High prevalence of dental fluorosis among adolescents is a growing concern: a school based cross-sectional study from Southern India

Identifying the oral microbiome of adolescents with and without dental fluorosis based on full-length 16S rRNA gene sequencing

Dental fluorosis, resulting from long-term environmental exposure to fluoride, is prevalent among diverse populations worldwide. Severe fluorosis not only compromises the aesthetic appeal of teeth but also impairs their functionality. This study aims to investigate the oral microbiome in dental fluorosis and the health individuals of adolescents living in the endemic fluorosis area of Guizhou, China through full-length 16S rDNA sequencing. Fourty-six individuals meet the sampling criteria, and we divided these samples into the following groups: a healthy group (H = 23) and a dental fluorosis group (F = 23), and two subgroups of Miao ethnicity: a healthy Miao group (Hm = 13) and a dental fluorosis Miao group (Fm = 15). A total of 660,389 high-quality sequences were obtained, and 12,007 Amplicon Sequence Variants (ASVs) were identified, revealing significant variations in oral microbiome between Fm and Hm groups. The composition of oral microbiota was similar between the H and F groups. At the genus level, Pseudopropionibacterium and at the species level, Streptococcus oralis_subsp.dentisani_clade_058 were less abundant in group F than in group H (P < 0.05). Further analysis revealed that the abundance of Capnocytophaga gingivalis and Kingella denitrificans was significantly lower in Fm fluorosis patients than in the Hm group (P < 0.05). Based on the LEfSe analysis, the potential core biomarkers in the oral of Fm fluorosis patients were identified at different taxonomic levels, ranging from phylum to species. These include Gammaproteobacteria, Prevotella sp_HMT_304, Gemella sanguinis, and Gracilibacteria_(GN02). Network analysis revealed that the microbiota in the fluorosis group exhibited more complex interactions with each other than the healthy group. Notably, within the Hm group, the potential biomarkers Capnocytophaga gingivalis and Kingella denitrificans exhibited a positive correlation. Finally, we employed PICRUSt2 analysis to explore the abundance clustering of the top 30 functional units in each sample, and we found that the metabolic pathway compositions of the four groups were similar. In summary, our findings suggest that the microbial composition of plaque in Hm patients with dental fluorosis is significantly altered, and we identified the potential marker microorganisms that contribute to these changes.

Systematic review of epidemiological and toxicological evidence on health effects of fluoride in drinking water

INTRODUCTION

Fluoride is a naturally occurring substance that is also added to drinking water, dental hygiene products, and food supplements for preventing dental caries. Concerns have been raised about several other potential health risks of fluoride.

OBJECTIVE

To conduct a robust synthesis of evidence regarding human health risks due to exposure to fluoride in drinking water, and to develop a point of departure (POD) for setting a health-based value (HBV) for fluoride in drinking water.

METHODS

A systematic review of evidence published since recent reviews of human, animal, and in vitro data was carried out. Bradford Hill considerations were used to weigh the evidence for causality. Several key studies were considered for deriving PODs.

RESULTS

The current review identified 89 human studies, 199 animal studies, and 10 major in vitro reviews. The weight of evidence on 39 health endpoints was presented. In addition to dental fluorosis, evidence was considered strong for reduction in IQ scores in children, moderate for thyroid dysfunction, weak for kidney dysfunction, and limited for sex hormone disruptions.

CONCLUSION

The current review identified moderate dental fluorosis and reduction in IQ scores in children as the most relevant endpoints for establishing an HBV for fluoride in drinking water. PODs were derived for these two endpoints, although there is still some uncertainty in the causal weight of evidence for causality for reducing IQ scores in children and considerable uncertainty in the derivation of its POD. Given our evaluation of the overall weight of evidence, moderate dental fluorosis is suggested as the key endpoint until more evidence is accumulated on possible reduction of IQ scores effects. A POD of 1.56 mg fluoride/L for moderate dental fluorosis may be preferred as a starting point for setting an HBV for fluoride in drinking water to protect against moderate and severe dental fluorosis. Although outside the scope of the current review, precautionary concerns for potential neurodevelopmental cognitive effects may warrant special consideration in the derivation of the HBV for fluoride in drinking water.

