Farnesal-loaded pH-sensitive polymeric micelles provided effective prevention and treatment on dental caries.

BACKGROUND: Farnesol is a sesquiterpene from propolis and citrus fruit that shows promising anti-bacterial activity for caries treatment and prevention, but its hydrophobicity limits the clinical application. We aimed to develop the novel polymeric micelles (PMs) containing a kind of derivative of farnesol and a ligand of pyrophosphate (PPi) that mediated PMs to adhere tightly with the tooth enamel. RESULTS: Farnesal (Far) was derived from farnesol and successfully linked to PEG via an acid-labile hydrazone bond to form PEG-hyd-Far, which was then conjugated to PPi and loaded into PMs to form the aimed novel drug delivery system, PPi-Far-PMs. The in vitro test about the binding of PPi-Far-PMs to hydroxyapatite showed that PPi-Far-PMs could bind rapidly to hydroxyapatite and quickly release Far under the acidic conditions. Results from the mechanical testing and the micro-computed tomography indicated that PPi-Far-PMs could restore the microarchitecture of teeth with caries. Moreover, PPi-Far-PMs diminished the incidence and severity of smooth and sulcal surface caries in rats that were infected with Streptococcus mutans while being fed with a high-sucrose diet. The anti-caries efficacy of free Far can be improved significantly by PPi-Far-PMs through the effective binding of it with tooth enamel via PPi. CONCLUSIONS: This novel drug-delivery system may be useful for the treatment and prevention of dental caries as well as the targeting therapy of anti-bacterial drugs in the oral disease.

Fluoride release and re-release from a bioactive restorative material.

PURPOSE: To compare the amount of fluoride release and re-release of three different restorative materials. METHODS: The three restorative materials included a resin-based composite (Z100TM, 3M-ESPE), a resin-modified glass ionomer cement (VitremerTM, 3M-ESPE) and a bioactive material (Activa Bioactive-RestorativeTM, Pulpdent,). Ten disks were fabricated from each material. The disks were immersed in deionized water and stored. Samples were taken from each vial on Days 1, 7, 14 and 30 for fluoride ion analysis. Each disk was then exposed to 2.0% neutral sodium fluoride gel (0.9% fluoride ion, Dentsply), immersed in deionized water and stored. Samples were taken on Days 1, 7, 14 and 30 for fluoride ion analysis utilizing a fluoride-specific ion-analyzer. RESULTS: Z100 released less fluoride on Days 1 (P< 0.001), 7 (P= 0.001) and 14 (P< 0.022) for Phase I (initial release) than Phase II (re-release). Vitremer and Activa released less fluoride on Days 7, 14 and 30 (P< 0.001) for Phase II than Phase I. For all intervals of Phase I, Vitremer released the most fluoride, Activa released the second most, and Z100 released the least. These results were the same for Days 7, 14 and 30 of Phase II. The level of fluoride release from Activa was less than that of Vitremer, and greater than that of Z100 for all intervals of Phase I. The results were the same for all but one interval of Phase II. CLINICAL SIGNIFICANCE: This in vitro study evaluated the fluoride release and subsequent re-release of fluoride following a topical fluoride treatment to analyze if the materials were truly bioactive. The results indicate the bioactive material does uptake fluoride and re-release it which could offer inhibition to caries at restoration margins.

Fluoride Uptake Profiles of Selected European Toothpastes into Hard Tissues and Plaque.

