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.

Fluoride release from two types of fluoride-containing orthodontic adhesives: Conventional versus resin-modified glass ionomer cements-An in vitro study

INTRODUCTION

Development of white spot lesions (WSLs) during orthodontic treatment is a common risk factor. Fixation of the orthodontic appliances with glass ionomer cements could reduce the prevalence of WSL's due to their fluoride release capacities. The purpose of this study was to evaluate differences of fluoride release properties from resin-modified and conventional glass ionomer cements (GICs).

METHODS

The resin-modified GICs Fuji ORTHO LC (GC Orthodontics), Meron Plus QM (VOCO), as well as the conventional GICs Fuji ORTHO (GC Orthodontics), Meron (VOCO) and Ketac Cem Easymix (3M ESPE) were tested in this study. The different types of GICs were applied to hydroxyapatite discs according to the manufacturer's instructions and stored in a solution of TISAB III (Total Ionic Strength Adjustment Buffer III) and fluoride-free water at 37°C. Fluoride measurements were made after 5 minutes, 2 hours, 24 hours, 14 days, 28 days, 2 months, 3 months and 6 months. One factor analysis of variance (ANOVA) was used for the overall comparison of the cumulative fluoride release (from measurement times of 5 minutes to 6 months) between the different materials with the overall level of significance set to 0.05. Tukey's post hoc test was used for post hoc pairwise comparisons in the cumulative fluoride release between the different materials.

RESULTS

The cumulative fluoride release (mean ± sd) in descending order was: Fuji ORTHO LC (221.7 ± 10.29 ppm), Fuji ORTHO (191.5 ± 15.03 ppm), Meron Plus QM (173.0 ± 5.89 ppm), Meron (161.3 ± 7.84 ppm) and Ketac Cem Easymix (154.6 ± 6.09 ppm) within 6 months. Analysis of variance detected a significant difference in the cumulative fluoride release between at least two of the materials (rounded p-value < 0.001). Pairwise analysis with Tukey's post hoc test showed a significant difference in the cumulative fluoride release for all the comparisons except M and MPQM (p = 0.061) and KCE and M (p = 0.517).

CONCLUSION

Fluoride ions were released cumulatively over the entire test period for all products. When comparing the two products from the same company (Fuji ORTHO LC vs. Fuji ORTHO from GC Orthodontics Europe GmbH and Meron Plus QM vs. Meron from VOCO GmbH, Mannheim, Germany), it can be said that the resin-modified GICs have a higher release than conventional GICs. The highest individual fluoride release of all GICs was at 24 hours. A general statement, whether resin-modified or conventional GICs have a higher release of fluoride cannot be made.

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.

Modified toothpaste application using prepared toothpaste delivering technique increases interproximal fluoride toothpaste delivery

OBJECTIVES

We devised a "prepared toothpaste delivering technique" (PTD technique), a modified the application of toothpaste method for using fluoride toothpaste more effectively. This study aimed to investigate the change in viscosity and fluoride intake into hydroxyapatite of a toothpaste, and deliverability of fluoride toothpaste to the interproximal site with the PTD technique using an interproximal model.

METHODS

Eight toothpaste samples were prepared at the following concentrations: ×1.00, ×1.25, ×1.50, ×1.75, ×2.00, ×3.00, ×4.00, and ×5.00. Viscosity of the toothpaste was measured by a Type-B viscometer. Dissolution rate of toothpaste and fluoride uptake into the hydroxy apatite pellet were analyzed by a fluoride selective electrode. Application paste volume and delivery rate was measured using interproximal model and image analysis software during using a finger brush front (FBF), finger brush back (FBB), and toothbrush.

RESULTS

As the dilution ratio increased, the viscosity of the toothpaste decreased sharply, F uptake decreased, and dissolution rate increased. F uptake was significantly reduced when the toothpaste was diluted more than 1.75 times. Therefore, in order to improve the effectiveness of the fluoride toothpaste, it is important to deliver the toothpaste to interproximal areas and pit clefts at low dilution. It was observed that PTD technique can be effectively implemented by the finger brush.

CONCLUSIONS

The use of a FBF surface in the analysis of an acrylic interproximal model could aid in applying pressure while blocking the space of the groove and preventing outflow of the toothpaste. It was considered that the PTD technique would improve the effects of the fluoride toothpaste, especially in the interproximal site.

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.

Low-fluoride Dentifrice and Gastrointestinal Fluoride Absorption after Meals

A low-fluoride (F) dentifrice has been recommended to reduce the risk of dental fluorosis, but its anti-caries efficacy is questionable compared with that of conventional dentrifices (1000–1100 μg F/g). The tested hypothesis was that conventional dentifrices might be safe if used soon after meals, since food interferes with F absorption. In a crossover, double-blind study, 11 volunteers ingested a dentifrice slurry containing 0 (placebo), 550 (low F), or 1100 μg F/g in 3 gastric content situations: on fasting, or 15 min after breakfast or lunch. F was analyzed in saliva and 24-hour urine samples. The conventional dentifrice ingested after lunch resulted in only 10% higher F absorption than the low-F ingested on fasting. Analysis of the data suggests that the risk of fluorosis could be reduced by the use of either a low-F dentifrice or a conventional dentifrice, if toothbrushing occurred soon after meals.

Bioavailability of Fluoride in Drinking Water: a Human Experimental Study

It has been suggested that systemic fluoride absorption from drinking water may be influenced by the type of fluoride compound in the water and by water hardness. Using a human double-blind cross-over trial, we conducted this study to measure cmax, Tmax, and Area Under the Curve (AUC) for plasma F concentration against time, following the ingestion of naturally fluoridated hard and soft waters, artificially fluoridated hard and soft waters, and a reference water. Mean AUC over 0 to 8 hours was 1330, 1440, 1679, 1566, and 1328 ng F•min•mL−1 for naturally fluoridated soft, naturally fluoridated hard, artificially fluoridated soft, artificially fluoridated hard, and reference waters, respectively, with no statistically significant differences among waters for AUC, cmax, or Tmax. Any differences in fluoride bioavailability between drinking waters in which fluoride is present naturally or added artificially, or the waters are hard or soft, were small compared with large within- and between-subject variations in F absorption. Abbreviations used: F, fluoride; AUC, Area under the Curve for plasma F concentration against time; AUC(0-3), Area under the Curve for plasma F concentration against time for 0 to 3 hours following water ingestion; AUC(0-8), Area under the Curve for plasma F concentration against time for 0 to 8 hours following water ingestion; cmax, maximum plasma F concentration corrected for baseline plasma F and dose ( i.e., F concentration of individual waters); Tmax, time of cmax.

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.

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

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.

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.

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.

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.

