Effect of fluoride or chitosan toothpaste and at-home bleaching in enamel roughness, tooth color, and staining susceptibility.

PURPOSE: To evaluate how fluoride- or chitosan-based toothpaste used during at-home bleaching affects enamel roughness, tooth color, and staining susceptibility. METHODS: Bovine enamel blocks were submitted to a 14-day cycling regime considering a factorial design (bleaching agent x toothpaste, 2 x 3), with n=10: (1) bleaching with 16% carbamide peroxide (CP) or 6% hydrogen peroxide (HP), and (2) daily exposure of a fluoride (1,450 ppm F-NaF) toothpaste (FT), chitosan-based toothpaste (CBT), or distilled water (control). Then, 24 hours after the last day of bleaching procedure the samples were exposed to a coffee solution. Color (ΔEab, ΔE00, L*, a*, b*) and roughness (Ra, µm) analyses were performed to compare the samples initially (baseline), after bleaching, and after coffee staining. The results were evaluated by linear models for repeated measures (L*, a*, b*, and Ra), 2-way ANOVA (ΔEab, ΔE00) and Tukey's test (α= 0.05). RESULTS: After the at-home bleaching procedure (toothpaste vs. time, P< 0.0001), the toothpaste groups presented a statistically lower Ra than the control (CBT 0.05). After coffee exposure, CBT presented lower ΔEab and ΔE00 values in the HP groups (toothpaste, P< 0.0001), and lower b* and a* values in the CP groups (toothpaste vs. time, P= 0.004). CLINICAL SIGNIFICANCE: Fluoride or chitosan delivered by toothpaste can reduce surface alterations of the enamel during at-home bleaching, without affecting bleaching efficacy.

Metabolomics reveals high fructose-1,6-bisphosphate from fluoride-resistant Streptococcus mutans.

BACKGROUND: Fluoride-resistant Streptococcus mutans (S. mutans) strains have developed due to the wide use of fluoride in dental caries prevention. However, the metabolomics of fluoride-resistant S. mutans remains unclear. OBJECTIVE: This study aimed to identify metabolites that discriminate fluoride-resistant from wild-type S. mutans. MATERIALS AND METHODS: Cell supernatants from fluoride-resistant and wild-type S. mutans were collected and analyzed by liquid chromatography-mass spectrometry. Principal components analysis and partial least-squares discriminant analysis were performed for the statistical analysis by variable influence on projection (VIP > 2.0) and p value (Mann-Whitney test, p < 0.05). Metabolites were assessed qualitatively using the Human Metabolome Database version 2.0 ( http://www.hmdb.ca ), or Kyoto Encyclopedia of Genes and Genomes ( http://www.kegg.jp ), and Metaboanalyst 6.0 ( https://www.metaboanalyst.ca ). RESULTS: Fourteen metabolites differed significantly between fluoride-resistant and wild-type strains in the early log phase. Among these metabolites, 5 were identified. There were 32 differential metabolites between the two strains in the stationary phase, 13 of which were identified. The pyrimidine metabolism for S. mutans FR was matched with the metabolic pathway. CONCLUSIONS: The fructose-1,6-bisphosphate concentration increased in fluoride-resistant strains under acidic conditions, suggesting enhanced acidogenicity and acid tolerance. This metabolite may be a promising target for elucidating the cariogenic and fluoride resistant mechanisms of S. mutans.

Effect of treatment with phosphate, casein phosphopeptide and fluoride on the remineralization: in vitro study.