OBJECTIVES: To compare the fluoridating potential of selected European toothpastes using a combination of enamel, dentin, and plaque in vitromodels. METHODS: Four in vitromodels were included: 1) Enamel Fluoride (F) Uptake (EFU); 2) Dentin F Uptake (DFU); 3) Enamel Solubility Reduction (ESR); and 4) Plaque F Uptake (PFU). A core set of marketed products was included in all studies, plus a standard toothpaste (1100 ppm F as NaF/silica) and placebo control (the PFU study did not include a placebo control). Test dentifrices: [A] Fluocaril® Bi-Fluoré 250 (1500 ppm F as NaF+1000 ppm F as SMFP); [B] LacerAnticaries (2500 ppm F as SMFP); [C] Elmex® Caries Professional™ (1450 ppm F as SMFP+1.5% arginine); [D] Colgate® Triple Action (1450 ppm F as SMFP); [E] Placebo (0 ppm F); and [F] standard toothpaste (1100 ppm as NaF/silica). In all studies (EFU, DFU, ESR, and PFU), assessments were compared for each pair using the Tukey-Kramer HSD test (p < 0.05). RESULTS: In all studies of fluoride uptake, the Fluocaril dentifrice [A] provided the greatest numerical benefit, regardless of the substrate. Statistical groupings were EFU: A > F = B = C = D > E; DFU: A > F = B = C = D = E; PFU: A = B > F = C = D). In demineralization prevention, the Fluocaril dentifrice [A] also provided the greatest benefit (ESR: A = F = C = B = D > E). In all studies that included a placebo control, all of the F-containing dentifrices performed better than the placebo control. CONCLUSIONS: While these results demonstrate that all of the marketed products tested provide effective anticaries benefits, the Fluocaril Bi-Fluoré 250 dentifrice consistently delivered unsurpassed performance. It delivered the highest level of F to plaque, provided greater measures of efficacy in both remineralization and inhibition of demineralization, and delivered substantial improvement in fluoridation of dentin, suggesting the potential for delivering both coronal and root caries benefits.

The effect of fluoride varnishes on caries lesions: an in vitro investigation.

OBJECTIVES: The purpose of this study was to investigate the effect of five commercially available fluoride varnishes (FV) on caries lesions. MATERIALS AND METHODS: Ninety bovine enamel specimens were assigned to five varnish groups (n = 18). Early caries lesions were created in the specimens and characterized using Vickers surface microhardness number (VHN). FV was applied to each group of specimens. Immediately afterwards, 7.5 ml of artificial saliva (AS) were pipetted over each group of specimens, collected and renewed every 15 min for 6 h. AS samples were analyzed for fluoride using an ion-specific electrode. Enamel fluoride uptake (EFU) was determined using the acid etch technique. Each group was then subjected to a pH cycling regimen for 5 days after which VHN was determined again. One-way analysis of variance (ANOVA) was used for data analysis. RESULTS: FVs differed in their rehardening capability (highest mean value was for Enamel Pro = 32.3 ± 5.8 and lowest mean value was for Vanish = 18.9 ± 11.3). No significant difference in EFU was found among groups. Total fluoride release over 6 h was in the order of MI Varnish (303 µg/ml) > Enamel Pro (217 µg/ml) > Flor-Opal (153 µg/ml) > PreviDent(84 µg/ml) > Vanish(28 µg/ml). CONCLUSIONS: ΔVHN and fluoride release characteristics differ among FV products. These differences may be attributed to the different compositions and physical properties of the tested FV. CLINICAL RELEVANCE: Fundamental, comparable research on FV and how different formulations affect early caries lesion rehardening, fluoride release into saliva, and uptake by teeth is scarce.

Assessment of the Influence of Meal Type on Fluoride Absorption due to Ingestion of professionally Applied Gels.

AIMS: The aim of this study is to assess the influence of eating, prior to application of professionally used gels, on the rate of fluoride absorption due to the ingestion of 1.23% acidulated phosphate fluoride (APF). MATERIALS AND METHODS: After fasting for 12 hours, 16 adult volunteers (> 65 kg) ingested two types of meal: Breakfast (n = 8) and Lunch (n = 8). Accidental ingestion of fluoride gel used in molding trays was simulated (12,300 ppm; 61.5 mg F; pH = 4.65) 15 minutes after eating. After ingestion of the fluoride solution, 3 mL of venous blood were collected at the following times: Zero (before ingestion) and 15, 30, 45 minutes, 1, 2, and 3 hours. Fluoride concentrations in blood plasma were determined using an ion selective electrode. RESULTS: With the exception of time 0 (p > 0.05), the average blood plasma concentration of the breakfast group (BG) (0.34 ± 0.04 mg/L) was higher than that of the lunch group (LG) (0.24 ± 0.03 mg/L), with the moment of peak concentration being 2 hours after ingestion for both groups (BG = 0.4 mg/L; LG = 0.28 mg/L). CONCLUSION: Results reinforce the idea that eating before undergoing professional application of fluoride is a factor of extreme importance regarding its safety, and that the time following a patient's heaviest meal should be the time of choice for planning clinical care. CLINICAL SIGNIFICANCE: Our results should be considered when planning collective action that involves the application of the gel on children in a school environment, thus ensuring the procedure's safety.

