How to optimize bonding procedures on healthy and hypomineralized enamel in orthodontics? / Comment optimiser les procédures de collage sur l'émail sain et hypominéralisé en orthodontie ?

Introduction: Bonding to enamel is a daily problem for the orthodontist. While bonding to healthy enamel is nowadays well mastered, bonding to hypomineralized enamel is much less so. The aim of this article was to help the orthodontist to optimise bonding, whatever the clinical situation. Material and Method: Based on data from the literature, the clinical and microscopic characteristics of healthy and hypomineralised enamel, including amelogenesis imperfecta (AI), molar incisor hypomineralization (MIH), fluorosis or erosion will be described. Proposals for optimising bonding will then be identified and summarized. Results: Bonding to enamel is reliable, but the use of an etch-and-rinse mode (even with a universal adhesive) is recommended. For AI, MIH and fluorosis, the use of sodium hypochlorite after etching seems to significantly increase bonding. No treatment is needed for eroded enamel. However, deep resin infiltration for severe MIH or superficial resin infiltration for fluorosis would reduce the risk of enamel fracture during bracket removal. Conclusion: It is important to be aware of the characteristics of the dental substrate and the materials used to optimize procedures.

Introduction: L'adhésion à l'émail est une problématique quotidienne de l'orthodontiste. Si le collage à l'émail sain est aujourd'hui maîtrisé, celui sur l'émail hypominéralisé l'est beaucoup moins. L'objectif de cet article était d'aider l'orthodontiste à optimiser son collage, quelle que soit la situation clinique. Matériel et méthode: À partir des données issues de la littérature, les caractéristiques clinique et microscopique de l'émail sain et de l'émail hypominéralisé en cas d'amélogenèse imparfaite (AI), d'hypominéralisation de molaire incisive (MIH), de fluorose ou d'érosion seront décrites. Puis, les propositions d'optimisation du collage seront recensées et synthétisées. Résultats: Le collage à l'émail est fiable, mais l'utilisation d'un mode mordançage-rinçage (même avec un adhésif universel) est conseillée. Pour l'AI, la MIH et la fluorose, l'utilisation d'hypochlorite de sodium après mordançage semble significativement augmenter l'adhérence. Aucun traitement n'est nécessaire pour l'émail érodé. Cela dit, une infiltration de résine en profondeur pour les MIH sévères ou superficielles pour la fluorose permettrait de réduire le risque de fracture d'émail à la dépose de l'attache. Conclusion: Il convient de connaître les caractéristiques du substrat sur lequel on colle et celles des matériaux utilisés pour optimiser ses procédures.

Epidemiological analysis of drinking water-type fluorosis areas and the impact of fluorosis on children's health in the past 40 years in China.

This study analyzed the effect of China's fluorosis prevention and control program, which has been in effect for more than 40 years, and the impact of fluorosis on children's health. Relevant research studies were retrieved from the following online databases from the time of their inception to May 2022: PubMed, ScienceDirect, Embase, Cochrane, China National Knowledge Infrastructure, and Wanfang. The Review Manager 5.3 software was used in statistical analyses. This article included seventy studies: Thirty-eight studies reported the effect of improving water quality and reducing fluoride content, the incidence rate of dental fluorosis in children, and the level of urinary fluoride, and thirty-two studies reported the intelligence quotient (IQ) and health status of children. Following water improvement strategies, the fluoride levels in drinking water decreased significantly; urinary fluoride levels and dental fluorosis decreased significantly in children. With regard to the effect of fluorosis on the IQ of children, the results showed that the IQ of children in areas with a high fluoride of fluorosis was lesser than that in areas with a low fluoride, and this difference was significant. Based on the prevalence of dental fluorosis and its effect on the intelligence of children, it appears that reducing fluoride levels in drinking water and monitoring water quality are important strategies for the prevention and treatment of fluorosis.

Aberrant gut microbiota and fecal metabolites in patients with coal-burning endemic fluorosis in Guizhou, China.

