Arginine promotes fluoride uptake into artificial carious lesionsin vitro

Arginine combination with fluoride and calcium glycerophosphate: effects of concentration and on biofilm fluid

Aim: To study the influence of varying concentrations of arginine (Arg) combined with fluoride (F) and/or calcium glycerophosphate (CaGP) on biofilms.Materials & methods: Biofilms were analyzed for acidogenicity, microbial viability and Ca, F and inorganic phosphorus (P) concentrations.Results: For total bacteria, the lowest viability was found in F-containing groups, regardless of the arginine concentrations and presence of CaGP. For aciduric bacteria, no significant differences were found among arginine concentrations in the presence of F. For MS, arginine concentrations did not influence MS viability in the presence of fluoride and CaGP only decreased viability at 3.2% Arg concentration. The arginine-treated groups showed the lowest acidogenicity. For ion concentrations in biofilms, CaGP showed the highest values for P; Arg+F for F; and CaGP/Arg+CaGP for Ca.Conclusion: Different concentrations of arginine did not affect the microbial viability or acidogenicity of biofilms. Moreover, 0.8% Arg did not increase ion concentration in biofilm fluid.

Systematic Review and Meta-Analysis of Remineralizing Agents: Outcomes on White Spot Lesions

Dental caries is a widespread issue impacting global oral health. White spot lesions, the earliest stage of caries, compromise enamel's esthetics and integrity. Remineralization therapies, both fluoride and non-fluoride based, aim to restore enamel, but limited comparative data exist on their effects on lesion depth and microhardness. Thus, the aim of this systematic review was to evaluate the efficacy of remineralizing agents on lesion depth and microhardness of human teeth. The literature search included the following five databases: PubMed, Web of Science, Scielo, SCOPUS, and EMBASE from the period 2012 to October 2022. Studies evaluating lesion depth and microhardness in human teeth after the application of a remineralizing agent were considered for review. The meta-analysis was performed using RevMan 5.4 (The Cochrane Collaboration, Copenhagen, Denmark). A random effect model was used to pool estimate of effect and its 95% confidence intervals (CIs) for surface microhardness and depth lesion. Subgroup analyses were performed considering the presence of fluoride or not in the remineralization agent. Thirty-three studies were included in the qualitative review. Of these, twenty-six studies were included in the meta-analysis. The main risks of bias associated with the studies included a lack of blinding of the test operator and failure to obtain sample size. To conclude, fluorinated agents are more effective in remineralizing artificially induced white spot lesion than non-fluoride remineralizing agents.

Effects of different toothpastes against erosive tooth wear of enamel and dentine in vitro

BACKGROUND

The increase in the prevalence of erosion lesions worldwide has led researchers to develop effective toothpastes with different ingredients to prevent erosion that can protect the tooth surface against acid attacks. There remains a lack of consensus in the literature regarding which toothpaste formulation exhibits the most effective preventive action against erosive tooth wear, highlighting the necessity for further investigation in this field. This study aimed to evaluate the preventive effect of brushing with toothpastes with different ingredients on enamel and dentine erosion.

METHODS

The crowns and roots of ninety recently extracted bovine incisors were seperated and ground flat to obtain enamel and dentine surfaces. The obtained specimens were then divided into six groups: Curaprox Enzycal Zero Flouride (fluoride-free), Colgate Total 12 (1450 ppm NaF), Splat Biocalcium (fluoride-free and Nano-HAP), Colgate ProRelief (1450 ppm NaF and arginine), Sensodyne Repair and Protection (1450 ppm NaF and novamin), Opalescence Whitening (1100 ppm NaF). The specimens were immersed in a demineralizing solution for 2 min and in an artificial saliva for 60 min 4 times a day for 5 days. Brushing was performed with the aid of a charged toothbrush immediately after the first and last erosive attacks. Initial and final surface roughness (at the end of fifth day) were measured using a 3D profilometer. The Wilcoxon test was used to compare initial and final roughness values (p < 0.05).

RESULTS

Opalescence Whitening and Curaprox Enzycal Zero Fluoride significantly increased both enamel and dentine surface roughness compared to baseline, demonstrating rougher surfaces than all other groups except Colgate ProRelief (p < 0.001). Sensodyne Repair and Protection and Colgate Total 12 resulted in the smoothest enamel and dentine surfaces, respectively. The increase in surface roughness was significantly higher for enamel samples compared to dentine samples in the Opalescence Whitening group (p < 0.001).

CONCLUSIONS

Whitening toothpastes may exacerbate dental erosion by increasing surface roughness. The protective properties of fluoride-free toothpastes vary depending on their active ingredient.

Caries preventive potential of professionally deliverable fluoride-containing agents with incorporated arginine: A scoping review

The scoping review objectives were to: 1) investigate the caries preventive potential of professionally deliverable fluoride (F)-containing agents with incorporated arginine (Arg); and 2) identify the future scope of research on Arg-F interventions for caries prevention. Of 150 identified records, 7 articles (6 in vitro investigations and 1 scoping review) were included for a complete review; with no clinical studies with/without appraisal. Arginine variants (L-Arg/Arg.HCl at 1% to 10% w/v.) were examined for a potential professional application aimed at caries prevention, as reported with in vitro studies. Of the included articles, four in vitro studies explored L-Arg enriched 5% NaF varnish (Duraphat®) as a promising caries preventive agent, while only one considered incorporating L-Arg in MI varnish®/nanohydroxyapatite and one investigated glass ionomer cement for primary/secondary and tertiary caries prevention. The scoping review highlighted the scope for incorporating Arg to professionally deliverable F-containing agents. No clinical data are available to make conclusive recommendations about the caries preventive potential of professionally deliverable F-containing agents with incorporated Arg. With Arg-F varnish being investigated predominantly through in vitro studies, the data so far suggest that Arg was incorporated exclusively in Duraphat®, while the potential of Arg to prevent caries in other F-containing varnishes remains unexplored.

