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REVIEW ARTICLE
Year : 2014  |  Volume : 6  |  Issue : 1  |  Page : 7-15

Fluorosis and periodontium: A report of our institutional studies


Department of Periodontics, College of Dental Sciences, Davangere, Karnataka, India

Date of Web Publication18-Aug-2014

Correspondence Address:
K L Vandana
Department of Periodontics, College of Dental Sciences, Davangere, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2231-0754.139084

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   Abstract 

Fluorosis is a world-wide prevalent endemic disease due to high-fluoride water intake, especially in the developing countries. Among the various environmental etiological factors, the influence of high-fluoride water intake on the periodontium is still unexplored. With this background, we conducted a group of epidemiological and in vitro studies in a single group of the population residing in high-fluoride water areas (1.5-3.0 ppm) of Davangere district, Karnataka, India. The studies not only explored an epidemiological association between fluorosis and periodontal disease, but also the influence of fluorosis on periodontal structures along with the comparison of influence of periodontal treatment on fluorosed and nonfluorosed teeth. These preliminary studies conducted in our institution are hereby elaborately presented and discussed in this article along with their important conclusions. The results of these studies necessitate further exploration of the influence of high-fluoride water intake on the periodontium in other affected populations of the world.

Keywords: Cementum, dental fluorosis, dentin, periodontal ligament


How to cite this article:
Vandana K L. Fluorosis and periodontium: A report of our institutional studies. J Int Clin Dent Res Organ 2014;6:7-15

How to cite this URL:
Vandana K L. Fluorosis and periodontium: A report of our institutional studies. J Int Clin Dent Res Organ [serial online] 2014 [cited 2019 Dec 13];6:7-15. Available from: http://www.jicdro.org/text.asp?2014/6/1/7/139084


   Introduction Top


Fluorosis plays havoc in more than 25 nations across the world and in many continents, the number of people suffering from fluoride poisoning is staggering. The most recent proclamation that more than 200 million people across the globe are "at risk" of fluorosis raises global alarm and anguish. In India, almost 60-65 million people drink fluoride contaminated groundwater, and the number affected by fluorosis are estimated at 2.5-3 million in many States, especially, Andhra Pradesh, Bihar, Gujarat, Madhya Pradesh, Punjab, Rajasthan, Tamil Nadu and Uttar Pradesh. In India, the safe limit of fluoride in potable water is between 0.6 and 1.2 mg/l. Lower limit of fluoride (<0.6 mg/l) than that of the prescribed limit causes dental caries, while higher limit of fluoride (>1.2 mg/l) results in fluorosis. [1]

On the other hand, periodontal disease is multifactorial in origin. The various determinants of periodontal disease are age, sex, race, socioeconomic status, and risk factors including tobacco usage and oral hygiene status. Microbial plaque is considered to be a major etiologic factor in periodontal disease. Among the various environmental etiologic factors, the influence of fluoride on periodontal health is still controversial.

To further probe the relationship between fluorosis and periodontal disease, we have conducted a series of preliminary studies in our institution (Department of Periodontics, College of Dental Sciences, Davangere, Karnataka, India) over a period of 14-year. These studies are hereby listed and described in the following paragraphs:

Study to evaluate the periodontal changes caused by fluorosis

Periodontal status in dental fluorosis subjects using CPITN. [2]

Scanning electron microscope studies to evaluate the hard tissues changes brought about by fluorosis

  • Periodontal tissue changes in fluorosed and nonfluorosed teeth by Scanning electron microscope (SEM). [3]
  • Surface roughness of periodontally healthy fluorosed and nonfluorosed teeth. [4]
  • Microhardness of fluorosed and nonfluorosed enamel. [5]
  • Microhardness of fluorosed and nonfluorosed cementum. [6]
  • Surface roughness of fluorosed and nonfluorosed teeth following use of different toothbrushes. [7]
  • Surface roughness of periodontally healthy fluorosed and nonfluorosed teeth following various types of instrumentation. [8]


