Salivary Fluoride Research Articles

Salivary Fluoride Concentration in Adults After Different Fluoride Procedures

Seppä L. Salmenkivi S, Hausen H. Salivary fluoride concentration in adults after different fluoride procedures.Today, several alternatives for fluoride therapy are available. To give advice on the choice of method, the dentist should have information on how effective different fluoride treatments are in increasing salivary fluoride concentration. The aim of the present study was to measure the fluoride concentration of saliva after the use of four different fluoride methods commonly used in the Nordic countries: F mouthrinse (0.023% q, F toothpaste (1.1% F), F lozenge (0.25 mg F), and F chewing gum (0.25 mg Q. In addition, a new method using toothpaste-water mixture as a mouthrinse was included in the study. Fourteen adult volunteers used each of the five methods on separate days. Unstimulated saliva samples were collected;it base line and 0, 10, 20, 30, 45, and 60 min after the fluoride procedure. Fluoride was separated by the microdiffusion method and analyzed using a fluoride-specific electrode. Fluoride mouthrinse and fluoride toothpaste increased the fluoride concentration of saliva significantly more than fluoride lozenge and fluoride chewing gum. For both of the latter, salivary fluoride concentration was still increased after 1 h. Toothpaste–water rinse was more effective than brushing with toothpaste. Rinsing with toothpaste-water mixture appears a good alternative for adults who need extra fluoride therapy but are not motivated enough to brush their teeth several times a day.

Studies on the Effect of Fluoride Released by Glass Ionomers in the Oral Cavity

Numerous in vitro studies have shown that fluoride released by glass ionomers can have effects on enamel, dentin, and plaque adjacent to the material. However, the action of fluoride in vivo may be different from that found in vitro. The aim of the present series of studies was to investigate the effects of glass ionomers in oral conditions. This was tested in clinical experiments conducted on adults who had freshly made or old glass ionomers in their mouths. The results of the studies showed that fluoride released by glass ionomers may increase the fluoride content of plaque close to the material. Fluoride content decreased rapidly with decreasing fluoride release from glass ionomer, but it was increased slightly even in plaque growing on three-year-old fillings. However, the effect appeared to be very local, and no increase in salivary fluoride content due to glass-ionomer fillings was found. Although the growth of plaque was not inhibited, the proportion of mutans streptococci was significantly reduced in plaque growing on glass ionomer during the six weeks after placement of the material. No such effect, however, could be seen in the case of three-year-old glass-ionomer fillings. Although in vitro studies have shown that glass ionomers can take up fluoride and subsequently release it, applying fluoride gel to old glass-ionomer fillings did not result in an increased fluoride concentration of plaque growing on the fillings in vivo. Further studies are needed to find out whether the recharging of glass ionomers with fluoride has clinical significance.

Caries-protective factors in saliva.

Saliva influences caries attack mainly by its rate of flow and by its content of fluoride. The salivary flow rate influences to a high degree the rate of oral and salivary clearance of bacterial substrates included in foods and snacks. This influence is site-dependent. The basal salivary fluoride concentration is low, about 1 mumol/L, independent of salivary flow rate, and not influenced by diurnal variation. After an exposure of the oral cavity to fluoride, the increased fluoride level is decreased by a process influenced mainly by the salivary flow rate and the volumes of saliva in the mouth before and after swallowing. Other less important caries-protective factors in saliva include its buffer ability, its content of calcium, inorganic phosphate, pH-increasing substances, and anti-microbial agents.

Effect of various post-brushing activities on salivary fluoride concentration after toothbrushing with a sodium fluoride dentifrice.

The study consisted of eight experiments, divided into three series, aimed at investigating the effect on the salivary fluoride (F) concentration of three post-brushing regimes: (1) rinsing once or twice with water, (2) rinsing either with a slurry of the toothpaste foam and water or with an 0.05% NaF solution, or a single NaF mouthrinse with no prior brushing, and (3) chewing and drinking ('eating') for 2 min. Brushing was done with 1.5 g of an 0.32% NaF dentifrice. The concentration of F in whole saliva was determined in 15 subjects at various time points up to 45 min after completing each experimental procedure. Results showed that the initial (0 min post-brushing) F concentration in saliva decreased about 1-2 times after a single, and 4-5 times after a double post-brushing water-rinse, as compared with no rinsing at all (p < 0.001). Brushing followed by a mouthrinse with an 0.05% NaF solution elevated the F concentration more than brushing alone (p < 0.001). Rinsing with the slurry of toothpaste foam and water gave only a somewhat (but not significantly) lower concentration of F in saliva than just rinsing with the 0.05% NaF solution. Eating immediately after brushing reduced the salivary F level about 12-15 times (p < 0.001) compared with brushing alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Mouthwashes of Variable NaF Concentration but Constant NaF Content on Oral Fluoride Retention

