Fluoride-containing Products Research Articles

Evaluation of parents' attitudes and behaviors towards products and practices containing fluoride

Aims: The aim of this study was to evaluate parents’ attitudes and behaviors about fluoride-containing products and practices. Methods: The study was conducted between April 2023 and February 2024. Parents of children who applied to Dicle University Faculty of Dentistry, Department of Pediatric Dentistry voluntarily participated in the study and a total of 350 parents participated. A face-to-face questionnaire consisting of 2 sections and a total of 26 questions was administered to the parents. Results: Among the parents who participated in our study, 56.86% stated that they had never heard of fluoride before. Those who had heard of fluoride stated that they had heard about it from school screenings and dentists. 16.86% of the parents stated that fluoride is harmful, but 68% of them did not have any information about it. 78.8% of the parents stated that they did not know the effect of brushing teeth with fluoride toothpaste on the prevention of dental caries and 76.57% stated that they did not look at the fluoride content when choosing toothpaste. 84% of the parents stated that they did not know the fluoride applications made by the physician and 74.57% stated that they would not have their children do it. The vast majority of those who would not have their children fluoridated (73.95%) stated that they would not do so because they did not have information about fluoride. We found that 92% of the parents did not know systemic fluoride applications, 90% did not know whether the drinking water they used contained fluoride, and 93.43% did not know whether fluoride in drinking water helps prevent dental caries formation. Conclusion: Considering the high caries risk and oral hygiene deficiencies in our country, the need to use fluoride in dental treatments is increasing. Therefore, the public’s lack of knowledge and concerns about fluoride should be addressed and the use of preventive treatments such as fluoride should be increased.

A ratiometric fluorescent probe with 1,2,4-triazole recognition unit for fluoride ion detection based on synchronous fluorescence spectroscopy

As an important inorganic chemical with wide applications and high toxicity, the detection of fluoride-containing products and environmental samples has gained the most interest. In this work, a ratiometric fluorescent probe (NIN2) is constructed with a triazole group as the new recognition site for the detection of F−. The synchronous fluorescence technology was introduced to obtain the well discrimination of two emission bands. The value of wavelength intervals (Δλ = λem. - λex.) is optimized to be set as 70 nm with the minimized overlap of two emission bands centered around 380 nm and 470 nm, respectively. In this way, NIN2 can detect F− in the region of 0–0.2 μM with a good linear relationship (R2 = 0.9989) and low LOD value (36 nM). Only F− can induce obvious ratiometric response (I470nm/I380nm) from 0.2 to 3.4 while the ratios of the samples containing other cations and anions are as low as the blank sample. For investigating the recognition mechanism of triazole, 1H, 13C and 19F NMR spectral technologies were used to verify the interaction between triazole and F−. Furthermore, the DFT calculation was also performed to discuss the electronic transition of NIN2 before and after interaction with F−. We believe this work provides a new recognition moiety for detecting F−.

Penetration of SDF and AgF from the infected dentine towards the unaffected tooth structure.

The use of SEM-EDS line scan analysis to evaluate the movement of ions from dental materials towards the tooth structure and the concept of ion movement is well established. This analysis technique was used to determine the ion movement of two commercially available silver- and fluoride-containing products. This study aimed to compare the elemental analysis of primary molar teeth treated with silver diamine fluoride (SDF) and water-based silver fluoride (AgF) and to analyse the penetration of SDF and AgF from the infected dentine towards the healthy dentine. The teeth were cleaned from debris and contaminants off the roots and stored until use. A total of 15 primary molars with large active cavitated lesions, not extending into the pulp (specimens), were divided into three test groups: silver diamine fluoride (SDF) (n = 5), water-based silver fluoride (AgF) (n = 5), and deionised water (W) (n = 5) as the control group. The teeth were sectioned, embedded, and received SEM-EDS line scans. The line scan had a total length of 82.65 μm. The visible end of the infected dentine and the start of the more affected dentine were chosen as the starting point to ensure that the infected caries' line distribution towards the affected dentine's transition area was as standardized as possible. Therefore, the infected dentine length of the scan was 22.80 μm (8 scan points of 2.85 μm apart), and the affected dentine, including the healthy dentine, was 59.8 μm (21 scan points). The SEM-EDS line scan from each specimen determined the average fluoride, iodide, and silver weight percentage for that specimen. The 15 sample SEM-EDS line scans were used to determine the average ion movement in wt%. The Kruskall-Wallis test and Tukey's HSD test were completed at a p < 0.05. SDF and AgF presented no significant fluoride movement in terms of the weight percentage. There was, however, significantly more fluoride movement from infected caries to the healthy dentine with SDF and AgF (p = 0.0010053) compared to the control specimens treated with deionised water. There was no significant difference between SDF and AgF for the movement of the iodide (p = 0.5953) and silver (p = 0.3708) from infected caries to the healthy dentine. SDF and AgF easily penetrated through infected caries and affected tooth structure to the healthy dentine for the line scan of 82.65 μm. There was no significant difference between SDF and AgF for the movement of ions within the infected dentine nor in the affected/healthy dentine.