Root surface changes following root bio-modification in fluorosed teeth

  • Effects of tetracycline (TTC), ethylenediaminetetraacetic acid (EDTA) and citric acid (CA) application on fluorosed dentin and cementum surfaces. [9]
  • Effects of TTC, EDTA and CA application on fluorosed dentin morphology. [10]
  • Attachment of nonfluorosed fibroblast on the fluorosed and nonfluorosed root specimens. [11]
  • Attachment of fluorosed fibroblasts on the fluorosed and nonfluorosed root fragments after SRP and EDTA root bio-modification. [12]
  • A study to compare the attachment of nonfluorosed and fluorosed fibroblasts on the fluorosed and nonfluorosed root fragments. [13]


Root surface changes following LASER irradiation in flurorosed teeth

  • Effect of erbium-doped:Yttrium, aluminum-garnet (Er:YAG) laser irradiation on fluorosed and nonfluorosed root surfaces. [14]
  • Effect of ND:YAG laser irradiation on flurorosed and nonfluorosed root surfaces. [15]


Genetics and periodontics

  • Study to evaluate the genetic susceptibility of an individual for periodontal disease. [16]


Effect of desensitizing agents on fluorosed and nonfluorosed teeth-in vitro Scanning electron microscope analysis

  • SEM study to evaluate the effect of densitizing agents on dentinal tubular morphology in fluorosed teeth. [17]


Effect of 980-nm diode laser-aided circumferential supracrestal fiberotomy (CSF) on fluorosed root surfaces [18]

Ongoing Projects


  • Effect of topical application of guduchi gel (herbal extract) in the treatment of periodontitis in fluorosed and nonfluorosed patients.
  • Dentinal hypersentitivity in fluorosed and non fluorosed population.
  • Association of ER Rsa 1 gene polymorphism with osteoporosis and chronic periodontitis in fluorosed and nonfluorosed subjects.
  • Bone and cemental changes in fluorosed and nonfluorosed subjects.


Clinical studies to evaluate the peridontal changes caused by fluorosis [2]

Though the effect of fluoride on reduction of dental caries is well-established, its effect on periodontal tissues is obscure. The fluoride concentration of drinking water is considerably high in places in Davangere District, Karnataka, India. The fluoride level ranges from 1.5 to 3.0 ppm in drinking water, there is virtually no dental care and the socioeconomic status is low. The unique population provides the opportunity of studying the effect of life long exposure of fluoride in drinking water on the periodontal status of the subjects with dental fluorosis and provides evidence for long term exposure to high-fluoride drinking water. Therefore, we conducted a cross-sectional clinical, epidemiological study in our institution to determine the periodontal status using CPITN index in the population aged between 15 and 74 years residing in the high-fluoride areas of Davangere district. [2] 1029 subjects, aged between 15 and 74 years suffering from dental fluorosis were assessed for their periodontal status. The factors that motivated us to undertake this study are routine clinical observation that female subjects with dental fluorosis reported to the clinic were suffering from periodontitis and the paucity of recent periodontal literature correlating periodontal health with dental fluorosis.

Results showed that gingivitis and periodontitis were more common in females (65.9% and 32.8%, respectively) than in males (75.1% and 24.2%, respectively). Periodontitis was significantly more common in females. As the age advanced from 15 to 55 years and above, gingivitis reduced from 81.0 to 42.9% and periodontitis increased steadily from 18.0 to 57.1%, which was significant. Periodontitis was high in subjects with poor oral hygiene (81.3%), compared to those with good oral hygiene (14.5%), which was significant. As the degree of fluorosis increased, severity of gingivitis reduced and periodontitis increased, i.e., with a degree fluorosis, gingivitis was 89.4% and periodontitis 8.5%, but with F degree fluorosis the former was 64% and the latter 35.8%, which was statistically significant. On comparing urinary fluoride level of fluorosed and non fluorosed groups, the mean urinary fluoride level (1.17 ± 0.14 mg/l) was highly significant in the fluorosed than the nonfluorosed group (0.48 ± 0.19 mg/l). We concluded that there is a strong association of occurrence of periodontal disease in high-fluoride areas. It is desirable that the prevalence of periodontal disease observed in the present study necessitates researching the toxic biologic effects of fluoride along with biologic analysis of dental plaque in order to confirm the effect of fluoride on periodontal conditions. The comparative assessment of periodontal status from nonfluoride areas was not attempted as it would simply report the effect of plaque alone similar to earlier studies.