Oral fluoride levels 1 h after use of a sodium fluoride rinse: effect of sodium lauryl sulfate.

Increasing the concentration of free fluoride in oral fluids is an important goal in the use of topical fluoride agents. Although sodium lauryl sulfate (SLS) is a common dentifrice ingredient, the influence of this ion on plaque fluid and salivary fluid fluoride has not been examined. The purpose of this study was to investigate the effect of SLS on these parameters and to examine the effect of this ion on total (or whole) plaque fluoride, an important source of plaque fluid fluoride after a sufficient interval following fluoride administration, and on total salivary fluoride, a parameter often used as a surrogate measure of salivary fluid fluoride. Ten subjects accumulated plaque for 48 h before rinsing with a 12 mmol/l NaF (228 µg/g F) rinse containing or not containing 0.5% (w/w) SLS. SLS had no statistically significant effect on total plaque and total saliva fluoride but significantly increased salivary fluid and plaque fluid fluoride (by 147 and 205%, respectively). These results suggest that the nonfluoride components of topical agents can be manipulated to improve the fluoride release characteristics from oral fluoride reservoirs and that statistically significant change may be observed in plaque fluid and salivary fluid fluoride concentrations that may not be observed in total plaque and total saliva fluoride concentrations.

On the relationship between the rate of salivary flow and salivary fluoride clearance.

The amount of fluoride retained in the mouth following the application of dentifrices, mouthwashes, etc. may be important in determining their anticaries efficacy. In this study we investigated the relationship between the salivary flow rate and salivary fluoride clearance. Ten adults tested six mouthrinses, consisting of aqueous sodium fluoride solutions (0.013, 0.026 mol/l) with and without added sodium chloride (1.28 mol/l) or sucrose (0.44 mol/l), in a randomised order. Prior to each test, subjects swallowed, rinsed for 2 min with 2 ml water and then expectorated into a preweighed container to obtain a measure of initial saliva flow rate. Next, the procedure was repeated using one of the test rinses. Finally, samples of unstimulated whole saliva were collected for up to 3 h after each mouthrinse application and analysed for fluoride. Salivary fluoride concentrations were significantly lower after application of mouthrinses that contained either sucrose or NaCl, both of which compounds markedly enhanced salivary flow, than after the use of corresponding mouthrinses without any additive. Area under the salivary fluoride clearance curve (AUC) values were inversely correlated with salivary flow rate on an individual basis (p < 0.01). The observed behaviour could not be completely attributed to treatment dilution by saliva at the time of application.

Fractional Urinary Fluoride Excretion (FUFE) of 3-4 year children in the Gaza Strip.

