Dental fluorosis: chemistry and biology

Peptide Characterization of Mature Fluorotic and Control Human Enamel

Exposure to high fluoride levels during amelogenesis causes enamel fluorosis. This study aimed to determine and compare the amino acid sequences in the enamel of fluorotic and control teeth. This investigation included enamel samples obtained from erupted and non-erupted third molars with either TF grade 4-6 (n=7) fluorosis or no sign of fluorosis (controls, n=7). The samples were kept frozen at -20 °C until protein extraction. Samples were etched and processed with a cocktail of proteinase inhibitors and immediately analyzed. Matrix Assisted Laser Desorption/Ionization-Time-Of-Flight/Time-of-Flight Mass Spectrometry (MALDI-TOF/TOF) followed by MASCOT search aided the peptides analysis. The more abundant peptides bore the N-terminal amelogenin sequences WYQSIRPPYP (which is specific for the X-encoded amelogenin) and MPLPPHPGHPGYINF (which does not show sexual dimorphism) were not different in control or fluorotic enamel. There was no missing proteolytic cleavage in the fluorotic samples, which suggested that the increased amount of protein described in fluorotic enamel did not stem from the decreased ability of proteinases to cleave the proteins in humans. This study showed how to successfully obtain peptide from superficial enamel. A relatively low number of teeth was sufficient to provide good data on the actual peptides found in mature enamel.

Enzymatic Activity of Glutathione S-Transferase and Dental Fluorosis Among Children Receiving Two Different Levels of Naturally Fluoridated Water

This study was conducted to measure the activity of the enzyme glutathione S-transferase (GST) in saliva and to compare the activity of this enzyme in children with and without dental fluorosis in communities with different concentrations of naturally fluoridated water. A total of 141 schoolchildren participated in this cross-sectional study. Children were selected from two communities: one with a low (0.4 ppm) and the other with a high (1.8 ppm) water fluoride concentration. Dental fluorosis was evaluated by applying the Thylstrup and Fejerskov Index (TFI) criteria. Stimulated saliva was obtained, and fluoride concentration and GST activity were measured. The GST activity was compared among children with different levels of dental fluorosis using multinomial logistic regression models and odds ratios (OR). The mean age of the children was 10.6 (±1.03) years. Approximately half of the children showed dental fluorosis (52.5 %). The average GST activity was 0.5678 (±0.1959) nmol/min/μg. A higher concentration of fluoride in the saliva was detected in children with a higher GST activity (p = 0.039). A multinomial logistic regression model used to evaluate the GST activity and the dental fluorosis score identified a strong association between TFI = 2-3 (OR = 15.44, p = 0.007) and TFI ≥ 4 (OR = 55.40, p = 0.026) and the GST activity level, compared with children showing TFI = 0-1, adjusted for age and sex. Schoolchildren with higher levels of dental fluorosis and a higher fluoride concentration in the saliva showed greater GST activity. The increased GST activity most likely was the result of the body's need to inactivate free radicals produced by exposure to fluoride.

Prolactin rs1341239 T allele may have protective role against the brick tea type skeletal fluorosis

Objective

Prolactin (PRL) has been reported to be associated with increased bone turnover, and increased bone turnover is also a feature of skeletal fluorosis (SF). Autocrine/paracrine production of PRL is regulated by the extrapituitary promoter and a polymorphism in the extrapituitary PRL promoter at -1149 (rs1341239) is associated with disturbances of bone metabolism in other diseases. Here, we have investigated the possibility that the rs1341239 polymorphism is associated with SF, which results from the consumption of brick tea.

Design

We conducted a cross-sectional study in Sinkiang, Qinghai, Inner Mongolia in China. Demography survey questionnaires were completed and physical examination and X-ray diagnoses were used to diagnose SF. Brick tea water fluoride intake (IF) and urinary fluoride (UF) were tested by an F-ion selective electrode method. A Sequenom MassARRAY system was used to determine PRL gene polymorphisms.

Results

Subjects who were younger than 45 years of age and carried the T allele had a significantly decreased risk of SF [OR = 0.279 (95%CI, 0.094–0.824)] compared to those carrying the homozygous G allele. This phenomenon was only observed in Kazakh subjects [OR = 0.127 (95%CI, 0.025–0.646)]. Kazakh females who carried T alleles has a decreased risk of SF [OR = 0.410 (95%CI, 0.199–0.847)]. For Kazakh subjects which IF is less than 3.5 mg/d, a decreased risk of SF was observed among the participants who carried T alleles [OR = 0.118 (95%CI, 0.029–0.472)]. Overall, subjects with 1.6–3.2 mg/L UF and carried T alleles had a significantly decreased risk of SF [OR = 0.476 (95%CI, 0.237–0.955)] compared to homozygous G allele carriers. This phenomenon was only observed in Kazakh subjects [OR = 0.324 (95%CI, 0.114–0.923)].

Conclusions

Our results suggested that the PRL rs1341239 T allele decreases the risk of brick tea SF.

LS8 cell apoptosis induced by NaF through p-ERK and p-JNK - a mechanism study of dental fluorosis

OBJECTIVE

To investigate the possible biological mechanism of dental fluorosis at a molecular level.

MATERIAL AND METHODS

Cultured LS8 were incubated with serum-free medium containing selected concentrations of NaF (0 ∼ 2 mM) for either 24 or 48 h. Subcellular microanatomy was characterized using TEM; meanwhile, selected biomolecules were analysed using various biochemistry techniques. Transient transfection was used to modulate a molecular pathway for apoptosis.

RESULTS

Apoptosis of LS8 was induced by NaF treatment that showed both time and concentration dependency. The activity of caspase-3, -8, -9 was found to be increased with NaF in a dose-dependent manner. Western blot revealed that the protein expression of p-ERK and p-JNK were decreased, while the expression of p-P38 was increased. Inhibition of the p-ERK and p-JNK pathways resulted in a similar decrease for caspase-3.

CONCLUSION

During NaF-induced apoptosis of LS8, p-ERK and p-JNK were closely associated with induction of apoptosis, which might be a mechanism of dental fluorosis.

Treatment of Fluorosis Spots Using a Resin Infiltration Technique: 14-month Follow-up

The aim of this study was to report a clinical case of moderate fluorosis spots treated with infiltration of low-viscosity resin. A commercial resin was applied to the facial surfaces on the anterior teeth in both the maxillary and mandibular arches. The white spots of fluorosis lost their whitish appearance and appeared similar to sound enamel. This technique, which might constitute an alternative to white-masking of fluorosis spots, showed optimal esthetic results.

Dental enamel development defects in children and adolescents with HIV infection: case-control study

To determine the frequency of Enamel Development Defects (DDE) and associated factors in children and adolescents infected with HIV. A case-control study was conducted in HIV-infected patients (n = 52), aged 3 to 15, and a control group formed by preschool and schoolchildren (n = 104) matched according to gender, age and household income. Data on medical history, neonatal and maternal conditions were obtained. For diagnosis of enamel defects was used modified DDE Index. DDE frequency was 61.5% in the case group and 58.7% in the control group (p = 0.569). Infection of the genitourinary tract and maternal hemorrhage were factors associated with DDE in the case and control groups, respectively. An association was observed between the use of antiretroviral regimens with protease inhibitors or efavirenz and DDE in the permanent dentition. Children and adolescents HIV-infected showed a DDE frequency similar to healthy patients, but factors associated with this condition were different between the groups.

