The severity of dental fluorosis in children exposed to water with a high fluoride content for various periods of time

Clinical changes in the severity of dental fluorosis: a longitudinal evaluation

BACKGROUND

Dental fluorosis (DF) has been one of the most prevalent pediatric dental conditions associated with aesthetic concern and treatment needs. This study aimed to identify the longitudinal clinical change in the severity of DF in 8-12-year-old children and its association with gender, age, severity, and tooth type.

METHODS

This observational study assessed the dental aspects of the 92 Colombian children in 2015 (mean age at beginning 9.71 years ± 1.23) and 2018 (mean age 13.69 years ± 1.41), from an area with high DF prevalence. DF was recorded in all permanent teeth by two calibrated examiners using the Thylstrup and Fejerskov Index (TFI). DF severity change (maximum-TFI-score) was analyzed with descriptive analysis at the tooth level. Associated factors were evaluated with the generalized linear model, binomial family, and logarithmic link function.

RESULTS

TFI scores ranged between 1 (very mild) to 6 (severe), being score 2 (41.7%) the most prevalent. After three years, 29.6% of the teeth presented score reduction, 24.1%, increased and 46.3% did not change; the significant association was related to increasing of the basal TFI = 1 score (44.2%) (RR = 9.7; 95% CI 1.7-56.5; p = 0.01) and with canines, premolars and second-permanent-molars teeth group (RR = 3.3; 95% CI 1.9-5.6; p = 0.005).

CONCLUSION

The present study based on clinical features about DF confirms the dynamic post-eruptive nature of this condition. After three years of follow-up, a considerable proportion of the teeth changed to a higher score. Furthermore, the canines, premolars, and second-permanent-molars showed a higher incidence of an increase in severity of TFI score.

The effects of 45S5 bioactive glass and Er:YAG Laser on the microtensile bond strength of fluorosed teeth

This vitro study aimed to evaluate the effects of 45S5 bioactive glass (BAG) and Er:YAG laser as desensitization treatments on the microtensile bond strength (MTBS) of fluorosed teeth. The 120 noncarious fluorosis were to obtain superficial dentin, being classified into four groups according to the Thylstrup and Fejerskov Index (TFI). Specimens from each group were randomly divided into five subgroups. After fluorosed teeth hypersensitivity models were established, the following pretreatments were applied on dentine surface: Subgroup 1: deionized water (Control); Subgroup 2: BAG; Subgroup 3: Er:YAG laser; Subgroup 4: BAG + Er:YAG laser, and Subgroup 5: Er:YAG laser + BAG. One sample was randomly selected from each subgroup for scanning electron microscope (SEM). The remaining samples were bonded with composite resin by Adper Single Bond 2 adhesive. Then water bath at 37°C for 24 hr. After 5,000 thermocycling, MTBS was tested and fracture mode was analyzed. The difference of MTBS between BAG group and Control group was found statistically significant (p < .05) in fluorosis. The Er:YAG laser + BAG group showed lowest MTBS values in fluorosis. In conclusion, the pretreatment of BAG might be beneficial to the adhesive of fluorosed teeth. Er:YAG laser desensitization alone or using BAG first and then Er:YAG laser desensitization might not affect the adhesive of fluorosed teeth, while Er:YAG laser desensitization followed by the pretreatment of BAG would be not conducive to the adhesive of fluorosed teeth.

The relationships between fluoride intake levels and fluorosis of late-erupting permanent teeth

OBJECTIVES

To examine the relationships between fluoride intake levels and fluorosis of late-erupting permanent teeth.

METHODS

The current study used information collected from 437 children in the longitudinal Iowa Fluoride Study. Participants' fluoride intake information was collected using questionnaires from birth to age 10 years. Estimated mean daily fluoride intake was categorized into low, moderate, and high intake tertiles for each age interval (2-5, 5-8, and 2-8 years). Bivariate analyses were performed to study the relationships between self-reported fluoride intake levels during three age intervals and dental fluorosis.

RESULTS

For canines and second molars, the prevalence of mostly mild fluorosis was less than 10% in the lowest fluoride intake tertile and more than 25% in the highest intake tertile. For both first and second premolars, the prevalence in the low and high intake tertiles was approximately 10-15% and 25-40%, respectively. When estimated total daily fluoride intake was 0.04 mg/kg BW during ages 2-8 years, the predicted probability of fluorosis was 16.0%, 20.5%, 21.8%, and 15.4% for canines, 1st and 2nd and premolars and 2nd molars, respectively. We found that an incremental increase in fluoride intake during the age 5- to 8-year interval led to greater odds for development of mostly mild dental fluorosis in late-erupting teeth compared to increases in fluoride intake during other age intervals.

CONCLUSIONS

Our results clearly show that dental fluorosis prevalence is closely related to fluoride intake levels and that teeth have greater susceptibility to fluoride intake during certain age intervals.

Timing of fluoride intake and dental fluorosis on late-erupting permanent teeth

OBJECTIVE

Very few studies have examined the relationship between timing of fluoride intake and development of dental fluorosis on late-erupting permanent teeth using period-specific fluoride intake information. This study examined this relationship using longitudinal fluoride intake information from the Iowa Fluoride Study.