Further, no effort appears to have reported in the literature to account for increased periodontal disease in high-fluoride areas apart from blaming oral poor hygiene and plaque levels. In addition to the inflammatory process that are common to high and normal fluoride levels of water, changes in fluorosed hard and soft tissues of the periodontium suggest that the fluoride should be suspected as an etiological (environmental) agent for periodontal disease. However, as far as we are aware, no direct experimental data are available comparing periodontal changes in human fluorosed and nonfluorosed otherwise healthy teeth.

Study to compare the cemental and periodontal ligament changes in fluororsed and non fluorosed teeth

Vandana et al. [3] conducted a preliminary in vitro study to compare cemental and periodontal ligament changes in 32 fluorosed and nonfluorosed noncarious healthy teeth. [3] The root surface was selected for examination by SEM analysis. Two important observations were made from the SEM impressions:

  1. Globular mineralized debris was 37.5% in the fluorosed group compared with 6.25% in the nonfluorosed group.
  2. Partial/initial mineralization of connective tissue fibers (periodontal ligament area) was 43.75% in the fluorosed group, but only 18.75% in the nonfluorosed group.


Within the limits of this study, we concluded that healthy fluorosed teeth exhibited a higher percentage of partial/initial mineralization of connective tissue fibers and globular mineralized deposits than nonfluorosed healthy (NFH) teeth. Further histologic evaluation and a larger sample size would be beneficial from a research point of view.

Evaluation of surface roughness of enamel and cementum of fluorosed and non fluorosed teeth (Scanning electron microscope-in vitro study)

Studies focusing on surface roughness of enamel and cementum of fluorosed teeth are rare. Hence, we conducted a study to measure the surface roughness of enamel and cementum of periodontally healthy 30 fluorosed and 30 nonfluorosed teeth using SEM and a noncontact profilometer. Using the SEM photographs, 2 mm 2 surface area of enamel and root were selected for analysis. Measurements were obtained with a computerized micro-profilometer that uses a scanning noncontact chromatic aberration technique. Computer software allowed determination of mean surface roughness in microns (Ra). [4] Results showed that the fluorosed enamel specimens showed a mean surface roughness of 5.06 ± 2.88 as compared to 2.77 ± 1.69 for the nonfluorosed enamel specimens. The difference between the surface roughness in fluorosed versus nonfluorosed category was significant (P ≤ 0.01). In fluorosed cementum specimens, the mean surface roughness was 3.80 ± 1.72 compared to 3.93 ± 2.14 in nonfluorosed cementum specimens which were not significant. Within the limitations of this in vitro study, we thus, concluded that fluorosed enamel and cementum specimens exhibited more tooth surface roughness than nonfluorosed teeth. The observed surface roughness needs to be carefully evaluated using a larger sample size and more sensitive techniques of surface roughness measurement, e.g., radiotracer (radioactive) and laser profilometric methods.

Evaluation of enamel and cementum hardness of fluorosed and nonfluorosed teeth

Hardness as a mechanical property to resist abrasion has not been studied in both fluorosed and nonfluorosed teeth. Hence, the first attempt was made to study the Vickers hardness of healthy fluorosed and nonfluorosed human enamel and cementum using computerized Vickers microhardness tester. [5],[6] This study was conducted on 15 fluorosed and nonfluorosed teeth that were collected from orthodontic patients, mean age of 18-25 years requiring first premolar extractions. Results showed that in fluorosed and nonfluorosed enamel specimens, the average hardness was 344 ± 57.1, 346 ± 49.1, 395 for occlusal, middle and cervical regions, respectively. Vickers hardness of fluorosed and nonfluorosed enamel was higher in the middle zone than the occlusal zone. The average Vicker hardness number (VHN), Diagonal length (DL), Depth of Indentation (DI) of nonfluorosed and nonfluorosed enamel was 322.60 ± 46.23, 12.15 ± 1.06, 1.73 ± 0.15 respectively. The hardness value was higher in occlusal than middle zone. There was no significant difference between the occlusal and middle zone within the groups and between the groups. The total VHN was calculated by taking average of all the values of different zones in each group On comparison of total VHN, the fluorosed enamel had significantly higher values (346 ± 52.89) than nonfluorosed enamel (322.6 ± 46.23). Furthermore, fluorosed cementum, the average hardness was 48.90 ± 6.85, 50.61 ± 5.29, 44.85 ± 3.82 for cervical, middle and apical regions respectively. There was no significant difference between the cervical and middle zone within the groups. However the middle zone of fluorosed cementum showed significantly higher values. In nonfluorosed cementum, hardness value was higher in cervical compared to the middle. The total VHN was 45.22 ± 8.07. On the comparison, fluorosed cementum demonstrated significantly higher values than nonfluorosed cementum. Considering the limitations of the study, we concluded that the fluorosed enamel and cementum demonstrated higher VHN than nonfluorosed teeth. However, there is a need to conduct a study while controlling for background variables, such as fluoridation and nutrition. The correlation of mineral content and hardness measurement would be a useful study. Further studies should be undertaken using the ultra-micro-indentation system to measure the hardness of tooth.