Previous work showed that oral fluoride levels increased with increasing applied F dose for both mouthwashes and dentifrices. This study aimed to determine whether the above dependence was related to applied fluoride concentration or applied fluoride amount. Ten adults mouthrinsed with aqueous NaF solutions of 1-10 ml, each of which contained 2.5 mg F, i.e. in the concentration range 250-2,500 ppm F. Subjects rinsed for 1 min and then spat out. Samples of mixed saliva were collected for 3 h afterwards, which were analysed for fluoride. Salivary fluoride clearance curves were obtained which could be fitted to a pharmacokinetic model involving processes ascribed to loss of fluoride from saliva by swallowing and to exchange of fluoride between saliva and an oral reservoir. Mean salivary fluoride concentrations increased significantly with increasing applied F concentration both within the first 3 h after single use and up to at least 18 h after regular daily use. These findings suggest that applied F concentration is a more important factor than applied F amount per se in determining the elevation of oral fluoride levels following topical fluoride use. This implies that application of a given F dose, in a smaller volume at higher concentration than the current norm, may increase efficacy without increasing the risk of adverse effects.

Factors related to fluoride retention after toothbrushing and possible connection to caries activity.

The aim of the present investigation was to study the brushing and toothpaste technique employed by caries-active and caries-inactive patients in a toothbrushing population. The study consisted of 47 patients at a public dental clinic in the County of Bohuslän, Sweden; 23 with low (group L) and 24 with high caries activity (group H). They were asked to brush their teeth with a fluoride dentifrice at the clinic using an identical technique to that which they employed at home. Various factors, such as brushing time, amount of dentifrice, water consumption and mouthrinsing habits after brushing, were carefully registered. Saliva samples for fluoride analyses were collected up to 45 min after brushing. The members of group L used less rinsing water (0.7 +/- 0.6 dl; mean +/- SD) than those of group H (1.9 +/- 1.0 dl, p < 0.001). Comparing the mouthrinsings with water after the brushing, a significantly higher frequency was observed in group H (3.6 +/- 1.9 rinsings) than in group L (1.5 +/- 0.7 rinsings; p < 0.001). There were no differences between the two groups regarding the amount of dentifrice used and the total brushing time. When the salivary fluoride concentration was plotted vs. time and the area under the curve (AUC) calculated, a significantly higher mean value was found in group L than in group H (p < 0.01). Calculation of the correlation coefficient (r) between the AUC value and the amount of water used gave r = 0.53 (p < 0.001) and between the AUC and the frequency of mouthrinsing r = 0.46 (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Distribution of fluoride in saliva and plaque fluid after a 0.048 mol/L NaF rinse.

An ultramicro method has recently been described for measurement of plaque-fluid fluoride concentration (Vogel et al., 1990a). This method was used: (1) for exploration of the variation in fluoride concentration of plaque fluid collected from the same buccal tooth sites following a 0.048 mol/L NaF (0.2%) rinse, and (2) for examination of the distribution of fluoride in plaque fluid and saliva within one hour after this rinse. Results indicated an average coefficient of variation (CV) of 31% for plaque-fluid fluoride in triplicate samples recovered simultaneously from the buccal-proximal region of two teeth after the rinse. This was similar to the CV found for plaque-fluid fluoride from the same sites after separate administrations of the rinse. A strong linear correlation was found between salivary and plaque-fluid fluoride at 30 and 60 min after rinse administration, showing that plaque-fluid fluoride is influenced by the concentration of salivary fluoride after administration of this rinse. Plaque-fluid fluoride concentrations were higher than that in saliva at baseline, 30, and 60 min. Very large inter-site and intersubject variations in plaque-fluid distribution were observed, with the central incisors showing the slowest clearance. These variations suggest that an examination of plaque-fluid fluoride from specific tooth regions may be essential for understanding the effects of fluoride on the site-specificity of caries.

An in situ model for simultaneous assessment of inhibition of demineralization and enhancement of remineralization.