Exploring fluoride-free content on Twitter: A topic modeling analysis

Abstract Social media discussions about the hypothetical side effects of fluoride-containing products have contributed to forming and strengthening health beliefs underpinning the anti-fluoridation movement. Given the importance of content analysis in mitigating online misinformation, this study aimed to investigate fluoride-free content on Twitter. Firstly, 21,169 tweets published in English between May 2016 and May 2022 concerning the keyword ‘fluoride-free’ were collected using the Twitter API. After the data preprocessing, Latent Dirichlet Allocation (LDA) topic modeling was conducted to identify the salient terms and topics inside the collected tweets. Then, the similarity between topics was calculated by an intertopic distance map. Furthermore, an investigator manually reviewed a sample of tweets that featured the most representative word groups associated with particular topics to determine the main issues. Finally, additional data visualization was performed using Elastic Stack software to analyze the total count and relevance of each topic related to fluoride-free records over time. The topic modeling analysis demonstrated a significant distance between the topics from a coherence score of 0.542, confirming the identification of three different issues: ‘healthy lifestyle’ (topic 1), ‘consumption of natural/organic oral care products’ (topic 2), and ‘recommendations for using fluoride-free products/measures’ (topic 3). Moreover, the number of fluoride-free publications decreased between 2016 and 2019 but increased again in 2020. Thus, recent increases in fluoride-free tweets appear driven by public concerns about adopting a healthy lifestyle, including the consumption of natural and organic products. Therefore, public health authorities, health professionals, and legislators must acknowledge the dissemination of fluoride-free content on social media to implement effective strategies to counteract its potential harm to the population's oral health. Key messages • People are concerned about the hypothetical side effects of fluoride-containing measures and products. • The consumption of fluoride-free content on social media is associated with adopting a healthy lifestyle.

Comparison of Childhood Caries Levels between Children of Pediatric Dentists and Children of General Dentists: A Cross-Sectional Study

Caries development in children is a prevalent childhood disease. Factors affecting chronic teeth lesions include nutrition, parental involvement, and executing proper dental health attitude. Professional dentists are perceived as role models for the oral health and hygiene of their families. The purposes of the research were 1. To compare caries rates in the children of pediatric dentists and children of general dentists. 2. To compare children's nutrition habits between pediatric dentists and general dentists. 3. To compare children's oral health and hygiene between pediatric dentists and general dentists. 4. To compare children's usage of fluoride-containing products between pediatric dentists and general dentists. A cross-sectional study was conducted by distributing self-reporting questionnaires to pediatric dentists and general dentists via the social media "snowball" platform. The following themes were surveyed: nutrition habits and oral hygiene of the children. The sample consisted of 176 participants. Children of pediatric dentists were found to have fewer cases of caries than children of general dentists (p = 0.018). Nutrition habits did not differ between the two groups. In addition, pediatric dentists reported that their children use more fluoridated toothpaste in comparison with general dentists. Professional training of pediatric dentists contributed to shaping the oral hygiene attitude of their children.

