Systemic Effects (Risks) of Water Fluoridation

Association of fluoride exposure with disease burden and neurodevelopment outcomes in children in South Korea

BACKGROUND

Community water fluoridation is an effective public health strategy for preventing dental caries, yet. Concerns exist about potential health problems. This study explores associations between tap water fluoride levels and pediatric disease burden, as well as neurodevelopmental outcomes at 6 years of age.

METHODS

This nationwide population-based cohort study included children born in Korean cities with and without tap water fluoridation projects, between 2006 and 2012, aiming for a fluoride concentration of 0.8 ± 0.2 mg/L in treated tap water. Data from the National Health Insurance Service were used, spanning from birth to 2018. The relationship between exposure to fluoridated tap water and incidence of 16 childhood diseases that were previously identified as potentially linked to fluoride exposure were examined. Additionally, we evaluated the neurodevelopmental outcomes across various domains, including gross motor, fine motor, cognition, language, social skills, and self-help functions. These assessments were performed using data from a comprehensive national health screening program for children aged six years.

RESULTS

A fluoride-unexposed group included 22,881 children, whereas a fluoride-exposed group comprised 29,991 children (52% males). Children in the fluoride-exposed group had a decreased risk of dental caries and bone fractures [hazard ratio (95% confidence interval, CI), 0.76 (0.63-0.93) and 0.89 (0.82-0.93), respectively] and increased risk of hepatic failures [1.85, (1.14-2.98)] compared to those in the unexposed group. Additionally, the risk ratio of abnormal neurodevelopmental screening outcomes increased by 9%, but this was statistically uncertain (95% CI, 0.95-1.26).

CONCLUSIONS

Fluoridated tap water was associated with an increased risk of hepatic failure but a decreased risk of bone fractures in children. The association between fluoridated tap water and neurodevelopmental screening outcomes at 6 years remains unclear, highlighting the need for further studies to clarify this association.

Control of Dental Caries in Children and Adolescents Using Fluoride: An Overview of Community-Level Fluoridation Methods

The maintenance of oral health is a crucial aspect of general well-being; however, a significant proportion of the worldwide population experiences a range of oral diseases. Dental caries is a highly prevalent non-communicable disease globally, especially in children and adolescents. Fluoride is involved in the control of dental caries, primarily by decreasing the critical pH for dental hard tissue dissolution and decreasing enamel solubility. Due to the substantial data supporting the efficacy of fluoride in controlling dental caries, many community-level fluoridation initiatives have been devised and executed as global public health preventive interventions. These initiatives encompass the fluoridation of water, salt, and milk. Water fluoridation is considered safe and effective when fluoride levels are maintained within the recommended range (0.6 to 1.1 mg/L). Salt fluoridation has a cariostatic potential similar to that of water fluoridation, and a fluoride concentration of 250 micrograms per gram in salt is not associated with an increased risk of developing dental fluorosis. However, there is currently an effort to reduce the consumption of table salt in order to mitigate the harmful effects of excessive salt consumption. It has been hypothesized that fluoride food supplementation, such as fluoridated milk, is associated with a decrease in caries experience in permanent teeth; however, the effect is not clear in primary teeth. Public-level fluoride interventions are more cost-effective than the operative care of caries lesions and limit the burden of care. The administration of fluorides should be conducted using safe methods, limiting ingestion, and adhering to the guidelines set by international and national health agencies in each country. This is particularly important when considering children with developing dentitions. Fluoride is an important tool in the control of dental caries, but it is crucial to combine it with good oral hygiene, a healthy diet, and regular visits to a dental professional to maintain long-term oral health.

Could fluoride be considered a genotoxic chemical agent in vivo? A systematic review with meta-analysis

The goal of this study was to perform systematic review (SR) to investigate the scientific literature regarding the genotoxicity effects of fluoride exposure (FE). The search of databases used for this study was PubMed/Medline, SCOPUS and Web of Science. The quality of included studies was assessed using the EPHPP (Effective Public Health Practice Project). A total of 20 potentially relevant studies were selected for evaluating the genotoxicity induced by fluoride. Few studies have revealed that FE induces genotoxicity. A total of 14 studies demonstrated negative results whereas 6 studies did not. After reviewing the twenty studies, 1 was classified as weak, 10 were considered moderate and 9 were considered strong, according to the EPHPP. Taken together, it has been established that genotoxicity of fluoride is limited.

