Plaque Fluoride Levels Research Articles

A comparative study of fluoride release from two different sealants.

Objectives: The introduction of fluoride releasing sealants and glass ionomer cements as fissure sealants adds another dimension to prevention of pit and fissure caries. The ability of resin sealants and glass ionomer cements to release fluoride on a long term basis to the sealed enamel and the adjacent unsealed pit and fissure and cuspal incline enamel may allow for further reduction in pit and fissure caries experience for children. Hence, the study was conducted to compare the amount of fluoride release in the plaque after placing fluoride releasing pit and fissure sealants and glass ionomer fissure sealants used in Atraumatic Restorative Treatment (ART) approach. To compare the fluoride release of both the materials at the different time intervals. Material and Methods: A total of 60 school going children were included in this study. Before application of the sealants, baseline plaque fluoride levels were estimated from all the study subjects. After application of sealants again the same was estimated at an interval of 24 hour, 9 days, 2 weeks and 4 weeks. Results: The peak plaque fluoride levels were achieved at 24 hours after application of fissure sealants in all the groups. Conclusions: Within the limitation of the study, the present study indicated that fluoride releasing fissure sealants may act as a source of fluoride in plaque which will help in preventing pit and fissure and smooth surface caries in the tooth sealed with fissure sealants. Key words:Plaque fluoride, pit and fissures sealants, dental caries.

Fluoride bioavailability in saliva and plaque

BackgroundDifferent fluoride formulations may have different effects on caries prevention. It was the aim of this clinical study to assess the fluoride content, provided by NaF compared to amine fluoride, in saliva and plaque.MethodsEight trained volunteers brushed their teeth in the morning for 3 minutes with either NaF or amine fluoride, and saliva and 3-day-plaque-regrowth was collected at 5 time intervals during 6 hours after tooth brushing. The amount of collected saliva and plaque was measured, and the fluoride content was analysed using a fluoride sensitive electrode. All subjects repeated all study cycles 5 times, and 3 cycles per subject underwent statistical analysis using the Wilcoxon-Mann-Whitney test.ResultsImmediately after brushing the fluoride concentration in saliva increased rapidly and dropped to the baseline level after 360 minutes. No difference was found between NaF and amine fluoride. All plaque fluoride levels were elevated after 30 minutes until 120 minutes after tooth brushing, and decreasing after 360 minutes to baseline. According to the highly individual profile of fluoride in saliva and plaque, both levels of bioavailability correlated for the first 30 minutes, and the fluoride content of saliva and plaque was back to baseline after 6 hours.ConclusionsFluoride levels in saliva and plaque are interindividually highly variable. However, no significant difference in bioavailability between NaF and amine fluoride, in saliva, or in plaque was found.

Effects of Regular and Low-fluoride Dentifrices on Plaque Fluoride

Previous studies have indicated that the use of low-fluoride dentifrices could lead to proportionally higher plaque fluoride levels when compared with conventional dentifrices. This double-blind, randomized, crossover study determined the effects of placebo, low-fluoride, and conventional dentifrices on plaque fluoride concentrations ([F]) in children living in communities with 0.04, 0.72, and 3.36 ppm F in the drinking water. Children used the toothpastes twice daily, for 1 wk. Samples were collected 1 and 12 hrs after the last use of dentifrices and were analyzed for fluoride and calcium. Similar increases were found 1 hr after the children brushed with low-fluoride (ca. 1.9 mmol F/kg) and conventional (ca. 2.4 mmol F/kg) dentifrices in the 0.04- and 0.72-ppm-F communities. Despite the fact that the increases were less pronounced in the 3.36-ppm-F community, our results indicate that the use of a low-fluoride dentifrice promotes a proportionally higher increase in plaque [F] when compared with that achieved with a conventional dentifrice, based on dose-response considerations.

The anti-caries efficacy of calcium carbonate-based fluoride toothpastes

To summarise clinical support for the anti-caries efficacy of fluoride toothpastes containing sodium monofluorophosphate (SMFP) and to discuss the possible means by which the abrasive particles in calcium carbonate-based SMFP toothpastes might complement and/or enhance fluoride efficacy. The anti-caries efficacy of fluoride has been proven beyond any reasonable doubt, and the efficacy of SMFP, when incorporated into a variety of compatible toothpaste formulations, has been established in numerous clinical trials. Calcium carbonate-based toothpastes may also influence caries by effecting an increase in plaque calcium levels; an inverse relationship between plaque calcium and caries is well-established. It has also been reported that plaque fluoride levels are dependent on plaque calcium levels. Hence elevated plaque calcium resulting from the use of calcium carbonate-based toothpastes has the potential to elevate plaque fluoride, itself linked to reduced caries experience. It has been shown that calcium carbonate particles are retained by plaque and this may also influence caries by neutralising harmful plaque acids and concurrently liberating calcium. Fluoride delivered from calcium carbonate-based SMFP toothpastes is an effective means of reducing caries. Further, calcium carbonate may confer additional benefits through elevation of oral calcium levels and neutralisation of plaque-acids.