In situ models to assess the ability of oral care products or food components to enhance remineralization and/or inhibit demineralization of tooth enamel or roots must be very carefully designed to minimize the confounding effects of the many variables involved. Controlling these variables as closely as possible is essential if meaningful answers are to be obtained from the models. We have developed an in situ model which combines the experience of several groups. Detailed screening of subjects is essential. Selection criteria should include good general health, good dental health, mandibular partial denture, at least eight natural teeth, no active caries lesions, known fluoride history, normal salivary function, and no medications that affect salivary function. Each subject carries a sound enamel slab and an enamel slab with a pre-formed caries-like lesion (demineralized in vitro) in his/her denture on each side of the mouth for test periods of two or four weeks. The demineralization challenge is controlled by extra-oral immersion of the appliances in sucrose daily. Daily product exposure or daily food component exposure is used as desired. Compliance indicators and a diet diary are included. Whole saliva flow rate (unstimulated), plaque acidogenicity, and salivary fluoride are monitored during the test periods. At the end of the test period, the test slabs are assessed for mineral change, after being sectioned, by means of cross-sectional microhardness or microradiography. The mineral loss or gain (delta M, microns x vol%), compared with adjacent control sections retained in the lab, is calculated as change in delta Z (microns x vol%), namely, delta M = delta ZTEST - delta ZCONTROL.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Mouthrinsing after Toothbrushing with a Fluoride Dentifrice on Human Salivary Fluoride Levels

In a recent clinical trial of sodium monofluorophosphate dentifrices, oral rinsing habits were found to influence dental caries. Thus an oral fluoride clearance study has been undertaken which was designed to test a possible mechanism for the observed effects. Eight subjects brushed with one of the trial dentifrices and then rinsed using 1 of 8 procedures of varying thoroughness. The salivary fluoride concentration measured 5 min after dentifrice application decreased significantly with increasing rinse volume, rinse duration, and rinse frequency (p less than 0.01, analysis of variance). The area under the clearance curve determined over a further 3 h was significantly higher (300%; p less than 0.01) following use of the least thorough rinsing procedure (5 ml x 2 s once) as compared with the corresponding area under the clearance curve following the most thorough procedure (20 ml x 10 s twice). These findings indicate that rinsing habits may play an important role in the oral retention of fluoride from dentifrices which may, in turn, affect their clinical efficacy.

Oral Fluoride Retention after Use of Fluoride Dentifrices

Fluoride is the only extensively clinically proven means of reducing dental caries. Despite a large body of epidemiological data on the effectiveness of fluoride, delivered in the form of dentifrices, mouthrinses, drinking water, etc., the precise mode of action of fluoride is not completely understood. The purpose of this paper is to report an investigation of the link between oral fluoride levels and applied fluoride dose from dentifrices. Human salivary fluoride clearance studies and equilibrium baseline studies of fluoride in saliva and plaque have been carried out with dentifrices which contained 1,000, 1,500 and 2,500 micrograms fluoride per gram as sodium monofluorophosphate. After a single brushing with a fluoride dentifrice, salivary fluoride decreased in two distinct phases: an initial rapid phase which lasted for 40-80 min, depending on the individual, and a second slow phase lasting for several hours. The latter phase is believed to be due to fluoride released from an oral fluoride reservoir. During regular repeated use of the test dentifrices, the equilibrium baseline fluoride concentration, attained in both saliva and plaque between one application and the next, increased significantly compared with placebo values. Such elevated baseline fluoride concentrations also increased with increasing Na2FPO3 content of the dentifrices. The present work supports the concept that labile fluoride, stored in an oral fluoride reservoir at the time of treatment application, may maintain a prolonged protective effect against dental caries.

A Study of the Effect of Fluoride Delivered from Solution and Dentifrices on Enamel Demineralization

An in vitro demineralization model has been developed and used to examine the effect of various fluoride treatments on early enamel demineralization. The effect of fluoride treatments on the calcium demineralization rate of enamel was studied by analyzing the amount of calcium which demineralized from teeth into solution when the teeth were exposed to weak acid solutions. Continuous (72 h total) exposure of enamel to very low levels of fluoride, 0.014 ppm, was observed to have a protective effect against demineralization, as was intermittent exposure to higher levels of fluoride delivered from solution and from dentifrices for shorter periods of time (40 min total). This work suggests that the residual salivary fluoride concentrations reported to be reached by water fluoridation (0.016 ppm) or brushing with a fluoride-containing dentifrice (0.014 ppm) give a level of fluoride in saliva which may give some protection to the dental enamel from demineralization.