Laboratory investigations into the potential anticaries efficacy of fluoride varnishes

PURPOSE

The purpose of this study was to investigate the potential anticaries efficacy of fluoride varnishes (FVs) by studying their ability to reharden and deliver fluoride to carious lesions and to release fluoride into saliva.

METHODS

Enamel carious lesions were created and allocated to 24 groups (11 FVs with two FV incubation times and two control groups) based on Knoop microhardness test values. FVs were applied to lesions, which were incubated in artificial saliva for two or six hours, with saliva being renewed hourly. FV was removed and lesions were remineralized in artificial saliva for 22 hours. Microhardness was measured and enamel fluoride uptake (EFU) was determined. Saliva samples (six-hour groups) were analyzed to determine fluoride release characteristics. Data were analyzed using analysis of variance.

RESULTS

FVs differed considerably in their ability to reharden and deliver fluoride to carious lesions and in their fluoride release characteristics. Little consistency was found between investigated study variables for virtually all tested FVs. For example, a particular FV showed the highest EFU and fluoride release values but the lowest rehardening value. A longer FV contact time led to increased EFU for five of the 11 FVs. Some FVs delivered more fluoride to lesions in two hours than others did in six hours.

CONCLUSION

Fluoride varnishes differ greatly in their in vitro anticaries efficacy.

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.

Physical exercise ameliorates the toxic effect of fluoride on the insulin-glucose system

Daily intake of water with fluoride concentrations >1.5 mg/l produces insulin resistance (IR). On the other hand, physical activity increases insulin sensitivity in the muscle. Therefore, the aim of this study was to evaluate the effect of physical activity on IR in rats treated with sodium fluoride (NaF) in drinking water. Sprague-Dawley rats were divided into three groups (n=10/group): Control (drinking water without NaF), NaF (drinking water with NaF 15 mg/l for 30 days), and Exercise (daily running on a treadmill for 60 min at 2.25 m/min and drinking water with NaF 15 mg/l for 30 days). IR was evaluated with the homeostasis model assessment-IR (HOMA-IR) index using fasting plasma levels of glucose and insulin. IR increased in rats treated with 15 mg/l NaF in drinking water. A decrease in IR was observed in rats that performed physical activity and drank water with 15 mg/l NaF; the Exercise group also showed an increase in the amounts of bone fluoride. The variation in the HOMA-IR values could be the consequence of variation in the sensitivity of tissues to insulin or decrease in plasma fluoride levels due to bone fluoride intake. These findings indicate that the performance of daily physical activity could reduce the negative effects of the chronic ingestion of NaF on glucose homeostasis.

Dissolution of xylitol from a food supplement administered with a novel slow-release pacifier: preliminary results

AIM

The aim of the study was to monitor the pattern of release and salivary xylitol concentrations during sucking of a slow-release pacifier used to deliver a novel food supplement.

METHODS

The food supplement tablet contained 300 mg xylitol and 0.5 x 10(10) colony-forming units of Bifidobacterium lactis Bb-12 (Bb-12). The reference tablet contained 300 mg xylitol and was used by 10 adults (mean age 32 years) in the study. Whole saliva samples were collected with 2.5 min intervals during pacifier sucking. The salivary xylitol concentrations were determined using an enzyme assay kit.

RESULTS

All subjects showed salivary xylitol concentrations exceeding 1% at least at one collection point. The xylitol and xylitol-Bb-12 tablets showed similar dissolving with no clear concentration peaks (comparison of saliva collection times; p = 0.139).

CONCLUSION

Xylitol released from the food supplement, delivered with the novel pacifier, may result in salivary xylitol concentrations high enough to inhibit mutans streptococci in vivo.

Role of nitric oxide and vascular endothelial growth factor in fluoride-induced goitrogenesis in rats

Endemic fluorosis is a serious problem in public health. Previous studies have indicated that patients with thyroid goiters usually live in fluoride-affected areas. However, the mechanism of goitrogenesis caused independently by fluoride is still unclear. The principle objective of this study was to investigate the possible roles of nitric oxide (NO) and vascular endothelial growth factor (VEGF) in the genesis of fluoride-induced nodular goiters. Eighty SD rats (40 males and 40 females) at the age of 4 weeks were used to establish animal models via fluoride-supplemented drinking water. These rats were randomly divided into four groups of 20. Group 1 was used as the control and were given deionized water. Group 2 (LF), group 3 (MF), and group 4 (HF) were given deionized water containing 50mg/L, 100mg/L, and 200mg/L of sodium fluoride (NaF), respectively. Thyroid samples were collected on day 150. Pathological observation was performed to evaluate structural changes in the thyroid gland. The expression of VEGF mRNA in the thyroid glands was assessed by reverse transcriptional PCR. The serum NO level was analyzed by spectrometric methods. In addition, immunohistochemistry was conducted to evaluate expression and deposition of VEGF in the thyroid gland. The results showed that the average relative weight of the thyroid glands of rats in the fluoride-treated groups was significantly higher than that in control rats (p<0.05). The proliferation and dilatation of capillary blood vessels, enlarged follicles with excessive colloid, and obvious nodules were found in the thyroid glands of fluoride-treated rats. Compared to the control group, the expression of VEGF mRNA in the thyroid gland and the serum NO levels in the fluoride-treated groups were significantly increased (p<0.05). Furthermore, the deposition of VEGF in epithelial and follicular cells of the thyroid gland was significantly higher in fluoride-treated groups than in the control group. These results suggested that abnormal expression of VEGF induced by fluoride can lead to the proliferation of vascular endothelial cells in the thyroid gland. Accordingly, VEGF oversecreted locally by vascular endothelial cells might contribute to the proliferation of epithelial and follicular cells, resulting in the formation of hyperplastic nodules and enlargement of the thyroid gland. Furthermore, we proposed that there might be a positive feedback mechanism between NO and VEGF expression in fluoride-induced goiter formation. It was concluded that angiogenic and vasodilative factors such as VEGF and NO must be involved in fluoride-induced thyroid goitrogenesis.

Fluoride dose-response of human and bovine enamel caries lesions under remineralizing conditions

PURPOSE

To investigate the relative fluoride dose-response of human and bovine enamel caries lesions under remineralizing conditions and utilizing an established pH cycling model.

METHODS

Early caries-like lesions were formed in human and bovine enamel, characterized using Vickers surface microhardness (VHN) and assigned to five dentifrice treatment groups: 0/250/1100 ppm fluoride as sodium fluoride (F as NaF) formulation 1; 1100 ppm F as NaF formulation 2; 1000 ppm F as monofluorophosphate (MFP) formulation 3. The daily pH cycling regimen comprised: 4x1-minute dentifrice slurry treatments; 1 x 4-hour acid challenge and intermittent remineralization in a 1:1-mixture of pooled human/artificial saliva. After 20 days, VHN of specimens were measured again and changes from lesion baseline calculated (REM). Subsequently, enamel fluoride uptake (EFU) was determined using the microdrill technique and specimens were demineralized again to determine their acid resistance (DEM). Data were analyzed using two-way ANOVA (factors: enamel, dentifrice).

