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.

Enhanced penetration of fluoride particles into bovine enamel by combining dielectrophoresis with AC electroosmosis.

Fluoride deposition into the pores of enamel is necessary at high concentrations to reduce enamel demineralization and with a high degree of penetration to account for loss by ingestion. Current diffusion and electrochemical methods are inadequate for effectively transporting fluoride greater than 20 µm into enamel. The study explores the coupling of dielectrophoresis (DEP) and AC electroosmosis (ACEO) to selectively concentrate fluoride particles from fluoride gel excipients and enhance their penetration into enamel. By measuring the frequency response of approximately 10-µm-sized sodium fluoride particles in an aqueous gel media, appropriate frequencies for positive DEP, negative DEP, and ACEO are identified. An assembly composed of two cross-planar interdigitated electrode (IDE) arrays with open slots is driven successively by fields at appropriate frequencies to drive fluoride particles through the slots of the IDE and into the enamel pores using a combination of DEP and ACEO methods. Fluoride uptake and penetration of 1.23% acidulated phosphate fluoride gel into bovine tooth enamel at various depths is measured using wavelength dispersive spectrometry to compare deposition by diffusion, DEP, and DEP plus ACEO. Fluoride levels in all DEP groups were significantly higher than diffusion groups at depths 10 and 20 µm. The highest fluoride concentrations at 10, 20, 50, and 100 µm depths occur under deposition conditions combining DEP with ACEO. Fluoride levels at 50 µm were equivalent to long-term prophylactic exposure. These methods may potentially benefit populations at high risk for development of caries and periodontal disease, including underserved children and disparate groups.

Breaking the fluoride diffusion barrier with combined dielectrophoresis and AC electroosmosis.

PURPOSE: To compare the deposition of fluoride particles into bovine enamel by diffusion (n = 20); dielectrophoresis (DEP) at 10 Hz and 5000 Hz (n = 10); and DEP (10 Hz and 5000 Hz) combined with AC electroosmosis (ACEO) at 400 Hz (DEP/ACE) (n = 10). METHODS: Fluoride particle movements induced at 10, 400, and 5000 Hz frequencies, were analyzed with light microscopy and stack imaging in real time. Fluoride concentrations were measured at various enamel depths using wavelength dispersive spectrometry. Results were analyzed by ANOVA/Student-Newman-Keuls post hoc (P = 0.05). RESULTS: Fluoride levels in teeth treated with DEP were significantly higher than diffusion at depths 10 and 20 microm. DEP and diffusion were relatively ineffective at greater depths. The highest fluoride concentrations at 10, 20, and 50 microm depths were found in the DEP/ACE group. After 20 minutes, DEP/ACE increased fluoride uptake by 600% at 50 microm and 400% at 100 microm compared to baseline levels (P < 0.05). Fluoride particle movement was induced by negative DEP at 10 Hz; positive DEP at 5000 Hz; and ACEO at 400 Hz frequency.

Artificial enamel dental caries treated with different topical fluoride regimes: an in situ study.

OBJECTIVES: To evaluate whether the topical fluoride application (acidulated phosphate fluoride, APF) at high concentration has an additional effect on the control of enamel lesions compared to fluoride dentifrice (FD; low concentration). The frequency of APF treatment on the arrestment of caries lesions and the amount of fluoride deposited on enamel after application of high and low fluoride concentrations were also evaluated. METHODS: Five subjects wore partial dentures with in vitro demineralized blocks during 35 days. All specimens (5p/subject) were brushed three times daily for 1 min with FD (1100 ppmF). Besides the FD treatment, four specimens were submitted to APF gel topical applications (12,300 ppmF) on weekly intervals (one to four applications). The enamel blocks were analyzed at baseline, after demineralization and after intraoral procedures regarding: surface roughness (SR), clinical aspects (brightness and texture), surface microhardness (SMH) and enamel fluoride content. Friedman's test was used to compare SMH and SR among the treatments. Analysis of variance, followed by Tukey's studentized range test, was used to evaluate fluoride content and SR among the groups. The significance level used was 5%. RESULTS: Changes in surface brightness, texture and SR were not detected. FD+3 APF and FD+4 APF were the only treatments capable of increasing SMH values and fluoride content compared to demineralized blocks (p < 0.001), although no differences could be observed within the treatments. CONCLUSIONS: This study showed that > or = 3 APF in addition to FD enhance enamel rehardening and produce a larger reservoir of fluoride.