The fluorosis conundrum: bridging the gap between science and public health

Fluorosis, a chronic condition brought on by excessive fluoride ingestion which, has drawn much scientific attention and public health concern. It is a complex and multifaceted issue that affects millions of people worldwide. Despite decades of scientific research elucidating the causes, mechanisms, and prevention strategies for fluorosis, there remains a significant gap between scientific understanding and public health implementation. While the scientific community has made significant strides in understanding the etiology and prevention of fluorosis, effectively translating this knowledge into public health policies and practices remains challenging. This review explores the gap between scientific research on fluorosis and its practical implementation in public health initiatives. It suggests developing evidence-based guidelines for fluoride exposure and recommends comprehensive educational campaigns targeting the public and healthcare providers. Furthermore, it emphasizes the need for further research to fill the existing knowledge gaps and promote evidence-based decision-making. By fostering collaboration, communication, and evidence-based practices, policymakers, healthcare professionals, and the public can work together to implement preventive measures and mitigate the burden of fluorosis on affected communities. This review highlighted several vital strategies to bridge the gap between science and public health in the context of fluorosis. It emphasizes the importance of translating scientific evidence into actionable guidelines, raising public awareness about fluoride consumption, and promoting preventive measures at individual and community levels.

Parental stress and dental caries experience in adolescents: analysis of data from a birth cohort study in Pelotas, Southern Brazil

PURPOSE

Analyze the association between parental stress and dental caries experience in adolescents in southern Brazil using data from the Pelotas 2004 Birth Cohort.

METHODS

Interviews and oral health examinations for the determination of the main exposure and outcome of the study were performed in the homes of the adolescents. The outcome was dental caries experience in the permanent dentition analyzed using the Decayed, Missing and Filling Surfaces (DMFS) index. The main exposure was parental stress measured using the Parenting Stress Index-Short Form administered to the parents of the adolescents. Demographic/socioeconomic characteristics, oral health characteristics and oral health-related quality of life were considered potential confounding factors. Negative binomial regressions estimated mean ratios (MR) and 95% confidence intervals (CI).

RESULTS

Nine hundred ninety-six adolescents were evaluated at 12 and 13 years of age. The prevalence of dental caries experience in the adolescents was 36.9% (95% CI: 33.8-40.0) and 15.1% (95% CI: 12.8-17.3) of the parents had parental stress. After adjusting for confounding factors, parental stress was associated with a higher mean number of decayed, missing and filling surfaces in the adolescents (MR = 1.10; 95% CI: 1.01-1.26; p = 0.045).

CONCLUSION

Adolescents of parents with parental stress have more dental caries experience compared to those whose parents do not have parental stress.

Distribution of Dental Fluorosis in the Southern Zone of Ecuador: An Epidemiological Study

In recent decades, the increase in fluoride exposure has raised the numbers of dental fluorosis in fluoridated and non-fluoridated communities In Ecuador, but the last national epidemiological study on DF was conducted more than a decade ago. The objective of this cross-sectional descriptive study was to determine the prevalence, distribution and severity of dental fluorosis (DF) using the Dean index in 1606 schoolchildren aged 6 to 12 years from urban and rural environments in provinces that make up the Southern Region of Ecuador. Participants met the inclusion criteria which were age, locality, informed consent document and no legal impediment. The results are presented using percentage frequency measures and chi-square associations. The prevalence of dental fluorosis was 50.1% in the areas of Azuay, Cañar and Morona Santiago, with no significant differences (x2 = 5.83, p = 0.054). The types of DF found most frequently were very mild and mild in all provinces; a moderate degree was more prevalent in Cañar (17%). There was no significant association (p > 0.05) between sex and the presence of dental fluorosis and, with respect to severity, the most frequent degree was moderate at the age of 12 years. The prevalence of dental fluorosis in the area evaluated is high, especially in the light and very light degrees, with a tendency toward moderate levels. It is necessary to carry out studies on the factors that are predisposing to the development of this pathology in the population studied. This research is an update regarding this pathology in Ecuador, so it is concluded that it is necessary to continue developing studies based on the findings obtained, thus contributing to the public health of the country.