RESULTS

Both enamel type and dentifrice as well as their interaction affected REM and DEM. EFU was only affected by dentifrice. Human and bovine enamel showed a good fluoride dose-response for REM and correlated well. However, bovine enamel showed more remineralization than human enamel. There were good correlations between dentifrice-F concentration vs. REM and EFU, and between REM vs. EFU, regardless of enamel type.

Laboratory enamel fluoride uptake from fluoride products

PURPOSE

To evaluate the fluoride concentration in enamel after the use of different fluoride products and 48 hours after the cessation of fluoride use.

METHODS

16 enamel slabs were divided and treated for 15 days as following: Group A, with an amine fluoride toothpaste and mouthrinse (1400 and 250 mg/L(-1), respectively); Group B, with an amine fluoride toothpaste (1400 mg/L(-1)) and mouthrinse without fluoride; Group C, with a sodium fluoride toothpaste (1400 mg/L(-1)) and mouthrinse (250 mg/L(-1)). Chemical biopsy and multiple means were used to determine fluoride concentration. The data were statistically analyzed using the two-way ANOVA and Tukey HSD tests (P<0.05).

RESULTS

After 15 days of fluoride product use, Group A samples had the highest fluoride uptake (0.19 microg mm(-2)) (P<0.05). 48 hours after the interruption of fluoride product usage, a higher fluoride concentration was found in Group A samples. Although all fluoride products led to an enamel uptake, amine fluoride products promoted the most effective long-term uptake.

Effect of post-brushing mouthwash solutions on salivary fluoride retention--study 1

OBJECTIVE

The aim of the present study was to evaluate the effects on post-brushing salivary F retention of rinsing with mouthwashes containing either 500 or 225 ppm F compared to not rinsing.

METHODS

The study was a randomized, investigator-blind, cross-over trial with three treatment arms. Thirty volunteers brushed with 0.5 g of 1450 ppm F paste for 40 seconds and then spat out the waste slurry. They then rinsed for one minute with 10 mL of their allocated mouthwash or they did not rinse after the brushing. Saliva samples were collected before brushing (0 minutes) and at one, three, five, 10, 20, 30, 45, and 60 minutes after brushing. The subjects were not allowed to speak, eat, or drink during these 60-minute test periods. The F levels in saliva were then calculated for each time point and the integrated area under the curve calculated (AUC0-60).

RESULTS

The mean AUCs were 626, 380, and 237 for the 500 ppm F, 225 ppm F, and no rinse treatments, respectively, and all pair-wise comparisons were statistically significant (p < 0.01).

CONCLUSION

It is concluded that rinsing with either 500 or 225 ppm F mouthwash significantly increases the level of F in saliva compared to not rinsing after brushing with 1450 ppm F toothpaste. The 500 ppm F mouthwash provided a significant increase in F retention compared to the 225 ppm F rinse (p = 0.001).

Effect of post-brushing mouthwash solutions on salivary fluoride retention--study 2

OBJECTIVE

This study evaluated the effects of three post-brushing mouthwashes containing 0 ppm F, 225 ppm F, and 500 ppm F, respectively, on salivary fluoride retention after brushing with 1450 ppm fluoride (as NaF) toothpaste and rinsing with water immediately after brushing.

METHODS

In this three-phase, randomized, cross-over study, an ion-specific electrode was used to measure salivary F levels in thirty trial participants before brushing (Time 0), and after brushing, rinsing with water, and then rinsing with one of the three mouthwashes. Time points evaluated after brushing were one, three, five, 10, 20, 30, 45, and 60 minutes. For saliva sample collections, subjects were asked to pool saliva in their mouths for 10 seconds before spitting out into a container for each of the time points.

RESULTS

The AUC0-60 means for F in saliva were 554, 252, and 20 for the 500, 225, and 0 ppm F mouthwash groups, respectively. The 500 ppm F mouthwash resulted in a 2660% increase in total fluoride salivary retention over 60 minutes when compared with the 0 ppm F group, and a 120% increase when compared with the 225 ppm F group. A significant difference (p < 0.001) in the AUC0-60 means between the three groups was observed using analysis of variance (ANOVA). Paired t-tests also showed significant differences in the mean fluoride retention over 60 minutes for all three pair-wise group comparisons (p < 0.001).

CONCLUSION

Use of a fluoride mouthwash containing 225 ppm F or 500 ppm F produced a significant increase in salivary fluoride retention following brushing with a 1450 ppm F toothpaste and rinsing with water compared to rinsing without fluoride. The use of the 500 ppm F mouthwash may be of particular benefit to those at high caries risk.

Mechanisms of action of fluoride for caries control

Fluoride was introduced into dentistry over 70 years ago, and it is now recognized as the main factor responsible for the dramatic decline in caries prevalence that has been observed worldwide. However, excessive fluoride intake during the period of tooth development can cause dental fluorosis. In order that the maximum benefits of fluoride for caries control can be achieved with the minimum risk of side effects, it is necessary to have a profound understanding of the mechanisms by which fluoride promotes caries control. In the 1980s, it was established that fluoride controls caries mainly through its topical effect. Fluoride present in low, sustained concentrations (sub-ppm range) in the oral fluids during an acidic challenge is able to absorb to the surface of the apatite crystals, inhibiting demineralization. When the pH is re-established, traces of fluoride in solution will make it highly supersaturated with respect to fluorhydroxyapatite, which will speed up the process of remineralization. The mineral formed under the nucleating action of the partially dissolved minerals will then preferentially include fluoride and exclude carbonate, rendering the enamel more resistant to future acidic challenges. Topical fluoride can also provide antimicrobial action. Fluoride concentrations as found in dental plaque have biological activity on critical virulence factors of S. mutans in vitro, such as acid production and glucan synthesis, but the in vivo implications of this are still not clear. Evidence also supports fluoride's systemic mechanism of caries inhibition in pit and fissure surfaces of permanent first molars when it is incorporated into these teeth pre-eruptively.