Could the Arginine-Fluoride Association Have a Real Impact on Caries Prevention?

In the context of preventive therapy, fluoride has allowed the reduction of the incidence and prevalence of caries. The establishment of the protective role of arginine in the neutralization of plaque acids has led to the development of new arginine-fluorine associations to potentiate this preventive aspect. Studies have reported that this association could provide superior efficacy compared to fluoride alone. A synergistic effect that could be potential and thus represent a promising ecological approach for caries prevention. However, confirmation of the effective efficacy of the arginine-fluoride association requires additional clinical studies to be carried out before establishing recommendations.

The combination of arginine and fluoride-containing bioactive glass acted synergistically in inhibiting enamel demineralization in permanent teeth

OBJECTIVES

To evaluate the in-vitro efficacy of inhibiting enamel demineralization using arginine in combination with fluoride-containing bioactive glass (FBG).

METHODS

In this study, the healthy enamel blocks were first demineralized in acetic acid for 24 h, then soaked in anti-demineralization treatment solutions containing either arginine or FBG or both for 96 h.The specimens treated in acetic acid were applied as the control group. The pH, calcium and phosphorus ion concentrations of the solutions were measured before and after treatment. Changes in enamel mineral weight, microhardness, and composition were also analyzed.

RESULTS

The present of arginine facilitated fluorine release from treatment solutions with the presence of FBG. Both arginine and FBG significantly increased the pH of treatment solutions and prevented the further mineral weight loss compared to the control group. All anti-demineralization treatment groups showed significant increases in microhardness, but there was no statistical difference among the treatment groups. The SEM analysis showed enamel restoration in the arginine and FBG groups upon treatment, while the combined groups showing a superior anti-demineralization efficacy. 19F NMR showed the formation of fluorapatite in samples treated with solutions containing FBG.

CONCLUSIONS

Both arginine and FBG could inhibit enamel demineralization to some extent, and their combination demonstrated an enhanced anti-demineralization efficacy. The low-concentration combination group exhibited anti-demineralization effects comparable to those of high-concentration ones.

CLINICAL SIGNIFICANCE

This study introduces a new approach for caries prevention by combining the application of arginine and FBG. The release of fluorine promoted by the presented arginine along with calcium and phosphorus ions from FBG facilitated FAP formation. Additionally, the increment of pH resulting from arginine and FBG degradation further prevents enamel demineralization.

Physical properties and enamel remineralization potential of arginine-fluoride varnishes

OBJECTIVE

The study objectives were to examine the physical properties and enamel remineralization potential of fluoride (F) varnishes incorporated with arginine (Arg).

METHODS

Four commercial F varnishes: 1) Duraphat®; 2) Flúor Protector®, 3) Fluor Protector S®, and 4) Fluorimax™ were supplemented with 2% w/v. Arg. The control/experimental varnishes underwent rheometric analysis to assess varnish density (δ), velocity (ν), and associated viscosity, both quantitatively (ν/δ) and qualitatively based on determined mass, volume, distance flow, and time under experimentation. The varnish wet/dry weights (at 2 h) were also analysed. Further, sound enamel specimens (T0) with artificial incipient caries-like lesions (T1) were treated with control/experimental varnishes and subjected to remineralization assay with artificial saliva for 6 h. Thereafter (T2), the specimens were characterized to estimate precipitated Ca and net enamel F uptake. Additionally, mineral density (MD) was assessed using micro-CT at T0, T1, and T2 to derive mineral gain (MG) and % remineralization for the treatment groups.

RESULTS

When Arg is incorporated, the physical properties of the F-containing varnishes undergo a significant transformation, resulting in higher density, varnish weight, dry varnish weight, and viscosity compared to their respective control varnishes (p < 0.05). Incorporating Arg-in Duraphat®, Fluor Protector S®, and Fluorimax™ significantly improved both enamel Ca precipitation and F uptake compared to the respective controls (p < 0.05). Additionally, the enamel F uptake was significantly higher with all the tested varnishes when enriched with Arg (p < 0.05). The combined data for MD, MG, and % remineralization suggests that the remineralization potential of F-varnishes significantly increased when enriched with Arg (p < 0.05).

CONCLUSION

Incorporating Arg in inorganic F varnishes improves their physical properties and enhances the enamel remineralization potential of the varnishes.

CLINICAL SIGNIFICANCE

This study highlights the possibility of incorporating Arg in distinct F-source varnishes. The synergism between active components (Arg-F) aids in enhanced remineralization and superior varnish physical properties, demonstrating a promising approach for high caries-risk patients.

Enhanced anti-biofilm and anti-caries potential of arginine combined with calcium glycerophosphate and fluoride

OBJECTIVE

The aim of this work was to evaluate the antibiofilm and anticaries properties of the association of arginine (Arg) with calcium glycerophosphate (CaGP) and fluoride (F).