AFFECTION ON CARIES AND ITS COMPLICATIONS OF TEMPORARY TEETH OF CHILDREN IN A REGION WITH EXCESS FLUORINE CONTENT IN DRINKING WATER

OBJECTIVE

Aim: The aim of the study was to determine the indicators of caries and its complications in the temporary teeth of children who permanently live in a region with a high fluoride content in drinking water.

PATIENTS AND METHODS

Materials and Methods: It was examined with the definition of caries and its complications 277 children in the age range from 2 to 13 years, who were born and permanently live in the urban-type settlement of Mashivka. The fluoride content in the drinking water of the settlement was 1.7-2.5 mg/l.

RESULTS

Results: During the analysis of data from the survey of children who were born and permanently lived in the urban-type settlement of Mashivka, it was determined that the prevalence of caries of temporary teeth probably increases with age. Half of the 3-5-year-old children had caries-affected teeth, and temporary tooth caries reached the highest rates in 10-year-old children. It should be noted that a fifth of children in the youngest age group (3-5 years old) suffer from pulpitis and periodontitis of temporary teeth.

CONCLUSION

Conclusions: The conducted examination of children urban-type settlement of Mashivka confirms the opinion that the excessive content of fluorine in drinking water does not have a caries-protective effect, and the intensity of the process reaches the indicators characteristic of regions with its optimal content. Such a situation requires strengthening measures for both primary and secondary prevention of dental diseases.

Fluoride Exposure and Salivary Glands: How Is Glandular Morphology Susceptible to Long-Term Exposure? A Preclinical Study

Despite a strong body of evidence attesting to the effectiveness of fluoride (F) in preventing and controlling caries, some studies have sought to investigate the influence of F exposure on the salivary glands, organs that are essential for the maintenance of cavity homeostasis through salivary production, finding that exposure to F can cause biochemical and proteomic changes. Thus, this study aimed to investigate the morphological effects of prolonged exposure to F on the salivary glands of mice, at concentrations that would correspond to optimally fluoridated water (suitable for human consumption) and to fluorosis-endemic regions. Twenty-four male mice (Mus musculus) were divided into three groups, according to F levels in the drinking water: 0 (control), 10, or 50 mg F/L, with an exposure period of 60 days. The glands were morphometrically analyzed for the total acinar area, parenchyma area, and stromal area, as well as for the immunohistochemical analysis of myoepithelial cells. The results showed that prolonged exposure to F at 10 mg F/L did not promote significant changes in the morphometry of the salivary glands of mice, which reinforces the safety of the chronic use of F in low doses.

Maternal Fluoride Exposure Exerts Different Toxicity Patterns in Parotid and Submandibular Glands of Offspring Rats

There is currently a controversial and heated debate about the safety and ethical aspects of fluoride (F) used for human consumption. Thus, this study assessed the effects of prenatal and postnatal F exposure of rats on the salivary glands of their offspring. Pregnant rats were exposed to 0, 10, or 50 mg F/L from the drinking water, from the first day of gestation until offspring weaning (42 days). The offspring rats were euthanized for the collection of the parotid (PA) and submandibular (SM) glands, to assess the oxidative biochemistry and to perform morphometric and immunohistochemical analyses. F exposure was associated with a decrease in the antioxidant competence of PA in the 10 mg F/L group, contrasting with the increase observed in the 50 mg F/L group. On the other hand, the antioxidant competence of the SM glands was decreased at both concentrations. Moreover, both 10 and 50 mg F/L groups showed lower anti-α-smooth muscle actin immunostaining area in SM, while exposure to 50 mg F/L was associated with changes in gland morphometry by increasing the duct area in both glands. These findings demonstrate a greater susceptibility of the SM glands of the offspring to F at high concentration in comparison to PA, reinforcing the need to adhere to the optimum F levels recommended by the regulatory agencies. Such findings must be interpreted with caution, especially considering their translational meaning.