This study aimed to evaluate in vitro the effect protocols and anticaries agents containing casein amorphous calcium fluoride phosphopeptide-phosphate (CPP-ACPF, MI Paste Plus), sodium trimetaphosphate (TMP) and fluoride (F), in remineralization of caries lesions. Bovine enamel blocks with initial caries lesions were divided into groups (n = 12): 1) Toothpaste without F-TMP-MI Plus (Placebo); 2) Toothpaste 1100 ppm F (1100F), 3) 1100F + MI Paste Plus (1100F-MI Paste Plus), 4) Toothpaste with 1100F + Neutral gel with 4,500 ppm F + 5%TMP (1100F + Gel TMP) and 5) Toothpaste with 1100F + Neutral gel with 9,000 ppm F (1100F + Gel F). For the 4 and 5 groups the gel was applied only once for 1 minute, initially to the study. For the 3 group, after treatment with 1100F, MI Paste Plus was applied 2x/day for 3 minute. After pH cycling, the percentage of surface hardness recovery (%SHR); integrated loss of subsurface hardness (ΔKHN); profile and depth of the subsuperficial lesion (PLM); concentrations of F, calcium (Ca) and phosphorus (P) in enamel was determined. The data were analyzed by ANOVA (1-criterion) and Student-Newman-Keuls test (p < 0.001). Treatment with 1100F alone led to ~ 28% higher remineralization when compared to treatment with 1100F associated with MI Paste Plus (p < 0.001). The 1100F and 1100F + Gel F groups showed similar values for %SHR (p = 0.150). 1100F + Gel TMP treatment also remineralized the enamel surface by ~ 30% and 20% when compared to the 1100F + Gel F and 1100F groups (p < 0.001). The lower lesion depth (ΔKHN) was observed for the 1100F + Gel TMP group (p < 0.001), where it was 54% and 44% lower in comparison to the 1100F and 1100F + Gel F groups (p < 0.001). Polarized light microscopy photomicrographs showed subsurface lesions in all groups, but these lesions were present to a lower extent in the 1100F + Gel TMP group (p < 0.001). Treatment with 1100F + Gel TMP promoted an increase in the concentration of Ca in the enamel by ~ 57% and ~ 26% when compared to the 1100F and 1100F + MI Paste Plus groups (p < 0.001), respectively. There were no significant differences between the 1100F, 1100F + MI Paste Plus and 1100F + Gel F groups (p > 0.001). Similar values of P in the enamel were observed in the 1100F, 1100F + MI Paste Plus and 1100F + Gel F groups (p > 0.001), except for the 1100F + Gel TMP group, which presented a high concentration (p < 0.001). We conclude that the 1100F+TMP gel treatment/protocol led to a significant increased remineralization when compared to the other treatments/protocols and may be a promising strategy for patients with early caries lesions.

Measurement and analysis of microbial fluoride resistance in dental biofilm models.

The interactions between communities of microorganisms inhabiting the dental biofilm is a major determinant of oral health. These biofilms are periodically exposed to high concentrations of fluoride, which is present in almost all oral healthcare products. The microbes resist fluoride through the action of membrane export proteins. This chapter describes the culture, growth and harvest conditions of model three-species dental biofilm comprised of cariogenic pathogens Streptococcus mutans and Candida albicans and the commensal bacterium Streptococcus gordonii. In order to examine the role of fluoride export by S. mutans in model biofilms, procedures for generating a strain of S. mutans with a genetic knockout of the fluoride exporter are described. We present a case study examining the effects of this mutant strain on the biofilm mass, acid production and mineral dissolution under exposure to low levels of fluoride. These general approaches can be applied to study the effects of any gene of interest in physiologically realistic multispecies oral biofilms.

Low-fluoride gels supplemented with nano-sized sodium trimetaphosphate reduce dentin erosive wear in vitro.

OBJECTIVE: The study assessed the effect of low-fluoride gels supplemented with micrometric or nano-sized sodium trimetaphosphate (TMP) on dentin erosive wear in vitro. DESIGN: Bovine dentin blocks (n = 154) were selected by surface microhardness and randomly allocated into seven groups (n = 22/group), according to the gels: Placebo; 4500 ppm F (4500F); 9000 ppm F (9000F); 5% TMP microparticulate plus 4500F (5TMPm+4500F); 2.5% TMP nanoparticulate plus 4500 F (2.5TMPn+4500F); 5% TMP nanoparticulate plus 4500F (5TMPn+4500F); and 12,300 ppm F acid gel (APF). All blocks were treated only once for 60 s and cyclically eroded (ERO, citric acid, 4 × 90 s/day) or eroded and brushed (4 × 15 s/day, five strokes/s, ERO+ABR) over five days (each subgroup n = 11). Dentin wear and integrated hardness loss in depth (ΔKHN) were determined, and the data were submitted to two-way ANOVA, followed by Tukey's test, and Spearman's correlation (p < 0.05). RESULTS: For ERO, all gels containing 4500F supplemented with TMP significantly reduced dentin wear compared with their counterpart without TMP, reaching values similar to 9000F. For ERO+ABR, 5TMPn+ 4500F gel led to significantly lower wear than all its counterparts, reaching values similar to 9000F and APF. As for ΔKHN, all gels containing TMP promoted superior protective effects compared with 4500F, reaching values similar to 9000F and APF under both challenges. A positive correlation between dentin wear and mineral content in depth was verified. CONCLUSIONS: Gels containing 4500F supplemented with TMP significantly reduced dentin erosive wear compared with pure 4500F, with additional benefit from the use of nanoparticles.