Fluoride tablet programs in healthy elderly subjects: distribution of fluoride in saliva and plaque with tablets in different sites

Based on root caries data and oral sugar clearance pattern, vestibular surfaces of upper incisors and lower molars may be regarded as risk areas along with the proximal surfaces. The aim of the present study was to use this information in improving fluoride tablet programs for the elderly. Six healthy elderly males with full dental arches took part. Flavored and unflavored tablets dissolved passively either under the tongue or in the vestibule close to the root caries risk areas. Salivary fluoride was determined at five to six intra-oral sites with a micro-sampling technique at intervals up to 10 min tablet use. Plaque samples were collected from single tooth surfaces before and after tablet use, and analyzed for total fluoride and total protein by micro-techniques. Salivary fluoride exposure to root caries risk areas was strongly increased when fluoride tablets were placed in the vestibule in these areas. The unflavored tablet gave higher fluoride retention in saliva than did the flavored brand. Plaque fluoride levels tended to be above baseline in the first couple of hours after tablet use, and then to decline. In the caries risk areas, at vestibular surfaces of lower posterior and upper incisor teeth, most of the fluoride taken up in plaque had been lost after 5 h and a bread meal, whereas in the non-risk areas it was largely retained. The study demonstrated that fluoride exposures to the vestibular caries risk areas can be strongly increased by placing fluoride tablets close to them. An unflavored tablet seemed to give higher exposures than a flavored one. The rapid loss of fluoride from plaque in slow clearance risk areas indicates that more than one daily treatment would be required for elderly caries risk subjects.

Changes in plaque fluoride levels by school-based fluoride rinsing and tablet programs in Bangladesh

The aim of this study was to evaluate the effects of school-based fluoride rinsing and tablet programs on plaque fluoride levels. A total of 42 children (8-9 years) were selected from two neighboring schools in Dhaka, Bangladesh. After caries recordings, vestibular plaque samples from the maxillary central incisors and mandibular first molars were collected and frozen on day 0 (baseline). The subjects of one school (rinsing group, n = 15) rinsed with 0.05% NaF, while those from the other school (tablet group, n = 16) used a 0.5 mg F tablet on the 5 school days during a 3-week period. The surfaces were sampled on the first and last school day every week. The fluoride and protein contents of each sample were analyzed using micro-techniques. The median plaque fluoride levels were 9.1 ppm at baseline in the rinsing group and 2.5 ppm in the tablet group (P < 0.05). This difference could in part be related to reported fluoride toothpaste usage. After 4 days on the fluoride programs, plaque fluoride levels in the rinsing group increased to 27.3, 24.5 and 14.2 ppm in the 3 consecutive weeks. The corresponding values after tablet usage were 8.0, 6.5 and 7.1 ppm, respectively. After 3 days without fluoride during the weekends, levels declined towards baseline values in both groups. Hence, the plaque fluoride levels in 8 to 9-year-old Bangladeshi children were increased by both rinsing and tablet programs, but the effect was not detectable 3 days later.

Fluoride concentration in supragingival dental plaque after a single intake or habitual consumption of fluoridated milk

The aim of this study was to evaluate the fluoride concentration in supragingival dental plaque after single and repeated intakes of fluoridated milk. The study group consisted of 22 schoolchildren, young adults and adults of both sexes, 8-41 years of age. After a 2-week fluoride depletion period and 3 days of plaque accumulation, 200 ml of fluoridated milk (1g F) was ingested along with a standardized lunch meal. Plaque samples were collected immediately before the intake and after 30, 120 and 240 min. From the adult participants (n = 9), additional samples were colleted after 12 and 18 h. After a fluoride-free washout period of at least 2 weeks, the whole experimental procedure was repeated after 4 consecutive daily intakes of fluoridated milk. The fluoride concentration was determined after micro-diffusion with a fluoride selective electrode. The results showed a statistically significant 3-fold increase of the plaque fluoride levels up to 4 h after the intake. At 12 and 18 h after the intake, the recorded levels went gradually back to baseline. There was no significant difference between the fluoride concentrations in the supragingival plaque after the single intake compared with the repeated intakes. In conclusion, the findings support the suggestion that milk is a suitable vehicle for local fluoride administration into the oral cavity, also when consumed together with a meal.

Studies on Plaque Fluoride After Use of F-Containing Dentifrices

Increased fluoride levels in plaque and saliva have been associated with improved protection against dental caries for dentifrices which contained sodium monofluorophosphate (Duckworth et al., 1992). The main aim of the present work was to test whether oral fluoride retention depended on F source after use of dentifrices containing either NaF or Na2FPO3. In study 1, plaque samples were collected from 474 subjects who had been using one of six test dentifrices for two years, and analyzed by F extraction with water. The dentifrices contained 1000 or 1500 micrograms F/g as either NaF or Na2FPO3. Significantly more fluoride was found in plaque from subjects who were using the NaF dentifrices than in plaque from subjects who were using Na2FPO3 dentifrices of the same F content. Subsets of plaque samples were large enough to divide into two parts for extraction by both acid and water. No significant difference was found between mean fluoride contents, indicating that the majority of fluoride retained in plaque from these conventional dentifrices appears to be relatively labile. The results of two small-scale human enamel studies showed that NaF dentifrices gave elevated F concentrations in plaque and saliva, respectively, compared with Na2FPO3 dentifrices of equivalent F content, consistent with the main plaque study 1. These findings demonstrate that oral F retention from dentifrices is dependent on the source of ionic fluoride and support the view that NaF dentifrices may be more clinically effective than dentifrices which contain the same amount of F as Na2FPO3.