UNLABELLED: A positive association between dental fluorosis prevalence and fluoride (F) concentration in drinking waters has been detected in Gaza Strip. Total Daily Fluoride Retention (TDFR), and Fractional Urinary Fluoride Excretion (FUFE) indicate F body burden; important in assessing fluorosis risk in susceptible age groups. OBJECTIVE: 1, To determine and compare Daily Urinary Fluoride Excretion (DUFE) and FUFE of 3-4-year-olds living in lower (< 0.7), moderate (0.7-1.2) or higher (> 1.2 ) ppm F tap water areas; 2, To determine any relationship between i, DUFE and tap water F; ii, DUFE and Total Daily Fluoride Intake (TDFI); iii, TDFI and TDFR. METHODS: 24-hour urine and tap water samples were collected from 216 children exposed to lower (n = 81), moderate (n = 72), or higher (n = 63) tap water F. ANOVA with Tukey's Test and Pearson's correlation were used to examine differences in mean DUFE and FUFE and relationships between variables. RESULTS: Mean drinking water F was 0.11(sd 0.17), 0.14 (sd 0.28) and 0.38 (sd 0.63) ppmF respectively. Differences (p < 0.0001) in mean DUFEs (0.17 (sd 0.13), 0.25 (sd 0.15) and 0.38 (sd 0.23) mg/day respectively) and mean FUFEs (48 (sd 39)%, 47 (sd 31)% and 63(sd 76)%) were found (p < 0.05). Significant (p < 0.0001) positive correlations were found between DUFE and tap water F; DUFE and TDFI, and; TDFI and TDFR. CONCLUSION: DUFEs of children drinking waters with 0.11 and 0.14ppm F, represented low F usage. The group drinking 0.38ppm F water represented optimal F usage. The weak significant positive association of DUFE with home tap water F suggests low validity for tap water F in estimating F exposure.

Salivary fluoride levels after use of high-fluoride dentifrice.

The aim of the study was to evaluate salivary fluoride (F) availability after toothbrushing with a high-F dentifrice. Twelve adult volunteers took part in this crossover and blind study. F concentration in saliva was determined after brushing with a high-F dentifrice (5000 µg F/g) or with a conventional F concentration dentifrice (1100 µg F/g) followed by a 15 mL distilled water rinse. Samples of nonstimulated saliva were collected on the following times: before (baseline), and immediately after spit (time = 0) and after 1, 2, 3, 4, 5, 10, 15, 20, 30, 45, 60, 90, and 120 min. F analysis was performed with a fluoride-sensitive electrode and the area under curve of F salivary concentration × time (µg F/mL × min(-1)) was calculated. At baseline, no significant difference was found among dentifrices (P > 0.05). After brushing, both dentifrices caused an elevated fluoride level in saliva; however salivary F concentration was significantly higher at all times, when high-F dentifrice was used (P < 0.01). Even after 120 min, salivary F concentration was still higher than the baseline values for both dentifrices (P < 0.001). High-F dentifrice enhanced the bioavailability of salivary F, being an option for caries management in patients with high caries risk.

In vitro effect of calcium-containing prescription-strength fluoride toothpastes on bovine enamel erosion under hyposalivation-simulating conditions.

PURPOSE: To evaluate the ability of calcium-containing prescription-strength fluoride (F) toothpastes in preventing enamel erosion under low salivary flow simulating conditions. METHODS: Enamel and dentin bovine specimens were assigned to the following groups: A - placebo; B - 1,100 ppm F/NaF (Aquafresh Advanced); C - 5,000 ppm F/NaF (Prevident 5000 Booster); D - 5000 ppm F/NaF+calcium sodium phosphosilicate (Topex Renew); and E - 5,000 ppm F/NaF+tri-calcium phosphate (Clinpro 5000). Specimens were positioned in custom-made devices, creating a sealed chamber on the surface, connected to peristaltic pumps. Citric acid was injected into the chamber for 2 minutes, followed by artificial saliva (0.05 ml/minute), for 60 minutes, 4x/day, for 3 days. Aquafresh was also tested under normal salivary flow (0.5 ml/minute), as reference (Group F). Specimens were exposed to the toothpastes for 2 minutes, 2x/day. After cycling, surface loss (SL) and concentration of loosely- and firmly-bound F were determined. Data were analyzed by ANOVA. Results: Group A (placebo) presented highest surface loss (SL), while Group F had the lowest, for both substrates. For enamel, none of the dentifrices differed from Group B or among each other. For dentin, none of the dentifrices differed from Group B, but Group E showed greater protection than Group C. Group E presented the highest F concentrations for both substrates, only matched by Group D for firmly-bound fluoride on enamel. All fluoridated dentifrices tested reduced SL, with no additional benefit from higher F concentrations. Some formulations, especially Clinpro 5000, increased F availability on the dental substrates, but no further erosion protection was observed.