Chronic exposure to excessive environmental fluoride has caused fluorosis to become a major public health problem worldwide. Although studies on stress pathways, signaling pathways, and apoptosis induced by fluoride have provided an in-depth understanding of the mechanism of this disease, its exact pathogenesis remains unclear. We hypothesized that the human gut microbiota and metabolome are associated with the pathogenesis of this disease. To get further insight into the profiles of intestinal microbiota and metabolome in coal-burning-induced endemic fluorosis patients, we conducted 16S rRNA sequencing of the intestinal microbial DNA and carried out non-targeted metabolomics of fecal samples from 32 patients with skeletal fluorosis and 33 matched healthy controls in Guizhou, China. We found that the gut microbiota of coal-burning endemic fluorosis patients displayed significant differences in composition, diversity, and abundance compared with healthy controls. This was characterized by an increase in the relative abundance of Verrucomicrobiota, Desulfobacterota, Nitrospirota, Crenarchaeota, Chloroflexi, Myxococcota, Acidobacteriota, Proteobacteria, and unidentified_Bacteria, and a significant decrease in the relative abundance of Firmicutes and Bacteroidetes at the phylum level. Additionally, at the genus level, the relative abundance of some beneficial bacteria, such as Bacteroides, Megamonas, Bifidobacterium, and Faecalibacterium, was significantly reduced. We also demonstrated that, at the genus level, some gut microbial markers, including Anaeromyxobacter, MND1, oc32, Haliangium, and Adurb.Bin063_1, showed potential for identifying coal-burning endemic fluorosis. Moreover, non-targeted metabolomics and correlation analysis revealed the changes in the metabolome, particularly the gut microbiota-derived tryptophan metabolites such as tryptamine, 5-hydroxyindoleacetic acid, and indoleacetaldehyde. Our results indicated that excessive fluoride might cause xenobiotic-mediated dysbiosis of human gut microbiota and metabolic disorders. These findings suggest that the alterations in gut microbiota and metabolome play vital roles in regulating disease susceptibility and multi-organ damage after excessive fluoride exposure.

Fuzzy K-Nearest Neighbor Based Dental Fluorosis Classification Using Multi-Prototype Unsupervised Possibilistic Fuzzy Clustering via Cuckoo Search Algorithm.

Dental fluorosis in children is a prevalent disease in many regions of the world. One of its root causes is excessive exposure to high concentrations of fluoride in contaminated drinking water during tooth formation. Typically, the disease causes undesirable chalky white or even dark brown stains on the tooth enamel. To help dentists screen the severity of fluorosis, this paper proposes an automatic image-based dental fluorosis segmentation and classification system. Six features from red, green, and blue (RGB) and hue, saturation, and intensity (HIS) color spaces are clustered using unsupervised possibilistic fuzzy clustering (UPFC) into five categories: white, yellow, opaque, brown, and background. The fuzzy k-nearest neighbor method is used for feature classification, and the number of clusters is optimized using the cuckoo search algorithm. The resulting multi-prototypes are further utilized to create a binary mask of teeth and used to segment the tooth region into three groups: white-yellow, opaque, and brown pixels. Finally, a fluorosis classification rule is created based on the proportions of opaque and brown pixels to classify fluorosis into four classes: Normal, Stage 1, Stage 2, and Stage 3. The experimental results on 128 blind test images showed that the average pixel accuracy of the segmented binary tooth mask was 92.24% over the four fluorosis classes, and the average pixel accuracy of segmented teeth into white-yellow, opaque, and brown pixels was 79.46%. The proposed method correctly classified four classes of fluorosis in 86 images from a total of 128 blind test images. When compared with a previous work, this result also indicates 10 out of 15 correct classifications on the blind test images, which is equivalent to a 13.33% improvement over the previous work.

Microstructural Analysis of Cancellous Bone in Fluorosis Rats.

Skeletal fluorosis likely alters bone structural properties on the cortical and cancellous tissue levels in view that fluorine ion replaces bone mineral composition. Our previous study showed high bone turnover occurred in cortical bone of skeletal fluorosis. Therefore, this study further analyzed the microstructure of cancellous bone in fluorosis rats. Rats were randomly assigned into three groups: the control, low-dose fluoride group (10 mgF-/kg·day), and high-dose fluoride group (20 mgF-/kg·day). Rats were orally administered with fluoride for 1, 2, and 3 months of periods. The trabecular bone parameters of tibia were detected with micro CT and analyzed with software. The activities of glutathione peroxidase (GPX), superoxide dismutase (SOD), and the content of malondialdehyde (MDA) in serum were measured. Results showed that severity of dental fluorosis rose with the increase of dose and prolongation of fluoride exposure. Meantime, the poorer connectivity and less trabecular bone network were observed in cancellous bone of rats treated with fluoride. Data analysis indicated that fluoride treatment significantly decreased bone volume and connectivity degree, but amplified trabecular space in 1 and 2 months of periods. Intriguingly, trabecular thickness significantly decreased in 1-month high-dose fluoride group, but returned to the control in 3 months of period. Fluoride treatment mainly inhibited the GPX activity and increased the MDA level to activate oxidative stress. This study confirmed that excessive fluoride impaired cancellous bone and caused redox imbalance.