Fluoride export is required for the competitive fitness of pathogenic microorganisms in dental biofilm models.

Microorganisms resist fluoride toxicity using fluoride export proteins from one of several different molecular families. Cariogenic species Streptococcus mutans and Candida albicans extrude intracellular fluoride using a CLCF F-/H+ antiporter and FEX fluoride channel, respectively, whereas oral commensal eubacteria, such as Streptococcus gordonii, export fluoride using a Fluc fluoride channel. In this work, we examine how genetic knockout of fluoride export impacts pathogen fitness in single-species and three-species dental biofilm models. For biofilms generated using S. mutans with the genetic knockout of the CLCF transporter, exposure to low fluoride concentrations decreased S. mutans counts, synergistically reduced the populations of C. albicans, increased the relative proportion of oral commensal S. gordonii, and reduced properties associated with biofilm pathogenicity, including acid production and hydroxyapatite dissolution. Biofilms prepared with C. albicans with genetic knockout of the FEX channel also exhibited reduced fitness in the presence of fluoride but to a lesser degree. Imaging studies indicate that S. mutans is highly sensitive to fluoride, with the knockout strain undergoing complete lysis when exposed to low fluoride for a moderate amount of time. Biochemical purification of the S. mutans CLCF transporter and functional reconstitution establishes that the functional protein is a dimer encoded by a single gene. Together, these findings suggest that fluoride export by oral pathogens can be targeted by specific inhibitors to restore biofilm symbiosis in dental biofilms and that S. mutans is especially susceptible to fluoride toxicity. IMPORTANCE: Dental caries is a globally prevalent condition that occurs when pathogenic species, including Streptococcus mutans and Candida albicans, outcompete beneficial species, such as Streptococcus gordonii, in the dental biofilm. Fluoride is routinely used in oral hygiene to prevent dental caries. Fluoride also has antimicrobial properties, although most microbes possess fluoride exporters to resist its toxicity. This work shows that sensitization of cariogenic species S. mutans and C. albicans to fluoride by genetic knockout of fluoride exporters alters the microbial composition and pathogenic properties of dental biofilms. These results suggest that the development of drugs that inhibit fluoride exporters could potentiate the anticaries effect of fluoride in over-the-counter products like toothpaste and mouth rinses. This is a novel strategy to treat dental caries.

Effect of strontium fluoride on mechanical and remineralization properties of enamel: An in-vitro study on a modified orthodontic adhesive.

OBJECTIVES: Evaluate the ability of strontium fluoride on bond strength and enamel integrity after incorporation within orthodontic adhesive system as a delivery vehicle. METHODS: Experimental orthodontic adhesive system Transbond™ XT were modified with 1% Sr2+, 0.5% SrF2, 1% strontium, 0.5% Sr2+, 1% F-, 0.5% F-, and no additions were control. Mixing of formulation was monitored using Fourier transform infrared spectroscopy. Small-molecule drug-discovery suite was used to gain insights into Sr2+, F-, and SrF2 binding. Shear bond testing was performed after 6-months of ageing. Enamel blocks were cut, and STEM pictures were recorded. Specimens were indented to evaluate elastic modulus. Raman microscope was used to collect Raman spectra and inspected using a scanning electron microscope. Crystal structural analysis was performed using X-ray diffraction. Effect of material on cellular proliferation was determined. Confocal was performed to evaluate the effect of formulation on biofilms. RESULTS: FTIR of modified adhesives depicted peak changes within range due to various functional groups existing within samples. TEM represented structurally optimized hexagonal unit-cell of hydroxyapatite. Mean shear bond strength is recorded highest for Transbond XT with 1% SrF2. Dead bacterial percentage appeared higher in 0.5% SrF2 and 1% F- specimens. Crystal lengths showed an increase in 0.5% and 1% SrF2 specimens. Phase contrast within TEM images showed a union of 0.5% SrF2 crystal with enamel crystal with higher elastic modulus and highly mineralized crystalline hydroxyapatite. Intensity of ν1 PO43- and ν1 CO32- along with carbonate - / ν1PO43- ratio displayed good association with strontium fluoride. The formulation showed acceptable cell biocompatibility (p < 0.353). All specimens displayed characteristic diffraction maxima of different apatite angles within XRD. SIGNIFICANCE: Experimental results suggested good biocompatibility, adequate mechanical strength, and far-ranging crystallization ability. This would provide a new strategy to overcome the two major challenges of fixed orthodontics, biofilm growth, and demineralization of enamel.