Fluoride in Dental Plaque and its Effects

Total plaque fluoride is in the range 5-10 mg/kg (ppm) on a wet-weight basis. The variability of literature data on plaque fluoride is partly ascribed to analytical problems, many assays being close to or below the concentration detection limit of the fluoride electrode. A change in classification of plaque fluoride compartments is necessary, since recent work indicates that there are two pools of plaque F: less than 5% of the total F is in plaque fluid as the free ion, and the large remaining portion of total plaque F is designated as bound F, with the total F being greater than 95% extractable by cold 0.5 mol/L perchloric acid. Sources of plaque fluoride include the diet, saliva, and crevicular fluid; enamel is unlikely to be a regular source for plaque F unless it is either coated daily with labile fluoride compounds, such as calcium fluoride, or released by demineralization. The location and nature of plaque bound F are not established, but the present evidence is consistent with an intracellular location. Bound F may be released by acids produced in plaque during sugar fermentation, but it is unlikely to reach ion concentrations high enough for sufficient time periods to exert significant inhibition of plaque acidogenesis. Epidemiological evidence showing correlations between pooled plaque F concentrations and caries prevalence in the plaque donors does not exclude the possibility of coincidental effects of water F on both caries and plaque F concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of a mouthrinse containing calcium lactate on the formation and mineralization of dental plaque.

In this study, a mouthrinse containing calcium lactate was tested for its effect on the accumulation of dental plaque and on the concentrations of calcium and phosphorus therein. Human volunteers rinsed four times per day with a calcium lactate (165 mmol/l) solution for 1 week. Plaque samples, collected 16 h after the last rinse, were analyzed chemically. Calcium lactate rinses had no effect on the plaque score, but resulted in approximately twofold increases of calcium and phosphorus in plaque. The incorporation of monofluorophosphate (5 mmol/l) into the rinsing solution failed to show any significant influence on calcium, phosphorus, and fluoride levels in plaque. Increased mineral deposition in the plaque may provide an explanation for the reduced caries development earlier observed in rats fed a diet containing calcium lactate.

Inhibition of acid production from oral bacteria by fluorapatite-derived fluoride.

The inhibitory effect of fluorapatite (FAP)-derived fluoride upon resting cell suspensions of Streptococcus mutans incubated at pH 4.5 and 6.5 was studied using lactic acid production from 0.1% sucrose as an indicator of fermentation activity. Cells incubated with FAP produced significantly less lactic acid than did cells incubated with hydroxyapatite (HAP). Addition of HAP to cell suspensions containing FAP reduced this inhibition, suggesting that dissolution of the FAP was necessary for inhibition. Incubation with low concentrations of NaF showed significant inhibition in cell suspensions incubated with as little as 0.45 micrograms/mL F at pH 5.0. These results provide further support to the hypothesis that fluoride levels in plaque and enamel, achievable through use of fluoridated water and/or fluoride dentifrices, may produce appreciable inhibition of glycolysis at the acidic pH levels which are readily achieved in plaque. Thus, bacterial acid production may activate plaque and enamel-bound fluoride, resulting in inhibition of further acid production, and thereby contribute substantially to the other cariostatic mechanisms of fluoride.

Superficial fluoride levels and response to in-vitro caries-like lesion induction of enamel from Bristol (U.K.) and Birmingham (U.K.) human deciduous teeth

Surface enamel fluoride levels were measured in deciduous canine teeth from Bristol, with non-fluoridated water supplies, and Birmingham, with fluoridated water supplies. Three populations studied were from Bristol (teeth shed before 1960), Bristol (after 1975) and Birmingham (after 1975). Up to 75 μm from the enamel surface, fluoride concentrations of post-1975 Bristol and Birmingham teeth were, respectively, × 1.3 and 3.4 greater than those of pre-1960 Bristol teeth. The increase in the Bristol teeth is presumably due mainly to the increased use of fluoride-containing toothpastes, that in Birmingham to fluoridated water plus the use of fluoride toothpastes. No difference in the rates of penetration into enamel of acid-gel induced, caries-like lesions were found between the two Bristol populations; Birmingham teeth showed a reduction of 10 per cent in penetration rate. It is suggested that raised fluoride levels in surface enamel do not reduce solubility sufficiently to account, by themselves, for the recent nationwide marked reduction in caries in children. Possibly, the raising of plaque fluoride levels is a more important factor, affecting demineralization, remineralization and bacterial activity.