The previous epidemiological evidence of the relationship of fluorosis and periodontal disease, SEM findings of fluorosed root surface, increased surface roughness and microhardness of fluorosed teeth prompted us to evaluate and compare the effect of various periodontal treatment procedures on fluorosed and NFH teeth.

Scanning electron microscope analysis of surface roughness of enamel and cementum following toothbrushing in fluorosed and non fluorosed teeth [7]

In this regard, we conducted in vitro study to measure the surface roughness of enamel and cementum of periodontally healthy fluorosed and nonfluorosed teeth, with and without controlled tooth brushing, using SEM and a noncontact profilometer. [7] 60 fluorosed, and nonfluorosed teeth were divided into equal groups of 10 teeth, each group being subjected to toothbrushing with 1 of the 3 different brushes (manual brush, electric brush and ultrasonic toothbrush). Brushing was done in the horizontal plane at the cemento-enamel junction with the brush head covering both enamel and root surface. Subsequent to the brushing procedure, teeth were longitudinally sectioned (using high speed and piece with water coolant) in a mesio-distal direction and the pulpal sides of the resultant specimens were flattened with a carborundum disc. Following sectioning, all specimens in each treatment group were subjected to surface profilometry to determine surface roughness. Using the SEM photographs, 2 mm 2 surface area of enamel and root were selected for analysis.

There was a significant increase in surface roughness values for cementum in the Manual Brush (P > 0.05) and Ultrasonic Brush (P > 0.05) groups. Intergroup comparisons showed a significant (P > 0.05) difference in surface roughness for enamel and cementum in only the Ultrasonic Brush group. Increased surface roughness values were noted in fluorosed teeth when compared to nonfluorosed teeth in case of ultrasonic brush groups (3.58 ± 0.75 μm vs. 2.93 ± 0.38 μm). The differences between untreated control specimens in fluorosed vs. nonfluorosed teeth was significant (P > 0.05) for enamel surfaces but not for cementum surfaces. In consideration of the limitations of this in vitro study, we concluded that the fluorosed enamel and cementum specimens exhibited more tooth surface roughness than nonfluorosed teeth. The observed effect of the ultrasonic brush needs to be carefully evaluated using a larger sample size and more sensitive techniques of surface roughness measurement, e.g., radiotracer (radioactive) and laser profilometric methods.

Evaluation of surface roughness following ultrasonic instrumentation in fluorosed and nonfluorosed teeth

Another in vitro study in our institution was conducted to evaluate the surface roughness changes induced by ultrasonic instrumentation in fluorosed and nonfluorosed teeth and the effect of fluorosis on the surface roughness of teeth. [8] The study specimens consisted of 56 longitudinal sections cut from 28 teeth. The teeth were divided equally between fluorosed and nonfluorosed. Prior to sectioning, each category of teeth was subdivided based on instrumentation with either manual curette or ultrasonic scaler. Subsequent to the instrumentation procedure, teeth were longitudinally sectioned (using high speed and piece with water coolant) in a mesio-distal direction and the pulpal sides of the resultant specimens were flattened with a carborundum disc. Following sectioning, all specimens in each treatment group were subjected to surface profilometry to determine surface roughness. Using a dissection microscope at Χ64 magnification, 2 mm 2 surface area of enamel and root were selected for analysis.