Prevalence of Dental and Skeletal Fluorosis Among School Children in Rural Areas of YSR Kadapa District, Andhra Pradesh, India

Background Andhra Pradesh (AP) is one of the states in India found to have districts with endemic fluoride and YSR Kadapa district is one among them. Fluorosis is a well-known endemic disease affecting the hard tissues of the human body like teeth and bone and soft tissues like the kidneys, gastrointestinal system, nervous system, etc. Dental fluorosis is being proven as a biomarker for exposure to fluoride. This study evaluated the toxicity of fluoride in drinking water on the teeth (dental fluorosis) and on the bones (skeletal fluorosis) in YSR Kadapa district, AP. Material and methods A cross-sectional study was done in schools in the study areas and a total of 488 school children aged between eight to 14 years were screened for fluorosis. Consent from parents or legal representatives was taken. The information regarding personal details, source of drinking water, diet, and socio-demographic characteristics was obtained from children through a questionnaire. Oral examination of teeth was done to assess dental fluorosis by the Deans's fluorosis index and a general physical examination to assess skeletal fluorosis as per guidelines given by the Central Government of India in the National Program for Prevention of Fluorosis in India. Fluoride in drinking water samples and urine samples of school children was assessed by a fluoride ion meter. Statistical analysis was done using IBM SPSS Statistics for Windows, Version 25, (Released 2017; IBM Corp., Armonk, New York, United States). Descriptive statistics were used to assess the percentage distribution and Chi-square test of Independence for comparison between variables. Results The mean fluoride levels in water in the study areas ranged between 1.5mg/l to 4.2mg/l and there was a prevalence of 44.05% dental fluorosis and 0% skeletal fluorosis in the school children. A total of 48.47% of girls and 40.64% of boys were affected with dental fluorosis. A prevalence of 23.06% mild, 22.1% moderate, 5.31% very mild, and 4.55% severe dental fluorosis was observed in the examined children. Conclusion Our study results showed the presence of dental fluorosis with no clinical evidence of skeletal fluorosis among school children in the YSR Kadapa district of Andhra Pradesh. This indicates the fluoride toxicity on teeth in children confirming the exposure to fluoride in the YSR Kadapa district. So, further long-term follow-up surveys are necessary to evaluate skeletal fluorosis in these children though there was no clinical skeletal fluorosis. This highlights that measures need to be enforced by the local governance for the supply of defluorinated water in these areas.

Probabilistic modelling is superior to deterministic approaches in the human health risk assessment: an example from a tribal stretch in central India

This case drew national attention in 2018. About 100 people died and more than 300 hospitalized in a span of few years in a village of 1200 people in a tribal stretch in central India. Medical teams visiting the area reported severe renal failure and blamed the local eating and drinking habits as causative factors. This human health assessment based on geochemical investigations finds nitrate (NO3-) and fluoride (F-) pollution as well in village's groundwater. Both deterministic and probabilistic techniques are employed to decipher the contamination pathways and extent of contamination. Source apportionments of NO3- and F- and their relationship with other ions in groundwater are carried out through chemometric modelling. Latent factors controlling the hydrogeochemistry of groundwater too are explored. While hazard quotients ([Formula: see text]) of the chemical parameters ([Formula: see text] and [Formula: see text]) identify ingestion as the prominent pathway, the calculated risk certainty levels (RCL) of the hazard index (HI) values above unity are compared between the deterministic and probabilistic approaches. Deterministic model overestimates the HI values and magnify the contamination problems. Probabilistic model gives realistic results that stand at infants ([Formula: see text] = 34.03%, [Formula: see text] = 24.17%) > children ([Formula: see text] = 23.01%, [Formula: see text] = 10.56%) > teens ([Formula: see text] = 13.17%, [Formula: see text] = 2.00%) > adults ([Formula: see text] = 11.62%, [Formula: see text] = 1.25%). Geochemically, about 90% of the samples are controlled by rock-water interaction with Ca2+-Mg2+-HCO3- (~ 56%) as the dominant hydrochemical facies. Chemometric modelling confirms Ca2+, Mg2+, HCO3-, F-, and SO42- to originate from geogenic sources, Cl- and NO3- from anthropogenic inputs and Na+ and K+ from mixed factors. The area needs treated groundwater for human consumption.

Fluoride distribution in selected foodstuffs from Nakuru County, Kenya, and the risk factors for its human overexposure

Critical data on the impacts of fluoride (F) in food systems along the Eastern Africa Rift Valley System (EARS) is needed for public health risk assessment and for the development of strategies for ameliorating its deleterious effects among the affected communities. Long-term F overexposure causes dental and skeletal fluorosis, and leads to neurotoxicity, which impacts several important body functions. Investigating F exposure pathways is of essence to inform and safeguard public health of the affected communities. The current study assessed the F levels in potatoes (Solanum tuberosum L.), beans (Phaseolus vulgaris L.) and garden peas (Possum sativa) from Nakuru County, Kenya, by potentiometric analysis using F ion-selective electrodes. It then evaluated the risk factors for excessive human exposure to F through contaminated foodstuffs. The mean F levels in the potatoes (8.50 ± 4.70 mg/kg), beans (8.02 ± 4.12 mg/kg) and peas (4.99 ± 1.25 mg/kg) exceeded recommended dietary allowances (RDA) level of 4 mg/kg endorsed by US Institute of Medicine for the different categories of people. The F distribution trends in beans and potatoes reflected the environmental patterns of F contamination of the study area but the spatial extent Fin the peas indicated existence of partial resistance of the pea plants to environmental F uptake. The results indicated that both the beans and the potatoes were more liable to accumulating greater amounts of F from the environment than garden peas and that all the three foodstuffs contained high F levels that posed greater risk of F overexposure and its deleterious impacts among the young children, male populations, and in people of greater body weight and high physical activity levels.