METHODS

Participants' fluoride exposure and intake (birth to 10 years of age) from water, beverages, selected food products, dietary fluoride supplements, and fluoride toothpaste was collected using questionnaires sent to parents at 3- and 4- month intervals from birth to 48 months of age and every 6 months thereafter. Three trained and calibrated examiners used the Fluorosis Risk Index (FRI) categories to assess 16 late-erupting teeth among 465 study participants. A tooth was defined as having definitive fluorosis if any of the zones on that tooth had an FRI score of 2 or 3. Participants with questionable fluorosis were excluded from analyses. Descriptive and logistic regression analyses were performed to assess the importance of fluoride intake during different time periods.

RESULTS

Most dental fluorosis in the study population was mild, with only four subjects (1%) having severe fluorosis (FRI Score 3). The overall prevalence of dental fluorosis was 27.8%. Logistic regression analyses showed that fluoride intake from each of the individual years from age 2 to 8 plays an important role in determining the risk of dental fluorosis for most late-erupting permanent teeth. The strongest association for fluorosis on the late-erupting permanent teeth was with fluoride intake during the sixth year of life.

CONCLUSION

Late-erupting teeth may be susceptible to fluorosis for an extended period from about age 2 to 8. Although not as visually prominent as the maxillary central incisors, some of the late-erupting teeth are esthetically important and this should be taken into consideration when making recommendations about dosing of fluoride intake.

Evaluation of mandibular bone mineral density using the dual-energy X-ray absorptiometry technique in edentulous subjects living in an endemic fluorosis region

OBJECTIVES

Fluoride is one of the biological trace elements with a strong affinity for osseous, cartilaginous and dental tissue. The dental and skeletal effects of high fluoride intake have already been studied in the literature, but little is known about the effects of high fluoride intake on edentulous mandibles. The purpose of this study was to evaluate the effects of high fluoride intake on mandibular bone mineral density (BMD) measured by the dual-energy X-ray absorptiometry (DXA) technique in edentulous individuals with systemic fluorosis.

METHODS

32 people who were living in an endemic fluorosis area since birth and 31 people who were living in a non-endemic fluorosis area since birth (control group) participated in this study. Systemic fluorosis was diagnosed in the patients using the sialic acid (NANA)/glycosaminoglycan (GAG) ratio. The BMDs of the mandibles were determined by the DXA technique.

RESULTS

The serum NANA/GAG ratios in the fluorosis group were significantly lower than those in the control group (p < 0.001). There was also a statistically significant difference in mandibular BMD measurements (p < 0.05) between the systemic fluorosis and control groups, as measured by the DXA technique. Mandibular body BMD measurements were higher in the fluorosis group (1.25 ± 0.24 g cm(-2)) than in the control group (1.01 ± 0.31 g cm(-2)).

CONCLUSIONS

The results of the study showed that fluoride intake higher than the optimum level causes increased mandibular BMD in edentulous individuals. Further dose-related studies are needed to determine the effects of high fluoride intake on bony structures of the stomatognathic system.

Comparison of the remineralizing potential of child formula dentifrices

BACKGROUND

Although child formula fluoridated dentifrices can be used safely by young children their remineralizing capability remains questionable.

AIMS

To evaluate the remineralizing potential of child formula dentifrices on primary teeth.

DESIGN

In vitro single-section technique utilizing a 7 days pH-cycling model.

METHODS

Primary teeth were placed in demineralizing solution for 96 h to produce artificial carious lesions 100 μm deep, and then cut longitudinally into 50 sections 100-150 μm thick and randomly assigned to five groups. Sections in Groups A to D were treated with dentifrices containing 500 ppm AmF, 500 ppm MFP, 500 ppm MFP and xylitol, or 500 ppm NaF, respectively. Group E sections were treated with a nonfluoridated dentifrice.

OUTCOME MEASUREMENTS

Lesions were evaluated using polarized light microscopy and microradiography.

RESULTS

Group D (500 ppm NaF) sections exhibited a significant decrease in lesion depth, whereas those in Group E (nonF) showed a significant increase in depth (P<0.05, paired t-test). Decrease in lesion progression was observed in Groups A, B and C.

CONCLUSIONS

The 500 ppm NaF dentifrice demonstrated remineralization of carious lesions by virtue of a significant decrease in lesion depth; whereas dentifrices that contained AmF, MFP and MFP with xylitol decelerated the progression of demineralization.

Occlusal caries: Evaluation of direct microscopy versus digital imaging used for two histological classification systems

OBJECTIVE

Histology is frequently used as a gold standard to validate caries detection devices. Poor assessment consistency could lead to apparent changes in diagnostic accuracy. In multi-center, multi-examiner studies electronic transfer of information would be convenient, provided there is no deteriation in quality. This study tested the hypothesis that examiner reproducibility in the assessment of caries lesion depth when viewing photographic images of histological sections on a computer monitor, is comparable with viewing the same sections under a microscope using two histological classification systems.