Fluoride metabolism

Knowledge of all aspects of fluoride metabolism is essential for comprehending the biological effects of this ion in humans as well as to drive the prevention (and treatment) of fluoride toxicity. Several aspects of fluoride metabolism - including gastric absorption, distribution and renal excretion - are pH-dependent because the coefficient of permeability of lipid bilayer membranes to hydrogen fluoride (HF) is 1 million times higher than that of F(-). This means that fluoride readily crosses cell membranes as HF, in response to a pH gradient between adjacent body fluid compartments. After ingestion, plasma fluoride levels increase rapidly due to the rapid absorption from the stomach, an event that is pH-dependent and distinguishes fluoride from other halogens and most other substances. The majority of fluoride not absorbed from the stomach will be absorbed from the small intestine. In this case, absorption is not pH-dependent. Fluoride not absorbed will be excreted in feces. Peak plasma fluoride concentrations are reached within 20-60 min following ingestion. The levels start declining thereafter due to two main reasons: uptake in calcified tissues and excretion in urine. Plasma fluoride levels are not homeostatically regulated and vary according to the levels of intake, deposition in hard tissues and excretion of fluoride. Many factors can modify the metabolism and effects of fluoride in the organism, such as chronic and acute acid-base disturbances, hematocrit, altitude, physical activity, circadian rhythm and hormones, nutritional status, diet, and genetic predisposition. These will be discussed in detail in this review.

Comparison of fluoride uptake into tooth enamel from two fluoride varnishes containing different calcium phosphate sources

OBJECTIVE

The objective of this in vitro study was to compare two 5% sodium fluoride varnishes, each containing different sources of calcium and phosphate, for their ability to deliver fluoride into treated sound tooth enamel and adjacent, but untreated demineralized enamel.

METHODS

Six sets of 12 bovine enamel cores were mounted in plexiglass rods and the exposed surfaces were polished. Synthetic lesions were formed in the surface of three sets by soaking in thickened, pH 5.0, 1M lactic acid, 50% saturated with calcium hydroxyapatite. A fluoride varnish containing tri-calcium phosphate (TCP) was applied to one set of sound enamel cores, and a second, delivering amorphous calcium phosphate (ACP), was applied to another. A third set of sound enamel cores was water-treated. Each treated sound core was paired with an untreated lesioned core, and the pairs were soaked in artificial saliva for 24 hours at 37 degrees C. The treated cores, but not their lesioned counterparts, were initially soaked in 1.0 N KOH saturated with calcium phosphate for 18 hours. Each core was separately etched with 1.0 N perchloric acid for exactly 15 seconds, and fluoride measured by an ion-sensitive electrode after neutralizing with NaOH and buffering in TISAB II. The amount of calcium extracted was also determined by atomic absorption spectrophotometry as a measure of etch depth.

RESULTS

Fluoride uptake average was 1677 +/- 193 ppm, 455 + 38 ppm, and 44 +/- 5 ppm for the sound enamel cores treated with ACP varnish, TCP varnish, and water treatment, respectively. Fluoride uptake into the demineralized enamel averaged 5567 +/- 460 ppm, 2126 +/-126 ppm, and 49 -/+ 4 ppm for demineralized enamel paired with the sound cores treated with ACP varnish, TCP varnish, and water, respectively. The differences between the ACP varnish, the TCP varnish, and the water treatments were statistically significant (p < 0.05).

CONCLUSION

The ACP varnish formulation delivers statistically significantly more fluoride to both intact and demineralized enamel than the formulation containing TCP.

Anticaries potential of commercial fluoride rinses as determined by fluoridation and remineralization efficiency

OBJECTIVE

The objective of this work was to compare the anticaries potential of several currently marketed fluoride-containing mouthrinse products using two in vitro approaches: 1) fluoride uptake studies of demineralized human enamel samples after exposure to rinse products; and 2) microhardness studies of sound enamel samples after exposure to the rinse products and demineralizing agents.

METHODS

Four currently marketed rinse products, formulated at 100 ppm F, were evaluated in fluoride uptake studies relative to a negative (water) rinse control (Study 1). The same rinse products were evaluated in microhardness studies (Study 2) against a positive control, ACT Anticavity rinse, which is formulated with 225 ppm F and carries the ADA Seal of Acceptance as an effective anticavity mouthrinse. Test products included ACT Total Care rinse (pH = 6.34), Listerine Total Care rinse (pH = 3.57), Crest Pro-Health for Me rinse (pH = 3.33), and Crest Pro-Health Complete rinse (pH = 3.43).

RESULTS

Study 1-Samples treated with any of the fluoride-containing rinses showed significantly higher (p < 0.05) levels of fluoride uptake than the negative (water) control. Two of the products (Crest Pro-Health for Me and Crest Pro-Health Complete) showed significantly higher (p < 0.05) levels of fluoride uptake into demineralized enamel than the other marketed rinses (Listerine Total Care and ACT Total Care). Study 2-Samples treated with the same two rinse products (Crest Pro-Health For Me and Crest Pro-Health Complete) showed significantly lower mineral loss than the other rinse products, as well as the positive control.

CONCLUSION

Results of these in vitro studies indicate that the Crest mouthrinse products evaluated here are capable of providing significantly better fluoridation of demineralized enamel, as well as significantly better protection against the initiation and progression of demineralization, compared to the other marketed fluoride-containing mouthrinse products tested.

Effect of post-brushing mouthrinse solutions on salivary fluoride retention

Fluoride (F) toothpaste is one of the most effective means of caries prevention. There is also evidence that mouthrinse solutions with antimicrobial agents reduce plaque formation and gingivitis and may be used as adjuncts to daily self-performed oral hygiene for risk patients. The authors hypothesize that using these solutions--without or with just a low F concentration after brushing--will have a "wash-out" effect on F toothpaste. Mouthrinse solutions with more F might be beneficial in this respect. Two groups of 10 (Series 1) and 12 (Series II) healthy subjects were recruited. They brushed for 1 min with toothpastes containing either 1450 or 5000 ppm F. After brushing and spitting out the toothpaste, the participants in Series I rinsed for 30 sec with 10 ml of a variety of products with various F concentrations (0, 100, 226 or 900 ppm F). In Series II, they first rinsed with water after the brushing and directly thereafter with 20 ml of the post-brushing rinsing solution for 30 sec. Saliva samples in both series were collected at different time points up to 1 h and the F concentration was measured. There was significantly less F in saliva after rinsing with no F or with a low F concentration (100 ppm) compared with just brushing with a F toothpaste. Rinsing with 226 ppm F displayed significantly higher F concentrations in saliva compared with only toothbrushing. Products with a high F concentration (i.e. toothpaste with 5000 ppm F or a mouthrinse solution with 900 ppm F) produced the highest F retention in saliva compared with all other protocols. The quantity of mouthrinse solution (20 vs. 10 ml) did not seem to have any effect on the F retention. The results from both test series show that a post-brushing rinsing solution without F or with just 100 ppm F exerts a "wash-out" effect on toothbrushing with either 1450 or 5000 ppm F, which may be negative for all patients, especially those with a risk of caries. The general population will benefit more from higher concentrations of F in mouthrinse solutions and, based on the results of the present investigation, 226 ppm F (corresponding to 0.05% NaF) should be the lowest concentration used. Furthermore, caries risk patients are recommended to use a high-F toothpaste (5000 ppm F) or a post-brushing mouthrinse solution with 900 ppm F (corresponding to 0.2% NaF).