Comparison of CPP-ACP, Fluoride Varnish and Gel effects on enamel microhardness of permanent teeth: In-Vitro

Background Dental caries occurs due to the imbalance in the course of demineralization-remineralization in favor of demineralization. With remineralization, some signs of halted progression could be observed in the primary stages. The aim of this study is to in-vitro investigation of the effect of Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP), fluoride varnish, and fluoride gel on the microhardness of the enamel of permanent teeth. Materials and Methods: In this in vitro study, 344 specimens prepared from human premolars were randomly divided into four groups (n=86 specimens in each group). After preparing the specimens, the initial enamel value was first evaluated by Vickers microhardness technique. The specimens were immersed in a demineralizing solution and then treated with remineralizing compounds (I. Control, II. Fluoride varnish, III. Fluoride gel and IV. CPP-ACP). Microhardness values were re-measured at the end of demineralization and remineralization stages. The data were analyzed using SPSS software (version 16.0). Results: The results of the present study indicated a statistically significant difference in all groups in terms of initial enamel microhardness (0.288 ± 42.77), remineralization (0.213 ± 26.89), and demineralization values (0.167 ± 63.87) (p <0.001). Besides, there was a statistically significant difference in different groups in terms of remineralization values (p <0.001). In other words, the mean microhardness was 241.21 ±15.60 in Group III, 221.12 ± 75.69 in Group II, 211.16 ± 43.04 in Group IV, and 178.21 ± 63.9 in group- I. Conclusion All remineralizing compounds resulted in enhanced microhardness of the enamel. Nevertheless, the fluoride-containing products showed greater potential in improving the level of microhardness and strength of the teeth compared to the compounds containing CPP-ACP.

Exposure to the oral environment enhances the corrosion of metal orthodontic appliances caused by fluoride-containing products: Cytotoxicity, metal ion release, and surface roughness

This study aimed to evaluate the metal ion release, cytotoxicity, and surface roughness of clinically used metal orthodontic appliances after immersion in different fluoride product solutions compared with those of new appliances. Used fixed appliances were debonded from 36 patients after their treatment was done. New appliances were as-received. Each used and new group comprised 36 sets of 20 brackets and 4 tubes that were divided into 3 groups by archwire type; stainless steel, nickel-titanium, and beta-titanium. The samples in each group were divided into 3 subgroups and immersed in solutions of fluoride toothpaste, 1.23% acidulated phosphate fluoride, or artificial saliva without fluoride as a control group. The immersion times were estimated from the recommended time for using each fluoride product for 3months. The samples were then immersed in Dulbecco's Modified Eagle's Medium for 7days. The cytotoxicity test was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay using primary gingival fibroblasts. Chromium, nickel, and iron ion release were detected using inductively coupled plasma mass spectroscopy. The surface roughness of the brackets and wires was measured by a scanning electron microscope and a noncontact optical 3-dimensional surface characterization and roughness measuring device. The data were analyzed using the paired t test and 2-way analysis of variance. Used brackets demonstrated a significantly higher ion release, surface roughness, and cytotoxicity than the new brackets. Acidulated phosphate fluoride significantly increased the ion release and surface roughness; however, it significantly decreased cell viability, especially in the titanium molybdenum subgroup. Used brackets were significantly prone to further corrosion. Acidulated phosphate fluoride gel should not be used in orthodontic patients with fixed metal appliances.

Fluoride Ion Release Characteristics of Fluoride-Containing Varnishes—An In Vitro Study

Despite the latest advances in orthodontic treatment, white spot lesions remain a common side effect of fixed appliance therapy. An effective treatment for the prevention of white spot lesions is the use of fluoride-containing products. The aim of the present in vitro study was to check the durability of the tested products for their fluoride release into the surrounding solution. Three varnishes (Protecto CaF2 Nano one-step seal, Bifluorid 12 single dose, and Fluor Protector S) were applied to hydroxyapatite discs and kept in diluted Total Ionic Strength Adjustment Buffer III (TISAB III) solution for fluoride ion release measurement. A group of clear hydroxyapatite discs served as the control group. The carrier discs (N = 40) underwent three thermal cycling runs for 20 days. Before the first run and after each run, the fluoride ion concentration in the solution was measured at appointed times (T) T0, T1, T2, and T3. Fluoride ion release was highest at T1 for all products (median values for Protecto CaF2 Nano one-step seal: 0.09 ppm, Bifluorid 12 single dose: 37.67 ppm, and Fluor Protector S: 3.36 ppm) except for the control group, showing its peak at T0 (0.04 ppm). There was a significant difference between the tested fluoride varnishes at all measurement times. Bifluorid 12 achieved significantly higher fluoride release values than the other products (p &lt; 0.05 at all measurement times). A solitary product application of only once or twice per year, as stated by the manufacturers, cannot be supported.