Fluoride Varnishes--Is There a Correlation Between Fluoride Release and Deposition on Enamel?

PURPOSE: Fluoride uptake of enamel after application of fluoride varnishes was compared with fluoride release into artificial saliva. The hypothesis was that fluoride uptake is higher for products exhibiting faster fluoride release. MATERIALS AND METHODS: Fluoride varnishes, i.e. Fluor Protector S, Duraphat, MI Varnish, Clinpro White Varnish, Profluorid Varnish and Enamel Pro Varnish were applied on bovine enamel specimens. Subsequently, specimens were incubated in artificial saliva. After removal of the varnishes, surface bound fluoride was extracted with potassium hydroxide and measured with an ion-selective electrode. Structurally bound fluoride was etched from the same specimens with perchloric acid. Fluoride release of varnish films into artificial saliva was measured for comparison. RESULTS: After 4 h in artificial saliva, the highest total enamel fluoride uptake of 47.9 µg F·cm-² was found with Fluor Protector S, followed by Enamel Pro Varnish with 22.1 µg F·cm-². The other products ranged between 12-16 µg F·cm-². This was several times higher than the negative control. Fluoride uptake did not correlate with release into artificial saliva. During the first 4 h, Duraphat released the lowest and MI Varnish the highest amount of fluoride with 7.7 and 249 µg F·cm-², respectively. The fluoride uptake of these two products was not statistically different. CONCLUSION: Enamel fluoride uptake cannot be predicted from the fluoride release rate of a product. Hence, based on the results of this study, fluoride release into artificial saliva is no measure for the efficacy of a fluoride varnish.

Influence of the Relative Enamel Abrasivity (REA) of Toothpastes on the Uptake of KOH-soluble and Structurally Bound Fluoride.

PURPOSE: To determine the influence of the relative enamel abrasivity (REA) of fluoridated toothpaste on the uptake of KOH-soluble and structurally bound fluoride into enamel. MATERIALS AND METHODS: Bovine enamel samples were randomly allocated to 6 groups (n=36 per group). Groups A to C were treated with sodium fluoride (NaF) toothpastes and groups D to F with amine fluoride (AmF) toothpastes (1500 ppm F each). The REA in groups A and D was 2, in groups B and E it was 6 and in groups C and F it was 9. Twice a day, 18 samples of each group were immersed for 2 min in a slurry (toothpaste:artificial saliva=1:3), while the remaining samples were brushed with the respective slurry (2.5 N force; 60 strokes/min; 2 min). All samples were stored at 37°C and 100% humidity. After five days, the amount of KOH-soluble and structurally bound fluoride was determined and statistically compared by Scheffe's post-hoc tests. RESULTS: REA value and mode of application (immersion or brushing) had no significant influence on the amount of either kind of fluoride from NaF toothpastes. Only for the NaF toothpaste with REA 6 was the amount of KOH-soluble fluoride significantly higher after brushing. With AmF toothpastes, KOH-soluble and structurally bound fluoride concentrations were significantly higher when the samples were brushed. Furthermore, in the REA-2 group, the amounts of KOH-soluble fluoride (brushed or immersed) and structurally bound fluoride (brushed) were significantly higher than in the other groups. CONCLUSION: The REA dependency of KOH-soluble and structurally bound fluoride was found only for the AmF toothpastes. Using AmF toothpaste, the mode of application influenced the uptake of KOH-soluble and structurally bound fluoride into enamel.

Exploratory Randomized Clinical Trial of an Experimental Gel-to-Foam Fluoride Dentifrice Formulation Using an In Situ Caries Model.