Advances in epidemiological status and pathogenesis of dental fluorosis

Fluoride is commonly consider as a "double-edged sword" because low consumption of fluoride can effectively prevent dental caries, but excessive consumption of fluoride can cause fluorosis. Dental fluorosis (DF) is a characteristic feature of fluorosis in the oral cavity that is manifested as tooth color changes and evident enamel defect. Presently, the pathogenesis of DF remains unclear. Herein, we have summarized the research progress in the pathogenesis and mechanism of DF in the past 5 years.

C, Barvaliya MJ, Kirte R, R. S, Ray SK, B. R, Chakma T, Murhekar MV, Roy S. A community-based study of dental fluorosis in rural children (6–12 years) from an aspirational district in Karnataka, India

Objectives

The present study was planned to estimate the prevalence of dental fluorosis in 6–12 years of children and its association with various drinking water sources, water, and urine fluoride levels among the subset of children under the umbrella of a larger study to address iodine deficiency disorders and iron deficiency anemia in 17 villages of Manvi and Devadurga talukas of Raichur district of Karnataka.

Methods

Analysis of subset of data and urine samples of children under the umbrella of a larger cross-sectional community-based study was conducted in 17 villages of Manvi and Devadurga taluks of Raichur district. House to house survey was carried out to collect data using a semi-structured questionnaire in ODK software. Demographic details, source of drinking water, clinical assessment of dental fluorosis, and height and weight measurements were performed by trained staff. Urine and water samples were collected for fluoride level estimation. The overall prevalence of dental fluorosis and its severity-wise prevalence were estimated. Association between dental fluorosis and age, gender, type of diet, source of drinking water, height for age, BMI for age, water fluoride level, and urine fluoride level were carried out using logistic regression analysis.

Results

The prevalence of dental fluorosis was 46.0%. Mild, moderate, and severe dental fluorosis was found in 37.9, 7.8, and 0.3% of children. With the increasing age of participants, the odds of dental fluorosis were found to increase by 2–4 folds. The odds of having dental fluorosis were significantly increased with increasing water fluoride levels of 3 to 5 ppm [AOR = 3.147 (1.585–6.248); P = 0.001] in comparison with water fluoride levels of &lt; 1 ppm. The similar trend was found with urine fluoride level &gt; 4 ppm [AOR = 3.607 (1.861–6.990); P &lt; 0.001]. As compared to river water, other sources of drinking water were significantly associated with higher odds of dental fluorosis.

Conclusions

Prevalence of dental fluorosis was high in 6 to 12 years due to overexposure of fluoride from drinking water. High water and urine fluoride levels in children indicate the chronic exposure to fluoride and suggest that the population is at high risk of developing chronic fluorosis.

Groundwater defluoridation efficacy of manganese-oxide-coated alumina prepared via two-step heating

Fluoride concentrations in groundwater can be high in some Brazilian aquifers and therefore these waters should be treated before consumption. This study assessed the properties of Mn-oxide-coated alumina (AM) prepared by two-step heating in water defluoridation. The release of secondary contaminants (e.g. Al³⁺ and Mn²⁺) from alumina was also examined, as their removal by vermiculite. The process of Mn-oxide coating changed some properties of the activated alumina (AA), decomposing the crystalline phases and reducing some parameters, e.g. specific surface area (from 295.90 to 94.51 m² g^-1) and pH_PZC (from 7.34 to 5.74). These changes increased the efficiency and kinetics of alumina in removing F^- from synthetic solutions and groundwater (from 80%/16 h to 100%/1 h). This efficiency was not affected by the presence of other anions in groundwater, such as HCO₃^- and SO₄^2-. The optimum rate of F^- removal occurred at pH 5; however, during the F^- removal, Al³⁺ and Mn²⁺ ions were released, respectively, from the AA (0.61 mg L^-1 Al³⁺) and from the AM ( 52 mg L^-1 Mn²⁺). Vermiculite used to remove these cations adsorbed about 86% Al³⁺ and 90% Mn²⁺. However, only Al³⁺ concentrations fell below the standard limit for drinking water of <0.5 mg L^-1. Therefore, AA has the advantage of not containing Mn, and after 3 h kept F^- concentrations in solutions 5 mg L^-1F^- below the standard limit of 1.5 mg L^-1. This study revealed that, depending on the groundwater characteristics, AA may be more efficient and sustainable for defluoridation than coated alumina.