Alternative therapies in controlling oral malodour: a systematic review

Is there a role for alternative therapies in controlling intra-oral halitosis? Treatments other than tongue cleaning and anti-halitosis products containing zinc, chlorhexidine and cetylpyridinium chloride were considered as alternative therapies. Four databases were searched (PubMed, EMBASE, Web of Science and The Cochrane Library). Inclusion criteria were: examination of alternative halitosis therapies, study population with oral malodour, a (negative or positive) control group and evaluation of breath odour via organoleptic and/or instrumental assessment. Data were extracted for descriptive analysis. The screening of 7656 titles led to the inclusion of 26 articles. Analysis showed heterogeneity concerning the population of interest (from cysteine-induced to genuine halitosis), the examined treatment and the reported outcomes. This made a meta-analysis impossible. Essential oils, fluoride-containing products and herbal substances were the most studied. Results varied enormously and none of the active ingredients had an unambiguously positive effect on the malodour. The risk of bias was assessed as high in all articles. Given the fact that little evidence was found for each of the investigated treatments, it could be concluded that there is currently insufficient evidence that alternative therapies are of added value in the treatment of halitosis. Clinical relevance Scientific rationale: Halitosis is a common problem causing social isolation. Out of embarrassment, patients search the internet, leading to many questions about alternative solutions (e.g. oil pulling, herbs). This is the first systematic review on these alternative therapies. Principal findings: Results varied among studies. Some promising results were found for fluoride-containing toothpastes and probiotics. For other products (such as herbal and antibacterial products and essential oils) results were inconsistent. Long-term follow-up studies on these products are scarce. Moreover, the quality of the studies was poor. Practical implications: No clear evidence was found to support a certain alternative anti-halitosis therapy.

Effects of magnetic fields from electric toothbrushes on fluoride- and oral bacteria-induced corrosion of orthodontic metallic wires.

Corrosion of metallic materials in the oral cavity could trigger metal allergy in patients. To clarify the risk elevation of magnetic fields (MFs) exposure on metallic corrosion when combined with fluoride-containing dental care products and indigenous oral bacteria, we investigated electric toothbrush-derived MF-induced corrosion of orthodontic stainless steel (SUS) and nickel titanium (Ni-Ti) wires in the presence of fluoride and oral bacteria, i.e. Streptococcus (S) mutans and S. sanguinis. MFs induced an electric current in the wires under both environments. Oral bacteria corroded SUS wires, and fluoride corroded SUS and Ni-Ti wires as previously reported; however, no additive or synergistic effects of MF exposure on fluoride- and microbiologically-induced metallic corrosion were observed. These results suggest that the MFs from electric toothbrushes do not increase the risk of corrosion of metallic appliances, given that the oral environment of patients is exposed to oral bacteria and fluoride-containing products.

Corrosion of metal orthodontic brackets and archwires caused by fluoride-containing products: Cytotoxicity, metal ion release and surface roughness

PurposeThe aims of this study were to determine the cytotoxicity, metal ion release and surface roughness of metal orthodontic appliances after immersion in different fluoride product solutions. Materials and methodsTwelve sets of 20 brackets and four tubes were ligated with three types of archwires: stainless steel, nickel-titanium, and beta-titanium. The samples in each archwire group were divided into three subgroups and immersed in solutions of fluoride toothpaste, 1.23% acidulated phosphate fluoride (APF), or artificial saliva without fluoride as a control group. The immersion times were estimated from the recommended time of using each fluoride product for 3 months. The samples were immersed in cell culture medium for 7 days. Primary gingival fibroblast cell viability was determined by an MTT assay. Metal ion (nickel, chromium, iron, and molybdenum) release and surface roughness were measured by inductively coupled plasma mass spectroscopy and a noncontact optical 3-dimensional surface characterization and roughness measuring device, respectively. The bracket and wire surface morphology was observed using scanning electron microscopy. The data were analysed by Two-way ANOVA. ResultsIn the APF groups, the four metal ion levels and surface roughness of the brackets and archwires significantly increased, while cell viability significantly decreased, especially in the TMA subgroup. The SEM results showed that the brackets and wires in the APF groups demonstrated more lines and grooves compared with the other groups. ConclusionUsing APF gel during orthodontic treatment with fixed metal appliances should be avoided.