Effect of long-term fluoride exposure on growth, nutrient utilization and fluoride kinetics of calves fed graded levels of dietary protein

In order to assess the influence of dietary protein levels on the fluoride (F) bioavailability, 30 crossbred calves (6-8 months; approximately 104 kg BW) initially exposed to different dietary protein levels were allotted into six groups in a 3 × 2 factorial design. The factors included three different levels of protein viz. normal (100%; NP), low (75%; LP), and high (125%; HP) as per Kearl recommendations besides two levels of supplemental fluorine (as sodium fluoride) at 0 or 200 mg/kg diet. The animals were fed on the respective concentrate mixture and wheat straw for 210 days. A metabolism trial was conducted at 200 days post-feeding to study digestibility, plane of nutrition, and nutrient balances. The final body weight at the end of 210 days was lower (p < 0.01) in animals fed 200 mg/kg F (164.2 ± 8.92 kg) compared to those fed no F (200.7 ± 8.05 kg). Calves on LP diets attained lower (p < 0.05) average daily gain in comparison to NP or HP fed calves. The F-supplemented calves exhibited lower (p < 0.01) voluntary feed intake than their non-supplemented control. The digestibility of proximate nutrients other than ether extract exhibited higher (p < 0.01) values in F-fed calves attributable chiefly to reduced consumption of dry matter. The calves fed extra F retained lower mean daily nitrogen; calcium, and phosphorus compared to the calves fed no F. The mean daily intake, excretion, and retention of F were higher (p < 0.01) in the F-supplemented calves. A significant (p < 0.01) interaction between protein levels and F was evident in the urinary excretion of F; calves on LP diet exhibiting lower urinary excretion. Consequently, the bioavailability of F tended to be higher on LP than NP or HP diets. From the results, it is concluded that protein levels in the diet do not impart significant influence on susceptibility to fluorosis in crossbred calves. However, the bioavailability of F tended to increase on diets low in protein.

Combination of high-fluoride toothpaste and no post-brushing water rinsing on enamel demineralization using an in-situ caries model with orthodontic bands

OBJECTIVE

To compare the effects on enamel demineralization and fluoride (F) retention of two different brushing–rinsing regimens.

MATERIAL AND METHODS

An in-situ caries model with orthodontic bands was used for 8–9 weeks. A total of 20 orthodontic patients participated. They were randomized into two groups: (1) a test group using 5000 ppm F (n = 10) with no post-brushing water rinsing; and (2) a control group using 1450 ppm F (n = 10) with three sessions of post-brushing water rinsing. Orthodontic stainless-steel bands were applied to the two upper first premolars, leaving 2–3 mm of space away from the exposed buccal surface in order to accumulate plaque and provoke initial caries development. The teeth were extracted after 8 and 9 weeks, then analysed using quantitative light-induced fluorescence (QLF). Additionally, oral F retention was compared for the two groups.

RESULTS

In comparison to the control group, the test regimen resulted in a non-significant smaller QLF lesion area and a significantly lower average QLF loss of fluorescence (P < 0.05). The highest F retention concentration under the band was found in the test group (P < 0.001).

CONCLUSIONS

The combination of using a 5000 ppm F toothpaste and no post-brushing water rinsing had a greater anti-caries potential and resulted in elevated oral F retention compared to a 1450 ppm F toothpaste with three sessions of post-brushing water rinsing.

Oral fluoride retention in orthodontic patients with and without fixed appliances after using different fluoridated home-care products

OBJECTIVE

To evaluate oral fluoride (F) retention after using fluoridated toothpastes, rinsing solutions and chewing sticks (Miswaks) in orthodontic patients with and without orthodontic appliances.

MATERIAL AND METHODS

Nine orthodontic patients, with a mean age of 16 years, were included in a randomized, cross-over, experimental study. Six different home-care F products, two NaF toothpastes (0.32% and 1.1%), two NaF mouthwash solutions (0.05% and 0.2%) and two NaF-impregnated Miswaks chewing sticks (0.05% and 0.5%), were used both during the orthodontic treatment and 1 week after debonding. Unstimulated whole saliva and approximal saliva were collected from two interdental sites, before and up to 60 min after using each product for 2 min. The retention of F was calculated as the area under the 60-min F-clearance curve (AUC).

RESULTS

In general, the F concentrations at the various sites were higher before than after debonding. Moreover, the products with a high F content (toothpaste, mouthwash and Miswaks) resulted in higher F retention than the corresponding products with a lower F content. In whole saliva, the highest AUC values were found in patients using 0.2% NaF mouthwash, followed by 1.1% NaF toothpaste (p < 0.05). In approximal saliva, the retention values were highest after using 0.5% NaF-impregnated Miswaks in patients wearing orthodontic appliances (p < 0.001).

CONCLUSIONS

The insertion of fixed orthodontic appliances appears to favor oral F retention for all the tested home-care F products. In addition, products with a high F content increase oral F retention.

Zinc polycarboxylate dental cement for the controlled release of an active organic substance: proof of concept

The potential of employing zinc polycarboxylate dental cement as a controlled release material has been studied. Benzalkonium chloride was used as the active ingredient, and incorporated at concentrations of 1, 2 and 3% by mass within the cement. At these levels, there was no observable effect on the speed of setting. Release was followed using an ion-selective electrode to determine changes in chloride ion concentration with time. This technique showed that the additive was released when the cured cement was placed in water, with release occurring by a diffusion mechanism for the first 3 h, but continuing beyond that for up to 1 week. Diffusion coefficients were in the range 5.62 x 10(-6) cm(2) s(-1) (for 1% concentration) to 10.90 x 10(-6) cm(2) s(-1) (for 3% concentration). Up to 3% of the total loading of benzalkonium chloride was released from the zinc polycarboxylate after a week, which is similar to that found in previous studies with glass-ionomer cement. It is concluded that zinc polycarboxylate cement is capable of acting as a useful material for the controlled release of active organic compounds.

Comparison of in vitro fluoride uptake from whitening toothpastes and a conventional toothpaste in demineralised enamel

Studies on the compatibility of abrasives and fluoride compounds deal exclusively with fluoride uptake and remineralization after storing the enamel specimens in a toothpaste-saliva mixture. The influence of brushing on the fluoride uptake when highly abrasive toothpastes are used has hardly been investigated so far. The aim of the present study was to investigate fluoride uptake in initially demineralised dental enamel after storage in, or brushing with, whitening toothpaste slurries, compared to a conventional toothpaste. For this purpose two widely available whitening toothpastes with ionically bound fluoride (sodium fluoride NaF), two with covalently-bound fluoride toothpastes (sodium monofluorophosphate, NaMFP) and a conventional amine fluoride toothpaste (AmF) were compared. The fluoride uptake after use of the AmF toothpaste was shown to be statistically significantly higher than that after application of the NaF toothpastes, which in turn was statistically significantly higher than the uptake resulting from NaMFP application. The fluoride uptake was slightly higher when the enamel samples were brushed with NaF toothpaste, rather than just stored in the respective toothpaste slurry. Brushing with highly abrasive toothpastes did not negatively influence fluoride uptake in demineralised dental enamel. The ionic form of the fluoride in toothpastes appears to be critical for increased fluoride uptake. The acidic components of the AmF toothpaste improved fluoride uptake compared to alkaline NaF toothpastes.