Hydrogeochemical characterization and quality assessment of groundwater resource in Savar - an industrialized zone of Bangladesh

Savar Upazila in the Dhaka District is a rapidly expanding city with a diverse range of industries and agricultural activities. This expansion poses environmental challenges including the threat to groundwater contamination. Based on these considerations, the objective of this research is to carry out a shallow groundwater hydrogeochemical characterization and an assessment of the suitablity of the groundwater for drinking and irrigational purposes using a geochemical approach, multivariate statistical techniques, and some indices of groundwater quality. The hydrogeochemical analyses of 42 groundwater samples from shallow depths (18 - 76 m) showed that the order of concentrations of cations, anions, and metals was Ca²⁺ > Na⁺ > Mg²⁺ > K⁺, HCO₃^- > Cl^- > SO₄^2- > NO₃^-, and Cr > As > Pb > Mn > Fe, respectively. Weathering of silicates was found to be the most significant hydrogeochemical process governing the chemistry of groundwater. Cation exchange also plays a significant role in the evolution of the groundwater chemistry. Principal component analysis and hierarchical cluster analysis suggested that anthropogenic activities are influencing groundwater quality. A drinking water quality index map showed that about 91% of the groundwater samples were in the excellent category and suitable for human consumption, with only a few samples exceeding the standards of the WHO and Bangladesh for concentrations of Ca²⁺, Mg²⁺, HCO₃^-, Fe, Mn, and As. An analysis of irrigation quality parameters found that most of the groundwater samples were either excellent or good for agricultural uses, except for one sample in the Tetuljhora Union that was unsuitable based on residual sodium carbonate. This finding may be useful to local governments in understanding the current status of groundwater quality, tracking potential threats of contamination, and initiating appropriate measures for long-term groundwater resource management.

The cholinergic system, intelligence, and dental fluorosis in school-aged children with low-to-moderate fluoride exposure

Disruption of cholinergic neurotransmission can affect cognition, but little is known about whether low-to-moderate fluoride exposure affects cholinergic system and its effect on the prevalence of dental fluorosis (DF) and intelligence quotient (IQ). A cross-sectional study was conducted to explore the associations of moderate fluoride exposure and cholinergic system in relation to children's DF and IQ. We recruited 709 resident children in Tianjin, China. Ion selective electrode method was used to detect fluoride concentrations in water and urine. Cholinergic system was assessed by the detection of choline acetyltransferase (ChAT), acetylcholinesterase (AChE) and acetylcholine (ACh) levels in serum. Compared with children in the first quartile, those in fourth quartile the risk of either developing DF or IQ < 120 increased by 19% and 20% for water and urinary fluoride. The risk of having both increased by 58% and 62% in third and fourth quartile for water fluoride, 52% and 65% for urinary fluoride. Water fluoride concentrations were positively associated with AChE and negatively associated with ChAT and ACh, trends were same for urinary fluoride except for ACh. The risk of either developing DF or having non-high intelligence rose by 22% (95%CI: 1.07%, 1.38%) for the fourth quartile than those in the first quartile of AChE, for having the both, the risk was 1.27 (95%CI: 1.07, 1.50), 1.37 (95%CI: 1.17, 1.62) and 1.44 (95%CI: 1.23, 1.68) in second, third and fourth quartiles. The mediation proportion by AChE between water fluoride and either developing DF or IQ < 120 was 15.7%. For both to exist, the proportion was 6.7% and 7.2% for water and urinary fluoride. Our findings suggest low-to-moderate fluoride exposure was associated with dysfunction of cholinergic system for children. AChE may partly mediate the prevalence of DF and lower probability of having superior and above intelligence.

R, C. M. Estimation of Fluoride and Sirtuin1 in Patients with Diabetic Nephropathy in Kolar District of Karnataka, India

Objective  Prevalence of type-2 diabetes mellitus (DM) and diabetic nephropathy is growing rapidly in Asian countries, affecting low- and middle-income groups. One of the epidemiological issues of Kolar district is fluorosis; advanced glycation end product, carboxymethyl lysine (CML), and a molecule of interest Sirtuin1 are employed in the present study. In the correlation of fluoride with sirtuin1and CML with sirtuin1 of cases lies the important rationale of the study to assess the extent of kidney damage.

Materials and Methods  This is a comparative cross-sectional study with three groups, each with 70 patients, as follows: G1, control; G2, diabetes with diabetic nephropathy; and G3, type-2 DM without any complications. Informed written consent was obtained from all study patients. All the routine investigations were performed by fully automated Vitro 5, 1 Fs, Vitros. Fasting insulin was analyzed by Vitro eCI and glycated hemoglobin was estimated by BioRad D10. Sirtuin1, CML, and fructosamine were estimated by double antibody sandwich technique.