Evaluation of fluoride release from teeth after topical application of NaF, SnF2 and APF and antimicrobial activity on mutans streptococci.

UNLABELLED: The objectives of this study were to evaluate and compare the amount and pattern of fluoride release from teeth after topical application of 2% NaF, 8% SnF2 and 1.23% APF at different time intervals. The growth inhibitory effects of this released fluoride ion was assessed on mutans streptococci (MS) and correlated with the fluoride release. Forty premolars divided into four groups were subjected to different topical fluoride treatments. All the teeth were immersed individually in deionized water and were transferred to containers at 1 hour, 1 day and 1 week time intervals. 240 samples in total were used for fluoride estimation by ion selective electrode method and the samples from the other subgroup were used for evaluation of antimicrobial activity on mutans streptococci (MS) by bacterial inhibition assay method. The results showed that the highest fluoride release (7.83 +/- 0.55 ppm) was seen in SnF2 treated specimens, as compared to that of NaF (3.71 +/- 0.60ppm) and APF (3.30 +/- 0.51ppm), the difference being statistically significant (P<0.01). This was observed immediately after 1 hour, followed by a drastic reduction thereafter. No zones of inhibition were observed at the released fluoride concentrations at different time intervals in the different groups. IN CONCLUSION: 8% SnF2 is expected to have greater anticaries property from the high fluoride releasing property for prolonged period of time.

Fluoride profiles in different sites of approximal surfaces of second primary molars after topical application of acidulated phosphate fluoride gel in vivo.

Thirty-four (17 paired) extracted second primary molars were obtained from 17 individuals (9 boys and 8 girls) aged from 9 yr 2 months to 12 yr 7 months. A tooth on one side was extracted as a control, and an acidulated phosphate fluoride (APF) gel was then applied to the paired contralateral second primary molar. Three months later, the experimental tooth was extracted. Nine sites were assayed by a microsampling technique from small areas of the approximal enamel surface. The fluoride and phosphorus concentrations were determined by a fluoride electrode and by colorimetric procedure, respectively. Fluoride concentrations were higher in the teeth treated with the APF gel than in the control teeth. The highest fluoride uptake was observed in the central area of the approximal surfaces. Deeper areas (> 10 microns) had a marked uptake of fluoride as compared with surface areas (< 3 microns). It was concluded that the APF gel application increased the fluoride levels of approximal tooth surfaces, particularly the mid-central site, of second primary molars, even at 3 months after application.

Fluoride retention following topical fluoride foam and gel application.

The purpose of this study was to compare the oral fluoride (F) retention following acidulated phosphate fluoride (APF) foam and gel applications in children. Fifty-nine children were divided into two groups, 6-9 years old and 10-13 years old. They each received a randomly assigned sequence of topical F foam and gel applications in two consecutive visits, using either sponge-lined or unlined trays. Approximately 0.6-0.8 g of APF foam, or 3-4 g of APF gel was used in each of the 4-min F applications. The amounts of F applied, recovered from the mouth, and retained were calculated for each treatment. The retention of an average of 1.26 mg F after an APF foam application was significantly less than 2.53 mg F for the APF gel. The sponge-lined trays also reduced significantly the F retention, compared with unlined trays. However, there was no significant difference in the amount of F retained between the two different age groups. The amount of F retained was reduced significantly from 3.65 mg F in the first appointment, to 1.24 mg F in the second appointment when unlined trays were used.

Enamel uptake and patient exposure to fluoride: comparison of APF gel and foam.

This crossover study with 46 child dental patients compared two topical APF products, a gel and a foam, with respect to the amounts of product and fluoride (F) applied, salivary F concentrations, and enamel F uptake. Half the subjects were treated for 4 min with the gel first and the other half with the foam. After approximately 16 days, each patient received a second treatment using the other product. An acid-etch enamel biopsy was performed and whole saliva samples were collected before and after each treatment. Significantly less F was applied to the teeth and retained by the subjects when the APF foam was used. Salivary F concentrations after treatment with the gel were higher than after treatment with the foam. The differences in enamel F uptake at both 15 min and 16 days after the APF applications, however, were not significant. We concluded that: 1) the two products are equivalent with respect to enamel F uptake; 2) only about one-fifth as much of the foam product is required for adequate coverage of the teeth, which significantly reduces F exposure and retention by the patient.