Results revealed interesting findings in that compared to nontreated controls, there was a significant increase in surface roughness values for both enamel and cementum in the ultrasonic scaler group. The curette treated group exhibited a significant increase in surface roughness values only for fluorosed cementum. Intergroup comparison showed a significant difference in surface roughness for fluorosed enamel using both curettes and the ultrasonic scaler. However, the ultrasonic scaler induced significant roughness in fluorosed cementum. The results confirmed that instrumentation brings about surface roughness changes.

Scanning electron microscope studies to evaluate results of root bio-modification in fluorosed teeth

Root bio-modification using TTC-HCl, EDTA and CA is a common regenerative procedure in periodontal therapy. A doubt arises whether the root bio-modification effects in fluorosed teeth would remain similar or different as compared to nonfluorosed teeth. Furthermore, dental fluorosis is known to cause hypomineralizaton of enamel [19] and dentin; [20] the influence of fluorosis on the cementum is not dealt in literature. Hence, we conducted a preliminary in vitro study using Scanning electron microscope for the evaluation of smear layer and collagen exposure in dentin specimens and appearance of fibrillar structures in cementum specimens of fluorosed and nonfluorosed teeth which comprised of periodontally healthy and diseased teeth, subsequent to the application of TTC, EDTA and CA. [9]

Results revealed that the fluorosed healthy (FH) group specimens exhibited more etching and smear layer formation when treated with TTC and CA than did NFH specimens. In contrast, when EDTA was used, the NFH specimens exhibited more surface etching and smear layer formation. Furthermore, the amount of smear layer removal and exposure of collagen matrix in dentin specimens were variable in different groups. The exposure of fibrillar structures on cementum specimens were seen significantly on healthy specimens when compared to diseased specimens. The biochemical and morphological changes in the root surface produced by the various mechanical techniques and conditioning agents are yet to be understood. Further experimental and clinical studies are needed to evaluate the significance of these differences.

Effect of tetracyclcine HCl, ethylenediaminetetraacetic acid and citric acid application and dentinal tubular changes in fluorosed healthy and nonfluorosed healthy) teeth

As an offshoot of the above study, we also evaluated the effect of application of TTC, EDTA and CA on the number of dentinal tubules, tubular width and surface area in dentin specimens of FH and NFH teeth which comprised of periodontally healthy and diseased teeth. The maximum tubular width (1.71 μ) was found in fluorosed group than in non fluorosed group 1.56 μ. [10] In this study, the overall expression of increased tubular width in fluorosed group (both healthy and diseased) is corroborated with the findings of Vieira et al. [20] who reported a positive correlation between fluorosed dentin and dentin tubule size, demonstrating wider dentinal tubules in teeth with higher levels of fluoride in dentin. This is interesting because fluoride concentration has been shown to influence crystal size, and same evidence indicates that the fluoride has an effect on cell function, either directly through interactions with the developing ameloblasts and/or odontoblasts or more indirectly by interacting with extracellular matrix. Another hypothesis is that the fluoride would influence crystal growth, forming an impaired dental structure with wider dentin tubules. The changes in surface area of dentinal tubule in this study were directly similar to the results of dentinal tubular width. These results point to the efficacy of these agents in conditioning fluorosed and nonfluorosed teeth and also relatively greater conditioning of fluorosed teeth compared to nonfluorosed teeth.

Study to evaluate the attachment of nonfluorosed fibroblasts on the fluorosed and nonfluorosed root fragments

We conducted a study to evaluate the attachment of non fluorosed fibroblast on the fluorosed and non fluorosed root specimens. [11] A total of 56 FH and NFH periodontally healthy were grouped into eight groups: FH and NFH, FD and Non Fluorosed diseased (NFD), Fluorosed diseased (FD) AND NFD + SRP) and similar group FD SRP + EDTA and NFD SRP + EDTA) burnishing treatment with 24% EDTA gel for 2 min. When fluorosed groups were compared with nonfluorosed, no significant changes were noted between the groups except for SRP + EDTA group showed lesser attachment in fluorosed (10%) in comparison with nonfluorosed group (70%).

Hence, we conclude that SRP proves yet to be standard requirement for fibroblast attachment to occur both in fluorosed and nonfluorosed teeth. Although, there is no significant difference in attachment between SRP and SRP + EDTA among nonfluorosed teeth. EDTA does not seem to be a promising agent for root bio-modification in fluorosed teeth in given concentration and time.

