised to receive FS and 502 were randomised to receive FV.

INTERVENTIONS

Resin-based FS was applied to caries-free FPMs and maintained at 6-monthly intervals. FV was applied at baseline and at 6-month intervals over the course of 3 years.

MAIN OUTCOME MEASURES

The proportion of children developing caries into dentine (decayed, missing, filled teeth in permanent dentition, i.e. D_4-6MFT) on any one of up to four treated FPMs after 36 months. The assessors were blinded to treatment allocation; however, the presence or absence of FS at assessment would obviously indicate the probable treatment received. Economic measures established the costs and budget impact of FS and FV and the relative cost-effectiveness of these technologies. Qualitative interviews determined the acceptability of the interventions.

RESULTS

At 36 months, 835 (82%) children remained in the trial: 417 in the FS arm and 418 in the FV arm. The proportion of children who developed caries into dentine on a least one FPM was lower in the FV arm (73; 17.5%) than in the FS arm (82, 19.6%) [odds ratio (OR) 0.84, 95% confidence interval (CI) 0.59 to 1.21; p = 0.35] but the difference was not statistically significant. The results were similar when the numbers of newly decayed teeth (OR 0.86, 95% CI 0.60 to 1.22) and tooth surfaces (OR 0.85, 95% CI 0.59 to 1.21) were examined. Trial fidelity was high: 95% of participants received five or six of the six scheduled treatments. Between 74% and 93% of sealants (upper and lower teeth) were intact at 36 months. The costs of the two technologies showed a small but statistically significant difference; the mean cost to the NHS (including intervention costs) per child was £500 for FS, compared with £432 for FV, a difference of £68.13 (95% CI £5.63 to £130.63; p = 0.033) in favour of FV. The budget impact analysis suggests that there is a cost saving of £68.13 (95% CI £5.63 to £130.63; p = 0.033) per child treated if using FV compared with the application of FS over this time period. An acceptability score completed by the children immediately after treatment and subsequent interviews demonstrated that both interventions were acceptable to the children. No adverse effects were reported.

LIMITATIONS

There are no important limitations to this study.

CONCLUSIONS

In a community oral health programme utilising MDCs and targeted at children with high caries risk, the twice-yearly application of FV resulted in caries prevention that is not significantly different from that obtained by applying and maintaining FSs after 36 months. FV proved less expensive.

FUTURE WORK

The clinical effectiveness and cost-effectiveness of FS and FV following the cessation of active intervention merits investigation.

TRIAL REGISTRATION

EudraCT number 2010-023476-23, Current Controlled Trials ISRCTN17029222 and UKCRN reference 9273.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 21. See the NIHR Journals Library website for further project information.

Nanocatalysts promote Streptococcus mutans biofilm matrix degradation and enhance bacterial killing to suppress dental caries in vivo

Dental biofilms (known as plaque) are notoriously difficult to remove or treat because the bacteria can be enmeshed in a protective extracellular matrix. It can also create highly acidic microenvironments that cause acid-dissolution of enamel-apatite on teeth, leading to the onset of dental caries. Current antimicrobial agents are incapable of disrupting the matrix and thereby fail to efficiently kill the microbes within plaque-biofilms. Here, we report a novel strategy to control plaque-biofilms using catalytic nanoparticles (CAT-NP) with peroxidase-like activity that trigger extracellular matrix degradation and cause bacterial death within acidic niches of caries-causing biofilm. CAT-NP containing biocompatible Fe3O4 were developed to catalyze H2O2 to generate free-radicals in situ that simultaneously degrade the biofilm matrix and rapidly kill the embedded bacteria with exceptional efficacy (>5-log reduction of cell-viability). Moreover, it displays an additional property of reducing apatite demineralization in acidic conditions. Using 1-min topical daily treatments akin to a clinical situation, we demonstrate that CAT-NP in combination with H2O2 effectively suppress the onset and severity of dental caries while sparing normal tissues in vivo. Our results reveal the potential to exploit nanocatalysts with enzyme-like activity as a potent alternative approach for treatment of a prevalent biofilm-associated oral disease.

Potential of an amelogenin based peptide in promoting reminerlization of initial enamel caries

OBJECTIVE

In this study we give a preliminary study of a rationally designed small peptide, which is based on the enamel matrix protein amelogenin, to investigate its effect on remineralization of initial enamel caries lesions.

DESIGN

A novel peptide was designed and synthesized to investigate its effects on the remineralization of initial enamel carious lesions during pH cycling that simulates intra-oral conditions. Initial lesions were created in bovine enamel blocks, which were then pH-cycled for 12 days in the presence of 25μM peptide, 1g/L NaF (positive control), 50mM HEPES buffer(negative control). Before and after pH cycling, enamel blocks were analyzed by surface microhardness testing, polarized light microscopy and transverse microradiography.

RESULTS

Percentage of surface microhardness recovery (SMHR%) after pH cycling was significantly higher in peptide group than HEPES group. Lower lesion depth and less mineral mineral loss were found in peptide or NaF treatment groups after the cycling, and were significantly different to HEPES group. No significant differences were observed between the blocks treated with peptide and those treated with NaF.

CONCLUSSION

This study provides in vitro evidence that this amelogenin based peptide promotes enamel caries remineralization, offering a promising remineralizing biomaterial in initial enamel carious treatment.

Preventive management plans recorded by dental therapists and oral health therapists using clinical vignettes for adolescents accessing public oral health services in New South Wales, Australia

BACKGROUND

The aim of this study was to investigate factors that influence dental therapists and oral health therapists (therapists) plan preventive oral health care for adolescents attending New South Wales public oral health services.

METHODS

A cross-sectional postal survey using two clinical vignettes was used to record the preventive care treatment plans offered by therapists working across 15 New South Wales local health districts. Data were tabulated and chi-square statistics used in the analysis.