METHODS

An active attachment, polymicrobial biofilm model obtained from saliva and bovine teeth discs were used. After the initial biofilm growth period, the enamel discs were transferred to culture medium. The treatment solutions were added to the culture media to achieve the desired final concentration. The following groups were used: negative control (Control); F (110 ppm F); CaGP (0.05 %); Arg (0.8 %) and their associations (F + CaGP; Arg + F; Arg + CaGP; Arg +F + CaGP). The following analyses were carried out: bacterial viability (total bacteria, aciduric bacteria and mutans streptococci), pH assessment of the spent culture medium, dry weight quantification, evaluation of surface hardness loss (%SH) and subsurface mineral content. Normality and homoscedasticity were tested (Shapiro-Wilk and Levene's test) and the following tests were applied: two-way ANOVA (acidogenicity), Kruskall-Wallis (microbial viability) and one way ANOVA (dry weight, %SH, mineral content).

RESULTS

The association Arg + F + CaGP resulted in the lowest surface hardness loss in tooth enamel (-10.9 ± 2.3 %; p < 0.05). Arg +F + CaGP exhibited highest values of subsurface mineral content (10.1 ± 2.9 gHAP/cm3) in comparison to Control and F (p < 0.05). In comparison to Control and F, Arg +F + CaGP promoted the highest reduction in aciduric bacteria and mutans streptococci (5.7 ± 0.4; 4.4 ± 0.5 logCFU/mL, p < 0.05).

CONCLUSIONS

The Arg-F-Ca association demonstrated to be the most effective combination in protecting the loss of surface hardness and subsurface mineral content, in addition to controlling important virulence factors of the cariogenic biofilm.

CLINICAL SIGNIFICANCE

Our findings provide evidence that the Arg-F-Ca association showed an additive effect, particularly concerning protection against enamel demineralization. The combination of these compounds may be a strategy for patients at high risk of caries.

A Comparative Evaluation of Arginine Complex Combined With Flouride and Two Standard Non-Fluoridated Remineralizing Agents: An In Vitro Study

Background Dental caries represents a dynamic process, often reversible in its early stages. Fluoride has conventionally served as the cornerstone for remineralization and early caries arrest. However, excessive fluoride intake can lead to both local and systemic toxicity. Hence, there's a pressing need to develop adjunct therapies that enhance fluoride's efficacy while minimizing its dosage. This study aims to assess and compare the remineralization potential of a novel combination comprising arginine bicarbonate and fluoride against established technologies such as Bioactive glass (NovaMin Technology; Sensodyne Repair and Protect, GlaxoSmithKline, UK) and CPP-ACP technology (GC Tooth Mousse; Tokyo Japan). Materials and methods The experiment utilized extracted premolars designated for orthodontic extraction. The initial evaluation employed the DIAGNOdentTM fluorescence method. Subsequently, teeth underwent demineralization and were measured for values. Following this, the teeth were subjected to seven cycles of remineralization, after which moment values were reassessed. Statistical analysis was performed on the recorded values. Results Participants were divided into six groups (BR-A, AR-A, BR-B, AR-B, BR-C, AR-C). T-tests demonstrated significant reductions in moment values within each group, indicating the effectiveness of all remineralizing agents. Group C exhibited the most substantial difference (-6.900 ± 0.4), followed by Group A and Group B. ANOVA analysis revealed statistically significant differences among all three groups (p=0.016). Tables showed significant distinctions between the remineralizing values of Groups A and C and Groups B and C (p=0.02 and 0.002, respectively), with no discernible distinction between Groups A and B. Conclusion The study elucidates the superior efficacy of the arginine complex with fluoride combination compared to CPP-ACP and Bioactive Glass individually. This finding underscores the potential of the novel combination therapy in enhancing remineralization while minimizing fluoride dosage, thus presenting a promising strategy for addressing early-stage dental caries.

Remineralization potential of dentifrices with calcium sodium phosphosilicate and functionalized tri-calcium phosphate in the deeper incipient carious lesions: An in vitro study

OBJECTIVES

This study evaluated the remineralization potential of calcium sodium phosphosilicate and functionalized tri-calcium phosphate (f-TCP) dentifrices in deeper incipient carious lesions (ICLs).

MATERIALS AND METHODS

Artificial ICLs were created by placing premolars into demineralizing solutions. Teeth were randomly assigned into four groups: calcium sodium phosphosilicate (Group 1), f-TCP (Group 2), 1450 ppm fluoride (Group 3), and distilled water (Group 4), which were subjected to 10-day pH cycling. Mineral density (MD) was assessed using microcomputed tomography (Micro-CT), while hardness (H) and elastic modulus (EM) were assessed using nanomechanical testing.

RESULTS

MD % gain was higher in Groups 1-3 than in Group 4. In addition, Groups 1 and 2 exhibited significantly higher MD % gain than Group 3. Also, Groups 1-3 showed significantly higher EM and H values than Group 4 in the outer enamel area; yet, Groups 1 and 2 displayed significantly higher EM and H values than Groups 3 and 4 in the inner enamel.

CONCLUSIONS

The MD, EM, and H of ICLs significantly increased with the addition of calcium sodium phosphosilicate or f-TCP to fluoridated dentifrices compared to standard fluoride dentifrices. The added active ingredients remineralized the deeper parts of the ICLs, while remineralization at the lesion surface was similar between tested dentifrices.

Combined Effect of a Bioinspired Self-Assembling Peptide and Fluoride Varnish on Remineralisation of Artificial Early Enamel Caries Lesion: An in vitro Study

INTRODUCTION

This study aimed to investigate the remineralisation effect of combined use of a bioinspired self-assembling peptide (P26) and fluoride varnish on artificial early enamel caries lesions.