Study to evaluate the attachment of fluorosed fibroblasts on the fluorosed and nonfluorosed root fragment

To understand the effect of fluorosis on periodontal healing, the initial step during healing, such as fibroblast attachment to the root surface, needs to be evaluated. Neha G and Vandana [12] conducted a study to evaluate the attachment of fluorosed fibroblasts on the fluorosed and nonfluorosed root fragments and concluded that SRP proves to be a standard requirement for fibroblast attachment to occur both in fluorosed and nonfluorosed roots. Although there was no significant difference in attachment between SRP and SRP + EDTA among fluorosed roots, EDTA does not seem to be a promising agent for root bio-modification in fluorosed roots in a given concentration and time of treatment.

Comparison between fluorosed and non fluorosed fibroblast attachment onto fluorosed and fluorosed root specimens

A study conducted by Vandana et al. compared the fluorosed and non fluorosed fibroblast attachment to fluorosed and non fluorosed roots. [13] On the comparison of fluorosed and nonfluorosed fibroblasts attachment in fluorosed diseased group treated with SRP, highly significant results were obtained with increased attachment seen in the group incubated with nonfluorosed fibroblasts. While the comparison of attachment of fluorosed and nonfluorosed fibroblasts on FH group, fluorosed diseased group treated with SRP + EDTA and fluorosed diseased group revealed no significant results. SRP proves yet to be a standard requirement for fibroblast attachment to occur both in fluorosed and nonfluorosed teeth. There was no significant difference in attachment between SRP and SRP + EDTA among fluorosed teeth, EDTA does not seem to be a promising agent for root bio-modification in fluorosed teeth in given concentration and time of treatment.

Scanning electron microscope studies to evaluate laser irradiation on roots of flurosed teeth (in vitro study)

The erbium-doped:Yttrium, aluminum-garnet laser has seen increasing use for treatment of root surfaces exposed to periodontitis. However, there is little information regarding the effects of the Er:YAG laser on root cementum of fluorosed teeth.

Root surfaces changes following erbium-doped:Yttrium, aluminum-garnet laser irradiation in fluorosed and non fluorosed teeth

An in vitro study by Dhingra et al. [14] was done in our department to evaluate and compare root surface changes following Er:YAG laser irradiation of fluorosed and nonfluorosed teeth, using SEM 30 periodontally healthy fluorosed and nonfluorosed root specimens were irradiated using an Er:YAG laser (2.94:M wavelength) at 140 mJ/pulse and 10 Hz under a surface-cooling water spray. Examination by SEM was performed to assess a laser induced ultrastructural changes in the root surfaces. Results showed that the root specimens in both treatment groups exhibited evidence of mild thermal-induced change, primarily surface melting. Other surface alterations noted in both treatment groups included surface etching, intermittent smear layer, exposure of collagen tufts, and open dentinal tubules. Intergroup comparisons using the dichotomous data indicated that except for melting of root surface, other undesirable morphological changes were found to be more common in nonfluorosed than fluorosed root specimens. We concluded that undesirable morphological changes were similar for both the FH and NFH groups. The results also indicate that further in vitro studies are required, using a variety of lower energy settings, before clinical trials can be initiated that would evaluate the use of the Er:YAG laser for treatment of teeth with fluorosed root structure. Furthermore, future studies comparing FH and NFH specimens should access both surface and subsurface physical and biochemical changes following laser irradiation.

Root surfaces changes following ND:YAG laser irradiation in fluorosed and non fluorosed teeth

Vandana and Roopa [15] conducted a study to evaluate root surface changes following ND:YAG laser irradiation. The results showed the percentage expression of melting charring open pdl insertion sites were maximum in both fluorosed and NFH root specimens. The percentile occurrence of smear layer open and closed pdl insertion sites was maximum in fluorosed diseased specimen.

Genetic marker study to evaluate the genetic susceptibility to periodontitis in fluorosed subjects

The inconsistency in a relationship of fluorosis to periodontal disease could be attributed to genetic reasons such as variation in occurrence of gene polymorphism among different population globally. Genetic polymorphism has racial variation, and it varies population-wise globally. Like any other complex disease, genetic variants at multiple loci associated with periodontitis synergistically contribute to the overall disease process.