RESULTS

One hundred and seventeen therapists returned questionnaires, giving a 64.6% response rate. The participants highlighted the importance of offering oral hygiene instruction (97.0%), dietary advice (95.0%) and topical fluoride applications (74.0%). Recommended home use products included fluoride toothpaste 5000 ppmF (59.0%) and casein phosphopeptide-amorphous calcium phosphate plus fluoride (CPP-ACPF) paste (57.7%). Over 50% used fissure sealants. More respondents (88%) would utilize motivational interviewing strategies for a patient with dental caries concerns; however, only 63% would use this technique for a patient in pain (p < 0.001).

CONCLUSIONS

Considerable variations were noted in therapists' recommendations for stabilizing and managing dental disease, suggesting a need for clinical directors to consider providing more advice to therapists on the scientific basis of preventing dental caries.

Novel tea polyphenol-modified calcium phosphate nanoparticle and its remineralization potential

Tea polyphenols (TP) are not only potent antimicrobial and antioxidant agents but also effective modifiers in the formation of nanosized crystals. Since nano-hydroxyapatite (n-HA) is known to enhance remineralization of dental hard tissue, our aims were to synthesize nanosized calcium phosphate particles incorporating TP and to test their potential as caries preventive agent. An ammonia water diffusion method was used to synthesize nanosized calcium phosphate particles (TP-CaP) in the presence of various amounts of TP. The resultant products were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The remineralization potential of the nano TP-CaP was then investigated in a 12-day pH-cycling model. Nano TP-CaP slurries, at pH 7.0 and pH 5.5, were applied onto preformed enamel lesions 4 × 3 min per day. n-HA slurries at pH 7.0 and pH 5.5 were used as positive controls, and deionized water was served as a negative control. SEM showed nanosized particles were only formed at 27 mg/mL of TP. Further characterization of the nanosized particles revealed the components were amorphous calcium phosphate, HA, and TP. Both surface microhardness and transverse microradiography analyses showed that nano TP-CaP at pH 5.5, but not at pH 7.0, significantly enhanced remineralization, to the same extent as the n-HA controls. Furthermore, significantly higher amount of TP was found in the supernatant of TP-CaP at pH 5.5 than those at pH 7.0. Since TP can inhibit bacterial growth and enzyme activities, the novel nanosized TP-CaP particle, at low pH, is a potential dual-functional-remineralization and antibacteria-product.

Factors affecting the placement or replacement of direct restorations in a dental school

Context:

The knowledge of the reasons for the placement of direct restorations makes possible to trace an epidemiological profile of a specific population and to direct the teaching of dentistry to techniques that are commonly used today and will be continued performed in the future.

Purpose:

The aim of this study was to verify the reasons for placement and replacement of direct restorations in patients treated in the Dental Clinic of the Uberaba University – Brazil.

Materials and Methods:

This study evaluated 306 restorative procedures carried out on 60 patients. During the treatment planning, a form that contained information about the patient's gender, tooth number, the classification of restorations, the reasons for placement and replacement of amalgam and tooth-colored restorations, the material that had to be removed and the new material used to fill the cavities was filled for each patient. Statistical analysis was carried out using Chi-square test (α = 0.05).

Results:

The data showed that most of the patients were female (66.7%). Of all the restorations placed, 60.45% were 1^st-time placements, while 39.55% were replacements. For 1^st-time restorations, the main reason for placement was primary caries (76.76%), followed by non-carious cervical lesions (15.14%). The amalgam restorations were replaced more frequently (67.77%). The primary reason for replacements was the presence of secondary caries (for both previous amalgam (42.68%) and composite (66.67%) restorations (P < 0.05). The resin composite was the most indicated material for the new restorations (98.04%) (P < 0.05).

Conclusions:

The main reason for placement of direct restorations was primary caries, while secondary caries was the main reason for replacements. In almost all cases, the material used to fill the cavities was the resin composite.

Cariogram Model in Assessment of Dental Caries among Mentally Challenged and Visually Impaired Individuals of Udaipur, India

OBJECTIVES

To assess the caries risk and contribution of diet, bacteria, circumstances and susceptibility sectors among special groups in comparison to the normal group of Udaipur using the Cariogram model.

MATERIALS AND METHODS

A Cariogram model was used to identify risk factors among 160 subjects (40 mentally challenged, 60 visually impaired and 60 normal healthy individuals) aged 7-36 years. Statistical analysis was done using Chi-square/ Fischer's Exact followed by Marascuilo procedure and Stepwise multiple linear regression.

RESULTS

Compared to the normal group (74%), mentally challenged (33%) and visually impaired (41%) groups showed less chances of avoiding future caries. Group (R= 0.660) was found to be strongest predictor for caries risk. Susceptibility sector contributed 61% for caries risk in all the groups.

CONCLUSION

The caries risk was high among special groups compared to normal group. Susceptibility sector illustrated the highest contribution for caries risk in all groups.

Novel anticaries and remineralizing agents: prospects for the future

Although the use of fluorides has been successful in reducing dental caries, the need remains to develop and evaluate new approaches and promising products for caries prevention. Comprehensive caries-prevention protocols should encompass fluoride and other agents affecting the de-/remineralization balance but also antimicrobial strategies. Different from the traditional restorative approach, the current opinion is that caries should be detected and monitored in its earliest stages, when a nonsurgical reversal can still be achieved. This paradigm shift has implications for methods of caries diagnosis, the choice of preventative materials and the design of randomized clinical trials. This article summarizes the highlights of a special conference dedicated to the topic of novel anticaries and remineralizing agents (ICNARA 2), and identifies the current consensus and remaining questions on pivotal issues in this field.