Characterisation of experimental flowable composites containing fluoride-doped calcium phosphates as promising remineralising materials.

OBJECTIVE: Remineralising composites with antibacterial properties may seal the cavity and prevent secondary caries. This study aimed at developing experimental flowable composites containing different concentrations of fluoride-doped calcium phosphate fillers and evaluating their remineralising and antibacterial properties. METHODS: Experimental resin-based composites containing different concentrations (0-20 %) of fluoride-doped calcium phosphate fillers (VS10/VS20) were formulated. The release of calcium (Ca), phosphate (PO) and fluoride (F) ions was assessed for 30 days. Remineralisation properties were evaluated through ATR-FTIR and SEM/EDX after storage in simulated body fluid (SBF). The metabolic activity and viability of Streptococcus gordonii was also evaluated through ATP, CFU and live/dead confocal microscopy. The evaluation of specific monomer elution from the experimental composites was conducted using high-performance liquid chromatography (HPLC). RESULTS: The composites containing VS10 showed the highest release of Ca, those containing VS20 released more F over time (p < 0.05), while there was no significant difference in terms of PO ions release between the groups (p > 0.05). A quick 7-day mineral precipitation was observed in the tested composites containing VS10 or VS20 at 10 %; these materials also showed the greatest antibacterial activity (p < 0.05). Moreover, the tested composites containing VS10 presented the lowest elution of monomers (p < 0.05). CONCLUSIONS: Innovative composites were developed with low monomers elution, evident antibacterial activity against S. gordonii and important remineralisation properties due to specific ions release. CLINICAL SIGNIFICANCE: Novel composites containing fluoride-doped calcium phosphates may be promising to modulate bacteria growth, promote remineralisation and reduce the risk of cytotoxicity related to monomers' elution.

The effect of combined use of resin infiltration with different bioactive calcium phosphate-based approaches on enamel white spot lesions: An in vitro study.

OBJECTIVES: This in vitro study aimed to evaluate the effect of resin infiltration combined with casein phosphopeptide-amorphous calcium phosphate with fluoride (CPP-ACPF) or bioactive glass (BAG) on the stability of enamel white spot lesions (WSLs) treatment. MATERIALS AND METHODS: Eighty-four enamel blocks were prepared from the buccal surfaces of sound human premolars. All enamel blocks were placed in a demineralisation solution for 3 days to establish the artificial enamel WSLs. Enamel blocks with WSLs were randomly divided into three groups (n = 28 each group): RI/B: one-off resin infiltration followed by twice daily BAG treatment; RI/C: one-off resin infiltration followed by twice daily CPP-ACPF treatment; RI: one-off resin infiltration treatment only (as control) and subjected to pH cycling for 7 days. Surface morphology, elemental analysis, crystal characteristics, surface roughness and microhardness of enamel surfaces were investigated by scanning electron microscopy and energy-dispersive spectrometry observation, X-ray diffraction (XRD), atomic force microscope and Vickers' hardness testing, respectively. RESULTS: Mean values of the surface roughness (mean±standard deviation (nm)) were 24.52±5.07, 27.39±5.87 and 34.36±4.55 for groups RI/B, RI/C and RI respectively (p = 0.003). The calcium to phosphate ratios were 1.32±0.16, 1.22±0.26 and 0.69±0.24 for groups RI/B, RI/C and RI respectively (p < 0.001). XRD revealed apatite formation in all three groups. The mean enamel surface microhardness (kg/mm2) of the groups were 353.93±28.49, 339.00±27.32 and 330.38±22.55 for groups RI/B, RI/C and RI respectively (p = 0.216). CONCLUSIONS: Resin infiltration combined with CPP-ACPF or BAG remineralisation appears to improve the surface properties of WSLs. CLINICAL SIGNIFICANCE: The combination of resin infiltration and CPP-ACPF/BAG remineralisation may be a potential treatment for the management of the WSLs.

Carbazole and Quinazolinone Derivatives from a Fluoride-Tolerant Streptomyces Strain OUCMDZ-5511.