Spectroscopic Determination of Fluoride Using Eriochrome Black T (EBT) as a Spectrophotometric Reagent from Groundwater

Fluoride health problem is a great concern worldwide, most often as a result of groundwater intake. Thus, determination of fluoride is vital to take appropriate measures upon fluoride contamination of water. Potentiometric method of analysis is reliable for the determination of fluoride in various samples. In addition, spectroscopic methods are found important to quantify fluoride levels from water; however, several factors hinder its easier determination. Among the bottlenecks, the use of toxic chemicals and tedious steps in preparing chemicals (e.g., SPADNS method) are to mention a few. In this study, a spectrophotometric method was developed for the determination of fluoride from groundwater using Eriochrome Black T (EBT) as a spectroscopic reagent. Experimental parameters that influence the determination of fluoride including ligand type, kinetics, pH, and ligand-to-metal ratio were assayed. Evaluation of fluoride levels showed that Beer–Lambert's law is obeyed in the range of 0.3–5.0 mg/L at 544 nm. The calibration curve, resulting in good linearity (R² = 0.9997), was considered during quantitative analysis of the samples and in the spiking analysis. The limits of detection (LOD) and quantification (LOQ) of the method were found to be 0.19 and 0.64 mg/L, respectively. The precision studied in terms of intraday and interday at three concentration levels showed less than 5.4% RSD. Applicability of the method was investigated by analyzing groundwater samples spiked with fluoride standards, and satisfactory recoveries in the range of 98.18–111.4 were demonstrated. The developed spectrophotometric method has been successfully applied for fluoride determinations in groundwater samples. Thus, it could be used as an attractive alternative for the determination of fluoride from groundwater.

Effect of fluoridated water on dental caries and fluorosis in schoolchildren who use fluoridated dentifrice

This cross-sectional study evaluated the prevalence and severity of dental caries and fluorosis in children and adolescents using fluoridated toothpaste, from areas with and without fluoridated water. Parents of 5-year-old children and 12-year-old adolescents from neighbourhoods that are supplied with and without fluoridated water answered questionnaires for determining socio-economic and demographic characteristics and habits related to oral health. The individuals were examined, and dental caries and fluorosis were measured by dmft/DMFT and TF indexes, respectively. Descriptive, bivariate and logistic regression analyses were performed (p < 0.05). Of 692 participants, 47.7% were 5-year-olds and 52.3% were 12-year-olds. The mean dmft/DMFT in the 5-year-olds/ 12-year-olds from Exposed and Not Exposed fluoridated water groups was 1.53 (± 2.47) and 3.54 (± 4.10) / 1.53 (± 1.81) and 3.54 (± 3.82), respectively. Children (OR = 2.86, 95% CI = 1.71-4.75) and adolescents (OR = 1.95, 95% CI = 1.24-3.05), who did not consume fluoridated water, had greater caries experience. Among adolescents, there was an association between fluoridated water and the prevalence of very mild/mild fluorosis (OR = 5.45, 95% CI: 3.23-9.19) and moderate fluorosis (OR = 11.11, 95% CI = 4.43-27.87). Children and adolescents, who consumed fluoridated water, presented lower prevalence and severity of dental caries compared to those who used only fluoridated toothpaste as the source of fluoride. There is an association between water fluoridation and very mild/mild and moderate fluorosis in adolescents.

Fluoride exposure decreased neurite formation on cerebral cortical neurons of SD rats in vitro

Fluoride, a geochemical element, can damage the brain and result in dysfunction of the central nervous system. In recent years, fluoride-induced neurotoxicity has become one of research focuses of environmental toxicology. Our previous study showed that fluoride could induce the structural damages of the cerebral cortex and reduce the learning and memory abilities of mice offspring. However, the underlying mechanisms of these effects remain unclear. In this study, primary neurons were isolated from the cerebral cortices of postnatal 1-day SD rats. The primary cultured cerebral cortical neurons were adherent and the cellular network was obvious. Neurons were identified by Nissl's staining and were used for experiments. Different concentrations of sodium fluoride (0.5, 1.0, 1.5, 2.0 and 2.5 mM) were chosen to explore its toxic effects on neuron of SD rats in vitro. Results showed that neuronal morphology was obviously damaged in 2.0 and 2.5 mM, but was not adversely affected in 0.5 and 1 mM. Further studies revealed that the neurites of neuron were shrunken and even became fractured with the increase in NaF dose, which have been detected by scanning electron microscopy (SEM). Meanwhile, TEM showed marginated chromatin, widened nuclear gaps, damaged nuclei and swollen or even absent mitochondria in 1.5, 2 and 2.5 mM group. The cytoskeletal staining was consistent with the above results. The number of neurites of cerebral cortical neuron significantly decreased after fluoride exposure by immunofluorescent assay. In summary, high fluoride (1.5, 2 and 2.5 mM) concentrations exerted a significant toxic effect on the cellular morphologies and neural formation of primary cultured cortical neurons. These findings provide new insights into the roles of NaF in neuronal damage and can contribute to an improved understanding of fluoride-induced neurotoxicity.