METHODS

Bovine enamel blocks with artificial early enamel caries lesions were prepared. The blocks were randomly allocated to four experimental groups to receive the following treatments: A = P26 + fluoride varnish, B = P26, C = fluoride varnish, and D. distilled water (negative control). The treated blocks were subjected to pH cycling. Enamel blocks were collected at time points of 7 days (d7) and 21 days (d21). The mineral gain, elemental analysis and crystal characteristics of the caries lesion were assessed by micro-computed tomography, scanning electron microscopy with energy dispersive X-ray and X-ray diffraction (XRD), respectively.

RESULTS

The mean ± standard deviation of mineral gain of group A to D were 17.4 ± 4.2%, 10.7 ± 2.2%, 10.1 ± 1.2%, and 6.8 ± 0.5% at d7, respectively, and 15.2 ± 2.6%, 8.7 ± 3.1%, 9.7 ± 1.2%, and 7.8 ± 2.3% at d21, respectively. A significant higher mineral gain was observed in group A when compared to other groups at both d7 and d21 (p < 0.05). The calcium-to-phosphate ratio remained consistent across all groups, ranging between 1.2 and 1.4. XRD analysis indicated that crystal composition on the surfaces was apatite for all groups.

CONCLUSION

In conclusion, the present study provided a first indication of better remineralisation effects of the combined use of the bioinspired self-assembling peptide P26 and fluoride varnish compared to the effects of the respective individual uses of P26 or fluoride varnish.

Effect of arginine-fluoride varnish on preventing enamel erosion by paediatric liquid medicaments

BACKGROUND

The study objective was to examine the effect of arginine-sodium fluoride (Arg-NaF) varnish on preventing enamel erosion by acidic paediatric liquid medicaments (PLM).

METHODS

The treatment groups were: 1) 2% Arg-NaF; 2) 4% Arg-NaF; 3) 8% Arg-NaF; 4) NaF; 5) MI (CPP-ACFP) varnishes; and 6) no varnish. The pH of PLM (paracetamol and chlorpheniramine) was measured at baseline and after immersing the Perspex® blocks coated with varnishes at 0 min, 30 min, 1 h, and 4 h. Seventy-two enamel specimens (n = 72) were randomly divided into 2 groups by PLM and further by treatment groups. Then, the specimens were pre-treated with varnishes and subjected to erosive cycles (5 min, 2×/day for 4 days) by PLM. After each erosive challenge, the specimens were stored in artificial saliva. At baseline and after 4 days, the specimens were assessed for surface roughness (Ra) using 2D-surface profilometric analysis (SPA) and atomic force microscopy (AFM). Additionally, the Ca/P ratio was determined using scanning electron microscopy with energy-dispersive X-ray spectroscopy. Paired samples dependent t-test, 1-way ANOVA and 2-way ANOVA with Bonferroni post-hoc tests were used to analyse data with the level of significance set at p < 0.05.

RESULTS

The pH of PLM with 8% Arg-NaF was significantly higher than the other groups at 30 min and 4 h (p < 0.05). With paracetamol, no significant difference was observed between the baseline and post-erosive cycle measured enamel Ra (by SPA/AFM) and Ca/P ratio for all treatment groups (p > 0.05). The Ra determined by AFM, at the post-erosive cycle with chlorpheniramine, when treated with 4 and 8% Arg-NaF was significantly lower than the other groups (p < 0.05); except CPP-ACFP (p > 0.05). With the chlorpheniramine post-erosive cycle, the Ca/P ratio for 4, 8% Arg-NaF and CPP-ACFP treated specimens was significantly higher than the baseline Ca/P (p < 0.05).

CONCLUSION

The 4%/8% Arg-NaF and MI varnish® application exhibit an enhanced preventive effect against low pH (pH < 3.0) PLM-mediated enamel erosive challenges compared to 5% NaF varnish.

Arginine: A New Paradigm in Preventive Oral Care

Dental caries is ubiquitous and one of the most prevalent oral diseases and the foremost cause of dental pain and poor quality of life (QoL). Fluoride is an effective caries preventive agent; however, despite its use, there remain some gaps in prevention of dental caries. Arginine, an amino acid, helps to maintain a noncariogenic plaque. It shows synergistic effects with fluoride in dental caries and can help nourish the tooth by enhancing the remineralization effect of fluoride. Supplementing fluoride dentifrices with arginine can bridge the gap in caries prevention. Several clinical studies with 1.5% arginine + fluoride provide evidence for its use in prevention of dental caries. This report throws light on the benefits of arginine in dental caries and guides on its use with fluoride. Recommendations given in the report will help in effective prevention of dental caries.

How to cite this article

Goyal V, Damle S, Puranik MP, et al. Arginine: A New Paradigm in Preventive Oral Care. Int J Clin Pediatr Dent 2023;16(5):698-706.

The effect of synbiotic-fluoride therapy on multi-species biofilm

OBJECTIVES

The study objective was to examine the effect of synbiotic-fluoride (SF) therapy within a multi-species cariogenic biofilm model system comprising of S. mutans, S. sanguinis, and S. gordonii.

METHODS

The SF therapy was prepared using 2% L-arginine (Arg), 0.2% NaF and probiotic L. rhamnosus GG (LRG). The 8 treatment groups were: Group 1: No treatment, Group 2: 2% Arg, Group 3: 0.2% NaF, Group 4: LRG, Group 5: 2% Arg+0.2% NaF, Group 6: 2% Arg+LRG, Group 7: 0.2% NaF+LRG, and Group 8: SF therapy (2% Arg+0.2% NaF +LRG). Multi-species biofilm model over 96 h comprising Streptococcus mutans, Streptococcus sanguinis, and Streptococcus gordonii was utilized. The biofilms received cariogenic challenge and SF therapy 2 × /day. The extracellular matrix components were analyzed for carbohydrates, proteins, and extra-cellular DNA (eDNA). The live/dead cells were imaged and quantified using confocal microscopy. The viable/dead bacterial concentrations were estimated using propidium monoazide-quantitative polymerase chain reaction (PMA-qPCR). The gene expressions for gtfB, sagP, arcA, argG, and argH were measured using real-time reverse transcriptase qPCR.