OBJECTIVE: To evaluate the in situ caries performance and safety of two experimental fluoride dentifrice formulations (1450 ppm fluoride) with and without 2% isopentane as an excipient, in comparison to a positive control, currently marketed dentifrice (1450 ppm fluoride) and a negative control dentifrice (0 ppm fluoride). METHODS: This was a single-center, examiner-blind, randomized, controlled, four-treatment cross-over study. During each treatment period, the subject wore a modified mandibular partial denture fitted with two gauze-covered, partially demineralized human enamel specimens, and brushed at home for one timed minute, twice daily, for two weeks. At the end of each treatment period, the enamel specimens were removed from the dentures for analysis. During the week between treatment periods, subjects returned to their usual dental hygiene practices for four to five days, received a dental prophylaxis, and used a study-designated non-fluoride dentifrice for two to three days before starting the next treatment. Treatment effect on enamel specimen remineralization was assessed by surface microhardness (SMH). Enamel fluoride uptake was assessed using microdrill enamel biopsy. RESULTS: All fluoride-containing dentifrices demonstrated significant, superior SMH recovery and levels of fluoride uptake compared to the negative control dentifrice. No significant differences were observed for either efficacy variable between the experimental dentifrice formulations and the positive control dentifrice. No significant difference was observed between the 2% isopentane dentifrice and the 0% isopentane dentifrice for SMH recovery. CONCLUSION: The addition of 2% isopentane did not positively or negatively affect fluoride efficacy in this model.

The influence of antibacterial toothpastes on in vitro Streptococcus mutans biofilm formation: a continuous culture study.

PURPOSE: To evaluate the in vitro effect of five toothpastes containing antimicrobial compounds including fluoride, triclosan or hydroxyapatite nano-particles on Streptococcus mutans (S. mutans) biofilm formation. Fluoride uptake by enamel after bacterial challenge was also evaluated. METHODS: Human enamel disks (n= 192) were randomly divided into six groups and brushed with five different toothpastes while the control group was brushed with distilled water. Each group was incubated for 24 and 72 hours with a S. mutans biofilm growing on a modified drip-flow reactor (MDFR). Biofilm formation was determined using a viable biomass assay based on a tetrazolium salt (MTT) and evaluated morphologically with confocal laser-scanning microscopy (CLSM) and scanning electron-microscopy (SEM). Fluoride uptake was evaluated using the enamel biopsy technique. Biofilm formation was also evaluated using 120 disks randomly divided into the same six groups. The number of viable bacteria was determined through plate count on Mitis Salivarius Bacitracin agar (MSB agar). RESULTS: Data from plate count showed the same overall trend of MTT assay. The latter showed that after 24 hours the effect of the tested toothpastes was significantly higher in reducing biofilm formation than after 72 hours. The toothpaste containing a high concentration of amine fluoride (AmF) had the highest performance in reducing biofilm formation. Fluoride uptake of enamel showed a positive trend related to the fluoride concentration in both incubation times.

Comparison of salivary calcium, phosphate and alkaline phosphatase levels in children with early childhood caries after administration of milk, cheese and GC tooth mousse: an in vivo study.

BACKGROUND AND OBJECTIVES: This study compares the Salivary Calcium, Phosphate and Alkaline Phosphataselevels in children with Early Childhood Caries after administration of Milk, Cheese and GC Tooth Mousse to a control group of caries resistant children. STUDY DESIGN: 90 kindergarten children both males and females aged 5 years, from the South Canara region were included in the study. Based on the dmfs score, children were divided into 3 groups: Control group, ECC group and S-ECC group. The Salivary Calcium, Phosphate and Alkaline Phosphatase levels in the sample were assessed before and after administration of Milk, Cheese and GC Tooth Mousse at three different intervals, i.e within 5 minutes, 30 minutes and 60 minutes by using Spectrophotometry. RESULTS: The mean Salivary Calcium levels were higher in caries free group whereas Phosphate and Alkaline Phosphatase were lower in the caries free group which was statistically highly significant (p < 0.001). The Tooth Mousse group showed higher bioavailability of calcium and phosphate which was statistically highly significant (p < 0.001). Salivary Calcium and Phosphate levels within 5 minutes after application of Milk, Cheese and Tooth Mousse were higher than at 30 and 60 minutes. Salivary Alkaline Phosphatase levels were lower than the baseline values at all the 3 intervals after administration of Milk, Cheese and Tooth Mousse and was statistically not significant (p > 0.05). CONCLUSION: Saliva should be saturated with Calcium and Phosphate to affect their bioavailability in amounts adequate for remineralizaton. Milk, Cheese and GC Tooth Mousse applicaton were equally beneficial in saturating the saliva with adequate amount of Calcium and Phosphate.