Natural history and long-term impact of dental fluorosis: a prospective cohort study

OBJECTIVE

The study assessed longitudinal changes in the presentation of dental fluorosis and evaluated the impact of fluorosis on the perception of oral health among young adults.

DESIGN AND SETTING

Prospective follow-up study during 2011-12 of a population-based study in South Australia conducted between 2003 and 2004.

PARTICIPANTS

8-13-year-old children initially examined in 2003 and 2004.

MAIN OUTCOMES

Dental fluorosis was assessed with the Thylstrup and Fejerskov (TF) Index. The impact on perceptions of oral health by the study participants and their parents was assessed with the Global Rating of Oral Health (GROH). Pairwise comparative analysis of the presentation of fluorosis was conducted at the individual and tooth levels. Multivariable models of changes in fluorosis were generated. An ordinal logistic regression model was used to evaluate the association between GROH with dental fluorosis, caries and other factors.

RESULT

A total of 314 participants completed the follow-up questionnaires and dental examination. Over 60% of teeth scored as TF 1 at baseline were scored as TF 0 at follow-up; 66% of teeth scored as TF 2 or 3 at baseline were scored as TF 0 or 1 at follow-up. In multivariable models, changes in fluorosis were not significantly associated with socio-economic factors or oral health behaviours, confirming that they were the result of a natural process. Perceptions of poor oral health were significantly associated with the number of untreated decayed tooth surfaces at follow-up, but not with fluorosis.

CONCLUSION

Very mild and mild dental fluorosis diminished with time. Dental fluorosis did not have a negative impact on perceptions of oral health.

Chamaecyparis obtusa Suppresses Virulence Genes in Streptococcus mutans

Chamaecyparis obtusa (C. obtusa) is known to have antimicrobial effects and has been used as a medicinal plant and in forest bathing. This study aimed to evaluate the anticariogenic activity of essential oil of C. obtusa on Streptococcus mutans, which is one of the most important bacterial causes of dental caries and dental biofilm formation. Essential oil from C. obtusa was extracted, and its effect on bacterial growth, acid production, and biofilm formation was evaluated. C. obtusa essential oil exhibited concentration-dependent inhibition of bacterial growth over 0.025 mg/mL, with 99% inhibition at a concentration of 0.2 mg/mL. The bacterial biofilm formation and acid production were also significantly inhibited at the concentration greater than 0.025 mg/mL. The result of LIVE/DEAD® BacLight™ Bacterial Viability Kit showed a concentration-dependent bactericidal effect on S. mutans and almost all bacteria were dead over 0.8 mg/mL. Real-time PCR analysis showed that gene expression of some virulence factors such as brpA, gbpB, gtfC, and gtfD was also inhibited. In GC and GC-MS analysis, the major components were found to be α-terpinene (40.60%), bornyl acetate (12.45%), α-pinene (11.38%), β-pinene (7.22%), β-phellandrene (3.45%), and α-terpinolene (3.40%). These results show that C. obtusa essential oil has anticariogenic effect on S. mutans.

A relationship between three-dimensional surface hydration structures and force distribution measured by atomic force microscopy

Hydration plays important roles in various solid-liquid interfacial phenomena. Very recently, three-dimensional scanning force microscopy (3D-SFM) has been proposed as a tool to visualise solvated surfaces and their hydration structures with lateral and vertical (sub) molecular resolution. However, the relationship between the 3D force map obtained and the equilibrium water density, ρ(r), distribution above the surface remains an open question. Here, we investigate this relationship at an interface of an inorganic mineral, fluorite, and water. The force maps measured in pure water are directly compared to force maps generated using the solvent tip approximation (STA) model and from explicit molecular dynamics simulations. The results show that the simulated STA force map describes the major features of the experimentally obtained force image. The agreement between the STA data and the experiment establishes the correspondence between the water density used as an input to the STA model and the experimental hydration structure and thus provides a tool to bridge the experimental force data and atomistic solvation structures. Further applications of this method should improve the accuracy and reliability of both interpretation of 3D-SFM force maps and atomistic simulations in a wide range of solid-liquid interfacial phenomena.

Reconstructing temporal variation of fluoride uptake in eastern grey kangaroos (Macropus giganteus) from a high-fluoride area by analysis of fluoride distribution in dentine

Trace element profiling in the incrementally formed dentine of mammalian teeth can be applied to reconstruct temporal variation of incorporation of these elements into the tissue. Using an electron microprobe, this study analysed fluoride distribution in dentine of first and third mandibular molars of free-ranging eastern grey kangaroos inhabiting a high-fluoride area, to assess temporal variation in fluoride uptake of the animals. Fluoride content in the early-formed dentine of first molars was significantly lower than in the late-formed dentine of these teeth, and was also lower than in both, the early and the late-formed dentine of third molars. As early dentine formation in M1 takes place prior to weaning, this finding indicates a lower dentinal fluoride uptake during the pre-weaning compared to the post-weaning period. This is hypothetically attributed to the action of a partial barrier to fluoride transfer from blood to milk in lactating females and a low bioavailability of fluoride ingested together with milk. Another factor contributing to lower plasma fluoride levels in juveniles compared to adults is the rapid clearance of fluoride from blood plasma in the former due to their intense skeletal growth. The combined action of these mechanisms is considered to explain why in kangaroos from high-fluoride areas, the (early-formed) first molars are not affected by dental fluorosis while the (later-formed) third and fourth molars regularly exhibit marked to severe fluorotic lesions.

Developmental and Post-Eruptive Defects in Molar Enamel of Free-Ranging Eastern Grey Kangaroos (Macropus giganteus) Exposed to High Environmental Levels of Fluoride

Dental fluorosis has recently been diagnosed in wild marsupials inhabiting a high-fluoride area in Victoria, Australia. Information on the histopathology of fluorotic marsupial enamel has thus far not been available. This study analyzed the developmental and post-eruptive defects in fluorotic molar enamel of eastern grey kangaroos (Macropus giganteus) from the same high-fluoride area using light microscopy and backscattered electron imaging in the scanning electron microscope. The fluorotic enamel exhibited a brownish to blackish discolouration due to post-eruptive infiltration of stains from the oral cavity and was less resistant to wear than normally mineralized enamel of kangaroos from low-fluoride areas. Developmental defects of enamel included enamel hypoplasia and a pronounced hypomineralization of the outer (sub-surface) enamel underneath a thin rim of well-mineralized surface enamel. While the hypoplastic defects denote a disturbance of ameloblast function during the secretory stage of amelogenesis, the hypomineralization is attributed to an impairment of enamel maturation. In addition to hypoplastic defects, the fluorotic molars also exhibited numerous post-eruptive enamel defects due to the flaking-off of portions of the outer, hypomineralized enamel layer during mastication. The macroscopic and histopathological lesions in fluorotic enamel of M. giganteus match those previously described for placental mammals. It is therefore concluded that there exist no principal differences in the pathogenic mechanisms of dental fluorosis between marsupial and placental mammals. The regular occurrence of hypomineralized, opaque outer enamel in the teeth of M. giganteus and other macropodids must be considered in the differential diagnosis of dental fluorosis in these species.