[Fluoride levels in springs and water sources and in the public supply networks of municipalities in the State of Pernambuco, Brazil]

Fluoridation is considered an effective and wide-ranging measure in combatting dental caries. Despite being mandatory in Brazil since 1974, the implementation continues to be unequal throughout the country. The objective was to describe and analyze fluorine levels in the waters of the public supply grid of the 2nd macro region of the state of Pernambuco in municipalities with 50,000 inhabitants or more. This is a descriptive study based on a comparison of data from Pernambuco Sanitation Company (Compesa), the Vigifluor Project, the Water Quality Surveillance Information System for Human Consumption (Sisagua) the Brazilian Institute of Geography and Statistics (IBGE) and the National Sanitation Information System (SNIS), on the fluoridation of water in municipalities of the 2nd health macro region of Pernambuco. Although the municipalities studied do not have artificial fluoridation, significant levels of natural fluorine were found in the sources that supply the regions. However, these levels of fluorine do not remain constant in the waters of the supply network of the municipalities studied, therefore there is no effective prevention against caries. Artificial fluoridation is an effective measure in preventing caries and should therefore be expanded in regions that are not yet fluoridated.

Fluoridated water impact on tooth decay and fluorosis in 17-20-year-olds exposed to fluoride toothpaste

OBJECTIVE

To determine the impact of water fluoridation on the prevalence and severity of dental caries and fluorosis in individuals aged 17-20 years exposed to fluoride toothpaste.

METHODS

The study population consisted of 660 students from public schools, residents of areas supplied with fluoridated water (exposed group) or not (not exposed group). Students from both groups had access to fluoride toothpaste throughout life. A questionnaire about socioeconomic demographic aspects, conditions related to access and exposure to fluoridated water, and habits related to oral health was applied. Dental caries was measured by the DMFT index and dental fluorosis by the TF index. The chi-square test, t test, and subsequently logistic regression were applied for data analysis.

RESULTS

Caries experience (DMFT≠0) was significantly higher in students from areas not exposed to fluoridated water, after adjustments to clinical conditions, demographic socioeconomic profile, and hygiene habits. The DMFT mean (±SD) was significantly higher in students from areas not exposed to fluoridated water than exposed (3.83 [±3.28] and 2.48 [±2.71] respectively). The prevalence of very mild/mild and moderate fluorosis was 41.1% and 21% for students either exposed to fluoridated water or not, respectively.

CONCLUSION

Exposure to fluoridated water was associated with a lower prevalence and severity of tooth decay, in spite of the use of fluoridated toothpaste. The prevalence of dental fluorosis at all levels was higher in fluoridated areas, however, in both groups, there were few cases with esthetic implications.

Community interventions and strategies for caries control in Latin American and Caribbean countries

Dental caries remains highly prevalent in Latin American and Caribbean countries (LACC). However, this disease can be controlled through interventions that implement evidence-based strategies in an affordable manner and that target all population groups instead of the most affluent only. Therefore, the aim of this report was to summarize the main scientifically documented community interventions and strategies based on restriction of sugars consumption, use of fluoride, and the use of occlusal sealants for caries control in LACC. A critical literature review was carried out in a systematic manner that included defined search strategies, independent review of the identified publications, and compilation of results in this report. Three systematic searches were conducted using the PubMed, LILACS, and SciELO databases to identify studies related to community interventions and strategies for caries control in LACC. Of the 37 publications identified, twenty-six focused on fluoride use, eight on occlusal sealant use, and three on the restriction of sugar consumption. Documented community interventions for sugars restriction were scarce in the region and were based on food supplementation, sugar replacement, and education. Thus, local and/or national policies should prioritize investment in upstream, coherent, and integrated population-wide policies such as taxes on sugary drinks and stronger regulation of advertising and promotion of sugary foods and drinks mainly targeting children. The main fluoride-based strategies used drinking water, refined domestic salt, cow milk, toothpaste and, to a lesser extent, mouth-rinses, acidulated phosphate fluoride (APF) gels, and varnishes to deliver fluoride to the population. Evidence of fluoride use was seen in Argentina, Belize, Bolivia, Brazil, Chile, Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador, El Salvador, Guatemala, Haiti, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Uruguay, and Venezuela. Studies reporting the use of occlusal sealants were mainly located in Brazil, Chile, Colombia, Costa Rica, Peru, Mexico, and Venezuela. Community interventions restricting sugar consumption should be implemented at the individual level and through public policies. The use of fluoride must be monitored at the local, regional, and national levels so as to achieve maximum anti-caries effect while also minimizing the risk of dental fluorosis. Moreover, fluoridated water and salt programs, used as a mutually exclusive community level strategy for caries control, should expand their benefits to reach non-covered areas of the LACC while also simultaneously providing adequate surveillance of the fluoride concentration delivered to the population. Regulating the concentration of soluble fluoride (for anti-caries effect) in dentifrice formulations is also necessary in order to provide the population with an effective strategy for disease control. Targeting culturally appropriate, economically sustainable caries control interventions to rural populations and native ethnic groups such as indigenous people, quilombolas (African-origin), and riverside Amazonian people remains a crucial challenge.