Argon laser irradiation and acidulated phosphate fluoride treatment in caries-like lesion formation in enamel: an in vitro study.

The purpose of this in vitro study was to determine the combined effects of argon laser irradiation (ArI) and acidulated phosphate fluoride treatment (APF) on caries-like lesion formation in human enamel. Each specimen was divided into tooth quarters with each quarter assigned to one of four groups: 1) control; 2) ArI Only; 3) ArI before APF treatment; 4) APF treatment before ArI. After a fluoride-free prophylaxis, acid-resistant varnish was applied to the tooth quarters, leaving sound enamel windows exposed on buccal and lingual surfaces. Argon laser irradiation was at 2 watts for 10s (100J/cm2). APF treatment was with a 1.23% APF gel for 4 min. Lesions were created in sound enamel windows with an acidified gel. After lesion formation, sections were obtained and imbibed with water for polarized light study. Body of the lesion depths were determined and compared among the four groups. Lesion depths were: 195 +/- 23 microns for control; 129 +/- 17 microns for ArI only; 96 +/- 14 microns for ArI before APF; and 88 +/- 11 microns for APF before ArI. Significant differences (P < 0.05) were found between the control group and all treatment groups, and between the ArI only group and both combined APF and ArI groups. Significant difference (P > 0.05) was not found between the ArI before APF and the APF before ArI groups. Laser irradiation alone reduced lesion depth by 34% compared with control lesions. When ArI was combined with APF treatment, lesion depth decreased by more than 50% compared with control lesions, and by 26 to 32% when compared with lased-only lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Fluoride uptake by enamel in vitro following application of various topical fluoride preparations.

Two conventional topical fluoride preparations; APF and neutral 2% NaF gel and two fluoride varnishes; Duraphat and Fluor Protector, were applied to 60 permanent and 20 primary teeth. The teeth were halved to provide test and control groups, and the fluoride uptake was measured using a micro acid etch technique, after 30 seconds and 60 seconds etching periods. All topical fluoride preparations in our study caused some fluoride uptake in permanent and primary tooth enamel compared to the control groups. Duraphat and APF were found to be more effective than the other agents.

The in vivo efficacy of Fluorinex topical fluoridation treatment.

OBJECTIVE: This randomized, single-controlled study was performed to validate in vivo the efficacy of single Fluorinex treatment by examining fluoride incorporation into enamel using electron microscopy. METHOD AND MATERIALS: Twenty healthy participants referred for routine dental treatment which also required extractions of at least two teeth as part of their treatment plan were included in this study. For each participant, one randomly selected tooth was extracted and sent for blind electron microscopic fluoride assay (control, C). Next, following a single Fluorinex treatment, the second (test, T) tooth was extracted and sent for the same assay. Intra-individual and intergroup fluoride content comparisons were performed, between control and test teeth. RESULTS: Highly significant intra-individual and intergroup differences were found between the treated and untreated teeth. Fluoride atomic percent (at%) and weight percent (wt%) estimated least squares means of untreated group were found to be 0.56 and 0.48, and in the treated group 17.35 and 14.35. This increase in fluoride at% [16.78 ± 2.3 (SE)], was also significant statistically (P < .0001); likewise, the increase in fluoride wt % [13.86 ± 1.97 (SE)] was similarly significant (P < .0001). The system was well tolerated by the participants with minimal transitional mild side effects. CONCLUSION: In vivo fluoride application using the active Fluorinex system resulted in a significant increase of fluoride content in the enamel of adult permanent teeth compared to untreated internal controls.

Effect of APF gel application time on enamel demineralization and fluoride uptake in situ.