METHODS

166 investigation sites (96 teeth) were selected for visual examination (ICDAS-II) and sections made using a novel technique which reduced risk of section damage and allowed accurate allocation of section to each investigation site. Digital images of the sections were produced and four examiners viewed the sections under a microscope and on a separate occasion corresponding digital images on a computer monitor. Presence and extent of caries was scored according to two histological classification systems (Downer, ERK).

RESULTS

The inter- and intra-examiner reproducibility for both histological classification systems and both examination techniques was substantial to almost perfect (weighted kappa=0.63-0.90). Comparing the kappa values between microscopy and viewing digital images, there was no effect or only a small effect between both examination techniques (effect size 0.00-0.28). There was also a strong relationship between the two viewing techniques (r(s)=0.748-0.844).

CONCLUSIONS

Viewing digital images of tooth sections produces results comparable to viewing images directly under a microscope and therefore has potential benefits for multi-centre studies.

Dental fluorosis and dental caries among 12-yr-old children from high- and low-fluoride areas in Lithuania

We investigated the prevalence and severity of dental fluorosis, and the occurrence of dental caries, among 12-yr-old children from high- and low-fluoride areas in a country with high caries figures and a developing oral healthcare system. The sample included a total of 600 lifetime residents from high-fluoride (HF; 1.7-2.2 ppm) and low-fluoride (LF; 0.2 ppm) areas in Lithuania. The diagnoses of dental fluorosis followed the Thylstrup-Fejerskov Index (TF), and a diagnosis of dental caries followed the World Health Organization criteria. In the HF area, 66% of the 12-yr-old children had dental fluorosis (TF score > 0) compared with 4% in the LF area. The maximum TF severity scores were 7 and 3, respectively. The mean number of teeth with fluorosis was 4.5 [95% confidence interval (CI) = 4.0, 5.0] for the HF group and 0.2 (95% CI = 0.1, 0.2) for the LF group. In the HF group, 72% had a decayed, missing or filled teeth (DMFT) score of > 0, compared with 87% in the LF group. The mean DMFT was 2.0 (95% CI = 1.8, 2.3) in the HF group and 3.5 (95% CI = 3.2, 3.8) in the LF group. Current untreated caries (DT) occurred (DT >0) in half of both the HF and LF groups. Regardless of the concentration of fluoride in the drinking water, the prevalence of past (DMFT > 0) and present (DT > 0) caries was high, calling for more emphasis on the prevention of tooth decay in countries, such as Lithuania, with high caries figures and a developing oral healthcare system.

Availability of fluoride from meals given to kindergarten children in Brazil

OBJECTIVES

The aim of this study was to evaluate the amount of fluoride supplied daily in the meals given in 44 public kindergarten schools in Bauru, Brazil. In addition, the fluoride concentration of water supplies and its impact on the amount of fluoride found in the meal samples were also investigated.

METHODS

Meal samples and water were collected during 2 weeks (10 working days) in public kindergarten schools. Samples of meals were homogenized with known volumes of deionized water. Fluoride present in meal samples was analyzed with the ion-specific electrode (Orion 9609), after hexamethyldisilazane-facilitated diffusion. Fluoride in water samples was analyzed with the same electrode, after buffering with TISAB II. All the analyses were made in duplicate.

RESULTS

Fluoride analyzed (mean+/-SD) was 0.50+/-0.20 microg/ml, ranging from nondetectable to 1.42 microg/ml for water samples (n=424) and 0.067+/-0.059 mg, ranging from 0.007 to 0.580 mg for meal samples (n=431). A weak but significant correlation was observed between the amount of fluoride in meals and fluoride concentration in water supplies (r=0.139, P=0.0042).

CONCLUSIONS

Despite the seemingly small role played by school meals in the total daily fluoride intake, they can contribute to the total fluoride intake of children on a chronic basis, when in association with other fluoride products. Additionally, the impact of fluoridated public water supply on the final fluoride concentration of the school meals analyzed may be regarded as low.

A standardized photographic method for evaluating enamel opacities including fluorosis

OBJECTIVES

The objective of this study was to demonstrate the reproducibility of a standardized photographic technique for recording fluorosis when used by a group of epidemiologists as part of a large multicentred European study.

METHODS

Studies were first carried out to develop the equipment specification and photographic method. The author (JAC) was then trained and calibrated in this method. She was then responsible for the training and calibration of examiners from a further six European study sites. The method involved taking two transparencies of the permanent maxillary central incisors of 8-year-old children, the first after 8 s while the teeth were still wet and the second after 105 s when the teeth had been allowed to dry out naturally. Data were collected at a central location during a training/calibration exercise and subsequently, during the conduct of a large study to measure fluorosis prevalence, at the seven sites. Intra- and interexaminer reproducibility of the photographic method were measured by grading the transparencies produced by all the examiners according to the DDE and TF indices.

RESULTS

The time period in which the transparencies were taken was to within 4 s among the examiners. Transparencies scored according to the TF index gave a range of Kappa values of 0.45-0.66 for intraexaminer reliability and 0.32-0.55 for interexaminer reliability. When using the DDE index Kappa values ranged from 0.43 to 0.70 for intraexaminer reliability and from 0.34 to 0.69 for interexaminer reliability.

