Developmental Defects of Enamel.

Amelogenesis, the intricate process governing enamel formation, is susceptible to a range of genetic, systemic, and environmental influences, resulting in distinct developmental defects of enamel (DDE), such as molar incisor hypomineralisation (MIH), enamel hypoplasia, dental fluorosis, and amelogenesis imperfecta (AI). This chapter aims to provide a comprehensive overview of amelogenesis and DDE, establishing correlations between histopathological findings and clinical manifestations. MIH, a qualitative enamel defect, occurs during the mineralisation and maturation phases, affecting first permanent molars and eventually incisors. Diagnostic challenges in MIH arise from the disorder's unique features, including variable tooth involvement and severity, influenced by a complex interplay of genetic, systemic, and environmental factors. Enamel hypoplasia, a quantitative defect, manifests in any tooth during enamel matrix secretion. Etiological factors include local, systemic, environmental, and genetic influences, with variable enamel matrix abnormalities depending on the stage of amelogenesis when aggression occurred. Dental fluorosis, a toxicological concern from chronic and excessive fluoride exposure, affects ameloblasts and compromises crystal growth of the homologous teeth during enamel development. Lastly, AI, an inherited condition, encompasses diverse phenotypes in enamel development. AI phenotypes, whether hypoplastic or hypomineralised, entail mutations in genes, such as AMELX, ENAM, MMP20, KLK4, WDR72, FAM83H, C4ORF26, amelotin, GPR68, and ACPT. Diagnosing AI involves considering family history and clinical observation. In conclusion, navigating the intricacies of amelogenesis, from MIH to AI, underscores the critical importance of accurate diagnosis for proper clinical management of DDE.

3D scanning electron microscopy applied to surface characterization of fluorosed dental enamel.

The enamel surfaces of fluorotic teeth were studied by scanning electron stereomicroscopy. Different whitening treatments were applied to 25 pieces to remove stains caused by fluorosis and their surfaces were characterized by stereomicroscopy in order to obtain functional and amplitude parameters. The topographic features resulting for each treatment were determined through these parameters. The results obtained show that the 3D reconstruction achieved from the SEM stereo pairs is a valuable potential alternative for the surface characterization of this kind of samples.

Severe dental fluorosis in juvenile deer linked to a recent volcanic eruption in Patagonia.

The Puyehue-Cordon Caulle volcanic eruption deposited large amounts of tephra (ashes) on about 36 million ha of Argentina in June of 2011. Tephra was considered chemically innoxious based on water leachates, surface water fluoride levels were determined to be safe, and livestock losses were attributable to inanition and excessive tooth wear. To evaluate effects on wild ungulates, we sampled wild red deer (Cervus elaphus) at 100 km from the volcano in September-November 2012. We show that tephra caused severe dental fluorosis, with bone fluoride levels up to 5,175 ppm. Among subadults, tephra caused pathologic development of newly emerging teeth typical of fluorosis, including enamel hypoplasia, breakages, pitting, mottling, and extremely rapid ablation of entire crowns down to underlying pulp cavities. The loss of teeth functionality affected physical condition, and none of the subadults was able to conceive. Susceptibility to fluorosis among these herbivores likely resides in ruminant food processing: 1) mastication and tephra size reduction, 2) thorough and repeated mixing with alkaline saliva, 3) water-soluble extraction in the rumen, and 4) extraction in the acidic abomasum. Although initial analyses of water and tephra were interpreted not to present a concern, ruminants as a major component of this ecosystem are shown to be highly susceptible to fluorosis, with average bone level increasing over 38-fold during the first 15.5 mo of exposure to tephra. This is the first report of fluorosis in wild ungulates from a volcanic eruption. The described impact will reverberate through several aspects of the ecology of the deer, including effects on population dynamics, morbidity, predation susceptibility, and other components of the ecosystem such as scavenger and plant communities. We anticipate further impact on livestock production systems, yet until now, existence of fluorosis had not been recognized.

Fluorosis and dental caries in Mexican schoolchildren residing in areas with different water fluoride concentrations and receiving fluoridated salt.