Effects of Different Concentrations of Fluoride in Oral Mucosal Cells in Albino Rats

INTRODUCTION

Fluoride has been described to be physiologically essential for the normal development and growth of human beings. However, it is well known that excessive fluoride causes skeletal, nonskeletal and dental complications. Therefore, outlining the cytogenetic effects induced by fluorosis is necessary.

OBJECTIVES

To evaluate the cytomorphology of exfoliated oral mucosal cells among various concentrations of fluoride.

STUDY DESIGN

Study group comprised of 12 Albino Wistar rats, categorized into A,B and C groups (fed with 25 ppm,50 ppm and 100 ppm concentration of NaF), each group consisting of 4 rats, with 4 controls (fed with 1ppm concentration of NaF in distilled water). Each group was fed for a period of 42 days.

MATERIALS AND METHODS

Cytological smears were taken from the buccal mucosa of each group after 42 days of fluoride administration. The samples were stained with the papanicolaou method and assessed for Cytomorphometrical changes in maximum diameter of nucleus, minimum diameter of nucleus, perimeter of the nucleus, maximum diameter of the cell, minimum diameter of the cell and perimeter of the cell by image analysis software and the results were statistically analysed using SPSS software.

RESULTS

Mean values of maximum diameter, minimum diameter and perimeter of the nucleus increased in fluoride induced study groups when compared to controls and the results showed that p-value was statistically significant (p-value: 0.000, 0.001). Mean value of maximum diameter, minimum diameter and perimeter of the cell decreased in fluoride induced subjects when compared with controls which were statistically not significant (p-value: 0.791, 0.600 & 0.719). A continuous increase in the nuclear size and decrease in the cell size was identified in fluoride induced groups as compared to controls.

CONCLUSION

The observations of our present study revealed that cellular changes occur with severity of fluorosis. These cellular morphological changes may possibly eventuate into dysplastic alterations, which can progress to malignant changes.

Proteomics of Secretory-Stage and Maturation-Stage Enamel of Genetically Distinct Mice

The mechanisms by which excessive ingestion of fluoride (F) during amelogenesis leads to dental fluorosis (DF) are still not precisely known. Inbred strains of mice vary in their susceptibility to develop DF, and therefore permit the investigation of underlying molecular events influencing DF severity. We employed a proteomic approach to characterize and evaluate changes in protein expression from secretory-stage and maturation-stage enamel in 2 strains of mice with different susceptibilities to DF (A/J, i.e. ‘susceptible' and 129P3/J, i.e. ‘resistant'). Weanling male and female susceptible and resistant mice fed a low-F diet were divided into 2 F-water treatment groups. They received water containing 0 (control) or 50 mg F/l for 6 weeks. Plasma and incisor enamel was analyzed for F content. For proteomic analysis, the enamel proteins extracted for each group were separated by 2-dimensional electrophoresis and subsequently characterized by liquid-chromatography electrospray-ionization quadrupole time-of-flight mass spectrometry. F data were analyzed by 2-way ANOVA and Bonferroni's test (p < 0.05). Resistant mice had significantly higher plasma and enamel F concentrations when compared with susceptible mice in the F-treated groups. The proteomic results for mice treated with 0 mg F/l revealed that during the secretory stage, resistant mice had a higher abundance of proteins than their susceptible counterparts, but this was reversed during the maturation stage. Treatment with F greatly increased the number of protein spots detected in both stages. Many proteins not previously described in enamel (e.g. type 1 collagen) as well as some uncharacterized proteins were identified. Our findings reveal new insights regarding amelogenesis and how genetic background and F affect this process.

Relationship between enamel fluorosis severity and fluoride content

OBJECTIVES

Enamel fluorosis is a hypomineralization caused by chronic exposure to high levels of fluoride during tooth development. Previous research on the relationship between enamel fluoride content and fluorosis severity has been equivocal. The current study aimed at comparing visually and histologically assessed fluorosis severity with enamel fluoride content.

METHODS

Extracted teeth (n=112) were visually examined using the Thylstrup and Fejerskov Index for fluorosis. Eruption status of each tooth was noted. Teeth were cut into 100 μm slices to assess histological changes with polarized light microscopy. Teeth were categorized as sound, mild, moderate, or severe fluorosis, visually and histologically. They were cut into squares (2 × 2 mm) for the determination of fluoride content (microbiopsy) at depths of 30, 60 and 90 μm from the external surface.

RESULTS

Erupted teeth with severe fluorosis had significantly greater mean fluoride content at 30, 60 and 90 μm than sound teeth. Unerupted teeth with mild, moderate and severe fluorosis had significantly greater mean fluoride content than sound teeth at 30 μm; unerupted teeth with mild and severe fluorosis had significantly greater mean fluoride content than sound teeth at 60 μm, while only unerupted teeth severe fluorosis had significantly greater mean fluoride content than sound teeth at 90 μm.

CONCLUSIONS

Both erupted and unerupted severely fluorosed teeth presented higher mean enamel fluoride content than sound teeth.

CLINICAL SIGNIFICANCE

Data on fluoride content in enamel will further our understanding of its biological characteristics which play a role in the management of hard tissue diseases and conditions.

Nutritional status and dental fluorosis among schoolchildren in communities with different drinking water fluoride concentrations in a central region in Mexico

Poor water quality and under nutrition are important factors affecting the health of many communities in developing countries. The aims of this study were: i) to describe the fluoride water concentration and the hydrogeological conditions in a region of a state located in the central in Mexico ii) to measure the association between undernutrition and dental fluorosis in children living in communities with different drinking water fluoride concentrations in a state located in the central region of Mexico.

METHODS

Field work was performed in the region to identify the prevailing groundwater flow characteristics and water wells were sampled to analyze water fluoride concentration. Children were selected from three communities that had different drinking water fluoride concentrations (i.e., 0.56, 0.70 and 1.60 mg/l). Fluoridated salt was available in these communities. The Thylstrup-Fejerskov Index (TFI) was used to assess dental fluorosis. Categories four or higher of this index involve changes in the entire tooth surface (ITF ≥ 4). The weight and height of the children were measured. The assessment of undernutrition was based on the World Health Organization criteria: children were classified as being at risk of low-height (Height-for-Age Z score < − 1.0 SD) and having low-height (Height-for-Age Z score < − 2.0 SD) for age and sex, the same cutoff points of the Z score were used to classify "risk of low-weight" and" low-weight children".