CONCLUSION

The photographic method was mostly robust and reproducible when used by epidemiologists from seven European study sites.

A comparison of the prevalence of fluorosis in 8-year-old children from seven European study sites using a standardized methodology

OBJECTIVES

The objectives of this study were to report on the prevalence of enamel opacities from seven European study sites using a standardized photographic method, and to investigate the importance of variables responsible for enamel fluorosis.

METHODS

The sample comprised a randomly selected group of 300 8-year-old children in each of the study areas. One examiner from each area was trained and calibrated in the use of a standardized photographic technique. Two transparencies were taken of each child's permanent maxillary central incisor teeth; one to represent the teeth 'wet' and one when the teeth had been allowed to dry out naturally for 105 s. The transparencies were viewed 'blind' by the author (JAC) and scored using the DDE and TF indices. Data relating to variables considered to be associated with enamel fluorosis were also collected.

RESULTS

The prevalence of diffuse opacities ranged from 61% in fluoridated Cork (Ireland) to 28% in Athens (Greece). The percentage of subjects with a TF score of three or more ranged from 4% in Cork and nonfluoridated Haarlem (the Netherlands) to zero in Oulu (Finland) and Athens. Fluoridated water and the prolonged use of fluoride tablets were found to be significant contributory factors to fluorosis.

CONCLUSIONS

The prevalence of fluorosis was found to be highest in fluoridated Cork. The prolonged use of fluoride supplements was also found to be a significant risk indicator associated with fluorosis.

Evaluation of the total fluoride intake of 4-7-year-old children from diet and dentifrice

This study measured the total daily fluoride (F) intake of 21 children, living in Bauru, a fluoridated community. F intake from diet (D) and dentifrice (B) was determined for 2 groups of children: A (4-5-year-old) and B (6-7-year-old). The method of 24-hour duplicate diet was used. F ingested from dentifrice was indirectly obtained, subtracting the amount expelled and the amount left on the toothbrush from the amount initially loaded onto the brush. F analysis was carried out with the ion specific electrode (Orion 9409), after hexamethyldisiloxane-facilitated diffusion. The amount of F intake from D and B was divided by the child weight and total intake (T) was calculated by adding D and B. Data were analyzed by Student’s "t" (p<0.05) test and by linear regression. Results (mean ± SD, mg F/Kg body weigh) of T, D and B were, respectively: 0.056±0.040; 0.018±0.12; 0.037±0.038 for all children; 0.055±0.026; 0.021±0.014; 0.034±0.027 for Group A and 0.057±0.052; 0.016±0.010; 0.041±0.046 for Group B. There was a strong positive correlation between the amount of dentifrice used and the amount of fluoride ingested (r = 0.92, p<0.0001). One-third of the children analyzed were exposed to a F dose above 0.07 mg / Kg body weight, which is recommended as the upper limit of daily F intake. Dentifrice was the main source of F ingested by children with percentages of 57.43 ± 29.02 for all children; 56.49 ± 31.82 for group A; and 58.29 ± 27.78 for group B. No significant differences were found between the 2 groups.

Intra-oral distribution of dental fluorosis in Newburgh and Kingston, New York

Previous studies of intra-oral distribution of dental fluorosis in low-fluoride areas reported that teeth that formed later in life were more frequently affected compared with the early-forming teeth. The steady increase of plasma fluoride with age, even under constant fluoride exposure, has been suggested as a possible mechanism for this clinical manifestation. To determine the intra-oral distribution of Dean's Index scores and the effect of fluoride exposure on early- and late-forming teeth, we analyzed data collected on 2193 seven- to 14-year-old lifelong residents of fluoridated or non-fluoridated areas. Logistic regression procedures were used to determine the effects of fluoridation, early brushing, daily supplements, and other socio-demographic variables on early- and late-forming teeth. The results show that the occurrence of very mild or greater levels of fluorosis in the upper anterior teeth was 7 to 10% in the fluoridated area and 5 to 9% in the nonfluoridated area. In the fluoridated area, the occurrence of fluorosis increased from anterior to posterior teeth. Both early- and late-forming teeth were affected by exposure to fluoridation, daily fluoride supplement use, or brushing before the age of two years. This analysis showed that the esthetic consequence of exposure to multiple sources of fluoride was less dramatic, as evidenced by the lower frequency in upper anterior teeth compared with posterior teeth. The longer maturation process of the posterior teeth and the thicker enamel appear to be the likely explanation for the higher occurrence of dental fluorosis in posterior teeth.