OBJECTIVE: To explore the association between fluoride in drinking water and the prevalence and severity of fluorosis and dental caries in children living in communities receiving fluoridated salt. MATERIAL AND METHODS: Participants were schoolchildren (n = 457) living in two rural areas of the State of Morelos, Mexico, where the water fluoride concentration was 0.70 or 1.50 ppm. Dental caries status was assessed using Pitts' criteria. Lesions that were classified as D3 (decayed) were identified to determine the decayed, missing, and filled teeth index (D3MFT). Fluorosis was assessed using the Thylstrup-Fejerskov Index (TFI). Information regarding drinking water source and oral hygiene practices (tooth brushing frequency, dentifrice use, and oral hygiene index) was obtained. RESULTS: The prevalence of fluorosis (TFI ≥1) in communities with 0.70 and 1.50 ppm water fluoride was 39.4 and 60.5% (p = 0.014), respectively, while the prevalence of more severe forms (TFI ≥4) was 7.9 and 25.5% (p < 0.001), respectively. The mean D3MFT was 0.49 (±1.01) in the 0.70 ppm community and 0.61 (±1.47) in the 1.50 ppm community (p = 0.349). A logistic regression model for caries (D3 >1) showed that higher fluorosis categories (TFI 5-6 OR = 6.81, p = 0.001) were associated with higher caries experience, adjusted by age, number of teeth present, tooth brushing frequency, bottled water use, and natural water fluoride concentration. CONCLUSIONS: The prevalence of fluorosis was associated with the water fluoride concentration. Fluorosis at moderate and severe levels was associated with a higher prevalence of dental caries, compared with lesser degrees of fluorosis. The impact of dental fluorosis should be considered in dental public health programs.

Analysis of the molecular structure of human enamel with fluorosis using micro-Raman spectroscopy.

The aim of this study was to analyze the molecular structure of enamel with fluorosis using micro-Raman spectroscopy and compare it with that of healthy enamel. Eighty extracted human molars were classified into four fluorosis groups according to the Thylstrup-Fejerskov Index (TFI) [TFI: 0, Healthy enamel; 1-3, mild; 4-5, moderate; 6-9, severe fluorosis]. All samples were analyzed by micro-Raman spectroscopy. The integral areas of ν(1) (960 cm(-1)) phosphate peak as well as B-type carbonate peak (1070 cm(-1)) were obtained to analyze structural differences among the specimens. Although the differences were not statistically significant (P > 0.05), the mean of integral areas of ν(1) phosphate peak among groups indicated greater mineralization in the severe fluorosis group. However, there were statistically significant differences in the intensities, and the integral areas of B-type carbonate peak among groups (P < 0.05). Therefore, mineralization of the carbonate peak at 1070 cm(-1) decreased significantly in fluorotic groups, suggesting that carbonate ions are easily dissolved in the presence of fluoride. Although structurally fluorotic teeth are not more susceptible to dental caries, serious alteration in its surface topography may cause retention of bacterial plaque and formation of enamel caries. Micro-Raman spectroscopy is a useful tool for analyzing the molecular structure of healthy and fluorotic human enamel.

Prevalencia de fluorosis dental y anomalías de desarrollo del esmalte en los niños de la Escuela Bolivariana "Juan Ruiz Fajardo" del Estado Mérida, Venezuela / Prevalence of dental fluorosis anomalie enamel developmente in children Escuela Bolivariana \"Juan Ruiz Fajardo\" Estado Mérida, Venezuela

Determinar la frecuencia de Fluorosis Dental, Opacidades e Hipoplasias del Esmalte, en niños en edad escolar entre 5 y 14 años, de la Escuela Bolivariana "Juan Ruiz Fajardo", del Estado Mérida, Venezuela. Se realizó un estudio descriptivo transversal. La población estuvo constituida por 445 niños entre 5 y 14 años de edad, de la Escuela Bolivariana "Juan Ruiz Fajardo" del Estado Mérida, Venezuela. Se estudiaron las variables fluorosis dental, opacidades e hipoplasia del esmalte, aplicando el Índice de Dean y el Índice de Desarrollo de Defectos del Esmalte (DDE) modificado, según metodología descrita por la Organización Mundial de la Salud (OMS). El 80,7% de la población estudiada no presentó fluorosis dental, en contraste con el 19,3% que si presentó, a predominio de fluorosis dudosa en un 9,9% y fluorosis muy leve en un 6,3%. El 76,2% de la población no presentó alteraciones en el desarrollo del esmalte, en contraste con un 12,4% y 3,6% que presentó opacidades delimitadas y difusas respectivamente. Se evidencia que el mayor porcentaje de la población estudiada no presenta fluorosis dental ni alteraciones en el desarrollo del esmalte. Sólo un pequeño porcentaje presentó fluorosis dudosa y muy leve, además de opacidades delimitadas y difusas