Randomized equivalence trial of intensive and semiannual applications of fluoride varnish in the primary dentition

For children in the primary dentition with high caries prevalence the standard semiannual application of fluoride varnish may not be successful in preventing tooth decay. Oftentimes this population is mobile and does not receive consistent preventive care. This trial tested whether an intensive fluoride 5% sodium varnish regimen (three applications/2 weeks) applied annually has an equivalent effect on caries progression in the primary dentition compared to single applications applied semiannually. This study was a randomized clinical trial with two treatment groups. All participants (n = 600; mean age +/- SD = 55.3 +/- 4.6 months) received three varnish applications (active varnish or placebo) at semiannual visits over 3 years. Once per year the intensive-treatment group received one set of three active treatments and three placebo treatments 6 months later, each time within 2 weeks. The standard group received one active and two placebo treatments every 6 months. Children were assessed clinically at baseline and 12, 24 and 36 months after the initiation of the study. The mean (SD) numbers of newly decayed primary tooth surfaces observed over 3 years were 9.8 (8.6) and 7.4 (7.7) in the intensive and standard groups, respectively. The adjusted rate ratio was 1.13 (95% CI = 0.94-1.37, p = 0.20). In conclusion, the trial failed to demonstrate clear evidence of a difference in efficacy. However, differences of up to 36% greater rates of caries in the intensive group could not be ruled out, thus equivalence of the treatments cannot be concluded.

The fractional urinary fluoride excretion of adults consuming naturally and artificially fluoridated water and the influence of water hardness: a randomized trial

AIMS

To assess whether there was any significant difference in the average fractional urinary fluoride excretion (FUFE) values among adults consuming (NaF) fluoridated Ca-free water (reference water), naturally fluoridated hard water and an artificially (H2SiF6) fluoridated soft water.

DESIGN

Sixty adult females (N=20 for each treatment) participated in this randomized, double-blind trial. The experimental design of this study provided an indirect estimation of the fluoride absorption in different types of water through the assessment of the fractional urinary fluoride excretion of volunteers.

RESULTS

Average daily FUFE values (daily amount of fluoride excreted in urine/daily total fluoride intake) were not significantly different between the three treatments (Kruskal-Wallis; p = 0.62). The average 24-hour FUFE value (n=60) was 0.69; 95% C.I. 0.65-0.73.

CONCLUSIONS

The results of this study suggest that the absorption of fluoride is not affected by water hardness.

In vitro assessments of experimental NaF dentifrices containing a prospective calcium phosphate technology

PURPOSE

To determine the fluoride dose response of experimental NaF dentifrices containing a prospective calcium phosphate technology, along with the corresponding relative enamel and dentin abrasion values.

METHODS

3 mm diameter bovine enamel specimens were mounted, ground and polished, and softened in a carbopol-lactic acid solution (pH = 5.0) for 36 hours at 37 degrees C. Specimens were then measured for baseline Vickers microhardness and stratified (N = 18, mean VHN = 33) into eight groups. These groups consisted of a placebo paste, four test dentifrices (A, B, C, D) with three of the four (A, B, C) containing a promising calcium phosphate ingredient, Crest Cavity Protection, MI Paste Plus, and PreviDent Booster 5000. The groups were cycled in a lesion reversal pH cycling model consisting of four 2-minute treatment periods (diluted 1:3 with DI water) and one 4-hour acid challenge (carbopol-lactic acid, pH = 5.0) per day. Between these events, specimens were immersed in artificial saliva (pH = 7.0). After 20 days of cycling, the specimens were microdrilled and analyzed for fluoride content, and also measured for Vickers surface microhardness after 10 and 20 days of cycling and after a 2-hour and 16-hour post-cycle acid challenge (carbopol-lactic acid, pH = 5.0). Separately, relative dentin and enamel abrasion (RDA and REA) were performed using the ADA recommended radiotracer method.

RESULTS

A fluoride dose response was observed for the test dentifrices after 10 and 20 days of pH cycling, with test dentifrice C promoting the highest remineralization among the groups while both the MI Paste Plus and PreviDent systems provide the least remineralization (one-way ANOVA, SNK, P < 0.05). With respect to enamel fluoride uptake, the group facilitating the highest incorporation of fluoride into the enamel lesion was test dentifrice C, while the least effective NaF system was the MI Paste Plus (one-way ANOVA, SNK, P < 0.05). In terms of formulation abrasion, the REA scores were similar among the test dentifrices, MI Paste Plus, and PreviDent and compared favorably to the ADA reference material score (one-way ANOVA, SNK, P < 0.05); relative to the ADA reference material RDA score, the data indicate that MI Paste Plus was essentially non-abrasive, while PreviDent was significantly more abrasive to dentin (one-way ANOVA, SNK, P < 0.05). Altogether, these data show the developmental test dentifrices demonstrate a fluoride dose response and show great promise in remineralizing white-spot enamel lesions relative to MI Paste Plus and PreviDent.

In vitro remineralization efficacy of NaF systems containing unique forms of calcium

PURPOSE

To determine the in vitro remineralization potential of a new calcium phosphate technology in a 1000 ppm F system.

METHODS

3 mm diameter bovine enamel specimens were mounted, ground and polished, and softened in a carbopol-lactic acid solution (pH = 5.0) for 36 hours at 37 degrees C. Specimens were then measured for baseline Vickers microhardness and stratified (N = 10, mean VHN = 35) into the following groups: Group A: distilled water (negative control); Group B: MI Paste Plus (900 ppm F); Group C: Theramed SOS (1450 ppm F); Group D: "control" dentifrice (1000 ppm F); and, Group E: "test" dentifrice (1000 ppm F) admixed with a new functionalized calcium phosphate system. The groups were then cycled for 10 days in a pH cycling model consisting of four 2-minute treatment periods (diluted 1:3 with distilled water) and one 4-hour acid challenge (carbopol-lactic acid, pH = 5.0) per day. Between these events, specimens were immersed in artificial saliva (pH = 7.0). After 10 days of cycling, the specimens were measured for Vickers surface microhardness and were subsequently microdrilled, with the powder measured for fluoride content using a calibrated fluoride-sensitive electrode.