Salivary Fluoride Concentrations in Children with Glass Ionomer Cemented Orthodontic Appliances

Salivary fluoride concentrations were determined in 10 children (mean age 12.0 years) undergoing fixed orthodontic therapy. The orthodontic appliances, a minimum of 4 bands and 8 brackets, were cemented with a glass ionomer cement. Unstimulated whole saliva was collected 4 times a day before (baseline value) and at 1, 7, 14 and 28 days after cementation. The samples of saliva were centrifuged and the supernatants were analyzed with a fluoride-sensitive electrode. At baseline, the mean salivary fluoride concentration was 0.85 mumol/l. There was a significant increase during the day after cementation (1.88 mumol/l). After 7, 14 and 28 days, salivary fluoride levels were slightly elevated, but not statistically different from the baseline values. The ingested fluoride dose during the 1st day was estimated to be 0.02 mg. It is concluded that in orthodontic treatment with fixed appliances, a slow release of fluoride from glass ionomer cements could exert a local cariostatic effect on adjacent caries-susceptible enamel.

Diurnal Fluoride Concentration in Whole Saliva in Children Living in a High- and a Low-Fluoride Area

Salivary fluoride concentrations were investigated in 12-year-old children living in areas with low (0.1 ppm) or high (1.2 ppm) fluoride concentration in the drinking water. Unstimulated whole saliva was collected from 27 children from the respective areas every 2nd hour for 46 h except during sleep. The mean salivary fluoride concentration was 0.32 +/- 0.013 mumol/l (n = 419) in the low-fluoride (LF) area and 0.87 +/- 0.047 mumol/l (n = 401) in the high-fluoride (HF) area. No significant rhythm could be found for the diurnal variations in the mean or individual salivary fluoride concentrations. However, in the HF area the individual salivary fluoride concentrations fluctuated widely and randomly.

The effect of salivary clearance of sucrose and fluoride on human dental plaque acidogenicity

Ten subjects rinsed with a 20% (0.58 M) sucrose solution with or without 0.2% NaF (905 parts/10 6 F −) added in two separate experiments. Saliva and plaque were collected before rinsing and after 2, 5, 10 and 30 min. Sucrose and fluoride concentrations in saliva and acid anion and fluoride concentrations in plaque were analysed. There was a statistically significant and positive correlation between the concentration of sucrose in the saliva 2 min after the rinse and the subsequent concentrations of lactate in plaque at 10 and 30 min after the rinse with sucrose alone but not in the presence of fluoride. Salivary fluoride concentrations during 2–30 min after the sucrose rinse were significantly correlated with plaque fluoride concentrations during the same time. The addition of fluoride to the sucrose rinse significantly inhibited lactate production.

Estimation of Fluoride Absorption from Swallowed Fluoride Toothpastes

Eight adults ingested five different toothpastes with and without 1,000 ppm (1 microgram/g) fluoride added as NaF or Na2PO3F. The systemic fluoride absorption was estimated by by comparing the areas under salivary fluoride concentration curves produced after the toothpaste ingestion. Of the toothpastes investigated--chalk, dicalcium phosphate dihydrate, silica or alumina with sodium monofluorophosphate, and silica with sodium fluoride--the fluoride absorption was found to be statistically significantly lower only from the dicalcium phosphate dihydrate toothpaste. Measuring changing fluoride levels in saliva appears to be an acceptable non-invasive technique for following systemic fluoride absorption.

Studies on fluoride excretion in human whole saliva and its relation to flow rate and plasma fluoride levels.

Five volunteers participated in two separate experiments where whole saliva was collected without stimulation or with stimulation by chewing on paraffin wax. The saliva was collected continuously for 120 min after ingestion of 1 mg fluoride as NaF. Blood was collected at intervals throughout the experiments. The results showed that the concentration of fluoride in whole saliva mirrored the fluoride concentration in plasma, but at a lower level. Variations in salivary flow rate (0.34 +/- 0.15 ml/min for unstimulated and 1.06 +/- 0.28 ml/min for stimulated) did not affect the salivary fluoride concentration. The amount of fluoride excreted into stimulated whole saliva was significantly correlated with the salivary flow rate, with a correlation coefficient of 0.98. The fraction of the ingested fluoride dose recovered in whole saliva within 2 h was 0.05 +/- 0.02 and 0.18 +/- 0.09% for the unstimulated and the stimulated whole saliva, respectively.