RESULTS

Carbohydrates and protein content with SF therapy were higher than non-LRG containing groups, while eDNA content was lower than other groups (p<0.05). Live bacterial proportions determined using confocal imaging with SF therapy were the lowest (p<0.05). The 2% Arg+LRG and SF therapy showed higher viable L. rhamnosus GG than 0.2% NaF+LRG (p<0.05). The dead S. mutans with SF therapy were higher than the other groups (p<0.05) with no difference from 2% Arg+0.2% NaF and 2% Arg+LRG (p>0.05). The SF therapy significantly downregulates gtfB and upregulates sagP, arcA, argG, argH gene expression (p<0.05).

CONCLUSION

Synbiotic-fluoride therapy effectuates multi-fold changes in the multi-species biofilm matrix and cellular components leading to superior ecological homeostasis than its individual contents, prebiotics (arginine), probiotic (L. rhamnosus GG), and fluorides (NaF).

CLINICAL SIGNIFICANCE

The ecological-based synbiotic-fluoride caries-preventive therapy aids in maintaining biofilm homeostasis to preempt/restore dysbiosis thereby sustaining dynamic-diverse health-associated microbial stability significant as a preventive regimen for high caries-risk patients.

Combined remineralizing effect of arginine and fluoride on artificially demineralized human primary dentin evaluated using quantitative light induced fluorescence

Introduction

One the most common chronic dental diseases affecting children is dental caries. Dentin caries is a condition in which caries has progressed to the dentin and caused a significant depth of lesion. Clinical studies have revealed that an increased caries risk is associated with a decreased alkali-producing capacity of the microbial populations colonizing the oral cavity of adults, which arginine somewhat compensates for.

Aims

To evaluate the remineralizing efficacy of fluoridated toothpaste, with fluoride-arginine containing toothpaste on demineralized dentin of primary teeth using quantitative light-induced fluorescence™.

Materials and Methods

Forty-five primary molars were decoronated and sectioned to prepare dentin specimens and mounted in an acrylic block in a uniform manner using a customized acrylic jig. Samples were randomized into three groups, were subjected to demineralization to create artificial dentin caries lesion. Following this, all the 45 samples were subjected to multispecies bacterial pH cycling for 21 days. All the specimens were evaluated for postdemineralization, pH cycling day 7, 14, and 21 on QLF™.

Results

On day 21, maximum fluorescence gain was observed by the positive control group followed by the arginine and negative control group. The variation observed between positive control and arginine group was found to be statistically significant.

Conclusions

An in vitro development of artificial caries such as demineralized lesion on primary dentin sample using plaque biofilm was observed successfully under QLF after 72 h. Arginine in combination with fluoride showed almost similar remineralization of demineralized primary dentin compared to fluoride alone after 21 days of multispecies bacterial pH cycling.

Synbiotic-fluoride synergism on enamel remineralization, cytotoxicity and genotoxicity

OBJECTIVE(S)

The objectives of the present study were to examine the - a) enamel remineralization potential of synbiotic-fluoride (SF) therapy using a multi-species bacterial pH-cycling model; and b) cytotoxic and genotoxic effects of SF therapy extracts.

MATERIALS AND METHODS

The SF therapy group comprised of 2% arginine (Arg), 0.2% NaF, and a probiotic Lactobacillus rhamnosus GG (LRG). The intervention groups studied were: 1) No treatment; 2) 2% Arg; 3) 0.2% NaF; 4) LRG; 5) 2% Arg+0.2% NaF; 6) 2% Arg+LRG; 7) 0.2% NaF+LRG; and 8) 2% Arg+0.2% NaF+LRG (SF therapy). The enamel remineralization potential of SF therapy was investigated under cariogenic biofilm challenge; while the cytotoxicity and genotoxicity of SF therapy extracts were examined on HGF-1 and Chinese hamster fibroblast V79, respectively. To determine the remineralization effect, the specimens were subjected to mineral density (MD) assessment using micro-CT, Ca/P molar ratio with SEM-EDX, and enamel fluoride uptake (EFU) estimates. The HGF-1 proliferation assessment was quantified using MTT/CCK-8 assays with qualitative analysis by nuclei staining Hoechst-based fluorescence imaging. The genotoxicity was determined by micronuclei formation test.

RESULTS

Mineral gain and %remineralization derived from MD assessment for the SF therapy were significantly higher than the other groups (p<0.05). The %ΔCa/P for the SF and 2% Arg+0.2% NaF were significantly higher than the other groups (p<0.05). The SF and 2% Arg+0.2% NaF groups had the highest EFU compared to the other groups (p<0.05). No significant difference in the %viable HGF-1 cells were observed between the treatment interventions and no treatment group (p>0.05). Compared to the EMS-positive control, the micronuclei formation for all the intervention groups was significantly lower (p<0.05), with no significant difference among the treatment groups (p>0.05).

CONCLUSION

The SF therapy enhanced enamel remineralization with no biocompatibility concerns.

CLINICAL SIGNIFICANCE

With the enhanced enamel remineralization potential discerned in the present study, the SF therapy can be used as a promising caries-preventive agent targeted for high caries-risk individuals.