RESULTS

In the region the mineralization of the water captured by the wells is the result of a reaction with volcanic materials. The water fluoride concentration in the region ranged from 0.2 to 1.6 mg/l. A total of 734 schoolchildren participated in the study. The percentage of children in fluorosis categories (ITF ≥ 4) was 15.9%, 21.1% of the children were at risk of low height-for-age, and 8.0% had low height-for-age. The percentage of children with fluorosis (ITF ≥ 4) was 6.3%, 9.1% and 31.9% (p ˂ 0.001) and low high-for-age was 2.9%, 2.5% and 8.4% (p ˂ 0.001), for the communities with F concentrations of 0.56 mg/l, 0.70 mg/l and 1.6 mg/l, respectively. The logistic regression model showed an association between dental fluorosis (TFI ≥ 4) and low height-for-age (OR 2.09, p = 0.022) after adjusting for sex, number of teeth erupted, source of drinking water, use of fluoridated toothpaste and tap water fluoride concentration in the community.

CONCLUSION

Children with low height-for-age were more likely to have dental fluorosis in the TFI categories that affect the entire tooth surface. The results suggest that subpopulations with chronic undernutrition are more susceptible to dental fluorosis.

A 3D culture model study monitoring differentiation of dental epithelial cells into ameloblast-like cells

The present study was designed to investigate whether a three dimensional (3D) culture of the rat incisor-derived dental epithelial cell line SF2 enhances its differentiation into ameloblast-like cells.

Diagnosing congenital syphilis using Hutchinson's method: Differentiating between syphilitic, mercurial, and syphilitic-mercurial dental defects

OBJECTIVES

This study focuses on the dental abnormalities observed by Sir Jonathan Hutchinson, Henry Moon and Alfred Fournier in patients with congenital syphilis and in those treated with mercury, in order to define alterations in dental morphology attributable to each of these causes. These definitions are applied to reported paleopathological cases, exploring various etiologies behind the defects, in order to aid in the diagnosis of congenital syphilis.

METHODS

Original works were examined for descriptions of dental abnormalities in congenital syphilis and in mercurial treatments. These descriptions were compared with dentitions of paleopathological cases (n = 4) demonstrating abnormalities attributed to congenital syphilis.

RESULTS

Distinct morphological differences were recognized between congenital syphilitic teeth and teeth affected by mercury. Mercury produces a pronounced deficiency in enamel of incisors, canines and first permanent molars that become rugged and pitted, and of dirty grey honeycombed appearance. Mercury-induced dental changes are evident in three out of four cases studied here. In one case, only syphilitic changes were present.

DISCUSSION

Dental changes in congenital syphilis range from no visible signs to those beyond the classical models of Hutchinson, Moon and Fournier. Treatment of neonates and infants with mercury produces additional changes. Signs of disease and treatment with mercury on teeth may occur together; permanent incisors, first molars and canines, are typically affected, premolars and second/third molars are usually spared. Signs of treatment with mercury might be the only evidence of the occurrence of the disease as mercury was rarely used to treat other diseases.

Dental fluorosis and skeletal fluoride content as biomarkers of excess fluoride exposure in marsupials

Particulate and gaseous fluoride emissions contaminate vegetation near fluoride-emitting industries, potentially impacting herbivorous wildlife in neighboring areas. Dental fluorosis has been associated with consumption of fluoride-contaminated foliage by juvenile livestock and wildlife in Europe and North America. For the first time, we explored the epidemiology and comparative pathology of dental fluorosis in Australian marsupials residing near an aluminium smelter. Six species (Macropus giganteus, Macropus rufogriseus, Wallabia bicolor, Phascolarctos cinereus, Trichosurus vulpecula, Pseudocheirus peregrinus) demonstrated significantly higher bone fluoride levels in the high (n=161 individuals), compared to the low (n=67 individuals), fluoride areas (p<0.001). Necropsy examinations of all six species from the high-fluoride area near the smelter revealed dental lesions considered characteristic of dental fluorosis in eutherian mammals. Within the high-fluoride area, 67% of individuals across the six species showed dental enamel lesions, compared to 3% in the low-fluoride areas. Molars that erupted before weaning were significantly less likely to display pathological lesions than those developing later, and molars in the posterior portion of the dental arcade were more severely fluorotic than anterior molars in all six species. The severity of dental lesions was positively associated with increasing bone fluoride levels in all species, revealing a potential biomarker of excess fluoride exposure.

Recommendations for fluoride limits in drinking water based on estimated daily fluoride intake in the Upper East Region, Ghana

Both dental and skeletal fluorosis caused by high fluoride intake are serious public health concerns around the world. Fluorosis is particularly pronounced in developing countries where elevated concentrations of naturally occurring fluoride are present in the drinking water, which is the primary route of exposure. The World Health Organization recommended limit of fluoride in drinking water is 1.5 mg F(-) L(-1), which is also the upper limit for fluoride in drinking water for several other countries such as Canada, China, India, Australia, and the European Union. In the United States the enforceable limit is much higher at 4 mg F(-) L(-1), which is intended to prevent severe skeletal fluorosis but does not protect against dental fluorosis. Many countries, including the United States, also have notably lower unenforced recommended limits to protect against dental fluorosis. One consideration in determining the optimum fluoride concentration in drinking water is daily water intake, which can be high in hot climates such as in northern Ghana. The results of this study show that average water intake is about two times higher in Ghana than in more temperate climates and, as a result, the fluoride intake is higher. The results also indicate that to protect the Ghanaian population against dental fluorosis, the maximum concentration of fluoride in drinking water for children under 6-8 years should be 0.6 mg F(-) L(-1) (and lower in the first two years of life), and the limit for older children and adults should be 1.0 mg F(-) L(-1). However, when considering that water treatment is not cost-free, the most widely recommended limit of 1.5 mg F(-) L(-1) - which is currently the limit in Ghana--may be appropriate for older children and adults since they are not vulnerable to dental fluorosis once the tooth enamel is formed.

Aesthetic Management of Fluoresced Teeth with Ceramic Veneers and Direct Composite Bonding - An Overview and A Case Presentation

Tooth discolouration is a common problem and affects people of all ages. Apart from the conventional treatment modalities for the same, newer options are available today with better techniques and materials. The present case report describes a 17-year-old girl who had stained and pitted teeth, attributable to dental fluorosis and she desired aesthetic treatment for the same. The pros and cons of all treatment options were carefully weighed and a multistep treatment process involving ceramic veneers and direct bonding were planned. The execution of the planned treatment yielded a good aesthetic and functional outcome.