"Risk periods" associated with the development of dental fluorosis in maxillary permanent central incisors: a meta-analysis

This systematic review of the dental literature (1966-98) concerns risk periods associated with dental fluorosis in the maxillary permanent central incisors. A literature search was organized through the MedLine and the ISI databases. In addition, one unpublished paper (in manuscript) was obtained, as well as one paper published before 1966. However, out of 143 catches, only 10 studies were included in this review. The main reason for exclusions was that the data presented did not meet the criteria given for the present meta-analysis. Among the included papers, 7 pertained to subjects whose exposure to fluoride started at different ages during the enamel formation (Group 1), and 3 were based on subjects who had been exposed from birth and then experienced an abrupt reduction in daily fluoride exposure at different ages during the amelogenesis period (Group 2). The meta-analysis for Group 1 found the odds ratio (OR) for dental fluorosis in children exposed to fluoride early in life (before 2 years of age) to be 7.24 (95% CI; 4.71-11.13) as compared to children exposed later in life (after 2 years of age). The meta-analysis for the studies in Group 2 found the overall OR to be 1.88 (95% CI; 1.35-2.61) for children who had a reduction in fluoride intake after 2 years of age, as compared to individuals who experienced reduction earlier (during the first 2 years). The studies from both groups were pooled and the duration of exposure to fluoride during the first 4 years of life was the independent variable. The meta-analysis now revealed an overall OR of 5.83 (95% CI; 2.83-11.94) for long periods of fluoride exposure (>2 out of the first 4 years) versus shorter periods of exposure (<2 out of the first 4 years of life) during the enamel formation in the maxillary central incisors. Based on the findings of the meta-analysis, no specific period of enamel formation is singled out as being the most critical for the development of dental fluorosis. The duration of fluoride exposure during the amelogenesis, rather than specific risk periods, would seem to explain the development of dental fluorosis in the maxillary permanent central incisor.

Fluoride ingestion from toothpaste by young children

OBJECTIVE

To investigate the reported and observed brushing habits of young children and their ingestion of fluoride from toothpaste.

DESIGN

In 1997, a random sample of 50 children, aged 30 months, from three districts in the North West region of England, were visited at home.

METHODS

The reported and observed toothbrushing behaviour was determined and the weight of toothpaste applied to the toothbrush was measured. The amount of fluoride retained in the mouth after brushing with either a 400 ppm F or 1,450 ppm F toothpaste was determined.

RESULTS

All parents claimed that their children's teeth were being brushed with a fluoride toothpaste at least once daily. The mean amount of toothpaste applied on the brush was 0.36 g of which 0.27 g (72%) was retained in the mouth. The mean amount of fluoride ingested per brushing was 0.42 mg when using the 1,450 ppm F toothpaste and 0.10 mg when using the 400 ppm F toothpaste. Although most parents applied a small amount of toothpaste a small minority applied a large amount. If using the 400 ppm F toothpaste twice daily no children of average weight would have exceeded ingestion of 0.05 mgF/kg body weight whereas 14 average weight children would have exceeded this value if using the 1450 ppm F toothpaste.

CONCLUSIONS

It is essential that parents of children aged less than 7 years apply a small (pea-sized) amount of fluoride toothpaste on the toothbrush and discourage swallowing.

Biological mechanisms of dental fluorosis relevant to the use of fluoride supplements

Fluorosis occurs when fluoride interacts with mineralizing tissues, causing alterations in the mineralization process. In dental enamel, fluorosis causes subsurface hypomineralizations or porosity, which extend toward the dentinal-enamel junction as severity increases. This subsurface porosity is most likely caused by a delay in the hydrolysis and removal of enamel proteins, particularly amelogenins, as the enamel matures. This delay could be due to the direct effect of fluoride on the ameloblasts or to an interaction of fluoride with the proteins or proteinases in the mineralizing matrix. The specific mechanisms by which fluoride causes the changes leading to enamel fluorosis are not well defined; though the early-maturation stage of enamel formation appears to be particularly sensitive to fluoride exposure. The development of fluorosis is highly dependent on the dose, duration, and timing of fluoride exposure. The risk of enamel fluorosis is lowest when exposure takes place only during the secretory stage, but highest when exposure occurs in both secretory and maturation stages. The incidence of dental fluorosis is best correlated with the total cumulative fluoride exposure to the developing dentition. Fluoride supplements can contribute to the total fluoride exposure of children, and if the total fluoride exposure to the developing teeth is excessive, fluorosis will result.

Morphometric assessment of enamel demineralisation from photographs

OBJECTIVES

To investigate the validity and reproducibility of a method of morphometric assessment of enamel demineralisation.

METHODS

An in vitro investigation was carried out on 22 human teeth. One investigator coated the crowns of the teeth with an acid-resistant varnish, leaving a small window on the buccal surface. This was incrementally occluded by varnish over a 14-day period, during which the teeth were placed in a demineralising gel at pH 4.5. After varnish removal, a second investigator blindly quantitated the demineralised area by three methods of examination; direct visual, microscopic and from photographs. The microscopic and photographic measurements were carried out using a morphometric assessment with a 121-dot array. Photographs and assessments were repeated after 1 week. The readings were analysed using the kappa statistic, the limits of agreement and the coefficient of repeatability.

RESULTS

Photographic assessments demonstrated excellent agreement for grid positioning (kappa > 0.81) and substantial agreement for reading reproducibility (kappa = 0.61-0.80). The coefficients of repeatability were found to be the same for repeat readings of the same slide and the repeated slides (5.0 mm2). They were higher for the microscopic technique (6.8 mm2) and for the direct visual technique (7.8 mm2). The limits of agreement are presented graphically.