Fluoride contamination of groundwater and its threat to health of villagers and their domestic animals and agriculture crops in rural Rajasthan, India.

In India, Rajasthan is the largest state and has seven divisions, namely Ajmer, Bharatpur, Bikaner, Jaipur, Jodhpur, Kota and Udaipur. Villagers of these regions, generally, used groundwater for drinking and irrigation purposes. The basic sources of groundwater in rural areas are hand pumps, step wells and borewells. Water of most of these sources is contaminated with fluoride (F) with varying amounts. Water of > 60% these sources has F beyond the recommended country standard (1.0 or 1.5 ppm) especially in tribal rural areas of Rajasthan. The highest F range, 0.1-34.0 ppm, has been found in groundwater of these sources in the villages of Ajmer division and the lowest 0.1-6.8 ppm in the Kota. Drinking of fluoridated groundwater for a long time is not safe for health and causes serious fluorosis disease in humans and domestic animals. In Rajasthan, around 40 lakh people are affected with fluorosis which is the highest in the country. At the F range of 1.3-6.7 ppm, the maximum prevalence of dental and skeletal fluorosis in villagers and bovine animals was found 84.0% and 32.7% and 88.9% and 37.8%, respectively. Using fluoridated groundwater in irrigation is also harmful and reduces crops productivity. In this communication, division-wise F distribution in groundwater of rural Rajasthan, F-induced diverse adverse health consequences in villagers and their domesticated animals and agriculture crops and preventive measures for control of F intoxication are critically reviewed. Findings of this review are useful in implementation of health policy for the mitigation of F poisoning in rural Rajasthan.

Fluoride Induced Neurobehavioral Impairments in Experimental Animals: a Brief Review.

Fluoride is one of the major toxicants in the environment and is often found in drinking water at higher concentrations. Living organisms including humans exposed to high fluoride levels are found to develop mild-to-severe detrimental pathological conditions called fluorosis. Fluoride can cross the hematoencephalic barrier and settle in various brain regions. This accumulation affects the structure and function of both the central and peripheral nervous systems. The neural ultrastructure damages are reflected in metabolic and cognitive activities. Hindrances in synaptic plasticity and signal transmission, early neuronal apoptosis, functional alterations of the intercellular signaling pathway components, improper protein synthesis, dyshomeostasis of the transcriptional and neurotrophic factors, oxidative stress, and inflammatory responses are accounted for the fluoride neurotoxicity. Fluoride causes a decline in brain functions that directly influence the overall quality of life in both humans and animals. Animal studies are widely used to explore the etiology of fluoride-induced neurotoxicity. A good number of these studies support a positive correlation between fluoride intake and toxicity phenotypes closely associated with neurotoxicity. However, the experimental dosages highly surpass the normal environmental concentrations and are difficult to compare with human exposures. The treatment procedures are highly dependent on the dosage, duration of exposure, sex, and age of specimens among other factors which make it difficult to arrive at general conclusions. Our review aims to explore fluoride-induced neuronal damage along with associated histopathological, behavioral, and cognitive effects in experimental models. Furthermore, the correlation of various molecular mechanisms upon fluoride intoxication and associated neurobehavioral deficits has been discussed. Since there is no well-established mechanism to prevent fluorosis, phytochemical-based alleviation of its characteristic indications has been proposed as a possible remedial measure.

Health Risk Assessment in Mexican Children Exposed to Fluoride from Sweetened Beverages.

The primary source of fluoride exposure is groundwater, but evidence suggests that beverages and food are additional fluoride sources. Intake of these products at an early age affects the optimal functioning of soft organs. An increase in sweetened beverage consumption by the pediatric population has been reported, suggesting an increase in fluoride exposure. The objectives of this study were to determine the fluoride concentrations in beverages and analyze the risk to human health from fluoride exposure to sweetened beverages consumed by children. Eighty-two sugar-sweetened beverages produced in different Mexican states were analyzed. The fluoride determination was carried out with an ion-selective electrode. The highest fluoride concentration was 1.92 mg/L; 73.2% of beverages showed fluoride values above permitted limits. Low-cost beverages had the highest fluoride values, suggesting that the water used for their production does not comply with fluorine regulations. According to the risk assessment in children from 3 to 6 years, the daily consumption of juices and sodas with concentrations that exceeded the normative of 0.7 mg/L could represent a risk to dental fluorosis development. It is crucial to control fluoride and regulate its concentrations in beverages for children to ensure food safety, especially in areas of endemic hydrofluorosis.