RESULTS

Significant differences resulted between the distilled water and fluoride-containing groups. Among the fluoride-containing groups, Group B demonstrated statistically low levels of enamel fluoride deposition and deltaVHN, while Group E statistically outperformed Group D. Among the groups with different calcium systems (Groups B, C, and E), Groups C and E were found to be statistically equivalent and superior to Group B with respect to both bioavailable fluoride and deltaVHN. Based on our results, these data demonstrated the combination of a new calcium phosphate technology plus 1000 ppm F, produced significantly greater remineralization relative to both the 1000 ppm F test dentifrice and MI Paste Plus, and was statistically equivalent to Theramed SOS.

Clinical success of compomer and amalgam restorations in primary molars. Follow up in 36 months

The purpose of this study was to evaluate the three-year clinical performance of a compomer and an amalgam in primary molars and to determine fluoride content in the enamel of these teeth after exfoliation. Twenty patients aged six to eight years randomly received one compomer and one amalgam restoration. Restorations were evaluated at baseline, 12, 24 and 36 months according to modified USPHS criteria. In six pairs of exfoliated teeth fluoride content at 1 and 5 mm distance from the restorations was determined. Replicas were made to determine marginal adaptation (MA) by scanning electron microscopy (SEM). At occlusal margins compomer restorations had better MA than amalgam restorations (p < 0.01). Compomer and amalgam restorations did not lead to different fluoride uptake in adjacent enamel and had an overall clinically satisfactory performance. The study confirmed that the assessed compomer is a suitable restorative material for class I and class II restorations in primary molar teeth.

Laboratory assessment of the anticaries potential of a new dentifrice

OBJECTIVE

The aim of the present study was to investigate the anticaries potential of a new sodium fluoride dentifrice in comparison to two commercial dentifrices containing different fluoride compounds by determining enamel fluoride uptake (EFU) and early caries lesion remineralization (REM) in an established in vitro caries remineralization/demineralization pH cycling model.

METHODS

Test products were: new dentifrice formulation in a fluoride dose-response (0; 675; 1426 ppm F as sodium fluoride [NaF-0; NaF-675; NaF]); Elmex Kariesschutz (1400 ppm F as amine fluoride [AmF]); and Oral-B Pro-Expert (1450 ppm F-1100 ppm F as stannous fluoride and 350 ppm F as sodium fluoride [SnNaF]). Artificial caries-like lesions were formed in human enamel specimens by immersion in lactic acid buffer (LA). Specimens were then subjected to a daily cycling regime for 20 days comprising four one-minute dentifrice slurry treatments (prepared in pooled human saliva), and one four-hour LA challenge and remineralization in pooled human saliva. After 20 days, REM was evaluated as the change in surface Vickers microhardness from lesion baseline and EFU using the microdrill technique. The data were analyzed using ANOVA.

RESULTS

A good fluoride dose-response was established for EFU and REM, with NaF delivering greater EFU and REM than NaF-675, which was superior to NaF-0 (p < 0.05). The new dentifrice NaF also showed greater EFU and REM than AmF and SnNaF (p < 0.05). In EFU, AmF and SnNaF were as efficacious as NaF-675 and superior to NaF-0 (p < 0.05). AmF and NaF-675 were also comparable in REM, whereas both products exhibited superior REM vs. SnNaF (p < 0.05), which was superior to NaF-0 (p < 0.05).

CONCLUSION

The present study has demonstrated that fluoride dentifrices vary in their capability of enhancing anticaries potential as determined using an established in vitro caries cycling model. The new dentifrice NaF showed superior predicted anticaries potential compared to the two commercial dentifrices AmF and SnNaF in this model, which demonstrates the importance of fluoride compound and formulation excipients on driving anticaries potential in vitro.

Influence of chlorhexidine on fluoride uptake by bovine dentin in vitro

PURPOSE

To evaluate five different mouthrinses with respect to fluoride uptake by sound and demineralized dentin.

METHODS

The pharmacy-made mouthrinses contained either (1) 0.06% chlorhexidine, (2) 0.025% sodium fluoride, (3) 0.06% chlorhexidine and 0.025% fluoride (NaF) or (4) water (control). Additionally, the commercially available solution (5) Chlorhexamed Lösung 0.06% + F (GlaxoSmithKline) was used. 240 cylindrical dentin blocks were obtained from 120 bovine incisors. Half of the specimens were divided into five groups of 24 samples each and immersed in one of the mouthrinses (2.5 ml/specimen, 30 seconds). Accordingly, the remaining specimens were again divided into five groups of 24 specimens each; prior to treatment with one of the mouthrinses, these specimens were subjected to a demineralization procedure (lesion depth: 90-100 microm) using Buskes' solution for 6 days. All specimens were assessed for KOH-soluble fluoride and structurally bound fluoride immediately after treatment. Structurally bound fluoride was determined in three successive layers of 30 microm each.

RESULTS

Compared with all other mouthrinses, only the application of NaF resulted in higher amounts of KOH-soluble fluoride, and, in the outer layer, of structurally bound fluoride in both sound and demineralized dentin. Similarly, in the deeper layers, only the NaF groups showed elevated fluoride levels.

Fluoride and casein phosphopeptide-amorphous calcium phosphate

Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) slows the progression of caries and remineralizes enamel subsurface lesions. The aim of this study was to determine the ability of CPP-ACP to increase the incorporation of fluoride into plaque and to promote enamel remineralization in situ. Randomized, double-blind, cross-over studies involved mouthrinses and dentifrices containing CPP-ACP and fluoride. The mouthrinses were used for 60 sec, three times/day for 5 days, and supragingival plaque was collected and analyzed for F. The dentifrices were rinsed as a water slurry for 60 sec four times/day for 14 days in an in situ model. The addition of 2% CPP-ACP to the 450-ppm-F mouthrinse significantly increased the incorporation of fluoride into plaque. The dentifrice containing 2% CPP-ACP produced a level of remineralization similar to that achieved with a dentifrice containing 2800 ppm F. The dentifrice containing 2% CPP-ACP plus 1100 ppm F was superior to all other formulations.

Fluoride oral retention after professional topical application in children with caries activity: effect of the immediate water consumption

PURPOSE

Since there is no agreement about the time patients must refrain from drinking or eating after a professional application of acidulated phosphate fluoride (APF), the purpose of this study was to evaluate the effect of water consumption on fluoride in saliva.

METHODS

This blind randomized crossover in vivo study involved children who received a professional APF gel application followed by either drinking a glass of water (experimental group) or without rinsing, drinking, or eating (control group) for 2 hours. The nonstimulated saliva was collected at 0, 5, 15, 30, 60, and 120 minutes following the professional APF application. After a 7-day washout period, the control and treatment groups were switched.

RESULTS

There was a statistically significant difference in the fluoride retention between groups in the times 0 to 5 minutes (P<.05).

CONCLUSIONS

The data suggest that the recommendation of asking patients to refrain from drinking water for 30 minutes following the professional APF application is excessive and can be reduced to 15 minutes.