This in situ crossover and blind study was conducted to investigate the effect of professional acidulated phosphate fluoride (APF) gel application time on the subsequent inhibition of enamel demineralization. During 3 phases of 28 days each, 15 volunteers wore palatal appliances containing 4 enamel blocks, which were subjected to 3 treatment groups: not treated (control) and pre-treated with APF gel for 1 or 4 min. Dental plaque was allowed to accumulate on the blocks and the appliances were immersed in 10% sucrose solution 3 times a day simulating a cariogenic challenge. After each phase, the blocks were removed to evaluate enamel demineralization and concentration of fluoride (F) remaining after the cariogenic challenge. F formed on enamel was determined in additional enamel blocks subjected only to APF gel application. APF gel was efficient in reducing enamel demineralization (p<0.05), irrespective of the application time (p>0.05). Also, the concentration of the F formed and retained on enamel was significantly higher after APF gel application (p<0.05), but the effect of time of application was not statistically significant (p>0.05). The results suggest that APF application for either 1 or 4 min is equally efficient to increase F concentration in enamel and reduce enamel demineralization.

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.

Fluoride release from CaF2 and enamel demineralization.

The anticaries effect of professional fluoride (F) application has been attributed to calcium-fluoride-like deposits (CaF(2)) formed on enamel, but this has not been clearly demonstrated. We hypothesized that CaF(2) formed on plaque-free enamel by F application would reduce enamel demineralization due to the increase of F availability in fluid of subsequently formed plaque. We created distinct levels of CaF(2) on enamel to evaluate a dose-response effect. Enamel blocks were mounted in contact with a S. mutans test plaque and used in situ by 10 volunteers. F released to the fluid phase of this substrate ("plaque fluid") was measured before a cariogenic challenge. "Plaque fluid" F concentration was highly correlated to the enamel CaF(2) concentration (r = 0.96, p < 0.001) and to consequent enamel demineralization (r = -0.75, p < 0.001). The results suggest that F released to plaque fluid from CaF(2) formed on enamel may play a significant role in the anticaries effect of professionally applied F agents.

Increase of enamel fluoride retention by low fluence argon laser beam: a 6-month follow-up study in vivo.

BACKGROUND AND OBJECTIVES: The aim of this 6-month in vivo study was to investigate if argon laser irradiation of enamel can increase the retention of fluoride. STUDY DESIGN/MATERIALS AND METHODS: Ninety-eight teeth in 12 patients were randomly divided into three groups: (1) EF group: 40 teeth were only treated with fluoride gel (applied for 5 minutes followed by a 1 minute rinsing with distilled water). (2) EFL group: 40 teeth were treated the same way as in the EF group but they were lased after fluoridation. (3) E group: 18 teeth were kept without any treatment as a control group. In order to quantify the fluoride content in the enamel samples, the teeth were analyzed by proton beam delivered by a tandem accelerator (PIgE, particle induced gamma-ray emission). A low energy density of argon laser beam was used: 10.74 J/cm2 (11 mm of beam diameter, irradiation time of 30 seconds, and an output power of 340 mW in continuous mode). RESULTS: The results after 6 months showed that the lased enamel still retained 52.55+/-8.47 ppm or 14.12% of fluoride after the fluoridation process, whereas the unlased enamel retained only 12.18+/-6.82 ppm or 3.27% of fluoride. The untreated and control enamel (E group: unlased and without fluoride treatment) had 1.16+/-4.27 ppm value of fluoride. The statistical test (ANOVA tests at 95% level) showed that the difference is significant between the fluoride retention in the group EFL and the group EF 6 months after fluoridation. CONCLUSIONS: The use of argon laser at low energy density (10.74 J/cm2) significantly increased the fluoride retention in lased enamel that had approximately 400 times more fluoride than the unlased enamel. We consider this procedure as an alternative clinical procedure to increase the fluoride content of enamel surface.

Fluoride uptake and resistance to further demineralisation of demineralised enamel after application of differently concentrated acidulated sodium fluoride gels.