Long-Term Fluoride Release from Dental Resins Affects STRO-1+ Cell Behavior

Fluoride-releasing restorative dental materials can be beneficial to remineralize dentin and help prevent secondary caries. However, the effects of fluoride release from dental materials on the activity of dental pulp stem cells are not known. Here we investigate whether different fluoride release kinetics from dental resins supplemented with modified hydrotalcite (RK-F10) or fluoride-glass filler (RK-FG10) could influence the behavior of a human dental pulp stem cell subpopulation (STRO-1(+) cells) known for its ability to differentiate toward an odontoblast-like phenotype. The 2 resins, characterized by similar physicochemical properties and fluoride content, exhibited different long-term fluoride release kinetics. Our data demonstrate that long-term exposure of STRO-1(+) cells to a continuous release of a low amount of fluoride by RK-F10 increases their migratory response to transforming growth factor β1 (TGF-β1) and stromal cell-derived factor 1 (SDF-1), both important promoters of pulp stem cell recruitment. Moreover, the expression patterns of dentin sialoprotein (dspp), dentin matrix protein 1 (dmp1), osteocalcin (ocn), and matrix extracellular phosphoglycoprotein (mepe) indicate a complete odontoblast-like cell differentiation only when STRO-1(+) cells were cultured on RK-F10. On the contrary, RK-FG10, characterized by an initial fluoride release burst and reduced lifetime of the delivery, did not elicit any significant effect on both STRO-1(+) cell migration and differentiation. Taken together, our results highlight the importance of taking into account fluoride release kinetics in addition to fluoride concentration when designing new fluoride-restorative materials.

Caries process on occlusal surfaces: evolving evidence and understanding

Management of the caries process on occlusal surfaces of permanent molars has proven a major challenge. The onset of caries on these surfaces takes place soon after their eruption, and the permanent first molars, followed by the second molars, remain the sites in the dentition which show the highest caries prevalence. This paper is structured in the form of questions and answers in which traditional concepts of caries susceptibility of occlusal surfaces are appraised and confronted with the current evidence. Then, research studies examining the role of biological determinants on the development and arrest of occlusal caries in young permanent teeth are discussed. Finally, the contribution of these studies in terms of developing the available scientific evidence and our understanding of the caries process on occlusal surfaces is analyzed. The current evidence does not support the concept that the early onset and high prevalence of occlusal caries in young permanent teeth are due to a particularly low inherent resistance of the occlusal surface or due to the presence of inaccessible fissure-like structures on these surfaces. Evidence is provided to show that the most influential biological determinants of the development and arrest of occlusal caries are thick plaque accumulation on the groove-fossa system and the stage of tooth eruption limiting mechanical oral function. Consequently, active occlusal lesions are significantly more prevalent in erupting than in fully erupted teeth. The major contribution of this review is to provide updated knowledge about the biological principles determining the development and arrest of caries on occlusal surfaces of erupting teeth.

Evaluation of Novel Microabrasion Paste as a Dental Bleaching Material and Effects on Enamel Surface

PURPOSE

Dental fluorosis is an enamel dysplasia that can cause serious aesthetic and psychological problems. An examination of the literature shows that the microabrasion method is the most effective way to treat fluorosis. This study aimed to produce a prototype microabrasion paste for the treatment of fluorosis stains and to examine the effects of the paste on tooth structure and color in vitro.

MATERIAL AND METHODS

Forty extracted upper incisor teeth were used in this study. The teeth were divided into four treatment groups: a prototype microabrasion paste group (N = 10), an Opalustre paste group (N = 10), a 37% phosphoric acid gel group (N = 10), and a distilled water (control) group (N = 10). Following treatment, all specimens in each of the four groups were examined by scanning electron microscopy for changes in their surface enamel. Changes in tooth color changes of the 1st and 2nd groups were measured before and after treatment by a VITA Easyshade Advance spectrophotometer.

RESULTS

In scanning electron microscopy evaluations, significant differences were not observed between the 1st and 2nd groups. Differences in three color-measuring coordinates between the 1st and 2nd were also not statistically significant (p > 0.05).

CONCLUSIONS

The study demonstrated that the prototype paste is a viable treatment option for dental fluorosis.

CLINICAL SIGNIFICANCE

The findings in this study demonstrated that the tested prototype microabrasion paste is extremely harmless, minimally invasive agent, and able to improve the color, shine and chrome values of the teeth.

Enamel crystals of mice susceptible or resistant to dental fluorosis: an AFM study

Objective

This study aimed to assess the overall apatite crystals profile in the enamel matrix of mice susceptible (A/J strain) or resistant (129P3/J strain) to dental fluorosis through analyses by atomic force microscopy (AFM).

Material and Methods

Samples from the enamel matrix in the early stages of secretion and maturation were obtained from the incisors of mice from both strains. All detectable traces of matrix protein were removed from the samples by a sequential extraction procedure. The purified crystals (n=13 per strain) were analyzed qualitatively in the AFM. Surface roughness profile (Ra) was measured.

Results

The mean (±SD) Ra of the crystals of A/J strain (0.58±0.15 nm) was lower than the one found for the 129P3/J strain (0.66±0.21 nm) but the difference did not reach statistical significance (t=1.187, p=0.247). Crystals of the 129P3/J strain (70.42±6.79 nm) were found to be significantly narrower (t=4.013, p=0.0013) than the same parameter measured for the A/J strain (90.42±15.86 nm).

Conclusion

Enamel crystals of the 129P3/J strain are narrower, which is indicative of slower crystal growth and could interfere in the occurrence of dental fluorosis.

Fluoride alters connexin expression in rat incisor pulp

OBJECTIVE

Connexins (Cxs) are important to control growth and cell differentiation of dental tissues. The aim of the present study was to assess the impact of chronic exposure to sodium fluoride (NaF) on Cxs expression and alkaline phosphatase (ALP) activity in dental pulp, and on morphometric parameters of adult rat mandible and incisors.

DESIGN

Three groups of male Wistar rats (22 days-old) were given water containing: (a) 0.3 mg/L (Control), (b) 10 mg/L and (c) 50 mg/L of NaF for eight weeks. Incisor pulp homogenates were prepared for determination of Cx32, Cx43 and Cx45 gene expression, using semi-quantitative RT-PCR, and of ALP activity. Morphometric parameters of mandible and incisors were determined on radiographs.

RESULTS

Cx43 gene expression increased with exposure to NaF in a dose-dependent manner. Cx32 mRNA levels were higher than controls in the 10mg/L NaF group only; Cx45 mRNA levels were lower in groups given 10 and 50mg/L of NaF than in controls. ALP activity was higher in both high-NaF dose groups compared to the control group (p<0.05). Lower incisor diameter was lower in the 50 mg/L NaF than in the control group (p<0.01). None of the mandibular growth parameters were affected by NaF treatment.

CONCLUSION

Our results showed that fluorotic alterations in rat incisor were associated with increased Cx43 expression and ALP activity, as well as with changes in the expression pattern of different Cxs in pulp tissue. The observed changes may have a stimulating effect on dentin mineralization.