Evaluation of the Effects of Fluoride Prophylactic Agents on Mechanical Properties of Nickel Titanium Wires using Scanning Electron Microscope

Orthodontic treatment these days is increasing in demand, and therefore, it is relatively imperative for the orthodontist to prescribe the use of fluoride-containing products, such as mouthwashes and gels, to help prevent dental caries and maintain healthy oral health. The aim of the study was to assess and evaluate the effects of fluoride prophylactic agents on mechanical properties of nickel titanium (NiTi) wires during orthodontic treatment using scanning electron microscope (SEM). We used the commercially available round preformed NiTi orthodontic archwire (3M company) and three different mouthwash solutions, i.e., Phos-Flur gel (1.1% sodium acidulated phosphate fluoride, APF, 0.5% w/v fluoride, pH = 5.1; Colgate Oral Pharmaceuticals) and Prevident 5000 (1.1% sodium fluoride neutral agent, 0.5% w/v fluoride, pH = 7; Colgate Oral Pharmaceuticals). All the specimens were subjected to a three-point bending test on a universal testing machine. To observe the surface morphological changes, one wire from each group was randomly selected and observed under a SEM. It was observed that there was not much difference in the values of both modulus of elasticity and yield strength obtained after loading of stress on the wires in all the three experimental conditions. A significant difference in both modulus of elasticity and yield strength was observed during unloading of stress. Further, when the surface characteristics were observed for all the specimens using SEM images, it was observed that NiTi wires treated with Phos-Flur showed large surface defects which appeared as round, pitted areas depicting corrosion, numerous white inclusions, and overall damaged surface structure of the wire as compared with the control. Thus, fluoridated mouthwashes are essential to maintain good oral hygiene and decrease instance of caries in patients undergoing orthodontic treatment. The prophylactic usage of topical fluoride agents on NiTi wire seems to diminish the mechanical properties of the orthodontic wire that could significantly affect future treatment outcomes. It has been proved that fluoride mouthwashes/gels do affect the structural surface qualities and strength of wires used during the orthodontic treatment irrespective of the composition of the wires. Therefore, it is the responsibility of the clinician to prescribe these prophylactic agents carefully while keeping in mind their pH so that the overall result of the treatment may not be hampered and delayed due to change in properties of the wires used.

Effects of Fluoride on Expression of P450, CREM and ACT Proteins in Rat Testes.

Fluoride (F) is an essential trace element that humans and animals ingest from water, air, and fluoride-containing products; however, excessive fluoride absorption can damage a variety of organs and tissues, including the male reproductive system. Our previous studies found that fluoride exposure lowered sperm quality and interfered with spermatogenesis; however, the exact mechanism remained unclear. Proteins cytochrome P450 (P450), cAMP-responsive element modulator (CREM), and activator of CREM in testis (ACT) play the key roles in spermatogenesis and sperm motility. To investigate whether fluoride affects the expression of P450, CREM, and ACT, we used immunohistochemical techniques to determine expression levels of these proteins in testes of rats administered 100mg NaF/L for 2weeks via drinking water. The results showed that P450 expression was decreased while CREM and ACT expression was increased in the fluoride group, compared to the control. These data suggest that fluoride can impair male reproduction by affecting expression of P450, CREM, and ACT in the testes.

Eficiencia in vitro de compuestos fluorados en la remineralización de lesiones cariosas del esmalte bajo condiciones cíclicas de pH

Fluoride-containing products are mainly used due to their anticariogenic effect upon dental enamel. ObjectiveThe aim of the present study was to determine the efficiency of three fluorinated compounds when used on demineralized enamel. MethodA de-mineralized surface was obtained by means of exposing the enamel of 120 permanent third molars to a demineralizing solution for 96 hours. Molars were randomly divided into four groups in order to receive topical treatment with the following fluorinated compounds: 1) silver ammonium fluoride, 2) difluorsilane, 3) acidulated phosphate fluoride and 4) a control group. All samples were immersed in a cyclic pH system (pH 4.4 to 7.0) and retrieved after 5, 10 and 15 days in order to be observed. Samples were examined under polarized light and Tholuet solution in a photomicroscope (Zeiss, Germany) in order to determine remineralization according to exhibited birefringence. Results: After 5 and 10 days, the group treated with silver ammonium fluoride showed significant difference with respect to other groups. Nevertheless, acidulated phosphate fluoride 10-day results remained equally unaltered at 15 days. ConclusionsThe group treated with silver ammonium fluoride presented more significant changes than groups treated with silver ammonium fluoride, difluorsilane as well as the control group.