A comparative evaluation of fluoride release and rechargeability in conventional GIC (type II), pediatric GIC (type IX), and Cention-N: an in vitro study.

PURPOSE: A comparative evaluation of fluoride release and re-chargeability in conventional glass ionomer cement (GIC) (type II), Pediatric GIC (type IX), and Cention-N-an in vitro study at an interval of first, fourteenth, and twenty first days. METHODS: Three groups of test materials, each with twenty samples, were prepared. Measurements of the cumulative fluoride release [parts per million (ppm)] and re-release measured on the first, fourteenth, and twenty first days. Analysis of variance (ANOVA) was used to compare the means for different readings, and Tukey's post hoc analysis was used to compare each group with each other. RESULTS: Initial and subsequent fluoride release of Cention-N at days one, fourteen, and twenty-one were all noticeably higher than those of conventional and pediatric GIC. CONCLUSION: Compared to the Conventional and Pediatric GIC restorative materials, Cention-N was more effective in the initial and fluoride re-release.

Divalent cations enhance fluoride binding to Streptococcus mutans and Streptococcus sanguinis cells and subsequently inhibit bacterial acid production.

One preventive effect of topical fluoride application is derived from the fact that fluoride can inhibit bacterial acid production. Furthermore, divalent cations such as Ca(2+) and Mg(2+) increase the binding of fluoride to bacterial cells. These findings suggest that exposure of oral bacteria to fluoride in the presence of divalent cations increases fluoride binding to bacterial cells and subsequently enhances fluoride-induced inhibition of bacterial acid production. This study investigated the effects of fluoride exposure (0-20,000 ppm F) in the presence of Ca(2+) or Mg(2+) prior to glucose challenge on pH fall ability by bacterial sugar fermentation, as well as fluoride binding to bacterial cells by exposure to fluoride, and fluoride release from bacterial cells during bacterial sugar fermentation, using caries-related bacteria, Streptococcus mutans and Streptococcus sanguinis. The pH fall by both streptococci was inhibited by exposure to over 250 ppm F in the presence of Ca(2+) (p < 0.01), whereas in the presence of Mg(2+), the pH fall by S. mutans and S. sanguinis was inhibited after exposure to over 250 and 950 ppm F, respectively (p < 0.05). The amounts of fluoride binding to and released from streptococcal cells increased with the concentration of fluoride the cells were exposed to in the presence of Mg(2+), but were high enough even after 250 ppm F exposure in the presence of Ca(2+). The enhanced inhibition of acid production in the presence of divalent cations is probably due to the improved efficiency of fluoride binding to bacterial cells being improved via these divalent cations.

Important considerations in the development of toothpaste formulations for children.

A number of factors should be taken into account when designing toothpaste formulations for use by children at the different stages of their development. While adult toothpaste formulations may provide caries prevention benefits for children at risk of caries, these formulations may also contain higher levels of abrasive in order to address the staining needs of the adult population owing to smoking and the consumption of dietary chromogens such as coffee and tea, which are not normally found in the diet of children. While toothpastes formulated for adults are also likely to contain higher concentrations of surfactant and flavour, many children prefer toothpastes with mild flavours and modest foaming characteristics. An ideal children's toothpaste formulation should therefore aim to maximise fluoride availability, with appropriate abrasivity, while still delivering effective cleaning, as well as levels and types of flavour and surfactant to provide an acceptable brushing experience. Selection of toothpaste flavour types for children of different ages should ideally be based directly upon preference data from children. Flavours perceived as pleasant during brushing studies have been linked to increased brushing time, which, in turn, can increase the delivery and efficacy of fluoride from toothpastes. Therefore, manufacturers select tested, child-friendly flavours to maximise compliance, providing a more pleasurable brushing experience and oral health benefits.