The acid-resistance potential of arginine-fluoride varnish treated enamel

The study objective was to examine the acid-resistance potential of enamel carious lesions treated with arginine (Arg)-sodium fluoride (NaF) varnishes using nano-mechanical testing and chemical mapping. L-arginine (at 1%, 2%, & 4%) was incorporated in 5% NaF varnish. The experimental/control groups were: 1% Arg-NaF, 2% Arg-NaF, 4% Arg-NaF, NaF, and no treatment. Enamel specimen blocks were subjected to incipient carious lesion formation. After treatment, the specimens underwent chemical pH-cycling for 8-days and acid challenge for 2 h. The specimens were characterised for surface nano-hardness (SNH) and calcium/phosphate content of the treated lesions to determine enamel solubility reduction (ESR). Post-acid challenge, X-ray diffraction crystallography (XRD), and energy dispersive X-ray spectrophotometry (EDX) were performed. The SNH for 2%/4% Arg-NaF demonstrated a higher resistance to acid challenge with significantly higher SNH recovery than NaF varnish (p<0.05). The ESR potential of 2%/4% Arg-NaF varnish was significantly higher than NaF varnish (p<0.05). The XRD crystalline phases demonstrated that 2%/4% Arg-NaF had intense hydroxyapatite peaks discerning its increased potential to resist demineralization than NaF varnish. The EDX results showed that 2%/4% Arg-NaF demonstrated Ca/P ratio closer to hydroxyapatite (~1.67) post-acid challenge. Incorporating 2%/4% L-arginine in a 5% NaF varnish enhances the acid-resistance potential of NaF varnish.

Physicochemical Characteristics of Arginine Enriched NaF Varnish: An In Vitro Study

The in vitro study objectives were to investigate the effect of arginine (Arg) incorporation in a 5% sodium fluoride (NaF) varnish on its physical and chemical properties including F/Arg release. Six experimental formulations were prepared with L-arginine (L-Arg) and L-arginine monohydrochloride at 2%, 4%, and 8% w/v in a 5% NaF varnish, which served as a control. The varnishes were subjected to assessments for adhesion, viscosity, and NaF extraction. Molecular dynamics were simulated to identify post-dynamics total energy for NaF=Arg/Arg>NaF/Arg<NaF concentrations. The Arg/F varnish release profiles were determined in polyacrylic lactate buffer (pH-4.5; 7 days) and artificial saliva (pH-7; 1 h, 24 h, and 12 weeks). Incorporation of L-Arg in NaF varnish significantly influences physical properties ameliorating retention (p < 0.001). L-Arg in NaF varnish institutes the Arg-F complex. Molecular dynamics suggests that NaF>Arg concentration denotes the stabilized environment compared to NaF<Arg (p < 0.001). The 2% Arg-NaF exhibits periodic perennial Arg/F release and shows significantly higher integrated mean F release than NaF (p < 0.001). Incorporating 2% L-arginine in 5% NaF varnish improves its physical properties and renders a stable matrix with enduring higher F/Arg release than control.

Enamel remineralization potential of arginine-fluoride varnish in a multi-species bacterial pH-cycling model

OBJECTIVES

To examine the enamel fluoride uptake and remineralization potential of arginine-fluoride (Arg-NaF) varnishes in a simulated clinical condition using a multi-species bacterial pH-cycling model.

METHODS

L-Arginine (at 1 %, 2 %, and 4 % by wt.) was incorporated in a 5 % NaF varnish. Experimental and control groups were: 1 % Arg-NaF; 2 % Arg-NaF; 4 % Arg-NaF; NaF and no treatment. Artificial incipient caries-like lesions were formed on 30 enamel specimen blocks (n = 6). The specimens underwent multi-species bacterial pH-cycling in an artificial mouth system using oral biofilm reactor for 72 h after treatment. The specimens were evaluated for mineral density using micro-CT, Ca/P ratio with SEM-EDX, enamel fluoride uptake (EFU) and plaque fluoride uptake (PFU).

RESULTS

Increasing concentrations of Arg in NaF varnish significantly increased the EFU of incipient caries-like lesions (p < 0.001). The PFU for 1 % Arg-NaF was significantly higher than 4 % Arg-NaF and the control NaF (p < 0.05). Post pH-cycling, Ca/P ratio with 1 %/2 % Arg-NaF was closest to hydroxyapatite (1.67). Mineral gain and % remineralization of 1 %/2 % Arg-NaF was significantly higher than the control NaF varnish (p < 0.05).

CONCLUSION

The prebiotic L-arginine (at 1 %/2 % by wt.) in a 5 % NaF varnish enhanced the enamel fluoride uptake and remineralization potential of the conventional 5 % NaF varnish.

CLINICAL SIGNIFICANCE

The Arg-NaF varnish addresses the limitations of fluorides on cariogenic biofilms. The Arg-NaF varnish appears a promising caries-preventive regimen that counters the pathogenic biofilms by Arg and promotes remineralization with fluorides. In high caries-risk patients, professional application of Arg-NaF varnish might aid to alleviate the global burden of dental caries.