Moderate and Severe Dental Fluorosis in the Rural Population of Anantapur, India: Change in Their Biological Susceptibility?

Dental fluorosis affects the quality of life. A cross-sectional, observational study was conducted in a community affected by endemic fluorosis for several generations with a conserved biological and social environment. The study included patients from the rural population of Anantapur, India. The Dean index (DI) and the Thylstrup and Fejerskov Index (TFI) were used for fluorosis classification. Additionally, water samples were collected for fluoride analysis, taken from the patients' living areas. The statistical association between the variables was analyzed. In total, 785 patients between 10 and 60 years old were included in the study (58.7% women and 41.3% men). Fluorosis signs were found in 94.6% of patients examined using the DI and 94.4% using the TFI. Moderate-severe dental fluorosis was observed in 62.8% by DI and 73.1% by TFI consuming untreated water with up to 2.9 ppm of fluoride. Furthermore, moderate-severe dental fluorosis was observed in 33.2% by DI and 39.9% by TFI consuming water with ≤1.5 ppm of fluoride. The high prevalence of moderate-severe dental fluorosis in patients consuming water with a low fluoride concentration suggests that other factors are involved. Biological susceptibility change could play an essential role in the severity of dental fluorosis in populations exposed for several generations, affecting its actual and future quality of life.

Role of oxidative stress-mediated cell death and signaling pathways in experimental fluorosis.

Free radicals and other oxidants have enticed the interest of researchers in the fields of biology and medicine, owing to their role in several pathophysiological conditions, including fluorosis (Fluoride toxicity). Radical species affect cellular biomolecules such as nucleic acids, proteins, and lipids, resulting in oxidative stress. Reactive oxygen species-mediated oxidative stress is a common denominator in fluoride toxicity. Fluorosis is a global health concern caused by excessive fluoride consumption over time. Fluoride alters the cellular redox homeostasis, and its toxicity leads to the activation of cell death mechanisms like apoptosis, autophagy, and necroptosis. Even though a surfeit of signaling pathways is involved in fluorosis, their toxicity mechanisms are not fully understood. Thus, this review aims to understand the role of reactive species in fluoride toxicity with an outlook on the effects of fluoride in vitro and in vivo models. Also, we emphasized the signal transduction pathways and the mechanism of cell death implicated in fluoride-induced oxidative stress.

Assessing Fluorosis Incidence in Areas with Low Fluoride Content in the Drinking Water, Fluorotic Enamel Architecture, and Composition Alterations.

There is currently no consensus among researchers on the optimal level of fluoride for human growth and health. As drinking water is not the sole source of fluoride for humans, and fluoride can be found in many food sources, this work aimed to determine the incidence and severity of dental fluorosis in Poland, in areas where a low fluoride content characterizes the drinking water, and to assess the impact of fluoride on the enamel composition and microstructure. The dental examination involved 696 patients (aged 15−25 years) who had since birth lived in areas where the fluoride concentration in drinking water did not exceed 0.25 mg/L. The severity of the condition was evaluated using the Dean's Index. Both healthy teeth and teeth with varying degrees of fluorosis underwent laboratory tests designed to assess the total protein and fluoride content of the enamel. Protein amount was assessed spectrophotometrically while the level of fluoride ions was measured by DX-120 ion chromatography. The clinical study revealed 89 cases (12.8%) of dental fluorosis of varying severity. The enamel of teeth with mild and moderate fluorosis contained a significantly higher protein (p-value < 0.001 and 0.002, respectively) and fluoride level (p < 0.001) than those with no clinical signs of fluorosis. SEM images showed irregularities in the structure of the fluorotic enamel. An excessive fluoride level during amelogenesis leads to adverse changes in the chemical composition of tooth enamel and its structure. Moreover, dental fluorosis present in areas where drinking water is low in fluorides indicates a need to monitor the supply of fluoride from other possible sources, regardless of its content in the water.