CONCLUSIONS

The photographic technique used was a reproducible method of measuring artificial enamel demineralisation. Measurement from photographs was more reproducible than direct measurement with the naked eye. Subjectiveness of the index leads to most variation and more objective means of assessing enamel demineralisation need to be found.

Enamel defects in the deciduous dentition as a potential predictor of defects in the permanent dentition of 8- and 9-year-old children in fluoridated Cheshire, England

It is claimed that dental fluorosis in both deciduous and permanent teeth is increasing in fluoridated and non-fluoridated communities. What is unclear is whether fluoride-induced enamel opacities in the deciduous dentition are associated with the subsequent appearance of enamel defects in the permanent dentition. The aim of this study was to establish whether a relationship existed between the presence of diffuse enamel defects on the deciduous molars and permanent incisors of schoolchildren who were lifetime residents in an optimally fluoridated community in Cheshire, England. The dentitions of eight-and nine-year-old children were examined by two examiners, each unaware of the findings of the other. There was a significant increased risk of diffuse enamel defects in the permanent incisors for those children who presented with diffuse defects on their first deciduous molars (Relative Risk, 1.45; 95% confidence interval, 1.05 to 2.0) or second deciduous molars (Relative Risk, 1.86; 95% confidence interval, 1.36 to 2.54). In light of these findings, it is worth considering the potential of the presence of enamel defects in deciduous molars in children aged 1 to 3 years as a predictor of the future appearance of similar lesions in their permanent incisors.

The risk of fluorosis in students exposed to a higher than optimal concentration of fluoride in well water

OBJECTIVES

In December 1991 the residents of the community of Rigolet, Labrador, Canada, discovered that they were exposed to higher than 2.0 ppm fluoride in the drinking water from the new town well, which became operational in December 1983. In 1993 an investigation of the occurrence of fluorosis in children exposed to the high-fluoride water during different ages of life was carried out.

METHODS

A dental examination for fluorosis was conducted using Pendrys' Fluorosis Risk Index. Out of 84 students in Rigolet, 74 were examined and the parents of 60 students agreed to be interviewed. Out of the 60 students, 48 lived all of their first six years of life in Rigolet.

RESULTS

Of the 48 children with life-long residence, the odds ratio of fluorosis on enamel zones that began forming during the first year of life was 8.31 (95% CI = 1.84, 38.59) for children exposed since birth or during the first year of life relative to those exposed after 1 year of age. The odds that a child had a maxillary central incisor with fluorosis were 5.69 (95% CI = 1.34, 24.15) times higher if exposure occurred during the first yea of life compared with exposure after 1 year of age. Only those exposed to the high-fluoride water during the first year of life developed fluorosis on the mandibular central incisors.

CONCLUSIONS

Within the limitations of this small population study, age relative to the date when the new water well became operational was a significant risk factor in development of fluorosis. The first year of life was a significant period for developing fluorosis on the mandibular and maxillary central incisors.

Prevalence of dental fluorosis in Sudanese children from two villages with 0.25 and 2.56 ppm fluoride in the drinking water

Dental fluorosis is endemic in Eastern Africa and a high prevalence has been found even in low-fluoride (approximately 0.5 ppm) areas. Substantial seasonal changes in the fluoride content of water have also been reported. The aim of the present study was to ascertain, through one year, the fluoride concentration in water from two underground reservoirs in Sudan, in Treit el Biga (TeB) and Abu Groon (AG), and to assess dental fluorosis in children aged 7-16 years who had been lifelong residents. The water in one of the reservoirs (TeB) was shown to have a low, very stable fluoride concentration (0.25 ppm SD 0.04) whereas the other (AG) had a tenfold higher, and slightly varying, fluoride concentration (2.56 ppm SD 0.26). Dental fluorosis was recorded on maxillary central incisors according to Dean's index. In TeB 91% of the children showed signs of dental fluorosis whereas in AG all children had fluorotic teeth. The Community Fluorosis Index in TeB and AG was 1.40 and 2.44, respectively. There was a significantly higher degree of fluorosis in boys than in girls in the low-fluoride area. In TeB, older boys tended to have more fluorosis than younger boys; the difference, however, was not statistically significant. No significant sex or age differences in fluorosis were found in AG. In both villages great inter-individual variations in dental fluorosis were recorded. The prevalence and severity of dental fluorosis in TeB was higher than that previously reported in areas with similar fluoride concentrations in the drinking water.

The prevalence of dental fluorosis in a school-based program of fluoride mouthrinsing, fluoride tablets, and both procedures combined

OBJECTIVES

The objective of the study was to describe and compare the prevalence and severity of dental fluorosis in children who participated in an eight-year clinical trial of the effectiveness of school-based fluoride procedures according to three treatment regimens and age of regimen initiation.