Examining the Relationship between Social and School Environment and Children's Caries Experience Using Primary and Secondary Data: A Cluster Analysis

Dental caries is still prevalent worldwide, even with advances in preventive and curative measures. The aim was to examine clustering patterns of socioeconomic and environmental characteristics of schools and their associations with caries experience of schoolchildren. An epidemiological survey with cross-sectional design was conducted in 2014/2015 and included 5,213 students (aged 2-11 years) from 38 public schools of Carapicuíba (SP, Brazil). Primary data consisted of dental examinations performed at schools by 6 calibrated examiners to evaluate caries experience (dmf/DMFT index). Secondary data were extracted from the last official Demographic Census (2010) and School Census (2014 and 2015) to assess the socioeconomic and environmental characteristics of the territorial units and infrastructure of each school, respectively. Cluster analysis and ANOVA were applied to identify schools with similar social and environmental aspects and children's caries experience. A logistic regression model was used to ascertain the effects of cluster variables on the likelihood that participants have caries experience, controlling for the stage of dentition and sex. Two valid and reliable clusters were identified: cluster 1 ("advantaged group"), characterized by 33 schools with the highest percentages of children without caries experience and located in regions with better socioenvironmental indicators, and cluster 2 ("least advantaged group"), characterized by 5 schools with higher percentages of children with caries experience, lower percentages of households with sanitary sewer and water supply, higher residents/household ratio and higher percentages of families living with up to 1 minimum wage. An increase in the odds of having caries experience for each percent of houses with well water and families which live with up to 1 minimum wage was observed. By using primary and secondary data, the study draws attention to the relationship between socioeconomic and environmental indicators and caries experience, identifying least advantaged regions and helping to design strategic health plans for this target population.

Fluoride exposure during pregnancy and lactation triggers oxidative stress and molecular changes in hippocampus of offspring rats

Long-term exposure to high concentrations of fluoride (F) can damage mineralized and soft tissues such as bones, liver, kidney, intestine, and nervous system of adult rats. The high permeability of the blood-brain barrier and placenta to F during pregnancy and lactation may be critical to neurological development. Therefore, this study aimed to investigate the effects of F exposure during pregnancy and lactation on molecular processes and oxidative biochemistry of offspring rats' hippocampus. Pregnant Wistar rats were randomly assigned into 3 groups in accordance with the drinking water received: G1 - deionized water (control); G2 - 10 mg/L of F and G3 - 50 mg/L of F. The exposure to fluoridated water began on the first day of pregnancy and lasted until the 21^st day of breastfeeding (when the offspring rats were weaned). Blood plasma samples of the offspring rats were collected to determine F levels. Hippocampi samples were collected for oxidative biochemistry analyses through antioxidant capacity against peroxyl (ACAP), lipid peroxidation (LPO), and nitrite (NO₂^-) levels. Also, brain-derived neurotrophic factor (BDNF) gene expression (RT-qPCR) and proteomic profile analyses were performed. The results showed that exposure to both F concentrations during pregnancy and lactation increased the F bioavailability, triggered redox imbalance featured by a decrease of ACAP, increase of LPO and NO₂^- levels, BDNF overexpression and changes in the hippocampus proteome. These findings raise novel questions regarding potential repercussions on the hippocampus structure and functioning in the different cognitive domains.