Nivel de conocimiento de los padres sobre el uso de pastas dentales en asociación con la ingesta estimada de fluoruro en niños / Level of knowledge in parents about the use of toothpaste in association with estimated fluoride intake in children

Resumen Introducción: Diversos estudios han demostrado que los padres aún no cuentan con el conocimiento suficiente sobre el uso de pastas dentales que deben consumir sus hijos. Muchos de ellos desconocen desde que edad se debe empezar con el uso de pastas dentales, la cantidad exacta que se debe colocar en el cepillo y sobre todo con qué frecuencia se deben cepillar. Objetivo: Asociar el nivel de conocimiento de los padres sobre el uso de pastas dentales con las características asociadas a la ingesta estimada de fluoruro en niños entre los 6 meses a 8 años de Lima Metropolitana y Callao. Materiales y métodos: Estudio de tipo observacional, descriptivo y transversal. Se realizó el cuestionario a 264 padres de familia residentes en Lima Metropolitana y Callao durante los meses de julio a septiembre del 2020. Se calcularon las frecuencias absolutas y relativas. Para el análisis bivariado, se utilizó la prueba de Chi cuadrado de El nivel de significancia estadística fue de 0.05. Resultados: Se observa que el 52.94% de los padres, así como el 60.41% de las madres presentan un nivel medio de conocimiento sobre el uso de pastas dentales con flúor. Además, se obtuvo que el 56.25% de los padres que afirmaron que sus hijos no se enjuagan con agua después del cepillado presentan un nivel alto de conocimiento sobre el uso de pastas dentales con flúor. Conclusión: Se obtuvo que el 57.58% de los padres tenían un nivel medio de conocimiento sobre el uso de pastas dentales con flúor. Se encontró asociación entre el nivel de conocimiento sobre el uso de pastas dentales con flúor y las características asociadas a la ingesta estimada de fluoruro.

Abstract Introduction: Various studies have shown that parents still do not have sufficient knowledge about the use of toothpastes that their children should consume. Many of them do not know from what age to start using toothpastes, the exact amount to be placed on the brush and especially how often they should be brushed. Aim: To associate the level of knowledge of parents about the use of toothpastes with the characteristics associated with the estimated intake of fluoride in children between 6 months to 8 years of Metropolitan Lima and Callao. Materials and methods: An observational, descriptive, and crosssectional study. The questionnaire was carried out on 264 parents residing in Metropolitan Lima and Callao during the months of July to September 2020. The absolute and relative frequencies were calculated. For the bivariate analysis, the Chi-square test of the level of statistical significance was used was 0.05. Results: It is observed that 52.94% of the fathers, as well as 60.41% of the mothers present a medium level of knowledge about the use of fluoride toothpastes. In addition, it was found that 56.25% of parents who stated that their children do not rinse with water after brushing have a high level of knowledge about the use of fluoride toothpastes. Conclusion: It was found that the 57.58% of parents had a median level of knowledge about the use of fluoride toothpastes. An association was found between the level of knowledge about the use of fluoride toothpastes and the characteristics associated with the estimated fluoride intake.

Association of Dietary Calcium Intake with Dental, Skeletal and Non-Skeletal Fluorosis among Women in the Ethiopian Rift Valley.

Fluorosis is a major public health problem in the Rift Valley of Ethiopia. Low calcium (Ca) intake may worsen fluorosis symptoms. We assessed the occurrence of fluorosis symptoms among women living in high-fluoride (F) communities in South Ethiopia and their associations with dietary Ca intake. Women (n = 270) from two villages provided clinical and questionnaire data. Dental fluorosis examination was done using Dean's Index, and skeletal and non-skeletal fluorosis assessment was carried out using physical tests and clinical symptoms. Daily Ca intake was estimated by a food frequency questionnaire. Food, drinking water and beverage samples were analyzed for F level. Many subjects (56.3%) exhibited dental fluorosis. One-third of the women were unable to perform the physical exercises indicative of skeletal fluorosis; about half had ≥2 symptoms of skeletal/non-skeletal fluorosis. The average F level in drinking water sources was ~5 mg/L. The F content in staple food samples varied from 0.8-13.6 mg/kg. Average Ca intake was 406 ± 97 mg/day. Women having ≤400 mg/day Ca intake had ~3 times greater odds of developing skeletal rigidity with joint pains [AOR = 2.8, 95%CI: 1.6, 5.0] and muscular weakness [AOR = 2.9, 95%CI: 1.3, 6.3] compared to those with higher intakes. No association of calcium intake was seen with dental fluorosis. As low dietary Ca intake was associated with symptoms related to skeletal and non-skeletal fluorosis, this warrants nutritional intervention on calcium intakes in this setting.

Neuro-medical manifestations of fluorosis in populations living in the Main Ethiopian Rift Valley.