Emissions of fine particle fluoride from biomass burning

The burning of biomasses releases fluorine to the atmosphere, representing a major and previously uncharacterized flux of this atmospheric pollutant. Emissions of fine particle (PM2.5) water-soluble fluoride (F-) from biomass burning were evaluated during the fourth Fire Laboratory at Missoula Experiment (FLAME-IV) using scanning electron microscopy energy dispersive X-ray spectroscopy (SEM-EDX) and ion chromatography with conductivity detection. F- was detected in 100% of the PM2.5 emissions from conifers (n=11), 94% of emissions from agricultural residues (n=16), and 36% of the grasses and other perennial plants (n=14). When F- was quantified, it accounted for an average (±standard error) of 0.13±0.02% of PM2.5. F- was not detected in remaining samples (n=15) collected from peat burning, shredded tire combustion, and cook-stove emissions. Emission factors (EF) of F- emitted per kilogram of biomass burned correlated with emissions of PM2.5 and combustion efficiency, and also varied with the type of biomass burned and the geographic location where it was harvested. Based on recent evaluations of global biomass burning, we estimate that biomass burning releases 76 Gg F- yr(-1) to the atmosphere, with upper and lower bounds of 40-150 Gg F- yr(-1). The estimated F- flux from biomass burning is comparable to total fluorine emissions from coal combustion plus other anthropogenic sources. These data demonstrate that biomass burning represents a major source of fluorine to the atmosphere in the form of fine particles, which have potential to undergo long-range transport.

[Methodological discussion about prevalence of the dental fluorosis on dental health surveys]

OBJECTIVE

To analyze the limitations of studying dental fluorosis in cross-sectional studies.

METHODS

Data from the Oral Health of the Brazilian Population (SBBrasil 2003) and the Brazilian Oral Health Survey (SBBrasil 2010) were used. Epidemiological trends for fluorosis in 12-year-old Brazilians, aspects of the reliability of the data as well as the accuracy of the estimates are assessed for these two studies. The distribution of prevalence of fluorosis was carried out according to the domains of the study (state capitals and regions) and the year in which the study took place. The confidence intervals (95%CI) were also shown for simple prevalence (without taking into account level of severity).

RESULTS

The prevalence of dental fluorosis showed considerable variation, between 0% and 61% in 2003 and 0% and 59% in 2010. Inconsistencies were observed in the data in individual terms (for year and for domain) and in the behavior of the trend. Considering the expected prevalence and the data available in the two studies, the minimum sample size should be 1,500 individuals in order to obtain 3.4% and 6.6% confidence intervals, considering the minimum coefficient of variation to be 15%. Given the subjectivity in its classification, examinations for dental fluorosis may show more variation than those for other oral health conditions. The power to establish differences between the domains of the study with the sample of the SBBrasil 2010 is quite limited.

CONCLUSIONS

Based on the 2003 and 2010 studies, it was not possible to analyze patterns of dental fluorosis in Brazil; these data are merely exploratory indicators of the prevalence of dental fluorosis. It was impossible to make comparisons due to different analysis models being used in the two surveys. Investigating dental fluorosis in population-based surveys is not even an economically viable technique, using localized epidemiological studies with a sampling plan would be more suitable [corrected].

Fluoride use in caries prevention in the primary care setting

Dental caries remains the most common chronic disease of childhood in the United States. Caries is a largely preventable condition, and fluoride has proven effectiveness in the prevention of caries. The goals of this clinical report are to clarify the use of available fluoride modalities for caries prevention in the primary care setting and to assist pediatricians in using fluoride to achieve maximum protection against dental caries while minimizing the likelihood of enamel fluorosis.

Color masking of developmental enamel defects: a case series

Developmental defects involving color alteration of enamel frequently compromise the esthetic appearance of the tooth. The resin infiltration technique represents an alternative treatment for color masking of these lesions and uniformization of tooth color. This technique is considered relatively simple and microinvasive, since only a minimal portion of enamel is removed. This article illustrates the color-masking effect with resin infiltration of fluorosis and traumatic hypomineralization lesions with a case series. The final esthetic outcomes demonstrated the ability of the resin infiltrant to mask the color of white developmental defect lesions, resulting in satisfactory clinical esthetic improvements. However, in more severe cases, the color-masking effect was not complete.

The effect of non-fluoride factors on risk of dental fluorosis: evidence from rural populations of the Main Ethiopian Rift

Elevated level of fluoride (F(-)) in drinking water is a well-recognized risk factor of dental fluorosis (DF). While considering optimization of region-specific standards for F(-), it is reasonable, however, to consider how local diet, water sourcing practices, and non-F(-) elements in water may be related to health outcomes. In this study, we hypothesized that non-F(-) elements in groundwater and lifestyle and demographic characteristics may be independent predictors or modifiers of the effects of F(-) on teeth. Dental examinations were conducted among 1094 inhabitants from 399 randomly-selected households of 20 rural communities of the Ziway-Shala lake basin of the Main Ethiopian Rift. DF severity was evaluated using the Thylstrup-Fejerskov Index (TFI). Household surveys were performed and water samples were collected from community water sources. To consider interrelations between the teeth within individual (in terms of DF severity) and between F(-) and non-F(-) elements in groundwater, the statistical methods of regression analysis, mixed models, and principal component analysis were used. About 90% of study participants consumed water from wells with F(-) levels above the WHO recommended standard of 1.5mg/l. More than 62% of the study population had DF. F(-) levels were a major factor associated with DF. Age, sex, and milk consumption (both cow's and breastfed) were also statistically significantly (p<0.05) associated with DF severity; these associations appear both independently and as modifiers of those identified between F(-) concentration and DF severity. Among 35 examined elements in groundwater, Ca, Al, Cu, and Rb were found to be significantly correlated with dental health outcomes among the residents exposed to water with excessive F(-) concentrations. Quantitative estimates obtained in our study can be used to explore new water treatment strategies, water safety and quality regulations, and lifestyle recommendations which may be more appropriate for this highly populated region.

Micromorphology analysis and bond strength of two adhesives to Er,Cr:YSGG laser-prepared vs. bur-prepared fluorosed enamel

Preservation of enamel during composite veneer restorations of fluorosed teeth could be achieved by conservative preparation with Erbium lasers. This study evaluated the effect of fluorosed enamel preparation with Er,Cr:YSGG vs. conventional diamond bur on the micromorphology and bond strength of a self-etch and an etch-and-rinse adhesives. Er,Cr:YSGG laser or diamond bur preparation was performed on the flattened midbuccal surfaces of 70 extracted human premolars with moderate fluorosis (according to Thylstrup and Fejerskov index, TFI = 4-6). Adper Single Bond (SB) with acid etching for 20 or 40 s and Clearfil SE Bond (SEB) alone or with additional etching was applied in four laser groups. The same adhesive procedures were used in three bur groups except for 40 s of etching along with SB. After restoration, microshear bond strength was measured (MPa). Data were analyzed using ANOVA and Tamhane tests (α = 0.05). Six additional specimens were differently prepared and conditioned for scanning electron microscopy evaluation. The highest and lowest bond strengths were obtained for bur-prepared/SB (39.5) and laser-prepared/SEB (16.9), respectively, with a significant difference (P = 0.001). The different adhesive procedures used associated to two adhesives exhibited insignificantly lower bonding in laser-prepared groups compared to bur-prepared ones (P > 0.05), with the exception of additional etching/SEB, which bonded significantly higher to bur-prepared (36.4) than to laser-prepared enamel (18.7, P = 0.04). Morphological analyses revealed a delicate etch pattern with exposed enamel prisms on laser-prepared fluorosed enamel after acid etching and less microretentive pattern after self-etching primer. The etch-and-rinse adhesive was preferred in the laser-prepared fluorosed enamel in terms of bonding performance.