Six new 9H-carbazole derivatives (1-6) and nine previously reported compounds (7-15) were isolated from a fermented solid medium of the Thailand mangrove-derived Streptomyces strain, OUCMDZ-5511, under fluoride stress. Compounds 2-5, 12, and 15 were exclusively present in the fluoride-supplemented fermentation medium, while compounds 7-9, 13, and 14 were newly discovered natural products. The molecular structures of the compounds were identified by a spectroscopic analysis. The new compound 2 displayed antiquorum sensing activity against Chromobacterium violaceum ATCC 12472 by reducing the violacein production and inhibiting the biofilm formation in a concentration-dependent manner. The study revealed that compound 2 could be a novel potential inhibitor of quorum sensing.

Riboflavin Attenuates Fluoride-Induced Testicular Injury via Interleukin 17A-Mediated Classical Pyroptosis.

Male reproductive toxicity of fluoride is of great concern worldwide, yet the underlying mechanism is unclear. Pyroptosis is a novel mode of inflammatory cell death, and riboflavin with anti-inflammatory properties has the potential to protect against fluoride damage. However, it is unknown whether pyroptosis is involved in fluoride-induced testicular injury and riboflavin intervention. Here, we first found that riboflavin could alleviate fluoride-caused lower sperm quality and damaged testicular morphology by reducing pyroptosis based on a model of ICR mice treated with NaF (100 mg/L) and/or riboflavin supplementation (40 mg/L) via drinking water for 13 weeks. And then, together with the results of in vitro Leydig cell modelsm it was confirmed that the pyroptosis occurs predominantly through classical NLRP3/Caspase-1/GSDMD pathway. Furthermore, our results reveal that interleukin-17A mediates the process of pyroptosis in testes induced by fluoride and riboflavin attenuation according to the results of our established models of riboflavin- and/or fluoride-treated IL-17A knockout mice. The results not only declare a new mechanism by which fluoride induces testicular injury via interleukin 17A-mediated classical pyroptosis but also provide evidence for the potential clinical application of riboflavin as an effective therapy for fluoride toxicity.

Adaptive responses of the ileum of NOD mice to low-dose fluoride: A proteomic exploratory study.

Fluoride (F) has been employed worldwide to control dental caries. More recently, it has been suggested that the consumption of low doses of F in the drinking water may reduce blood glucose levels, introducing a new perspective for the use of F for the management of blood glucose. However, the exact mechanism by which F affects blood glucose levels remains largely unexplored. Given that the small gut plays a pivotal role in glucose homeostasis, the aim of this study was to investigate the proteomic changes induced by low doses of F in the ileum of female nonobese-diabetic (NOD) mice. Forty-two female NOD mice were divided into two groups based on the F concentration in their drinking water for 14 weeks: 0 (control) or 10 mgF/L. At the end of the experimental period, the ileum was collected for proteomic and Western blot analyses. Proteomic analysis indicated an increase in isoforms of actin, gastrotropin, several H2B histones, and enzymes involved in antioxidant processes, as well as a decrease in enzymes essential for energy metabolism. In summary, our data indicates an adaptive response of organism to preserve protein synthesis in the ileum, despite significant alterations in energy metabolism typically induced by F, therefore highlighting the safety of controlled fluoridation in water supplies.

Enhanced remineralisation ability and antibacterial properties of sol-gel glass ionomer cement modified by fluoride containing strontium-based bioactive glass or strontium-containing fluorapatite.

OBJECTIVES: This study aimed to compare two types of bioactive additives which were strontium-containing fluorinated bioactive glass (SrBGF) or strontium-containing fluorapatite (SrFA) added to sol-gel derived glass ionomer cement (SGIC). The objective was to develop antibacterial and mineralisation properties, using bioactive additives, to minimize the occurrence of caries lesions in caries disease. METHODS: Synthesized SrBGF and SrFA nanoparticles were added to SGIC at 1 wt% concentration to improve antibacterial properties against S. mutans, promote remineralisation, and hASCs and hDPSCs viability. Surface roughness and ion-releasing behavior were also evaluated to clarify the effect on the materials. Antibacterial activity was measured via agar disc diffusion and bacterial adhesion. Remineralisation ability was assessed by applying the material to demineralised teeth and subjecting them to a 14-day pH cycle, followed by microCT and SEM-EDS analysis. RESULTS: The addition of SrFA into SGIC significantly improved its antibacterial property. SGIC modified with either SrBGF or SrFA additives could similarly induce apatite crystal precipitation onto demineralised dentin and increase dentin density, indicating its ability to remineralise dentin. Moreover, this study also showed that SGIC modified with SrBGF or SrFA additives had promising results on the in vitro cytotoxicity of hASC and hDPSC. SIGNIFICANT: SrFA has superior antibacterial property as compared to SrBGF while demonstrating equal remineralisation ability. Furthermore, the modified SGIC showed promising results in reducing the cytotoxicity of hASCs and hDPSCs, indicating its potential for managing caries.