Influence of flow rate, pH and plasma fluoride concentratons on fluoride concentration in human parotid saliva

In two separate studies the influence of some physiological factors on salivary fluoride excretion was investigated. In the first study, parotid saliva, at two predetermined flow rates, and capillary blood were sampled after ingestion of 1 mg fluoride. In the second study, parotid saliva was collected at five different flow rates, starting 1 h after ingestion of 5 mg fluoride. Capillary blood was sampled throughout the experiment. The first study showed that parotid saliva and plasma fluoride concentrations were closely correlated ( r = 0.81). The mean parotid salivary and plasma fluoride concentration ratio (S/P ratio) ± SD ranged from 0.29 ± 0.11 to 0.65 ± 0.15. The fractions of the ingested fluoride dose excreted from one parotid gland were 0.08 and 0.18% at flow rates of 0.25 ± 0.02 and 0.49 ± 0.06 ml/min, respectively. The second study showed that at the mean basal plasma fluoride concentration of 0.65 ± 0.18 μmol/l the mean S/P ratio was 0.55 ± 0.24. At a plasma fluoride concentration ranging from 3.5 to 11.6 μmol/l the S/P ratio was 0.73 ± 0.15. Thus the S/P ratio was influenced by the plasma fluoride concentration, but not by variations in parotid salivary flow rate or pH.

Controlled-release therapeutic systems: technology applicable to the treatment of oral disease.

Controlled-release therapeutic systems are designed to deliver a pre-determined amount of drug to a specific anatomical site for an extended period of time. A single controlled-release delivery system no larger than an ordinary tablet or capsule and placed at the desired site of drug action can produce long-term therapeutic effects that previously could only be achieved through multiple administration of conventional dosage forms. Transient spikes in drug concentration seen with multiple dose regimens are eliminated, decreasing the chance of adverse reactions. Because they are effective for an extended period of time, controlled-release therapeutic systems minimize the involvement of the patient in drug administration , a factor which can increase both patient compliance with a prescribed regimen and patient satisfaction with the treatment schedule compared with conventional therapy. Controlled-release technology can be utilized to deliver therapeutic agents ranging in size from small ions to macromolecules. Clinically-proven controlled-release drug delivery systems are currently available with durations of action ranging from several days (e.g., for the prevention and treatment of angina pectoris and motion-induced nausea and the treatment of glaucoma) to one year (e.g. for contraception). A therapeutic system for contraception with a five-year effective lifetime is in clinical trial. Intra-oral controlled-release therapeutic systems are being investigated for the delivery of fluoride and antibiotics. A system for fluoride has reduced experimental dental caries in rats by over 50% and has significantly elevated salivary fluoride concentrations during a six-month trial in adolescents. Tetracycline-containing polymeric fibers can provide site-specific delivery of the antibiotic to periodontal pockets for 10 days or more. An intra-oral controlled-release pellet for tetracycline with a duration of action of one to two weeks is being developed, and additional possibilities exist for the intra-oral use of this versatile technology.

Effect of salivary flow rate on salivary fluoride clearance after use of a fluoride-containing chewing gum.

The fluoride concentration in whole saliva and the effect of variations in salivary flow rate were studied in 5 volunteers after use of a chewing gum (Fluomin®) containing 0.25 mg fluoride as sodium f

Distribution and retention of salivary fluoride from a sodium fluoride tablet following various intra-oral dissolution methods.

The distribution and retention of salivary fluoride were investigated according to the following intra-oral dissolution methods of a sodium fluoride tablet: active chewing/swishing, active sucking/swishing, and passive dissolution in the maxillary and mandibular labial vestibule. The results suggested that the oral cavity was somewhat compartmentalized, in that homogeneous distribution of a dissolved fluoride tablet did not occur throughout the mouth, but rather each site sampled was influenced by various rates of clearance and retention. Tablet chewing may have an advantage over tablet sucking in terms of salivary fluoride retention, and there was a tendency for fluoride to be preferentially retained in the maxillary labial vestibule following swishing. The passive tablet dissolution methods resulted in a less homogeneous distribution of fluoride. Although the fluoride retention values for passive dissolution were impressively superior to either active dissolution method, the alarmingly high salivary fluoride concentrations (4000 ppm F) recorded at the passive dissolution sites should discourage its use until the potential cytotoxicity of this approach is thoroughly investigated.