A minimally invasive technique for the management of severely fluorosed teeth: A two-year follow-up

Objective:

Severely fluorosed and heavily discolored teeth that have large enamel defects give rise to esthetic concerns and require permanent treatment. In such cases, restorative techniques such as porcelain or composite laminate veneers or crowns are generally preferred, in which tooth preparation is inevitably required.

Materials and Methods:

This clinical report describes a patient with severely fluorosed teeth who was successfully treated with a minimally invasive technique including enamel microabrasion (6.6% hydrochloric acid slurry with silicon carbide micro-particles, Opalustre, Ultradent Products, Inc., South Jordan, UT, USA) followed by in-office bleaching (38% hydrogen peroxide, Opalescence Boost, Ultradent). Enamel microabrasion was conducted in two visits while three visits were required for in-office bleaching. Patient was followed-up after 2 years.

Result:

A slight staining had occurred during this period, but it was acceptable for patient. No adverse effects were observed.

Conclusions:

The minimally invasive technique including enamel microabrasion and in-office bleaching was efficient and may represent a good alternative to traditional restorative techniques for the management of severely fluorosed teeth.

Asporin and the mineralization process in fluoride-treated rats

Microarray analysis of odontoblastic cells treated with sodium fluoride has identified the asporin gene as a fluoride target. Asporin is a member of the small leucine-rich repeat proteoglycan/protein (SLRP) family that is believed to be important in the mineralization process. In this study, asporin expression and distribution were investigated by systematic analysis of dentin and enamel, with and without fluoride treatment. Specific attention was focused on a major difference between the two mineralized tissues: the presence of a collagenous scaffold in dentin, and its absence in enamel. Normal and fluorotic, continually growing incisors from Wistar rats treated with 2.5 to 7.5 mM sodium fluoride (NaF) were studied by immunochemistry, in situ hybridization, Western blotting, and RT-qPCR. Asporin was continuously expressed in odontoblasts throughout dentin formation as expected. Asporin was also found, for the first time, in dental epithelial cells, particularly in maturation-stage ameloblasts. NaF decreased asporin expression in odontoblasts and enhanced it in ameloblasts, both in vivo and in vitro. The inverse response in the two cell types suggests that the effector, fluoride, is a trigger that elicits a cell-type-specific reaction. Confocal and ultrastructural immunohistochemistry evidenced an association between asporin and type 1 collagen in the pericellular nonmineralized compartments of both bone and dentin. In addition, transmission electron microscopy revealed asporin in the microenvironment of all cells observed. Thus, asporin is produced by collagen-matrix-forming and non-collagen-matrix-forming cells but may have different effects on the mineralization process. A model is proposed that predicts impaired mineral formation associated with the deficiency and excess of asporin.

High fluoride and low pH level have been detected in popular flavoured beverages in Malaysia

OBJECTIVE

In children, excessive ingestion of fluoride from different sources including bottled drinking water and flavoured beverages or soft drinks can lead to the development of dental fluorosis. In addition, the pH level of beverages is important. Low pH can cause dental erosion. In this study we explore the fluoride content and pH level of certain popular beverages available in Malaysian supermarkets and hawkers' stalls.

METHODS

Bottled drinking water and selected popular flavoured packet drinks were purchased from a supermarket and the corresponding flavoured hawkers' drinks, from a hawker's stall in Kuala Lumpur. Fluoride and pH of the beverages were determined using digital fluoride meter and digital pH meter respectively.

RESULTS

It was found that fluoride content and pH level vary among the beverages. The mean fluoride content in both packet and hawkers' drinks (7.64±1.88 mg/L, 7.51±1.60 mg/L, respectively) was approximately 7 times higher than the bottled drinking water (1.05±0.35 mg/L). Among the beverages, the tea packet drink was found to contain the highest amount of fluoride (13.02±0.23 mg/L). The mean pH of bottled-drinking water was near neutral (6.96±0.17), but acidic for both supermarket (4.78.00±0.49) and hawkers' drinks (5.73±0.24). The lychee packet drink had the lowest pH level (2.97±0.03).

CONCLUSIONS

Due to the wide variation of the fluoride content and pH level of the drinks tested in this study, it is recommended that steps should be taken to control the fluoride concentration and pH level in beverages if dental fluorosis and erosion are to be prevented.

Stress response pathways in ameloblasts: implications for amelogenesis and dental fluorosis

Human enamel development of the permanent teeth takes place during childhood and stresses encountered during this period can have lasting effects on the appearance and structural integrity of the enamel. One of the most common examples of this is the development of dental fluorosis after childhood exposure to excess fluoride, an elemental agent used to increase enamel hardness and prevent dental caries. Currently the molecular mechanism responsible for dental fluorosis remains unknown; however, recent work suggests dental fluorosis may be the result of activated stress response pathways in ameloblasts during the development of permanent teeth. Using fluorosis as an example, the role of stress response pathways during enamel maturation is discussed.

Barrier formation: potential molecular mechanism of enamel fluorosis

Enamel fluorosis is an irreversible structural enamel defect following exposure to supraoptimal levels of fluoride during amelogenesis. We hypothesized that fluorosis is associated with excess release of protons during formation of hypermineralized lines in the mineralizing enamel matrix. We tested this concept by analyzing fluorotic enamel defects in wild-type mice and mice deficient in anion exchanger-2a,b (Ae2a,b), a transmembrane protein in maturation ameloblasts that exchanges extracellular Cl(-) for bicarbonate. Defects were more pronounced in fluorotic Ae2a,b (-/-) mice than in fluorotic heterozygous or wild-type mice. Phenotypes included a hypermineralized surface, extensive subsurface hypomineralization, and multiple hypermineralized lines in deeper enamel. Mineral content decreased in all fluoride-exposed and Ae2a,b(-/-) mice and was strongly correlated with Cl(-). Exposure of enamel surfaces underlying maturation-stage ameloblasts to pH indicator dyes suggested the presence of diffusion barriers in fluorotic enamel. These results support the concept that fluoride stimulates hypermineralization at the mineralization front. This causes increased release of protons, which ameloblasts respond to by secreting more bicarbonates at the expense of Cl(-) levels in enamel. The fluoride-induced hypermineralized lines may form barriers that impede diffusion of proteins and mineral ions into the subsurface layers, thereby delaying biomineralization and causing retention of enamel matrix proteins.