Amelogenin-inspired peptide, calcium phosphate solution, fluoride and their synergistic effect on enamel biomimetic remineralization: an in vitro pH-cycling model.

BACKGROUND: Several methods were introduced for enamel biomimetic remineralization that utilize a biomimetic analogue to interact and absorb bioavailable calcium and phosphate ions and induce crystal nucleation on demineralized enamel. Amelogenin is the most predominant enamel matrix protein that is involved in enamel biomineralization. It plays a major role in developing the enamel's hierarchical microstructure. Therefore, this study was conducted to evaluate the ability of an amelogenin-inspired peptide to promote the remineralization potential of fluoride and a supersaturated calcium phosphate solution in treating artificially induced enamel carious lesions under pH-cycling regimen. METHODS: Fifty enamel slices were prepared with a window (4*4 mm2 ) on the surface. Five samples were set as control healthy enamel and 45 samples were subjected to demineralization for 3 days. Another 5 samples were set as control demineralized enamel and 40 enamel samples were assigned into 8 experimental groups (n=5) (P/I, P/II, P/III, P/AS, NP/I, NP/II, NP/III and NP/AS) according to peptide treatment (peptide P or non-peptide NP) and remineralizing solution used (I; calcium phosphate solution, II; calcium phosphate fluoride solution, III; fluoride solution and AS; artificial saliva). Samples were then subjected to demineralization/remineralization cycles for 9 days. Samples in all experimental groups were evaluated using Raman spectroscopy for mineral content recovery percentage, microhardness and nanoindentation as healthy, demineralized enamel and after pH-cycling. Data were statistically analysed using two-way repeated measures Anova followed by Bonferroni-corrected post hoc test for pairwise multiple comparisons between groups. Statistical significance was set at p= 0.05. Additionally, XRD, FESEM and EDXS were used for crystal orientation, surface morphology and elemental analysis after pH-cycling. RESULTS: Nanocrystals clumped in a directional manner were detected in peptide-treated groups. P/II showed the highest significant mean values in mineral content recovery (63.31%), microhardness (268.81±6.52 VHN), elastic modulus (88.74±2.71 GPa), nanohardness (3.08±0.59 GPa) and the best crystal orientation with I002/I300 (1.87±0.08). CONCLUSION: Despite pH changes, the tested peptide was capable of remineralizing enamel with ordered crystals. Moreover, the supplementary use of calcium phosphate fluoride solution with peptide granted an enhancement in enamel mechanical properties after remineralization.

The effect of nano silver fluoride, self-assembling peptide and sodium fluoride varnish on salivary cariogenic bacteria: a randomized controlled clinical trial.

OBJECTIVES: To compare the antibacterial effect of Nanosilver Fluoride varnish (NSF) varnish, P11-4 and Sodium Fluoride (NaF) varnish against salivary Streptococcus mutans (S. mutans) and Lactobacilli. METHODS: 66 patients aged 10-24 years old were randomly assigned to receive single application of NSF, P11-4 or NaF varnish. Baseline unstimulated saliva samples were collected before the agents were applied and S.mutans and Lactobacilli colony forming units (CFU) were counted. After one, three and six months, microbiological samples were re-assessed. Groups were compared at each time point and changes across time were assessed. Multivariable linear regression compared the effect of P11-4 and NSF to NaF on salivary S. mutans and Lactobacilli log count at various follow up periods. RESULTS: There was a significant difference in salivary S. mutans log count after 1 month between P11-4 (B= -1.29, p = 0.049) and NaF but not at other time points nor between NSF and NaF at any time point. The significant reduction in bacterial counts lasted up to one month in all groups, to three months after using P11-4 and NaF and returned to baseline values after six months. CONCLUSION: In general, the antimicrobial effect of P11-4 and NSF on salivary S. mutans and Lactobacilli was not significantly different from NaF varnish. P11-4 induced greater reduction more quickly than the two other agents and NSF antibacterial effect was lost after one month. CLINICAL RELEVANCE: NSF varnish and P11-4 have antimicrobial activity that does not significantly differ from NaF by 3 months. P11-4 has the greatest antibacterial effect after one month with sustained effect till 3 months. The antibacterial effect of NSF lasts for one month. NaF remains effective till 3 months. TRIAL REGISTRATION: This trial was prospectively registered on the clinicaltrials.gov registry with ID: NCT04929509 on 18/6/2021.