The objective of this study was to analyse fluoride uptake and microhardness alteration of carious-like demineralised enamel after application of differently concentrated acidulated sodium fluoride gels and to determine the effect of fluoridation on enamel resistance against subsequent demineralisation. Artificial caries-like lesions of bovine enamel specimens were treated with sodium fluoride gels of different concentration (group A: 1.25%, group B: 0.62%, group C: 0.31%, group D: 0.15%; n=20 each group) for 5 min and stored in artificial saliva for 24 h. This cycle was carried out three times. Subsequently, KOH-soluble and structurally bound fluoride (determined at depths of 30, 60, and 90 microm) were analysed. In the second part of the study, for each 12 enamel specimens surface microhardness was determined before and after demineralisation, after fluoridation with the differently concentrated gels A-D, and after a second demineralisation. With all groups uptake of KOH-soluble and structurally bound fluoride resulted in higher levels than baseline content. Statistical analysis revealed significant differences between fluoride uptake among the groups, with highest uptake for the 1.25% gel and lowest for the 0.15% gel. Moreover, with all gels highest uptake was observed in the outermost enamel layer (P<0.05). Microhardness values after second demineralisation increased with increased concentration of the applied sodium fluoride gel. Increasing concentration of the applied gel implies better protection of the enamel specimens against subsequent demineralisation (P<0.05). It is concluded that differently concentrated acidulated sodium fluoride gels resulted in concentration-related significant uptake of fluoride in carious-like demineralised enamel, leading to a better demineralisation protection with increasing fluoride concentration in the gel.

[The effect of ammonium fluoride solution at various concentrations on enamel].

The fluoride concentrations of ammonium fluoride solution (NH4F,pH 4.4), which has the same effect on enamel powder as conventional APF solution, were studied. Human enamel powder (200 mesh passed) was treated with solutions of NH4F (1,000 ppmF-, 3,000 ppmF-, 5,000 ppmF-, 7,000 ppmF-, 9,000 ppmF-, pH 4.4) and APF (9,000 ppmF-, pH 3.4) for 5 min. at 37 degrees C. Some of the specimen was washed with 1MKOH solution for 48 hours. Fluoride uptake by enamel powder was analyzed by means of chemical analysis and reaction products identified using X-ray diffractometry. The fluoride uptake of 5,000 ppmF- of NH4F-treated enamel was the same as that of APF-treated enamel. X-ray diffractometry showed that CaF2 was formed in the experimental groups. CaF2 with high crystallinity was formed in the NH4F-treated enamel, and the peak height of X-ray diffraction pattern of CaF2 in 3,000 ppmF- of NH4F-treated enamel was the same as that of APF-treated enamel. In conclusion, the ammonium fluoride solution of 3,000-5,000 ppmF- had a similar effect on enamel powder as conventional APF solution.

Combined Raman and SEM study on CaF2 formed on/in enamel by APF treatments.

Raman spectra containing the distinct band at 322 cm-1 due to CaF2 or CaF2-like material formed in/on fluoridated bovine enamel were recorded using a micro-Raman spectrograph. Due to increasing levels of background fluorescence with increasing thickness of enamel, the Raman measurements were carried out on thin regions of wedged enamel sections. The distribution of the CaF2 or CaF2-like material was estimated using a simple model. The results indicate that 1/3 of the total CaF2 was concentrated within the narrow depth < 2 microns with high CaF2 concentrations (> 10 wt%), and that the majority of the CaF2 was distributed over the depths up to 26 microns (1 wt% CaF2). SEM observations on fractured fluoridated enamel confirmed that morphological changes were present in the depth range comparable to that of the high CaF2 concentration region expected from the Raman analysis. In deeper regions where lower concentration (< 10%) but a large amount of CaF2 was still expected, the SEM images failed to distinguish between the normal and fluoridated enamel. After KOH treatment, the Raman spectra did not show evidence of the CaF2 peak and the SEM micrographs also confirmed the removal of globules. The peak position of the Raman band of the CaF2 formed by the fluoridation was identical to that of pure CaF2. However, the linewidth was 23 cm-1 (FWHM) and a factor of 2 broader than that of pure CaF2 (12 cm-1). This implies that the lattice dynamics of the CaF2 formed by fluoridation is different from of pure CaF2, and that the material formed is 'CaF2-like' or 'disordered CaF2'.

In vitro evaluation of fluoride uptake with application of acidulated phosphate fluoride to interproximal enamel of primary teeth using dental floss.

As a result of application of acidulated phosphate gel with a dental floss on adjoining surfaces of primary molars it has been established that there has been significant fluoride intake as compared with the control group. It has been concluded that it is an efficient method of increasing fluoride content of the primary teeth.