METHODS

At baseline in 1981, 1,640 kindergarten and first grade children residing in a fluoride-deficient community (Springfield, OH) were assigned randomly to a group that (1) rinsed once a week with a 0.2 percent neutral NaF solution; (2) chewed, rinsed, and swallowed daily a neutral 2.2 mg NaF tablet; or (3) carried out both procedures. DMFS examinations were conducted at baseline and after two, five, and eight years of treatment. As a follow-up in 1992, fluorosis examinations using Dean's index were conducted on 448 remaining subjects.

RESULTS

Overall, the prevalence of fluorosis was 4.4 percent with 20 children classified as having some definitive level of the condition. No statistically significant differences existed in the prevalence or severity of fluorosis: (1) among the preventive regimens; (2) among children who began the regimens at ages 5, 6, or 7; or (3) by eruptive status of teeth.

CONCLUSION

These results reiterate the safety of school-based fluoride mouthrinse, fluoride tablet, or combined regimens in communities with fluoride-deficient water supplies.

Proton microprobe assessment of the distribution of fluoride in the enamel and dentine of developing central incisors of sheep and changes induced by daily fluoride supplements

Ten sheep were given 0.5 mg fluoride (F) and 10 sheep 0.2 mg F/kg body wt orally for periods of 1-6 months while 8 sheep received no additional F. One incisor from each sheep was sectioned longitudinally in the midline and, using the proton microprobe, multiple scans for calcium and F were made across the enamel and dentine. F was determined by proton-induced gamma-ray emission and calcium by X-ray emission. Tooth length and hence the stage of ameloblast activity for each of the 28 teeth at the start of the experiment was determined using a tetracycline marker. In addition, the stage of enamel development of the eight control teeth (no dietary F) at the time of their extraction was assessed from their macroscopic appearance. Continuous changes in F levels occurred in both enamel and dentine throughout tooth development and also in the mature enamel and associated dentine after ameloblast regression. All scans for all stages of tooth development and all F treatments showed a high F concentration at the enamel surface. Early in the secretory phase, a wide-based F peak occupied the entire width of the enamel with a similar F peak in the dentine. In the control teeth, no consistent increase in F concentration occurred at the enamel surface during later development. When F supplements were started early in the maturation phase an increase in F concentration only at the enamel surface was recorded. When F supplements were also given during the secretory phase, higher F concentrations were recorded not only at the enamel surface but also for the inner enamel and dentine plateau. These findings, based on a small number of sheep, indicate that further research is needed to clarify the method and control of F uptake and to determine the changes in these processes during the different stages of tooth development.

Dental fluorosis and caries prevalence in children residing in communities with different levels of fluoride in the water

OBJECTIVES

This study investigated the prevalence of dental fluorosis and caries in 7-14-year-old children residing in communities with negligible (NF: 0.2 ppm), optimal (OPF: 1.0 ppm), and four-times optimal (4X OPF: 4.0 ppm) naturally occurring fluoride in their water systems.

METHODS

Examinations were performed on 344 children who were lifetime residents of their communities.

RESULTS

Whether using the tooth surface index of fluorosis or Dean's index, children examined in the 4X OPF community had the highest prevalence of dental fluorosis. While the severity of fluorosis seen in the OPF and NF communities was mild in appearance, the results indicate that fluorosis does occur in optimally and negligibly fluoridated communities. Compared to the NF community, DMFT and DMFS scores in the OPF community were 9.2 percent and 21.2 percent lower, respectively.

CONCLUSIONS

The ingestion of water containing 1 ppm or less fluoride during the time of tooth development may result in dental fluorosis, albeit in its milder forms. However, in these times of numerous products containing fluoride being available, children ingesting water containing 1 ppm fluoride continue to derive caries protection compared to children ingesting water with negligible amounts of fluoride. Thus, the potential for developing a relatively minor unesthetic condition must be weighed against the potential for reducing dental disease.

Enamel formation and the effects of fluoride

The exact biochemical events which result in enamel lesions from excess fluoride ingestion are still unknown. A number of effects of fluoride on enamel organs and on the enamel matrix components of developing teeth are, however, known. These are briefly reviewed, making reference to more recent studies. Two major influences of chronic, low-level fluoride exposure are proposed: fluoride interferes with the processes responsible for the efficient removal of organic matrix components, resulting in protein retention and disorganized enamel crystal formation, or fluoride disrupts the activities of the enamel organ cells which indirectly interferes with normal crystal formation.

Dental fluorosis: its use as a biomarker

Several epidemiological studies, beginning with those of Dean and co-workers in the 1940's, clearly demonstrate the relationship between dental fluorosis in humans and the level of fluoride in water supplies. These studies and others have shown that, in a population, there is a direct relationship among the degree of enamel fluorosis, plasma and bone fluoride levels, and the concentration of fluoride in drinking water. However, dental fluorosis is a reflection of fluoride exposure only during the time of enamel formation, somewhat limiting its use as a biomarker. In addition, the degree of fluorosis is dependent not only on the total fluoride dose, but also on the timing and duration of fluoride exposure. At the level of an individual response to fluoride exposure, factors such as body weight, activity level, nutritional factors, and the rate of skeletal growth and remodeling are also important. These variables, along with an individual variability in response to similar doses of fluoride, indicate that enamel fluorosis cannot be used as a biological marker of the level of fluoride exposure for an individual.