Prolonged exposure to higher concentrations of fluoride (> 1.5 mg/L) is associated with dental and skeletal fluorosis. The effects of fluoride on dental and skeletal system have been studied extensively; however, the neurological consequences of fluoride in population-based studies are limited. The study aims to assess the epidemiology of neurological and other manifestations of fluorosis among rural populations living in the Main Ethiopian Rift valley. In this cross-sectional study, we enrolled 316 individuals from 23 rural communities in the Main Ethiopian Rift valley. Fluoride concentration was measured in drinking water samples collected from 23 community wells. Association between fluoride concentrations and clinical features of fluorosis was assessed using student t test, chi square, multivariable regression using adjusted odds ratio (OR). The mean fluoride concentration in the drinking water was 6.8 ± 4.3 mg/L (range: 0.3-15.5 mg/L). At least one clinical sign of skeletal fluorosis was observed in 54.4% (n = 175) of the study participants. Headache and joint pain reported by 67.1% and 56.3% of the participants as the most common neurological manifestation, and skeletal fluorosis symptom, respectively. The mean fluoride level was higher for those individuals who reported paresthesia compared to those with no-paresthesia. Loss of appetite, constipation, and fatigue were reported by 48.0%, 45.6%, and 56.6% of the participants, respectively. Signs of crippling fluorosis were observed in small proportion (1.6%) of the participants. Individuals who reported headache are most likely exposed to higher fluoride concentrations in drinking water compared to those reported no-headache (p < 0.001). The study demonstrates high prevalence of neuro-medical manifestations of fluorosis in population living in the Main Ethiopian Rift valley. Fluoride concentration in drinking water and joint pain were independent predictors of fluorosis.

Study of Chitosan Ingestion Remitting the Bone Damage on Fluorosis Mice with Micro-CT.

Chronic excessive fluoride exposure may lead to fluorosis, which causes health problems like a decrease in bone mechanical strength. It was speculated that chitosan may combine with fluorine to form in vivo organic fluorine, and may reduce the damage caused by fluorine. Hence, it is necessary to conduct a study to investigate the influence of chitosan on fluorosis mice. To investigate this problem, forty-four 4-week-old male Kunming mice were randomly divided into four groups, the control group, the fluoride group, the fluoride plus chitosan group, and the chitosan group. After 100 days of feeding, the femurs were collected to scan the Micro-CT image. The ultimate load of the femur in the fluoride group was significantly lower than control group. The trabecular separation was increased in the fluoride group compared with the fluoride plus chitosan group and the chitosan group. The level of trabecular thickness was increased in the fluoride plus chitosan group compared with the fluoride group. Our findings suggest that chitosan ingestion can improve the condition of cancellous bone and cortical bone affected by fluorine.

Produção científica sobre fluorose em regiões endêmicas: estudo bibliométrico de Anais das Reuniões da Sociedade Brasileira de Pesquisa Odontológica / Scientific production on fluorosis in endemic regions: bibliometric study of Meeting Annals of the Brazilian Society of Dental Research

Objetivo: Identificar os resumos publicados nas Reuniões Anuais da Sociedade Brasileira de Pesquisa Odontológica sobre fluorose em regiões endêmicas e verificar a contribuição da Ciência Brasileira para o assunto. Métodos: Este estudo descritivo foi realizado com dados secundários do período entre 2005 e 2020; os estudos elegíveis foram identificados a partir dos descritores presentes no título e/ou resumo: flúor, fluorose, fluorose dental, fluorose dentária, fluoretação, intoxicação por flúor. Critérios de inclusão: estudos em regiões declaradas como de fluorose endêmica ou que citassem o teor de flúor acima de 0,8 mg F/L. Foram excluídos estudos que não declarassem estudar fluorose em regiões endêmicas ou não citassem o teor de flúor na água. Os dados foram coletados por dois examinadores de modo independente e a distribuição de frequências dos dados foi realizada (Microsoft Excel para Mac v.16.16.12). Resultados: Observou-se que de 41.953 resumos publicados durante esses 15 anos, 1190 (2,83%) foram elegíveis; 426 (1,01%) abordaram especificamente o tema fluorose e24 (0,06%) a fluorose em regiões endêmicas. Os assuntos abordados envolveram tratamento (n = 4; 14,81%); desenvolvimento de programas de promoção de saúde bucal (n = 2; 7,69%);avaliação da potabilidade da água (n = 2; 7,41%); implementação de sistemas de desfluoretação (n = 2; 7,41%); prevalência e severidade (n = 2; 7,41%); distribuição da fluorose na dentição (n = 1, 3,70%); impacto na qualidade de vida (n = 2; 7,41%); percepçãoestética(n = 5; 18,52%); uso e ingestão de flúor (n = 3; 11,11%); fluorose óssea (n = 2; 7,41%); análise da possibilidade de alteração no padrão cognitivo (n = 1; 3,70%), nas funções motoras e no equilíbrio (n=1; 3,70%).Conclusão: Diferentes aspectos relacionados à fluorose em região endêmica foram abordados. A Ciência Brasileira tem se dedicado ao tema ao longo dos anos. Entretanto, há um número restrito de estudos, em especial sobre a relação dose-reposta.