To determine the frequency of dental fluorosis, enamel opacities and hypoplasia in 5-14-year-old-school children from the Bolivariana School "Juan Ruiz Fajardo" in Mérida, Venezuela. The study was descriptive and transversal. Participants were 445 children aged between 5 y 14 years. Children were attending the Bolivariana School "Juan Ruiz Fajardo" in Mérida, Venezuela. The variables dental fluorosis, enamel opacities and hypoplasia were considered by using Dean's Fluorosis Index and the Enamel Defect Index (EDI) Modified, according to WHO's methodology. 80.7% of the studied population did not show signs of dental fluorosis, opposite to 19.3% that presented fluorosis, with a higher score for doubtful fluorosis equal to 9.9%. In relation to alterations in enamel 76.2% of the participants did not present alterations in contrast to 12.4% and 3.6% who presented delimitated and diffuse opacities, respectively. It was evident that the higher percentage of the participants did not show either dental fluorosis or alterations in enamel development. Just a small percentage of children presented doubtful and very mild fluorosis as well as both delimited and diffuse opacities

Exposure to lead exacerbates dental fluorosis.

AIM: Our aim was to test the hypothesis that co-exposure to lead and fluoride alter the severity of enamel fluorosis. MATERIALS AND METHODS: Wistar rats were allocated in four groups: control, and 3 groups that received water containing 100 ppm of fluoride (F), 30 ppm of lead (Pb), or 100 ppm of F and 30 ppm of Pb (F+Pb) from the beginning of gestation. Enamel analysis and F and Pb determinations in enamel, dentine, and bone were performed in 81-day-old animals. Fluorosis was quantified using a new fluorosis index based on the identification of incisor enamel defects (white bands and white islets, representing hypomineralization, and cavities) weighted according to their severity and quantity. Hypomineralization was validated histopathologically by polarizing microscopy and microradiography. Scores were given by two blinded calibrated examiners (intra and interexaminer kappa values were 0.8 and 0.86, respectively). RESULTS: The control and the Pb groups presented normal enamel. The F+Pb group presented more severe enamel defects compared with the F group (P<0.0001). CONCLUSIONS: This study shows that lead exacerbates dental fluorosis in rodents, suggesting that co-exposure to lead may affect the degree of fluorosis.

Fluoride effect on the secretory-stage enamel organic extracellular matrix of mice.

The formation of an ordered enamel organic extracellular matrix (EOECM) seems to be a crucial step for the proper formation of the enamel mineral phase. The ordered supramolecular structure of the EOECM in the secretory stage can be analyzed using polarizing microscopy, as it is strongly birefringent. Excessive fluoride (F) ingestion during tooth development can cause enamel fluorosis, leading to increased porosity in mature enamel. We analyzed the effects of F on the birefringence of the EOECM in the A/J, CBA, and DBA/2 strains of mice given 0, 11.25, and 45 ppm of fluoride in drinking water. In the CBA and DBA/2 strains, the 11.25 and 45 ppmF groups presented a significant decrease in optical retardation (OR) when compared with the respective 0 (CBA 11.25 ppmF p = 0.0056 and 45 ppmF p < 0.0001; DBA/2 11.25 and 45 ppmF p < 0.05). ORs in A/J 0 ppmF were significantly higher than in 45 (p < 0.0001). The enamel of the A/J strain was more severely affected by fluoride than it was in the other strains of mice and exhibited the lowest levels of fluoride in plasma, whereas its normal secretory enamel presented a significantly higher protein absorbance than it did in CBA and DBA mice (p = 0.0099 and p = 0.0025, respectively). The results showed that experimental fluorosis can alter the supramolecular organization of EOECM in the secretory stage of amelogenesis and that the susceptibility to dental fluorosis seems to be influenced by the inherent characteristics of the developing enamel.