Remineralisation of enamel and dentine with stabilised stannous fluoride dentifrices in a randomised cross-over in situ trial.

OBJECTIVES: To compare the remineralisation efficacy and ion bioavailability of two novel SnF2-containing dentifrices in a blinded, cross-over, randomised in situ clinical study. METHODS: Six participants wore removal palatal appliances holding human enamel and dentine blocks with subsurface lesions. Appliances were worn for two treatment periods of 14 consecutive days each, with a one-week washout period in-between. Participants were randomly allocated to rinse with a 1:5 diluted coded slurry of one of two dentifrices containing either 5 % casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) +1100 ppm F as SnF2 [MIPOP], or 1100 ppm F as SnF2 [CT], for 1 min, four times a day. Saliva was collected post-treatment and analysed for tin, calcium, inorganic phosphate and fluoride ions using atomic absorption spectrophotometry and ion chromatography. Enamel and dentine lesions were analysed for percent remineralisation (%R) using transverse microradiography and percent surface microhardness recovery (%SMHR). RESULTS: MIPOP released significantly higher F (3.00 ± 0.27 mM), Ca (15.23 ± 3.23 mM) and Sn (1.18 ± 0.13 mM) into saliva whereas CT released 2.89 ± 0.32 mM F and only 0.84 ± 0.11 mM Ca and 0.28 ± 0.10 mM Sn. MIPOP produced significantly higher %R than CT: 25.6 ± 1.5 % compared to 15.2 ± 0.7 % in enamel, and 33.6 ± 3.1 % compared to 20.6 ± 1.1 % in dentine. Additionally, MIPOP produced significantly higher %SMHR (18.2 ± 7.9 %) compared to CT (4.1 ± 0.6 %). CONCLUSIONS: Both dentifrices promoted remineralisation, but the MIPOP dentifrice with added CPP-ACP and the ion-stabilising effects of CPP released higher amounts of bioavailable tin and produced significantly higher remineralisation and surface microhardness recovery. CLINICAL SIGNIFICANCE: Modern dentifrices contain SnF2 for a range of oral health benefits. Challenges associated with stability of these formulations can affect ion bioavailability, reducing efficacy. Two dentifrices with SnF2 promoted remineralisation in situ, however the dentifrice with the added saliva biomimetic CPP-ACP was superior and therefore may produce greater health benefits.

Characteristics of tin-containing fluoride toothpastes related to erosive tooth wear protection.

OBJECTIVES: To assess the effect of different tin-containing toothpastes on the control of erosive tooth wear in enamel and dentin. METHODS: Enamel and dentin slabs were randomly distributed into 7 experimental groups (n = 10/substrate): C-: negative control (Artificial saliva); AmF (regular fluoridated toothpaste without tin); Sn-1 (SnF2/NaF); Sn-2 (SnF2/NaF/SnCl2); Sn-3 (SnCl2/NaF); Sn-4 (SnF2/SnCl2); Sn-5 (SnCl2/AmF/NaF/chitosan). Specimens were submitted to 5-day erosion-abrasion cycling. Surface loss (SL) was determined with an optical profilometer. Tin deposition on the tooth surfaces and some characteristics of the toothpastes (pH, potentially available F-, %weight of solid particles, and RDA) were also assessed. Data were statistically analyzed (α = 0.05). RESULTS: For enamel, the Sn-2 presented the lowest SL, not differing significantly from AmF, C+, and Sn-3. The SL of these groups was significantly lower than the C-, except for Sn-3. Sn-1 and Sn-4 were also not significantly different from C-. For dentin, C- significantly showed the highest SL values, whilst, Sn-1 presented the lowest SL, not differing significantly from AmF, Sn-2, C+, and Sn-3. There was a significant positive association between enamel SL and the pH and tin deposition. Dentin SL was significantly negatively associated with the %weight of solid particles and RDA. CONCLUSIONS: Most of the tin-toothpastes were able to exhibit some protection against ETW. In this process, the toothpastes characteristics play a role, as lower enamel SL was significantly associated with lower pH values and tin deposition; and lower dentin SL was associated with higher %weight of solid particles and RDA of the toothpastes. CLINICAL SIGNIFICANCE: Tin-containing toothpastes can be used for erosive tooth wear protection, but our study showed that their effect depends on the pH, amount of tin deposition, % weight of solid particles and RDA of the toohpastes.