The effect of dentifrice quantity and toothbrushing behaviour on oral delivery and retention of fluoride in vivo.

While toothpaste F(-) concentration and rinsing regimen have well-characterised impacts on fluoride's effectiveness, other aspects of brushing regimen have much less well-established effects, in particular, dentifrice quantity and brushing duration. An in vivo study (n = 42) of oral fluoride delivery (i.e. oral disposition post-brushing), and retention (i.e. concentration of F(-) in saliva post-brushing, a known efficacy predictor), was performed to compare effects observed with those of dentifrice F(-) concentration and rinsing regimen. Subjects brushed with a NaF-silica dentifrice (Aquafresh Advanced, 1,150 ppm F(-) ) or a control dentifrice (250 ppm F(-) , same base), for 45, 60, 120 or 180 seconds with 0.5 or 1.5 g dentifrice, and rinsed with 15 ml water once or three times in a cross-over design. The F(-) concentration was measured in post-brushing expectorate, rinse and toothbrush washing samples, and in saliva between 5-120 minutes after brushing. Using 1.5 g versus 0.5 g dentifrice increased F(-) in all samples: oral retention of F(-) was almost doubled by this increase. Increasing duration of brushing had more complex effects. The amount of F(-) in the expectorate increased but decreased in both rinse and toothbrush washing samples. Oral F(-) retention increased, but only in the period 30-120 minutes after brushing. Over the ranges investigated, the order of importance on oral F(-) retention was: dentifrice F(-) concentration > quantity > rinsing regimen > brushing duration. Hence, increasing dentifrice quantity and, to a lesser extent, the duration of brushing, can elevate oral fluoride post-brushing. Evidence is accumulating that the importance of these variables to fluoride efficacy may have been underestimated.

A randomised clinical study to evaluate experimental children's toothpastes in an in-situ palatal caries model in children aged 11-14 years.

OBJECTIVES: To compare three children's sodium fluoride toothpastes to placebo with respect to enamel remineralisation potential, enamel fluoride uptake and net acid resistance using an in situ palatal caries model in children aged 11-14 years following a single brushing. DESIGN: This was a randomised, single blind (laboratory analyst), single-centre, four-treatment, crossover study with a 7-day washout period between treatments. The treatments were 1,426 ppm fluoride, 1,000 ppm fluoride, 500 ppm fluoride and 0 ppm fluoride (placebo) toothpaste (NaF/silica). A custom made in situ palatal appliance was used by each subject in all treatment periods. At each of the four treatment visits subjects wore the appliance containing four partially demineralised human enamel specimens for 5 minutes and then brushed their teeth using a standardised procedure for 60 seconds under supervision using 1.0 g (±0.1 g) of their assigned toothpaste. After 4 hours the appliance was removed and enamel specimen recovered. This process was repeated until all subjects completed all four study treatment visits. Recovered enamel specimens were analysed for per cent surface microhardness recovery (%SMHR; Knoop) and enamel fluoride uptake (EFU; microdrill biopsy). Subsequently, specimens were demineralised in vitro to determine their % net acid resistance (%NAR; Knoop). RESULTS: All three fluoride toothpastes demonstrated significantly greater %SMHR, EFU and %NAR compared with 0 ppm F toothpaste. The model demonstrated a dose response over the range 0 to 1,426 ppm fluoride for %SMHR, EFU and %NAR. There was no significant difference between 500 ppm F and 1,000 ppm F for %SMHR and between 1,000 ppm F and 1,426 ppm F for %SMHR, EFU and %NAR. CONCLUSIONS: The present in situ study demonstrated that the children's fluoride toothpastes tested are capable of delivering cariostatic amounts of fluoride to early caries lesions following a single brushing.