Influence of genetic background on fluoride metabolism in mice.

A/J and 129P3/J mouse strains have different susceptibilities to dental fluorosis, due to their genetic backgrounds. This study tested whether these differences are due to variations in water intake and/or F metabolism. A/J (susceptible to dental fluorosis) and 129P3/J mice (resistant) received drinking water containing 0, 10, or 50 ppm F. Weekly F intake, excretion and retention, and terminal plasma and femur F levels were determined. Dental fluorosis was evaluated clinically and by quantitative fluorescence (QF). Data were tested by two-way ANOVA. Although F intakes by the strains were similar, excretion by A/J mice was significantly higher due to greater urinary F excretion, which resulted in lower plasma and femur F levels. Compared with 129P3/J mice given 50 ppm F, significantly higher QF scores were recorded for A/J mice. In conclusion, these strains differ with respect to several features of F metabolism, and amelogenesis in the 129P3/J strain seems to be unaffected by high F exposure.

Morphological characterization of rat incisor fluorotic lesions.

The morphological characterization of fluorotic rat incisor enamel was carried out. Experimental adult animals received drinking water with 45 mg F/L of fluoride, and the control group received distilled water. Fluoride concentrations found in the control and fluorosis groups were 0.04 and 0.09 microg/mL (plasma), 0.26 and 0.66 microg/mg (whole tibia), and 0.24 and 2.3 microg/mg (tibia surface), with P < or = 0.001 for all comparisons between the groups. A succession of white and pigmented bands was observed in the fluorotic rat incisors. Under polarizing light microscopy, cross-sections of superficial areas corresponding to the white bands (from the surface to approximately 20 microm) showed high positive birefringence. These fluorotic lesions also exhibited the lowest resistance to superficial acid etching. No morphological differences in inner enamel were seen under scanning electron microscopy. In fluorotic enamel, only the surface layer related to the white areas presented lower birefringence compared with the enamel of control teeth and the surface layer of the pigmented areas (normal ones) of fluorotic teeth. In conclusion, the white bands of fluorotic rat enamel represent hypomineralized superficial areas and are not subsurface lesions. The detailed description of these lesions is important to understand dental fluorosis.

Reexamination of caries and fluorosis experience of children in an area of Jamaica with relatively high fluorosis prevalence.

The aim of this cross-sectional study was to reexamine in 2006 caries and fluorosis experience among 5- to 6- and 11- to 12-year-olds (n = 789) in St. Elizabeth, Jamaica, an area found to have a high prevalence of dental fluorosis in 1999. Mean (+/- SD) dmft/DMFT scores were 2.4 +/- 3.1 (n = 275) and 2.2 +/- 2.3 (n = 133), fluorosis prevalence (tooth surface index of dental fluorosis >0) of upper central incisors was 67% (n = 109) and 39% (n = 132) among 6- and 12-year-olds, respectively. Results indicate slightly reduced caries experience for 6-year-olds compared to 1999. Fluorosis prevalence was high particularly in 6-year-olds. Thus, risks and benefits from use of fluorides from multiple sources should be monitored carefully.

Dental fluorosis prevalence and severity using Dean's index based on six teeth and on 28 teeth.