A randomised in situ trial, measuring the anti-erosive properties of a stannous-containing sodium fluoride dentifrice compared with a sodium fluoride/potassium nitrate dentifrice

To determine if a stabilised, stannous-containing sodium fluoride dentifrice provides greater enamel protection in situ against intraoral dietary erosive challenges compared with a sodium fluoride/potassium nitrate dentifrice. A single-centre, investigator blind, randomised, supervised, two-treatment, non-brushing, four-period crossover in situ study was undertaken, with each test period being 15 days. Thirty-five healthy adult subjects were recruited to participate in the study, which included four erosive acid challenges per day. Subjects were randomised to product treatment, which included either: (1) a stannous-containing sodium fluoride dentifrice (Oral-B(®) Pro-Expert Sensitive) or (2) a sodium fluoride/potassium nitrate dentifrice (Sensodyne(®) Pronamel(®) ). Each study subject wore an intraoral appliance retaining two sterilised, polished human enamel samples for 6 hours/day. Subjects swished with an allocated dentifrice slurry twice a day and with 250 ml of orange juice for 10 minutes (25 ml/minute over a 10-minute period) four times per day. The primary and secondary outcomes for this study were enamel loss measured using contact profilometry at days 15 and 5, respectively, using parametric analysis methods. At day 15, a 38% lower enamel loss (P < 0.0001) was observed, with estimated medians of 2.03 μm (SE 0.247) and 3.30 μm (SE 0.379), in favour of the stannous-containing dentifrice. At day 5, specimens treated with the stannous-containing sodium fluoride dentifrice demonstrated 25% less enamel loss than those treated with the sodium fluoride/potassium nitrate dentifrice. Treatment differences at day 5 were also statistically significant (P < 0.05), with estimated medians of 1.37 μm (SE 0.177) and 1.83 μm (SE 0.223), respectively. Results of this in situ study suggest the stabilised, stannous-containing sodium fluoride dentifrice could be used to provide significantly greater protection to enamel from erosive acid challenge compared with that provided by conventional fluoride-containing products.

Effects of corrosion from fluoridecontaining products on static friction between stainless steel brackets and different types of archwires

Effects of corrosion from fluoridecontaining products on static friction between stainless steel brackets and different types of archwires

Effect of acidic fluoride solution on β titanium alloy wire

The interaction between acidic fluoride solution and beta titanium alloy was investigated to explore the changes that occur in beta titanium alloy by fluoride-containing acetic acid solutions. For this, alloy crystal structure, tensile strength, and elements released from the alloy wires were determined using four solutions (0.05%/pH 6, 0.05%/pH 4, 0.2%/pH 6, and 0.2%/pH 4) for 1 or 3 days. The immersed wire did not form any identifiable new crystal structure compared with the as-received wire. The tensile strength of the immersed wires was significantly reduced compared to the as-received wires in the test solutions if the period of immersion increased from as-received to 3 days. The fractured area of the immersed wire was reduced compared to the as-received one. The dimple pattern at the inner part and a cup-cone morphology at the outer part of the fractured wires were similar in both as-received and immersed wires. After a 3-day immersion, the amount of the released Ti and Mo has much increased for higher NaF concentration and lower pH value. During the long-period orthodontic treatment, both patient and clinical doctor should carefully use the fluoride-containing products to minimize unexpected damage on orthodontic wires.