Aim: Identify the abstracts published at the Brazilian Society for Dental Research's Annual Meetings regarding Fluorosis in endemic regions, as well as verify the contribution of Brazilian science to the subject. Methods:This descriptive study was conducted using secondary data from the period between 2005 and 2020; the eligible studies were identified from the descriptors present in the title and/or abstract, as follows: fluoride, fluorosis, dental fluorosis, dental fluorosis, fluoridation, fluoride poisoning. Inclusion criteria: studies in regions with endemic fluorosis were included. Studies that did not address fluorosis in endemic regions were excluded. Data were collected by two independent examiners and the distribution frequency of the data was performed (Microsoft Excel for Mac v.16.16.12). Results: It was observed that of the 41,953 abstracts published during these 15 years, 1,190 (2.83%) were eligible; 426 (1.01%) specifically addressed the theme of fluorosis, and of these, 24 (0.06%) reported on fluorosis in endemic regions. The subjects addressed involved treatment (n = 4; 14.41%), the development of oral health promotion programs (n = 2; 7.41%), the evaluation of water potability (n = 2; 7.41%), the implementation of defluoridation systems (n = 2; 7.41%), prevalence and severity (n = 2; 7.41%), the distribution of fluorosis in dentition (n = 1, 3.70%), impacts on the quality of life (n = 2; 7.41%), esthetic perceptions (n = 4; 18.52%), fluoride use and ingestion (n = 3; 11.11%), bone fluorosis (n = 2; 7.41%), the analysis of alterations in the cognitive pattern (n = 1; 3.70%) and change in motor functions and balance (n=1; 3,70%).Conclusion: Different aspects related to fluorosis in an endemic region were addressed. Brazilian Science has been devoted to the theme over the years; however, there have been a limited number of studies published in the literature concerning the dose-response ratio.

[Microscopic observation of the enamel microstructures of SD rats with different degrees of fluorosis].

Objective: To establish a dental fluorosis model of SD rats with various degrees, to observe the microstructures of enamel samples under scanning electron microscope and to clarify the changes of enamel microstructures with various degrees of dental fluorosis, so as to provide clinical reference for the treatment of patients with moderate and severe dental fluorosis. Methods: Thirty male SD rats (6 weeks of age) were randomly divided into 3 groups with 10 rats in each group. The control group was fed with deionized water without fluoride, the low fluoride group was fed with 50 mg/L NaF deionized water and the high fluoride group was fed with 100 mg/L NaF deionized water in order to establish the dental fluorosis model of rats. After feeding for 6 weeks, the rats were sacrificed and the mandibular incisor teeth were collected and recorded. The surface and sagittal plane of each tooth were observed by scanning electron microscopy and the enamel thickness was measured. Results: In the control group, the enamel color was brown yellow. Enamel color discoloration occurred both in low-fluoride group and high-fluoride group. The enamel color in low-fluoride group was mostly yellow and white striped while in high-fluoride group was mostly chalky white. Under electronic microscope, the enamel rods were alternately arranged and their structure was clear and plump in the control group. The enamel rods of moderate fluorosis were arranged in a straight orientation like tips of bamboo shoots. The enamel rods of severe fluorosis, however, became thinner and the tips of rods were broken. In the control group, sagittal images of enamel turned out to be a dense outer structure with clear boundaries among the inner. The structure of the middle layer was reticulated showing a clear boundary with middle and outer layers. The structure of enamel rods in the inner layers was arranged vertically and horizontally. In the moderate fluorosis group, the outer layer of the enamel became thinner and the middle layer disappeared although the boundary between the outer and middle layers was still clear. In the inner layer, the vertically arranged enamel rods seemed still clear, however the horizontal enamel rods disappeared. In the severe fluorosis group, the outer layer could not be traced. The middle layer was exposed to the air and the inner enamel rods contracted. The inner layers of the enamel had gradually become thinner with the development of the dental fluorosis. The thicknesses of inner layers in control, moderate and the severe groups were (180.71±7.01), (157.10±11.04) and (121.10±12.56) µm respectively. As for the thicknesses of the full layers in the above mentioned three groups, the same trend was observed. The thicknesses, in order of the severity of dental fluorosis, were (241.54±7.76), (207.42±14.36) and (143.79±14.60) µm. Conclusions: With the development of dental fluorosis, the outer enamel layers became thinner or disappeared and the inner enamel layers became thinner or lost its normal structure as well. It is highly recommended that the resin penetration could be used for the proper treatment of moderate and severe dental fluorosis and the strong bleaching and the micro-grinding should be used cautiously.