To contrast the sensitivity, specificity, and positive-negative predictive values between dental fluorosis prevalence scored on 28 (DF28) and on six permanent teeth (DF6), we undertook a cross-sectional study on 1,538 adolescents (12 and 15 years old) residing in Hidalgo State, Mexico, a naturally fluoridated (>0.7 ppm) area at an elevated altitude (>2,500 m above sea level). Dental fluorosis was scored using Deans modified index. Using the scores obtained for all teeth present (DF28) as a gold standard, we calculated the sensitivity, specificity, positive-negative predictive values, and receiver operating characteristic and concordance index pertaining to the scores based on six teeth (upper incisors and canines). DF28 fluorosis prevalence was 81.7%; based on DF6, it was 58.7% (23% difference). Among 12 year olds, the difference between DF28 and DF6 was 20.1% (84.5 vs. 64.4%); among 15 year olds, it was 25.4% (79.4 vs. 54%). Among girls, it was 23.2% (81.1 vs. 57.9%) and among boys, 22.8% (82.2 vs. 59.4%). The fluorosis community indices were 1.75 (DF28) and 1.11 (DF6). All positive predictive values reached 100% while negative predictive values were below 45%. Concordance between DF28 and DF6 was 53.9%, and kappa coefficient was 0.40. Partial scoring of fluorosis based on esthetically important permanent teeth underestimated prevalence, compared to full-mouth scoring. The decision to use an abridged Dean's index protocol must take into account the number of teeth examined, and which specific teeth are examined, to appraise the benefit of reduced data collection effort against possible information loss.

Dentin in severe fluorosis: a quantitative histochemical study.

Dentin responds to different alterations in the enamel with hypermineralization, and is a biomarker of fluoride exposure. We hypothesized that severe fluorosis would lead to hypermineralization of the dentin when the enamel was severely affected. We used scanning electron microscopy and quantitative electron-probe microanalysis to compare dentin and enamel from healthy and fluorotic teeth. The dentin in fluorotic teeth was characterized by a highly mineralized sclerotic pattern, in comparison with control teeth (p < 0.001) and fluorotic enamel lesions (p < 0.001). Enamel near the lesions showed hypercalcification in comparison with dentin (p < 0.001). In response to the effects of severe fluorosis in the enamel, the dentin showed hypermineralization, as found in other enamel disorders. The hypermineralization response of the dentin in our samples suggests that the mechanism of the response should be taken into account in dental caries and other dental disorders associated with severe fluorosis.

Fluoride's effect on human dentin ultrasound velocity (elastic modulus) and tubule size.

Despite fluoride (F) use in caries prevention, not much is known about its effects on tooth quality. This study evaluated the effect of tooth F concentration ([F]) on selected dentin structural and mechanical properties. Third molars (n = 136) from Toronto, which has 1 part per million (p.p.m.) water [F], Montreal (0.2 p.p.m. water [F]), and Fortaleza (Brazil) (0.7 p.p.m. water [F]), were analyzed for [F], dental fluorosis (DF) severity, ultrasound velocity, and dentin tubule size and density. The enamel [F] was found to vary between 32 and 940 p.p.m., the dentin [F] was found to vary between 110 and 860 p.p.m., while the DF severity varied between TF0 and TF4. The enamel [F] showed no correlation with dentin [F], DF severity, ultrasound velocity, dentin tubule size or density. The dentin [F] correlated with DF severity, dentin tubule size, and ultrasound velocity. DF severity showed a correlation with dentin [F] and ultrasound velocity. It was concluded that dentin [F] is an indicator of dentin structural properties (dentin tubule size and ultrasound velocity), while DF severity is an indicator of dentin mechanical properties (ultrasound velocity).

Fluoride content of several breakfast cereals and snacks found in Brazil / Conteúdo de flúor em diversos cereais matinais e salgadinhos encontrados no Brasil

Cereais matinais e salgadinhos são guloseimas altamente apreciadas pelas crianças, e a possibilidade de conterem quantidades substanciais de flúor, associada ao seu indiscriminado consumo, pode torná-los importantes contribuintes para a ingestão diária total de flúor. O objetivo deste estudo foi analisar o conteúdo de flúor em diversos cereais matinais (A) e salgadinhos (B) adquiridos no Brasil. As análises foram feitas após difusão facilitada por HMDS (Taves), usando o eletrodo íon específico (9609). As concentrações médias de flúor SD (amplitude, unidade g F/g) foram: A= 0,76 0,60 (0,08-1,86, n=15) e B= 0,32 0,09 (0,22-0,55, n=18). Nossos resultados sugerem que a quantidade de flúor presente em alguns produtos pode contribuir significantemente com a ingestão diária total de flúor. Os rótulos dos produtos deveriam informar seu conteúdo de flúor para prevenir fluorose no período de risco.