Statistical Analysis  The statistical analysis was performed by SPSS 20 (IBM) software. Means of normally distributed data were compared using analysis of variance (ANOVA), and not normally distributed data were compared by Kruskal–Wallis test. A p -value of less than 0.05 was considered statistically significant.

Results  A decrease in sirtuin1, serum, and urine fluoride of group 2 (34.74 [25.08–53.2], 0.24 [0.2–0.5], and 0.24 [0.16–0.41]) was observed compared with other groups. Increased CML and fluoride act as prooxidant, restricting the effect of sirtuin1 on cellular damage, causing further complications such as increased insulin resistance and decreased insulin sensitivity.

Conclusion  The alterations in serum sirtuin1 levels indicate the severity of damage due to stress during hyperglycemia and fluoride toxicity; hence, sirtuin1 can be considered as biomarker of aging. Subsequently, the correlation of CML, estimated glomerular filtration rate (eGFR), and fluoride with sirtuin1 indicates that increasing sirtuin1 may defend the forthcoming damage and could be considered in therapeutics.

Cross-cultural adaptation and psychometric properties of the Hindi version of Child Perception Questionnaire (CPQ11-14 ) in school children

BACKGROUND

There is a need to validate OHRQoL measures in Hindi to assess the OHRQoL of Indian children.

AIM

To develop a Hindi version of the CPQ_11-14 and to appraise its validity and reliability for use among North Indian children aged 11-14 years.

DESIGN

The cross-culturally adapted Hindi version of CPQ_11-14 was achieved by forward translation, backward translation, committee review, and pretesting. A total of 1000 children were recruited from schools, chosen by two-stage cluster random sampling technique. After completing the self-administered questionnaire CPQ_11-14 by the child, oral examination was conducted using decayed/missing/filled teeth (DMFT) index, malocclusion index, and Dean's fluorosis index. Test-retest reliability was checked on 100 participants after one week.

RESULTS

The floor effect was present in 3.6% individuals, and there was no ceiling effect. Cronbach's alpha for the overall CPQ_11-14 scale was 0.963. Intra-class correlation (ICC) coefficient was 0.952 for the entire scale. Cronbach's alpha value for test-retest was 0.918. There was a non-significant change in domain-level and overall median CPQ_11-14 scores with an increase in DMFT scores. For malocclusion and fluorosis, there was a statistically significant increase in overall and domain-level scores with increased severity scores. CPQ_11-14 and individual domains significantly correlated with both the global questions.

CONCLUSION

Hindi version of CPQ_11-14 is a reliable scale to assess OHRQoL in Hindi speaking 11- to 14-year-old children.

The occurrence, severity degree, and associated risk factors of dental fluorosis among the 12-year-old schoolchildren in Jilin, China

This study aims to describe the occurrence, severity degree, and correlated risk factors of dental fluorosis among the 12-year-old schoolchildren of Jilin, China.We conducted a cross-sectional, observational, and descriptive study among 960 12-year-old schoolchildren in Jilin. The Dean index was utilized to evaluate the severity degree of dental fluorosis. A questionnaire was sent to the guardians of children. Community fluorosis index was measured to estimate the importance of enamel fluorosis for the whole population's public health. The logistic regression analysis was also utilized to identify the correlation between fluorotic teeth and the independent variables.Nine hundred sixty children were assessed. Among them, 480 (50%) were female. 30.5% of subjects had dental fluorosis, 7.19% had very mild dental fluorosis, 10.73% experienced mild dental fluorosis, 9.58% suffered moderate dental fluorosis, and 3.02% encountered severe dental fluorosis. The overall community fluorosis index was 0.73. The results of logistic regression showed that schoolchildren who brushed teeth more frequently (OR: 2.012, 95% CI 1.767-2.342), deficiency of parental supervision (OR: 4.219, 95% CI 3.887-4.573), and lived in rural areas (OR: 2.776, 95% CI 2.163-3.489) were more correlated with enamel fluorosis. Moreover, schoolchildren whose mothers or fathers were of high education level (OR: 0.336, 95% CI 0.217-0.413 and 0.346, 95% CI 0.113-0.512) and only child (OR: 0.378, 95% CI 0.213-0.415) were protective factors for dental fluorosis.In the Jilin province of China, the risk indicators for dental fluorosis include rural areas, more frequency of brushing, low educational background of parents, and deficiency of parental supervision.