Effectiveness of a Novel Dentifrice Containing Stabilized Chlorine Dioxide, Sarkosyl, and Sodium Fluoride

This in vitro study evaluated the effectiveness of a novel dentifrice containing stabilized chlorine dioxide, sodium lauroyl sarcosinate (sarkosyl), and sodium fluoride in enhancing enamel fluoride uptake, remineralization, pellicle cleaning and inhibiting biofilm regrowth. Remineralization was measured by fluoride uptake and surface microhardness assessment tests. Artificial stains were removed and scored based on pellicle cleaning ratio. Biofilm regrowth was measured by counting colonies on the agar plates. All studies were conducted using bovine teeth specimens. The efficacy of Toothpaste C (CloSYS anticavity toothpaste) was compared with United States Pharmacopoeia Reference Dentifrice, Toothpaste B (discontinued CloSYS anticavity toothpaste formulation) and leading commercial toothpastes. The enamel fluoride uptake and remineralization by Toothpaste C was 96.1% to 303.3% and 38.0% to 102.4% higher than the tested toothpastes, respectively. The mean pellicle cleaning ratio of Toothpaste C was similar to American Dental Association Reference Material. Toothpaste C had a significant reduction in regrowth of the oral polymicrobial biofilm compared to the control. All tested toothpastes contained 0.24% sodium fluoride. Toothpaste C exhibited significantly superior performance towards fluoride uptake and remineralization compared to the tested toothpastes. Therefore, toothpaste ingredients other than sodium fluoride accounted for the enhanced fluoride uptake and remineralization.

A Scoping Review on Arginine in Caries Prevention

OBJECTIVES

Emerging science on arginine or arginine formulations has driven the need to examine the research in the field. The scoping study objectives were (1) to identify the extent, range, and type of evidence on the role of arginine or arginine formulations in caries prevention and (2) to explore the future scope of research on arginine-containing caries-preventive agents.

METHODS

A systematic search was performed in PubMed, Scopus, and Web of Science. In vitro studies, clinical trials, narrative reviews, systematic reviews and or meta-analysis, and umbrella reviews or meta-evaluation examining arginine or arginine formulations for caries prevention were included. The data-charting process involved extracting variables followed by evidence synthesis. Arginine variants investigated up to date were discussed to explore future scope of research.

RESULTS

Thirty-nine articles were included for review from 105 identified citations comprising of in vitro studies, clinical trials, and reviews. Most articles studied 1.5% arginine-fluoride toothpaste. Most studies were from Asia, followed by North America, with fewest studies from Europe and South America. Arginine or arginine formulations demonstrated a superior caries-preventive effect compared with their matched controls (including fluorides); however, the evidence is with high risk of bias. Until now, three arginine variants have been investigated with l-arginine monohydrochloride as the least explored variant.

CONCLUSIONS

The evidence on the caries-preventive effect of arginine or arginine formulations has a high risk of bias. High-quality clinical trials are needed to assess the caries-preventive potential of arginine in commercial formulations. The role of l-arginine monohydrochloride in caries prevention can further be explored by incorporating in self-applied and professionally applied caries-preventive agents.

Evaluation of the Efficacy of Different Remineralizing Agents on Artificial Early Enamel Lesions of Primary Teeth: An In Vitro Study

Aim:

To analyze the remineralization efficacy of casein phosphopeptide–amorphous calcium phosphate (CPP–ACP) and 8% arginine on artificial early enamel lesions on primary teeth enamel samples.

Materials and Methods:

In this in vitro study, artificial enamel lesions were created in 120 primary teeth. Teeth were randomly divided into 5 groups: group C: CPP–ACP paste; group CF: CPP–ACPF paste with 900 ppm flour; group A: paste with 8% arginine; group K+: 500 ppm NaF as a positive control; and group K–: deionized water as a negative control. After 4 weeks of the remineralization process, the effect of remineralization on samples of agents used the microhardness, atomic force microscope, and scanning electron microscope analyses. Statistical analysis was done using Statistical Package for the Social Sciences (SPSS version 20.0, SPSS Inc., Chicago, IL, USA). ANOVA and Tukey Post-Hoc multiple comparison test were applied ( p < .05).

Results:

Increasing percentage values of the microhardness at groups C, CF, and A were significantly better than group K– ( p < .05), whereas there is no statistically significant difference with group K+ ( p > .05). The average surface roughness values of groups C and CF were similar with group K+ in AFM analysis, whereas average surface roughness values of group A were significantly higher than K+ group.

Conclusion:

The CPP–ACP, CPP–ACPF, and arginine are effective agents for remineralization of early childhood caries lesions.

The combined antimicrobial effect of arginine and fluoride toothpaste

The aim of the study was to investigate the antibacterial effect of arginine (Arg) in NaF toothpaste. 24-h mono-/3-species biofilm cultures of S. mutans, S. sanguis and S. gordonii inoculated sHA discs were subjected to treatment with toothpaste supernatants prepared as - [1]:2% Arg -NaF (0.147% F), [2]:4% Arg-NaF (0.144% F), [3]:8% Arg - NaF (0.138% F), [4]:NaF (0.15%) and [5]:deionized water. After 24-h incubation, the mono-species biofilms were subjected to viability assay using WST-8, SEM and confocal imaging (CLSM). The 3-species biofilm were quantified for bacterial composition by PCR analysis, SEM, CLSM, and RNA isolation with reverse-transcription PCR analysis. Increasing arginine concentrations in NaF toothpaste had no effect on microbial viability. The mono-/3-species biofilm imaging depicted that the 2% Arg-NaF and 4% Arg-NaF had a biofilm disrupting effect. The 3-species biofilm bacterial composition indicated that the 2% Arg-NaF group maintained an ecological homeostasis by inhibiting S. mutans growth and enriching the growth of S. sanguis and S. gordonii. The 2% Arg-NaF group significantly downregulated the expression of virulent gtfB gene and upregulated the expression of sagP with relative dominance of arcA. Incorporation of 2% arginine in NaF toothpaste might enrich the alkali-producing bacteria and provide enhanced counter mechanisms against cariogenic pathogen when compared to NaF toothpaste.