Review on Health Impacts from Domestic Coal Burning: Emphasis on Endemic Fluorosis in Guizhou Province, Southwest China.

Endemic fluorosis in Guizhou Province, Southwest China was firstly reported by Lyth in 1946 and was extensively concerned since the early 1980s. Initially, the pathological cause of endemic fluorosis in Guizhou Province was instinctively ascribed to the drinking water. However, increasing evidences pointed that the major exposure route of fluorine for the local residents is via the roasted foodstuffs, especially the roasted pepper and corn. Source of fluorine in roasted foodstuffs was once blamed on the local coal and subsequently imputed to clay mixed in the coal. In fact, both are probably the source. Geogenic fluorine concentration in soil and clay is indeed high in Guizhou Province, but is not likely to be the direct cause for endemic fluorosis. The real culprit for endemic fluorosis in Guizhou Province is the unhealthy lifestyle of the local residents, who usually roasted their foodstuffs using local coal or briquettes (a mixture of coal and clay), resulting in the elevated fluorine in roasted foodstuffs. Nowadays, endemic fluorosis in Guizhou Province has substantially mitigated. Nevertheless, millions of confirmed cases of dental fluorosis remain left. In addition to endemic fluorosis, other health problems associated with domestic coal burning may also exist, because of the enrichment of toxic/harmful elements in the local coal. It is necessary to determine how serious the situation is and find out the possible solution. As people in other developing countries may suffer from similar health issues, same health issues around the world deserve more attention.

[Analysis on results of occupational health examination in 677 workers exposed to inorganic fluorine].

Objective: To analyze the health hazards of fluorine and its inorganic compounds to workers exposed to fluorine, and to provide technical support for the protection of workers exposed to fluorine and the revision of occupational disease diagnostic standards. Methods: In January 2019, 677 workers exposed to fluorine in a fluorine chemical company in Hunan Province were selected by cluster sampling, and occupational health examination was conducted. The suspected occupational poisoning workers were diagnosed as occupational diseases, which were divided into poisoning group and non-poisoning group. T test and Pearson χ(2) test were used for statistical analysis. Results: A total of 73 occupational chronic fluorosis patients were diagnosed. 93.15% (68/73) of the skeletal lesions were multiple, and the most frequent sites were the upper tibia and fibula. 35.00% (21/60) , 50.00% (18/36) and 58.82% (10/17) of the tibia, fibula, ulna and radius had periosteal changes only on one side. Other abnormal results were mainly dental calculus (60.71%, 411/677) , fatty liver (48.89%, 331/677) , abnormal electrocardiogram (44.17%, 299/677) , decreased bone mass (33.53%, 227/677) and increased ALT (13.15%, 89/677) . Compared with non-poisoning group, the age, length of service exposed to fluoride and fatty liver detection rate of poisoning group were higher, and the differences were statistically significant (P<0.01) . Conclusion: The changes of long bone caused by inorganic fluoride only occur in one side, so the basic location of occupational health examination should include bilateral long bone to avoid missed diagnosis. It is difficult to diagnose occupational poisoning with single slight periosteal ossification, it is suggested that the standard should be revised to specify the degree.

Dental Fluorosis: the Risk of Misdiagnosis-a Review.

Fluoride has been considered as the single factor most frequently responsible for causing enamel mottling. However, in humans, either endogenous and/or exogenous factors not related to fluoride exposure may also cause enamel mottling. In this sense, various studies in the international literature have reported severe mottling of the teeth that could not be attributed to fluoride exposure. Thus, misdiagnosis of non-fluoride-induced enamel defects may occur frequently. Reports of unexpectedly high population prevalence and individual cases of fluorosis, where such diagnoses are irreconcilable with the identified fluoride history, highlight the necessity for a more precise definition and diagnosis of dental fluorosis. Also, a more discriminating diagnostic procedure is suggested. Particularly, positive identification of environmental fluoride levels to which the communities and individuals are exposed shall be developed before the confirmation of a diagnosis of fluorosis. It is considered that a more critical methodology for the diagnosis of fluorosis will be helpful in the rational use and control of fluorides for dental health, and in the identification of factors that may induce enamel defects.