Structural changes in the oral microbiome of the adolescent patients with moderate or severe dental fluorosis

Dental fluorosis is a very prevalent endemic disease. Although oral microbiome has been reported to correlate with different oral diseases, there appears to be an absence of research recognizing any relationship between the severity of dental fluorosis and the oral microbiome. To this end, we investigated the changes in oral microbial community structure and identified bacterial species associated with moderate and severe dental fluorosis. Salivary samples of 42 individuals, assigned into Healthy (N = 9), Mild (N = 14) and Moderate/Severe (M&S, N = 19), were investigated using the V4 region of 16S rRNA gene. The oral microbial community structure based on Bray Curtis and Weighted Unifrac were significantly changed in the M&S group compared with both of Healthy and Mild. As the predominant phyla, Firmicutes and Bacteroidetes showed variation in the relative abundance among groups. The Firmicutes/Bacteroidetes (F/B) ratio was significantly higher in the M&S group. LEfSe analysis was used to identify differentially represented taxa at the species level. Several genera such as Streptococcus mitis, Gemella parahaemolysans, Lactococcus lactis, and Fusobacterium nucleatum, were significantly more abundant in patients with moderate/severe dental fluorosis, while Prevotella melaninogenica and Schaalia odontolytica were enriched in the Healthy group. In conclusion, our study indicates oral microbiome shift in patients with moderate/severe dental fluorosis. We identified several differentially represented bacterial species enriched in moderate and severe fluorosis. Findings from this study suggests that the roles of these bacteria in oral health and related diseases warrant more consideration in patients with moderate and severe fluorosis.

Comparative Evaluation of Hair, Fingernails, and Toenails as Biomarkers of Fluoride Exposure: A Cross-Sectional Study

Background

The increased prevalence of fluorosis has led to a search for biomarkers of fluoride exposure. Among the biomarkers of sub-chronic exposure to fluoride, hair, fingernails, and toenails have the advantage of being noninvasively collected, easily transported, and stored.

Objective

The objective of this study was to comparatively evaluate coronal hair, fingernails, and toenails as biomarkers of fluoride exposure from drinking water; the study was designed as a population-based observational cross-sectional study.

Materials and Methods

A population-based observational cross-sectional study was conducted in 60 children (20 subjects per group) of ages 12-17 years in three villages of Nilakottai block, Dindigul district, Tamil Nadu, India (Thomaspuram, Bangalapatti, and Singampatti). The fluoride concentration in the household drinking water was analyzed and compared with the fluoride content in the coronal hair, fingernail, and toenail clippings, which was estimated by potentiometric method (fluoride-ion-selective electrode) and expressed in ppm (parts per million). A two-tailed probability value of P < 0.05 was considered significant.

Results

The mean fluoride concentration in drinking water was 0.63ppm in Thomaspuram, 1.63ppm in Bangalapatti, and 2.92ppm in Singampatti. The mean fluoride content in hair samples was 2.84ppm, 4.67ppm, and 6.53ppm; fingernail clippings was 2.99ppm, 4.94ppm, and 6.84ppm; and toenail clippings was estimated as 3.13ppm, 5.10ppm, and 7.24ppm in Thomaspuram, Bangalapatti, and Singampatti residents, respectively. The mean fluoride content in the hair, fingernails, and toenails was significantly higher as compared to the mean fluoride content in the drinking water (viz., toenail fluoride > fingernail fluoride > hair fluoride).

Conclusion

Coronal hair, fingernails, and toenails are useful biomarkers for both sub-chronic and chronic fluoride exposure from drinking water. Due to ample sample availability and the highest fluoride content, toenails are the most suitable biomarkers of fluoride exposure from drinking water.

Effects of at-home bleaching and resin infiltration treatments on the aesthetic and psychological status of patients with dental fluorosis: A prospective study

OBJECTIVE

This study aims to evaluate the effect of the combination approach of at-home bleaching (HB) and resin infiltration (RI) techniques on different severity degrees of dental fluorosis (DF) and further analyze the psychological changes caused by HB and RI in patients.

METHOD

Twenty-two patients (4 males, 18 females, 27.8 ± 1.6 yrs) with 186 fluorotic teeth were included in this study and classified into mild (N = 56), moderate (N = 100) and severe (N = 30) DF groups according to the Dean's index. The treatment effects on patients with DF were assessed by questionnaires including the changes in patients' subjective evaluation of their teeth and psychological status before and after treatments. Standardized digital photographs were taken at each time point of the treatment process, including baseline (T1), after bleaching (T2), immediately after RI treatment (T3) and more than six months after RI treatment (T4). The color alterations (ΔE) between the fluorotic (F2) and the surrounding relatively sound areas (F1) were analyzed.

RESULTS

Bad tooth appearance caused 13.64% of patients often depressed, frustrated, or disappointed, whereas 72.72% occasionally had these feelings. After treatment, the satisfaction of DF patients regarding tooth appearance increased from 0% (satisfied) to 58.82% (satisfied) and 23.53% (very satisfied). Moreover, these treatments improved all patients' confidence in smiling, laughing and showing their teeth. The percentage of fluorotic teeth with ΔE values more than 3.0 and 3.7 units decreased gradually from T1 stage to T3 stage in mild and moderate DF groups (p < 0.05), whereas the ΔE value in T3 stage was significantly lower than that of T2 stage in severe DF group (p < 0.05). In T4 stage, no significant difference was observed in the ΔE values between T4 and T3 stages (p > 0.05).