Recent Advances in Dental Hard Tissue Remineralization: A Review of Literature

The dental caries is not simply a continuous and unidirectional process of the demineralization of the mineral phase, but a cyclic event with periods of demineralizations and remineralisation. The remineralization process is a natural repair mechanism to restore the minerals again, in ionic forms, to the hydroxyapatite (HAP) crystal lattice. It occurs under near-neutral physiological pH conditions whereby calcium and phosphate mineral ions are redeposited within the caries lesion from saliva and plaque fluid resulting in the formation of newer HAP crystals, which are larger and more resistant to acid dissolution. Numerous types of remineralizing agents and remineralizing techniques have been researched and many of them are being used clinically, with significantly predictable positive results. The recent researches on remineralization are based on biomimetic remineralization materials, having the capability to create apatite crystals within the completely demineralized collagen fibers.

HOW TO CITE THIS ARTICLE

Arifa MK, Ephraim R, et al. Recent Advances in Dental Hard Tissue Remineralization: A Review of Literature. Int J Clin Pediatr Dent 2019;12(2):139-144.

Evaluation of Different Dentifrice Compositions for Increasing the Hardness of Demineralized Enamel: An in Vitro Study

This study aimed to evaluate microhardness of a dentifrice containing fluoride and arginine compared to a positive control (fluoride only) and a negative control (no fluoride) on sound and demineralized bovine enamel surfaces. Specimens were randomly assigned to different treatments that included daily pH cycling and brushing three times a day with one of the following dentifrices (n = 8): Neutraçucar (arginine and fluoride), Colgate Total 12 (fluoride) and My First Colgate (no fluoride). Enamel carious lesions were artificially created one week before the beginning of these treatments (demineralized bovine enamel (DE) groups). The same groups were also tested in sound enamel (sound bovine enamel (SE) groups). Microhardness was measured at baseline and after one, two, and five weeks of treatment using a Knoop indenter. Statistical analysis involved two-way Analysis of Variance (ANOVA) and Tukey’s test. After five weeks, both Total 12 and Neutraçucar had increased the microhardness of DE specimens (p < 0.05). Only Neutraçucar had increased the microhardness of the sound enamel after five weeks of treatment. Thus, it could be concluded that arginine-based dentifrices increase the microhardness of sound and demineralized bovine enamel surfaces.

Effect of Toothpaste Use Against Mineral Loss Promoted by Dental Bleaching

AIM

To investigate the effect of different toothpaste formulations used prior to dental bleaching with 35% hydrogen peroxide (HP) on the mineral content and surface morphology of enamel.

METHODS

Seventy bovine enamel blocks (4×4×2 mm) were submitted to in vitro treatment protocols using a toothbrushing machine prior to dental bleaching or a placebo procedure (n=10) as proposed in the following groups: unbleached control (PLA), bleached control (HP), and brushing with differing toothpastes prior to HP bleaching, including: potassium nitrate toothpaste containing sodium fluoride (PN), sodium monofluorophosphate/MFP toothpaste (FT), arginine-carbonate (8% arginine) (PA) or arginine-carbonate (1.5% arginine) toothpaste (SAN), and toothpaste containing bioactive glass (NM). Phosphorus concentration in gel ([P]) was evaluated (μg of P/mg of gel), and the elemental levels (wt%) of Ca, P, and Na as well as the proportion between Ca and P and spectra graphics were determined using an energy-dispersive X-ray spectrometer (EDS). The surface morphology was assessed using scanning electron microscopy (SEM). The data were subjected to analysis of variance and the Tukey test (α=0.05).

RESULTS

HP demonstrated the greatest [P] values in gel, being statistically different from PLA. The [P] of NM was statistically similar to PLA. HP showed a significant decrease in the Ca% and Ca/P values when compared to PLA in EDS analysis. PA showed Ca/P values statistically different from HP. In accordance with SEM analysis, the PA, SAN, and NM groups presented a smooth and uniform enamel surface, while HP and FT demonstrated some alterations in morphology.

CONCLUSION

The toothpastes containing bioactive glass or arginine carbonate used prior to dental bleaching were effective in protecting enamel against mineral loss promoted by the whitening procedure.

Ecological Effect of Arginine on Oral Microbiota

Dental caries is closely associated with the microbial dybiosis between acidogenic/aciduric pathogens and alkali-generating commensal bacteria colonized in the oral cavity. Our recent studies have shown that arginine may represent a promising anti-caries agent by modulating microbial composition in an in vitro consortium. However, the effect of arginine on the oral microbiota has yet to be comprehensively delineated in either clinical cohort or in vitro biofilm models that better represent the microbial diversity of oral cavity. Here, by employing a clinical cohort and a saliva-derived biofilm model, we demonstrated that arginine treatment could favorably modulate the oral microbiota of caries-active individuals. Specifically, treatment with arginine-containing dentifrice normalized the oral microbiota of caries-active individuals similar to that of caries-free controls in terms of microbial structure, abundance of typical species, enzymatic activities of glycolysis and alkali-generation related enzymes and their corresponding transcripts. Moreover, we found that combinatory use of arginine with fluoride could better enrich alkali-generating Streptococcus sanguinis and suppress acidogenic/aciduric Streptococcus mutans, and thus significantly retard the demineralizing capability of saliva-derived oral biofilm. Hence, we propose that fluoride and arginine have a potential synergistic effect in maintaining an eco-friendly oral microbial equilibrium in favor of better caries management.