Dental tissue effects of fluoride

It is now well-established that a linear relationship exists between fluoride dose and enamel fluorosis in human populations. With increasing severity, the subsurface enamel all along the tooth becomes increasingly porous (hypomineralized), and the lesion extends toward the inner enamel. In dentin, hypomineralization results in an enhancement of the incremental lines. After eruption, the more severe forms are subject to extensive mechanical breakdown of the surface. The continuum of fluoride-induced changes can best be classified by the TF index, which reflects, on an ordinal scale, the histopathological features and increases in enamel fluoride concentrations. Human and animal studies have shown that it is possible to develop dental fluorosis by exposure during enamel maturation alone. It is less apparent whether an effect of fluoride on the stage of enamel matrix secretion, alone, is able to produce changes in enamel similar to those described as dental fluorosis in man. The clinical concept of post-eruptive maturation of erupting sound human enamel, resulting in fluoride uptake, most likely reflects subclinical caries. Incorporation of fluoride into enamel is principally possible only as a result of concomitant enamel dissolution (caries lesion development). At higher fluoride concentrations, calcium-fluoride-like material may form, although the formation, identification, and dissolution of this compound are far from resolved. It is concluded that dental fluorosis is a sensitive way of recording past fluoride exposure because, so far, no other agent or condition in man is known to create changes within the dentition similar to those induced by fluoride. Since the predominant cariostatic effect of fluoride is not due to its uptake by the enamel during tooth development, it is possible to obtain extensive caries reductions without a concomitant risk of dental fluorosis.

Epidemiologic indices for measuring the clinical manifestations of dental fluorosis: overview and critique

Several indices have been used to describe the clinical appearance of dental fluorosis. The purpose of this paper is to describe and compare the three principal ones in use today: those developed by Dean (1934, 1942), Thylstrup and Fejerskov (1978), and Horowitz et al. (1984). A recent index (Fluorosis Risk Index) developed by Pendrys (1990) is also included in this review. The continued use of Dean's classification system and derived index (CFI) for more than a half century is testimony to its simplicity and utility. The index has been criticized because the unit of analysis is the person, because criteria are unclear for some categories, or that they lack sensitivity, particularly for severe fluorosis, and because of the way in which data are summarized and reported. The Thylstrup and Fejerskov Index is appealing to clinicians and epidemiologists alike in that it corresponds closely to histological changes that occur in dental fluorosis and to enamel fluoride concentrations, thereby having biological validity. The TSIF described by Horowitz et al. makes a useful contribution because it provides clearer diagnostic criteria and provides for an analysis based on esthetic concerns. The Fluorosis Risk Index appears to be particularly useful for analytical epidemiologic studies, because it is designed to permit a more accurate identification of associations between age-specific exposures to fluoride and the development of dental fluorosis. All three indices in common use today provide useful indices for the study of dental fluorosis. The utility of the Fluorosis Risk Index will be determined as it receives wider use. The selection of one of these indices for use in an epidemiologic study depends in large measure on the purpose of the study. Research needs to continue on the validity of these indices, particularly for mild fluorosis, and on the public's perception of the cosmetic appearance of teeth with different severity levels of fluorosis.

Review of fluorosis risk of self-applied topical fluorides: dentifrices, mouthrinses and gels

The literature on the risks of dental fluorosis and the benefits from the use of fluoride dentifrices, mouthrinses and self-applied gels has been briefly reviewed. While there are several studies that have investigated the impact of dentifrices on the development of dental fluorosis, results are mixed. Although there is far less research investigating the relationship between the use of mouthrinses and dental fluorosis, the available evidence generally fails to identify this technology as one of the major causes of dental fluorosis. Although there is little direct evidence to suggest that the use of self-applied fluoride gels contributes to the development of dental fluorosis, ingestion of fluoride from these systems is of genuine concern and their use by preschool age children is not recommended.

Fluoride intake from beverage consumption in a sample of North Carolina children

Since the 1940's, the prevalence of dental fluorosis has increased in the US, concomitant with a reduction in dental decay. These changes have been attributed in part to the widespread use of systemic and topical fluorides. Various sources of increased systemic fluoride exposure have been investigated. However, little is known regarding fluoride intake from beverages in a sample of children of ages susceptible to dental fluorosis. The purpose of this study was to estimate the amount of fluoride ingested from beverages by a sample of North Carolina (NC) children of ages 2-10 years. Data on beverage consumption were collected by means of a diary format. A questionnaire was included so that demographic information and self-assessment on the accuracy of the diaries could be obtained. Beverages reported in the diaries were purchased, and their fluoride content was assayed. Daily total fluid intake ranged from 970 to 1240 mL, and daily beverage consumption ranged from 585 to 756 mL. The estimated mean daily fluoride intakes from beverages for children 2-3, 4-6, and 7-10 years of age were 0.36, 0.54, and 0.60 mg, respectively.