THE SCIENCE AND PRACTICE OF CARIES PREVENTION

Dental caries is a bacterially based disease. When it progresses, acid produced by bacterial action on dietary fermentable carbohydrates diffuses into the tooth and dissolves the carbonated hydroxyapatite mineral--a process called demineralization. Pathological factors including acidogenic bacteria (mutans streptococci and lactobacilli), salivary dysfunction, and dietary carbohydrates are related to caries progression. Protective factors--which include salivary calcium, phosphate and proteins, salivary flow, fluoride in saliva, and antibacterial components or agents--can balance, prevent or reverse dental caries. Caries progression or reversal is determined by the balance between protective and pathological factors. Fluoride, the key agent in battling caries, works primarily via topical mechanisms: inhibition of demineralization, enhancement of remineralization and inhibition of bacterial enzymes. Fluoride in drinking water and in fluoride-containing products reduces caries via these topical mechanisms. Antibacterial therapy must be used to combat a high bacterial challenge. For practical caries management and prevention or reversal of dental caries, the sum of the preventive factors must outweigh the pathological factors.

Proper use of fluoride products in fluoridated communities

The decision to add 1 mg fluoride per litre of water (or 1 ppm) was based on an extensive series of epidemiological surveys in communities with different concentrations of fluoride in their drinking water. These surveys had shown that in communities with fluoride at 1 ppm the prevalence of dental caries was 50‐65% lower than that in communities with only trace levels of fluoride. Only 10‐12% of children showed evidence of the mildest forms of dental fluorosis. 2 Dental fluorosis is a hypomineralisation of enamel of teeth caused by the chronic ingestion of excessive amounts of fluoride during the period when teeth are forming within the jaw. 3 Milder forms of dental fluorosis are characterised by whitish spots, striations, or diffuse opacities of teeth. Fluorosis does not affect the health of teeth or of an individual, but, in its more severe forms, may cause cosmetic concerns. Permanent teeth other than third molars are susceptible to the development of fluorosis in children aged up to 6 years. Excessive fluoride ingestion early in life tends to produce fluorosis in early forming and erupting permanent teeth, the incisors and first molars, whereas excessive ingestion in the later preschool years affects later forming and erupting permanent teeth, the canines, premolars, and second molars. In the 1950s and 1960s, several countries started to fluoridate their water. Hong Kong and Singapore fluoridated all their water supplies, and countries that provide fluoridated water to more than half their residents include Australia, Ireland, New Zealand, and the USA. Other countries with large water-fluoridation programmes include Brazil, Canada, Chile, and Malaysia. At the time fluoridation programmes began, fluoride that occurred naturally in drinking water and that which occurred naturally in some foods, primarily tea, seafood, and some grains, were essentially the only sources of ingested fluoride. Since then, several fluoride-containing products have been developed as alternatives to fluoridated water (dietary fluoride supplements) or as agents to provide fluoride topically to erupted teeth (fluoride toothpastes and mouth rinses and solutions, gels, and varnishes for professional application). About 20 years ago, investigators began to notice increased prevalences of dental fluorosis in school-aged children who were participants in epidemiological surveys or in clinical field trials in countries with established market economies. Most of the fluorosis observed was still mild, but there have been some increases as well in the intensity of fluorosis. Increases in the prevalence of fluorosis have been noted in non-fluoridated as well as fluoridated communities. 4 , 5

Prevention and reversal of dental caries: role of low level fluoride.

Dental caries is a bacterially based disease that progresses when acid produced by bacterial action on dietary fermentable carbohydrates diffuses into the tooth and dissolves the mineral, that is, demineralization. Pathological factors including acidogenic bacteria (mutans streptococci and lactobacilli), salivary dysfunction, and dietary carbohydrates are related to caries progression. Protective factors which include salivary calcium, phosphate and proteins, salivary flow, and fluoride in saliva can balance, prevent or reverse dental caries. Fluoride works primarily via topical mechanisms which include (1) inhibition of demineralization at the crystal surfaces inside the tooth, (2) enhancement of remineralization at the crystal surfaces (the resulting remineralized layer is very resistant to acid attack), and (3) inhibition of bacterial enzymes. Fluoride in drinking water and in fluoride-containing products reduces tooth decay via these mechanisms. Low but slightly elevated levels of fluoride in saliva and plaque provided from these sources help prevent and reverse caries by inhibiting demineralization and enhancing remineralization. The level of fluoride incorporated into dental mineral by systemic ingestion is insufficient to play a significant role in caries prevention. The effect of systemically ingested fluoride on caries is minimal. Fluoride "supplements" can be best used as a topical delivery system by sucking or chewing tablets or lozenges prior to ingestion.