Ion uptake into demineralized dentine from glass ionomer cement following pretreatment with silver fluoride and potassium iodide

BACKGROUND

Diamine silver fluoride (Ag(NH3)2F), referred to as AgF, has been shown to provide a pronounced antimicrobial action against caries. The clinical application of this material has been limited by the staining associated with both teeth and tooth coloured restorative materials. The application of potassium iodide (KI) after AgF eliminates stain formation. The purpose of this study was to determine if a prior application of silver fluoride and potassium iodine to demineralized dentine affected the uptake of strontium and fluoride from a glass ionomer cement restoration.

METHOD

Three cavities were prepared in each of five recently extracted human third molars. The cavities were demineralized and treated as follows. In each tooth, one cavity was left as a control, one cavity was restored with glass ionomer cement and one cavity was treated with 1.8M AgF and a saturated KI solution and then restored with glass ionomer cement. The penetration of the various elements into demineralized dentine was measured by their relative percentage weights using electron probe microanalysis (EPMA).

RESULTS

Fluoride uptake was significantly higher in the AgF and KI treated samples compared to the other two samples and significantly higher in the glass ionomer restored sample compared to the control. The application of AgF and KI did not significantly interfere with the transfer of strontium from glass ionomer cement into dentine. Silver and iodine deposits were present in the demineralized dentine treated with AgF and KI.

CONCLUSIONS

The application of AgF and KI onto dentine prior to the placement of glass ionomer cement did not significantly affect the strontium uptake into the subjacent demineralized dentine and the fluoride levels in this zone were significantly increased.

Fluoride release for restorative materials and its effect on biofilm formation in natural saliva

This study investigated the influence of natural saliva of varying pH on surface biofilm formation of restorative materials and how this influenced fluoride release. Columnar specimens of glass ionomer cement (GIC), resin modified glass ionomer cement (RMGIC), compomer, giomer and composite, were prepared, matured for 24 h at 37 degrees C and 100% humidity, lapped and then placed in natural stimulated saliva with a pH of 3.8 or 7.1. Fluoride release was determined daily using an ion-selective electrode. The surfaces of selected specimens were observed using Confocal Laser Scanning Microscopy in conjunction with a fluorescent dye. The surface biofilm formation and bacterial growth was most dominant under neutral conditions and on the surfaces of GICs compared with other materials. GICs released significantly higher amounts of fluoride than other materials. The results suggest that the increased fluoride release of GICs did not reduce the amount of bacterial growth and biofilm formation on the surfaces of these materials when stored in natural saliva.

Effect of the CO2 laser combined with fluoridated products on the inhibition of enamel demineralization

AIM

This in vitro study evaluated the combined effects of a 10.6 microm CO2 laser, fluoridated dentifrice, and mouthrinse on the reduction of lesion progression in carious human enamel.

METHODS AND MATERIALS

Slabs of previously demineralized dental enamel were assigned to nine groups, either treated with/without a CO2 laser, with/without fluoridated dentifrice, and with/without fluoridated mouthrinse. After a pH-cycling regime, fluoride concentrations were determined in the demin- and remineralizing solutions. A qualitative polarized light analysis was performed on enamel, and enamel mineral loss was determined by cross-sectional microhardness testing.

RESULTS

All treatments were able to decrease mineral loss, and the inhibition of demineralization progression ranged from 48% to 60%.

CONCLUSION

The 10.6 microm CO2 laser irradiation alone or combined with fluoridated products reduced demineralization progression in enamel. However, there was no significant additional demineralization inhibitory effect with the use of the combined laser-fluoride treatments.

CLINICAL SIGNIFICANCE

CO2 lasers have proven to be efficient in reducing subsurface enamel demineralization. Its association with a high frequent fluoride therapy may enhance this protective effect.

Remineralization of artificial interproximal carious lesions using a fluoride mouthrinse

PURPOSE

To evaluate remineralization and fluoride uptake of demineralized enamel specimens in artificial interproximal spaces using a 250 ppm fluoride mouthrinse (100 ppm amine fluoride and 150 ppm sodium fluoride) compared to a placebo-mouthrinse.

METHODS

This was a two-way, double-blind, in situ study. 24 volunteers wore intraoral appliances in the lower jaw with mounted demineralized enamel specimens forming an artificial interproximal space. The volunteers rinsed their mouths for 28 days, twice a day with the respective mouthrinse and brushed their teeth at least twice a day with a fluoride-free dentifrice. The specimens were cleaned once a day to simulate the use of dental floss. For analysis methods transversal microradiography, fluoride content measurement and quantitative light-induced fluorescence were used.

RESULTS

Mineral gain was significantly higher after the use of the fluoride mouthrinse: 571.88 Vol.% x microm (+/- 79.33 Vol.% x microm SEM) compared to the placebo treatment 51.14 Vol.% x microm (+/- 72.14 Vol.% x microm SEM). Significantly more fluoride uptake was observed after using the fluoride mouthrinse: 3666.39 microg/cm3 (+/- 513.50 microg/cm3 SEM) than after the placebo mouthrinse: 516.95 microg/cm3 (+/- 75.83 microg/cm3 SEM). The quantitative light-induced fluorescence showed a significant remineralizing effect after the fluoride treatment: -388.47 % x mm2 (+/- 18.76% x mm2 SEM) compared to the placebo treatment -27.88% x mm2 (+/- 20.19% x mm2 SEM).

A three layer structure model of fluoridated enamel containing CaF2, Ca(OH)2 and FAp

OBJECTIVES

The aim of this study was to develop a molecular-based structural model of human teeth after fluoridation with a commonly used amine fluoride, which is highly significant for understanding the effectiveness of topical fluoridation.

METHODS

This multi method study used XPS, MAS-NMR and Raman-spectroscopy measurements in order to analyze powdered synthetic hydroxylapatite (HAp), powdered human enamel samples and human enamel pieces treated with amine fluoride (Elmex) fluid) in vitro.

RESULTS

The results lead to a complete structural characterization of the fluoridation products. A three layer composition of calcium hydroxide, calcium fluoride and an apatite species was identified.

SIGNIFICANCE

The top surface CaF(2) layer acts as a fluoride reservoir and covers a layer of antimicrobial effective Ca(OH)(2). Ca(OH)(2) is a well-known therapeutic agent. However, up to now Ca(OH)(2) has not been described as a reaction product after topical fluoridation. Below the Ca(OH)(2) layer an acid resistant apatite species (FAp) was detected which reached directly into the bulk enamel HAp species. The three layer composition identified helps to understand the influence of fluoride application in the pathogenic mechanisms of tooth decay. Each component in this newly suggested structure model has a specific function, which explains how topical fluoridation of enamel reduces dental caries and influences its pathogenic mechanisms.