Esthetic improvement following enamel microabrasion on fluorotic teeth: a case report.

Enamel microabrasion is a proven method of removing intrinsic and superficial defects from teeth, establishing esthetics with minimal loss of dental enamel. This article reports one case in which two different microabrasion techniques were used to remove fluorotic stains from teeth.

Mecanismos biológicos e influência de fatores ambientais na fluorose dentária e a participaçäo do flúor na prevençäo da cárie: revisäo de literatura / Biological mechanisms and influence of environmental factors in the dental fluorosis. The role of fluoride in the caries prevention: a literature review

O flúor tem uma importante participaçäo na prevençäo da cárie dentária, estando disponível principalmente na água de abastecimento. Este íon tem sido associado com a inibiçäo da desmineralizaçäo e a aceleraçäo da remineralizaçäo durante o processo carioso. A presença constante do flúor nos fluídos bucais constitui o principal fator na prevençäo da cárie. Além disso, tem-se demonstrado que o flúor na placa bacteriana pode inibir a produçäo de ácidos pelas bactérias cariogênicas. Entretanto, fluorose dentária pode ocorrer se as concentraçöes de flúor forem excessivas no interior ou nas proximidades do esmalte em formaçäo, durante sua fase de desenvolvimento pré-eruptiva. A fluorose caracteriza-se pelo aumento da porosidade na superfície e subsuperfície do esmalte, resultando em esmalte com aparência opaca. Os efeitos tóxicos do flúor sobre o esmalte em desenvolvimento estäo associados com sua influência tanto sobre os ameloblastos, como sobre o estágio de maturaçäo da formaçäo do esmalte. No momento da prescriçäo de terapia com flúor, os profissionais devem ter conhecimento da exposiçäo total do paciente ao flúor, bem como dos fatores ambientais que podem influenciar a sua absorçäo e aumentar a incidência e gravidade da fluorose dentária. O objetivo desta revisäo é discutir os mecanismos biológicos e a influência dos fatores ambientais na fluorose dentária. A participaçäo do flúor na prevençäo da cárie também será discutida, abordando a desmineralizaçäo e remineralizaçäo dentária e seu efeito inibitório sobre a placa bacteriana

Prevalencia e intensidad de fluorosis dental en escolares de 10-13 años de edad en San Carlos y Santa Bárbara de Zulia, Venezuela / Prevalence and intensity of dental fluorosis in 10-13 year-old schoolchildren from San Carlos and Santa Barbara of Zulia, Venezuela

San Carlos y Santa Bárbara de Zulia son poblaciones que por años han padecido de aparente fluorosis dental, lo que se considera un problema de salud pública. Con el propósito de conocer la prevalencia e intensidad de fluorosis dental, así como su asociación con la procedencia del agua de consumo, se realizó un estudio epidemiológico transversal en una muestra de 500 niños en edades comprendidas entre los 10 y 13 años. Dicha muestra fue seleccionada de acuerdo al lugar de residencia en áreas urbanas y periurbanas de estas dos poblaciones. De un total de 5 escuelas y 10 escuelas ubicadas en San Carlos y Santa Bárbara del Zulia, respectivamente, se seleccionaron en forma aleatoria 2 escuelas de cada una de las dos áreas. La recolección de los datos fue realizada por un odontólogo previamente entrenado y calibrado, quien utilizó los criterios del índice de Dean para diagnosticar y medir la intensidad de fluorosis dental. También se tomaron muestras del agua de consumo de diferentes procedencias, con el fin de conocer su contenido en fluoruro. Se realizó el análisis descriptivo de todas las variables, y fueron comparadas la razón de proporcionalidad (odds ratio) total y estratificada entre las proporciones de fluorosis o no fluorosis para la población servida por agua de acueducto y para la población cuyas aguas provienen de pozos. El análisis de los datos revela que existe una elevada prevalencia de fuorosis representada en un 98.6 por ciento. La asociación entre fluorosis y procedencia del agua de consumo fue significativa (razón de proporcionalidad 26.1) 59.8 por ciento del total de la muestra presentó fluorosis moderada