Lines of evidence-incremental markings in molar enamel of Soay sheep as revealed by a fluorochrome labeling and backscattered electron imaging study

We studied the structural characteristics and periodicities of regular incremental markings in sheep enamel using fluorochrome injections for vital labeling of forming enamel and backscattered electron imaging in the scanning electron microscope. Microscopic analysis of mandibular first molars revealed the presence of incremental markings with a daily periodicity (laminations) that indicated successive positions of the forming front of interprismatic enamel. In addition to the laminations, incremental markings with a sub-daily periodicity were discernible both in interprismatic enamel and in enamel prisms. Five sub-daily increments were present between two consecutive laminations. Backscattered electron imaging revealed that each sub-daily growth increment consisted of a broader and more highly mineralized band and a narrower and less mineralized band (line). The sub-daily markings in the prisms of sheep enamel morphologically resembled the (daily) prisms cross striations seen in primate enamel. Incremental markings with a supra-daily periodicity were not observed in sheep enamel. Based on the periodicity of the incremental markings, maximum mean daily apposition rates of 17.0 µm in buccal enamel and of 13.4 µm in lingual enamel were recorded. Enamel extension rates were also high, with maximum means of 180 µm/day and 217 µm/day in upper crown areas of buccal and lingual enamel, respectively. Values in more cervical crown portions were markedly lower. Our results are in accordance with previous findings in other ungulate species. Using the incremental markings present in primate enamel as a reference could result in a misinterpretation of the incremental markings in ungulate enamel. Thus, the sub-daily growth increments in the prisms of ungulate enamel might be mistaken as prism cross striations with a daily periodicity, and the laminations misidentified as striae of Retzius with a supra-daily periodicity. This would lead to a considerable overestimation of crown formation times in ungulate teeth.

Parenteral monofluorophosphate (MFP) is a more potent inducer of enamel fluorotic defects in neonatal hamster molars than sodium fluoride

Supra-optimal intake of sodium fluoride (NaF) during early childhood results in formation of irreversible enamel defects. Monofluorophosphate (MFP) was considered as less toxic than NaF but equally cariostatic. We compared the potency of MFP and NaF to induce pre-eruptive sub-ameloblastic cysts and post-eruptive white spots and pits in developing hamster enamel. Hamster pups were injected subcutaneously with either NaF or MFP in equimolar doses of either 9 mg or 18 mg F/kg body weight. At 9 mg F/kg, MFP induced more but smaller sub-ameloblastic cysts with a collective cyst volume twice as large as that induced by NaF. Eight days after F injection, all F-injected groups had formed 4-6 white spots per molar, with an additional 2 pits per molar in the low MFP group. Twenty-eight days after injection, most white spots had turned into pits (5-6 per molar) and only the high MFP group still contained 2 white spots per molar. We conclude that parenterally applied MFP is more potent in inducing enamel defects than NaF. Most white spots formed turn into pits by functional use of the dentition. The higher potency of parenteral MFP may be associated with sustained elevated F levels in the enamel organ by enzymatic hydrolysis of MFP by alkaline phosphatase activity.

Seven years of external control of fluoride levels in the public water supply in Bauru, São Paulo, Brazil

Fluoridation of the public water supplies is recognized as among the top ten public health achievements of the twentieth century. However, the positive aspects of this measure depend on the maintenance of fluoride concentrations within adequate levels.

Assessment of groundwater quality in a region of endemic fluorosis in the northeast of Brazil

The aim of this study was to estimate the risk for caries and fluorosis in a desertification area, applying the calcium/fluoride concentration ratio of underground water and the quality of water in a selected geographical region. This study was performed in the municipality of São João do Rio do Peixe, located in the tropical semiarid lands of Brazil. A total of 111 groundwater samples were collected. Fluoride concentration varied from 0.11 to 9.33 mg/L. Thirty percent of all samples analyzed showed values above 1.5 mg/L, while 64 % were above the ideal limit of 0.7 mg/L. Mean calcium concentration was 47.6 mg/L, and 14.4 % of all samples presented values above the WHO acceptable limits. The proportional value of calcium/fluoride in water showed that only 12 % of the samples were suitable for dental caries prevention with minimal risk for dental fluorosis. Mapping of the fluoride distribution indicated that approximately 2,465 people could be affected by dental fluorosis and 1,057 people might be affected by skeletal fluorosis. It can be concluded that, in addition to fluoride, many water parameters were not suitable for the drinking water. Mapping out calcium/fluoride ratio may indicate areas of water suitability for caries control, whereas the fluoride concentration solely can indicate the areas with the risk for fluorosis. This approach can be relevant for health authorities for identifying communities where dental caries or dental fluorosis is prevalent.

Developmental enamel defects in children prenatally exposed to anti-epileptic drugs

Objective

Some anti-epileptic drugs (AED) have well-known teratogenic effects. The aim of the present study was to elucidate the effect of prenatal exposure to AED and the risk of enamel defects in the primary and permanent dentition.

Methods

A total of 38 exposed and 129 non-exposed children, 6–10 years of age, were recruited from the Aarhus Birth Cohort and the Department of Neurology, Viborg Regional Hospital, Denmark. Medication during pregnancy was confirmed by the Danish Prescription Database. All children had their teeth examined and outcomes in terms of enamel opacities and enamel hypoplasia were recorded.

Results

Children prenatally exposed to AED have an increased prevalence of enamel hypoplasia (11% vs. 4%, odds ratio (OR) = 3.6 [95% confidence interval (CI): 0.9 to 15.4]), diffuse opacities (18% vs. 7%, OR = 3.0; [95% CI: 1.0 to 8.7, p<0.05]), and numerous (>3) white opacities (18% vs. 10%, OR = 2.2; [95% CI: 0.8 to 6.1]) in the primary dentition. In the permanent dentition, an increased risk of numerous (>3) white opacities (34% vs. 12%, OR = 3.3; [95% CI: 1.3 to 8.4]) was found.

Conclusions

The present study shows that children prenatally exposed to AED have an increased risk of developing numerous teeth with white opacities in their primary and permanent dentition. In addition, they also have an increased risk of developing diffuse opacities and enamel hypoplasia in their primary teeth.

Use of clinical bleaching with 35% hydrogen peroxide in esthetic improvement of fluorotic human incisors in vivo

AIM

The aim of the study was to evaluate esthetic improvement with the use of 35% hydrogen peroxide clinical bleaching as related to the different grades of enamel fluorosis in vivo and to study adverse effect of clinical bleaching with 35% hydrogen peroxide on teeth and gingiva.

MATERIALS AND METHODS

A total of 60 children of different grades of fluorosis were included in the study. With 35% hydrogen peroxide-based dual activated bleaching system, in-office vital teeth bleaching was carried out for each subject. Clinical evaluation for improvement in esthetics, effect on teeth and gingiva were performed for each child during preoperative, immediate postoperative and later 6 months postoperative period. For evaluation and comparison, all the collected data were subjected to statistical analysis.

RESULTS

Although in all the subjects, partial shade relapse was seen over a period of time, good homogeneous and esthetic results were seen in very mild and mild cases. A total of 35% hydrogen peroxide in-office bleaching has no adverse effect on teeth and gingiva.

CONCLUSION

Comparing all the three groups who participated in the study, 35% hydrogen peroxide in-office bleaching seems to be very effective in very mild and mild forms of fluorosis.

CLINICAL SIGNIFICANCE

In very mild and mild forms of fluorosis, in-office vital tooth bleaching with 35% hydrogen peroxide is the most conservative and effective approach in esthetic improvement.