Effect of adhesive components in experimental fluoride varnish on fluoride release within 30 days in vitro study.

We aimed to determine whether adhesive components could increase the release time of effective fluoride concentration from an experimental fluoride varnish applied to bovine teeth. An experimental fluoride varnish containing 5% sodium fluoride (EX1) was prepared and combined with 35% hydroxyethyl methacrylate (HEMA) (EX2), 5% glutaraldehyde (EX3), or 35% HEMA/5% glutaraldehyde mixture (EX4). Two commercially available fluoride varnishes were used for comparison. Each group was applied to bovine incisors, and the fluoride release and pH were monitored for 30 days. Cell viability analysis, scanning electron microscopy, and energy-dispersive spectroscopy were performed. EX4 released the highest and most effective concentration of fluoride for the longest period and reached neutral pH at the earliest; the release was maintained for up to 30 days without cytotoxicity. In conclusion, EX4 is considered to be the most effective varnish to prevent dental caries.

Impact of pH-adjusted fluoride and stannous solutions on the protective properties on the pellicle layer in vitro and in situ.

This study evaluates the ideal pH for anti-erosion and anti-adherent efficacy of fluoride and stannous solutions (sodium fluoride (SF), amine fluoride (AF), sodium monofluorophosphate (SMFP), stannous fluoride (SnF2) with 500 ppm fluoride concentration each and stannous chloride (SnCl2, 1563 ppm stannous)). In vitro, solutions were tested at pH 4.5 and 5.5. The main in situ experiments were carried out at the pH of 4.5: For pellicle formation 6 volunteers wore bovine enamel slabs intraorally for 1 min, rinsed with 8 ml solution for 1 min and continued for up to 30 min/8 h. Physiological pellicle samples served as controls. After incubation in HCl (2.0, 2.3) for 2 min mineral release was determined photometrically. Bacterial counts on 8 h biofilms were determined by fluorescence microscopy (BacLight™ and DAPI with Concanavalin A). Modification of the pellicle ultrastructure was examined by TEM. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney-U tests with Bonferroni-correction (p < 0.05). SnF2 showed a significant erosion protection. AF, SnF2, and SnCl2 were most anti-adherent. SnF2 and SnCl2 caused a pronounced basal pellicle with stannous precipitates. Compared to other fluoride monosubstances, stannous ions offer greater protection against erosive acidic attacks. Stannous ions act as crucial co-factor in this process.

Antibacterial and clinical effectiveness of a mouthwash with a novel active system of amine + zinc lactate + fluoride: a randomized controlled trial.

OBJECTIVES: To support the daily oral hygiene of patients experiencing gum inflammation, a new mouthwash was developed containing an amine + zinc lactate + fluoride system. In vitro and clinical efficacy was assessed using traditional methods as well as using novel site-specific and subject-specific analyses of the clinical data. MATERIALS AND METHODS: This mouthwash was evaluated in a 12-h biofilm regrowth assay against a negative control mouthwash and in a 6-month plaque and gingivitis clinical study as compared to a negative control mouthwash. Analyses of healthy versus inflamed sites, visible plaque versus non-visible plaque sites, as well as subject-level evaluations bring new perspectives to the overall performance of this mouthwash and its significance from a patient outcome perspective. RESULTS: Studies demonstrated that this new mouthwash provided long-term (12-h) antibacterial activity after single application in vitro and reduced clinically all plaque and gingivitis parameters after 3 months and 6 months of use when compared to the negative control mouthwash. Examination of site-level and subject-level data determined that this mouthwash significantly increased the number of healthy sites in the oral cavity and significantly improved the gum health of subjects in the study, as compared to the negative control mouthwash. CONCLUSIONS: In vitro and clinical research has demonstrated the antibacterial and clinical benefits of this mouthwash containing an amine compound + zinc lactate + fluoride system. CLINICAL RELEVANCE: Our subject-specific and site-specific analyses provide the dental practitioner with tools that can be used to guide patients who suffer from gingivitis toward optimal product selection and use. CLINICAL TRIAL REGISTRATION: The trial was registered at ClinicalTrials.gov (reference no. NCT05821712).