CONCLUSION

This study shows the obvious positive aesthetic effect of HB and RI treatment on different severity degrees of DF and the great improvements in psychological discomforts.

CLINICAL SIGNIFICANCE

The combination treatment of RI and low concentration HB gel improves the aesthetics of DF and may have a stable effect after 6-months follow-up, suggesting that this approach is a valuable clinical choice for dentists to treat DF.

Hydrogeochemical Characterization and Irrigation Quality Assessment of Shallow Groundwater in the Central-Western Guanzhong Basin, China

Groundwater is the major water resource for the agricultural development of the Guanzhong Basin, China. In this study, a total of 97 groundwater samples (51 from the North Bank of the Wei River (NBWR) and 46 from the South Bank of the Wei River (SBWR)) were collected from the central-western Guanzhong Basin. The aim of this study was to investigate the hydrogeochemical characteristics of the basin and to determine the suitability of shallow groundwater for irrigation. The groundwater of the entire study area is alkaline. The groundwater of the SBWR is fresh water, and the NBWR groundwater is either freshwater or brackish water. The average concentration of ions (except for Ca²⁺) in SBWR samples is lower than in NBWR samples. HCO₃^- is dominant in the groundwater of the study area. Ca²⁺ is dominant in the SBWR while Na⁺ is dominant in the NBWR. The SBWR groundwater is mainly of the HCO₃-Ca·Mg type, and has undergone the main hydrogeochemical processes of rock weathering-leaching. The hydrochemical facies of the majority of the NBWR groundwater samples are the HCO₃-Na type with several minor hydrochemical facies of the HCO₃-Ca·Mg, SO₄·Cl-Na, and SO₄·Cl-Ca·Mg types. Its chemistry is mainly controlled by rock weathering, cation exchange, and evaporation. Salinity hazard, sodium percentage, sodium adsorption ratio, residual sodium carbonate, magnesium hazard, permeability index, Kelley's ratio, potential salinity, synthetic harmful coefficient, and irrigation coefficient were assessed to evaluate the irrigation quality of groundwater. The results of the comprehensive consideration of these indicators indicate that the percentage of NBWR water samples suitable for irrigation purposes ranges between 15.7% and 100% at an average level of 56.7%. Of the SBWR water samples suitable for irrigation, the percentage ranges from 78.3% to 100% with an average of 91.8%. Land irrigated with such water will not be exposed to any alkali hazard, but will suffer from a salinity hazard, which is more severe in the NBWR. Thus, most of the water in the NBWR can be used for soils with good drainage conditions which control salinity.

Occurrence of fluorosis in a population living in a high-fluoride groundwater area: Nakuru area in the Central Kenyan Rift Valley

Endemic fluorosis caused by the consumption of high-fluoride groundwater is a public health problem in Nakuru, in the Kenyan Rift Valley. The present study was carried out during the period January-February 2017 to determine the prevalence and severity of dental fluorosis among patients of two Nakuru healthcare facilities, namely St. Mary's Hospital-Gilgil and Egerton University-Njoro Dental Clinic. The patients consisted of both young and old members of the Nakuru population served with groundwater containing high levels of fluoride ranging from 0.1 to 72 mg/l. The Thylstrup-Fejerskov (TF) index was used to estimate the severity of dental fluorosis. Among the patients of St. Mary's Hospital-Gilgil, the prevalence of dental fluorosis was 86% (n = 100), whereby 54% of the patients were found to have mild to moderate dental fluorosis and 32% had severe dental fluorosis. Whereas the prevalence of dental fluorosis in patients below the age of 14 years was higher (92%) than in older patients (85.56%), severity was reversed (average TF = 3.77 for older patients; average TF = 2.18 for younger patients). No significant variation in severity and prevalence of dental fluorosis was recorded with respect to both genders of the patients. The dental fluorosis prevalence rate amongst the patients of the Egerton University-Njoro Dental Clinic was found to be 79.49% (n = 73). However, a comparative analysis of the two age groups revealed a much higher prevalence rate of 100% for patients below the age of 14 relative to the older patients (79.49%). While a high number of cases of dental fluorosis from both healthcare facilities were reported in patients residing in Njoro, Nakuru town, Gilgil and Bahati, the fewer cases were from Solai and Rongai. The results seem to suggest a much higher occurrence of dental fluorosis within the younger population group. This implies that rapid population growth and urbanization puts more pressure on public water resources which leads to a strong reliance on fluoride contaminated groundwater and the concomitant increased cases of dental fluorosis. Therefore, there is a need for a change of local government policy to enhance access to safe water and public education on fluorosis in the areas that were under investigation.