Influence of topical fluoride on shear bond strength of orthodontic brackets and enamel white spot lesions formation

Abstract Introduction Fluoride is considered a key element in the remineralization process of tooth enamel. Objective To evaluate the influence of a topical solution of sodium fluoride (NaF) on the shear bond strength of orthodontic brackets and white spot lesions formation. Material and method Sixty bovine teeth were divided into three groups (n=20). Group 1 (Control): shear bond strength; Group 2: shear bond strength after pH cycling; Group 3: shear bond strength after pH cycling and treatment with 0.04% NaF solution. Groups 2 and 3 underwent pH cycling with demineralizing (6hs) and remineralizing (17hs) solutions at pH of 4.3 and 7.0 respectively for 15 days. The specimens were submitted to the shear bond strength and the Adhesive Remnant Index was verified (ARI). The specimens of each group (n=3) were qualitatively analyzed by means of Scanning Electron Microscopy (SEM). Kruskal-Wallis test assessed the shear bond strength and Fisher's exact test evaluated ARI, with significance level of 5%. Result There was no significant difference among the three groups in shear bond strength (p=0.2679). Significant difference was found in ARI (p=0.0199). The frequency of ARI 1 was 55% in group 1, 90% in group 2, and 80% in group 3. SEM showed difference between the enamel and bonding. Group 2 showed structural change of the enamel surface, adjacent to the bond area; and group 3 showed enamel with characteristics similar to those of group 1. Conclusion It was concluded that there was no NaF influence on the bracket shear bond strength and even in low concentrations it prevented the development of areas of demineralization of white spot lesions.

Effects of Fluoride Long-Term Exposure over the Cerebellum: Global Proteomic Profile, Oxidative Biochemistry, Cell Density, and Motor Behavior Evaluation

Although the literature does not provide evidence of health risks from exposure to fluoride (F) in therapeutic doses, questions remain about the effects of long-term and high-dose use on the function of the central nervous system. The objective of this study was to investigate the effect of long-term exposure to F at levels similar to those found in areas of artificial water fluoridation and in areas of endemic fluorosis on biochemical, proteomic, cell density, and functional parameters associated with the cerebellum. For this, mice were exposed to water containing 10 mg F/L or 50 mg F/L (as sodium fluoride) for 60 days. After the exposure period, the animals were submitted to motor tests and the cerebellum was evaluated for fluoride levels, antioxidant capacity against peroxyl radicals (ACAP), lipid peroxidation (MDA), and nitrite levels (NO). The proteomic profile and morphological integrity were also evaluated. The results showed that the 10 mg F/L dose was able to decrease the ACAP levels, and the animals exposed to 50 mg F/L presented lower levels of ACAP and higher levels of MDA and NO. The cerebellar proteomic profile in both groups was modulated, highlighting proteins related to the antioxidant system, energy production, and cell death, however no neuronal density change in cerebellum was observed. Functionally, the horizontal exploratory activity of both exposed groups was impaired, while only the 50 mg F/L group showed significant changes in postural stability. No motor coordination and balance impairments were observed in both groups. Our results suggest that fluoride may impair the cerebellar oxidative biochemistry, which is associated with the proteomic modulation and, although no morphological impairment was observed, only the highest concentration of fluoride was able to impair some cerebellar motor functions.

Stannous Fluoride Effects on Enamel: A Systematic Review

In recent years there has been a lot of talk about toothpastes with a particular chemical compound: stannous fluoride (SnF2). Its presence is currently still highly controversial, as the latter could have negative health effects. The different companies that produce toothpastes express its dosage in ppm. The purpose of this systematic literature review is to analyze all randomized clinical trials in the literature over the last 10 years and to draw clear results on the function of stannous fluoride, for this purpose the authors performed a Mann-Whitney U Test.

MATERIALS

The first analysis of the literature produced a number greater than 800 results, subsequently applying the inclusion and exclusion criteria, and following a manual analysis of the results, 26 manuscripts have been obtained.

RESULTS

From the results analyzed in this review, it could be shown that stannous fluoride does not present important contraindications, if not those commonly reported for fluorine. A meta-analysis on enamel loss has been conducted, it shows that SnF2 products provide better results with a p < 0.05 value.

CONCLUSION

This compound could have significant effects in favor of erosion and recalcification of the enamel, on the biofilm formation, gingival inflammation, and in addition, it could be an important aid in the removal of tooth stains and halitosis.