Overview of Calcium Phosphates used in Biomimetic Oral Care

Background:

The use of biomimetic agents is an emerging field in modern oral care. Promising biomimetic substances for such applications are calcium phosphates, because their chemical composition is very similar to that of the mineral phase in human teeth, especially of natural enamel. Examples for their application include the remineralization of early caries lesions and repair of small enamel defects.

Objective:

This review provides an interdisciplinary view on calcium phosphates and their applications in biomimetic oral care. The aim of this work is to give an overview of in vivo and in situ studies comparing several calcium phosphates in preventive dentistry that can be used as a knowledge base for the development of innovative alternative oral care concepts.

Methods:

Books, reviews, and original research papers with a focus on in vivo and in situ studies were included. The databases PubMed^® and SciFinder^® were used for literature search. Calcium phosphates that are frequently utilized in oral care products are covered in this review and were used as search terms alone and together with the following key words: in vivo, in situ, caries, clinical study, and remineralization. From 13,470 studies found, 35 studies complied with the inclusion criteria and were used for this review.

Results:

Published in vivo and in situ studies demonstrate calcium phosphates’ potential in enamel remineralization. However, more studies are needed to further substantiate existing results and to extend and refine the application of calcium phosphates in modern oral care.

Conclusion:

Calcium phosphates represent an innovative biomimetic approach for daily oral care because of their high similarity to natural enamel that will broaden the range of future treatments in preventive dentistry.

A comparative study of dental fluorosis and non-skeletal manifestations of fluorosis in areas with different water fluoride concentrations in rural Kolar

Background:

Fluorosis is an endemic disease which results due to excess exposure to high fluoride from different sources. The climatic factors and dependency on ground water add to the risk of fluorosis in Kolar. In addition to it, the epidemiological studies conducted on fluorosis in Kolar are very few.

Aims:

(1) To estimate age-specific prevalence of dental fluorosis in the study population. (2) To determine the proportion of study subjects with non-skeletal manifestations of fluorosis (3) To assess and compare the influence of various socio-epidemiological factors in the occurrence of dental fluorosis among the study population in areas with high and normal fluoride.

Methodology:

A cross-sectional study was conducted among the residents of three randomly selected villages, Thimmasandra and Batwarahalli (high fluoride) and Maddinayakanahalli (normal fluoride) belonging to Bangarpet taluk, Kolar for 1 year. Dental fluorosis was assessed by the Dean's grading. Non-skeletal manifestations were elicited based on clinical features. Fluoride levels of drinking water sources were estimated by ion-electrode method. The Chi-square and Fisher's exact tests were used to see the difference in proportions and a P value of <0.05 was considered for statistical significance.

Results:

The prevalence of dental and non-skeletal fluorosis in the study groups with high and normal fluoride groups were 13.17%, 5.5%, 3.84%, 1.9%, respectively. The prevalence of dental fluorosis was significantly higher among the children and adolescents compared to adults (P < 0.05).

Conclusion:

Dental fluorosis is a public health problem mainly affecting children and adolescents in Bangarpet.

Effect of Fluoride Concentration in Drinking Water on Intelligence Quotient of 12-14-Year-Old Children in Mathura District: A Cross-Sectional Study

Aims:

The aim was to assess and correlate the influence of the concentration of fluoride in ingested water on the intelligence quotient (IQ) of 12–14-year-old youngsters in Mathura district.

Materials and Methods:

A total of 219 children were selected, 75 from low F area, 75 medium F area, and 69 from high F area. The concentration of fluoride in the routinely ingested water was estimated using “Ion Selective Electrode method”; then, Raven's Test was utilized to estimate the IQ of the study participants. Independent t-test, Tukey's post hoc, Chi-square an analysis of variance tests were used to associate the mean and proportion IQ scores in high-, medium-, and low-fluoride regions along with inter-group significant differences (P ≤ 0.05).

Results:

The comparison of IQ score showed that 35 (46.7%) participants from the high fluoride and 10 (13.3%) participants from the medium-fluoride areas had below average IQ. Further, it was noted that the lowest mean marks were obtained by the children in the high-fluoride region (13.9467) followed by those in medium (18.9467) and uppermost in least noted fluoride area (38.6087). However, gender-based intergroup comparison did not produce a significant relation with fluoride (P ≥ 0.05).

Conclusion:

Concentration of Fluoride in the ingested water was significantly associated with the IQ of children. It has also coined the proportional variability in mental output in accordance to the ingested fluoride level. As two sides of a coin, fluoride cannot be utterly blamed for a lower intelligence in a population; it puts forward a fact that intelligence is a multifactorial variable with a strategic role played by genetics and nutrition to develop cognitive and psychosomatic activities in an individual.