The occurrence of periodontitis in high water fluoride areas has shown a global variation due to involvement of multiple risk factors in its causation. The fluorosis may play as an environmental factor in causing periodontitis through its effects on hard and soft tissues of the periodontium. Environmental factors play an important role in the expression of periodontitis. These environmental factors include oral hygiene/bacterial plaque, smoking, stress and systemic factors that may exacerbate the inflammatory pathology associated with periodontitis. The role of smoking as an environmental risk factor demonstrates variability in causing periodontitis, that is, all smokers do not suffer from periodontitis, could be attributed to genetic polymorphism. Based on this view, fluorosis that is possibly considered as an environmental factor wherein fluorosed subjects may or may not suffer from periodontitis can be attributed to putative genetic factors. To analyze this issue, role of genetic polymorphism requires to be probed in dental fluorosis subjects with periodontitis.

But the association of gene polymorphism in the subjects suffering from dental fluorosis and periodontitis has not being focused so far and hence the current study was conducted by Goswami and Vandana [16] to assess the association of collagen 1 alpha 2 (COL1A2) gene polymorphism in subjects with dental fluorosis and periodontitis and showed no evidence of the association between polymorphisms in the COL1A2 gene with dental fluorosis in high-fluoride exposed populations.

Scanning electron microscope study to evaluate the dentinal tubular changes caused by application of desensitizing agents on fluorosed and non fluorosed teeth (in vitro study)

Fluorosis is one of the factors that bring about mineralisation changes in a dentinal structure leading to dentin hypersensitivity. Mahajan and Vandana, 2013 [17] conducted a study to compare and evaluate the dentinal tubular changes in fluorosed and nonfluorosed teeth subsequent to the application of CA, strontium acetate based sodium fluoride (SAF), Arginine based sodium monofluorophsphate (ARG) using SEM and concluded that while there was significant difference in tubular width of partial occlusion ≤25%, being more in fluorosed group compared to nonfluorosed group after application SAF, ARG. Application of desensitizing agents demonstrated higher number of dentinal tubular occlusion and diameter reduction in nonfluorosed dentin compared to fluorosed dentin.

Effect of 980-nm diode laser-aided circumferential supracrestal fiberotomy on fluorosed root surfaces.

Dhingra et al. conducted a study to evaluate and compared the root surface morphological changes after 980-nm diode laser-aided CSF on fluorosed and nonfluorosed teeth. [18] and showed that there were differences in surface morphology among fluorosed and nonfluorosed roots in the control group. The root specimens of both fluorosed and nonfluorosed teeth irradiated by diode laser exhibited no evidence of smear layer, laser-induced pitting or cavitation, linear cuts/markings, carbonization of surface, and heat-induced surface cracking. However, glazed or slightly melted appearance was observed in root specimens of fluorosed teeth after diode laser irradiation. These findings suggest that the diode laser-aided CSF procedure is free from thermal hazard on nonfluorosed root surfaces but may provoke some thermal changes on fluorosed root surface.

Ongoing projects

  1. Effect of topical application of guduchi gel (herbal extract) in the treatment of periodontitis in fluorosed and non fluorosed patients.
  2. Dentinal hypersentitivity in fluorosed and non fluorosed population.
  3. Association of ER Rsa 1 gene polymorphism with osteoporosis and chronic periodontitis in fluorosed and non fluorosed subjects.
  4. Bone and cemental changes in fluorosed and non fluorosed subjects.


The institutional studies presented above apart from being preliminary were all self-funded and carried out with the single motive of exploring the effect of fluorosis on the periodontium. The age group of the population in these studies was between 15 and 74 years for epidemiological survey [2] and a constant 18-25 years (periodontally healthy teeth extracted due to orthodontic reasons) in in vitro studies [3],[4],[5],[6],[7],[8],[9],[10],[11],[12],[13],[14],[15] that allows for better comparisons of study results within the same study population. In an epidemiological survey, a strong association of occurrence of periodontal disease in high-fluoride areas was found. The evidence of fluoridation's effect on periodontal health is insufficient and mixed. In general, a higher level of gingival inflammation has been observed in fluorosis than in nonfluorosis areas. [21],[22],[23] However, several studies have found no difference in periodontal conditions between fluoride and nonfluoride areas, [24],[25] better gingival conditions in fluoride compared with nonfluoride areas have been reported by others. [26],[27] The possible reasons for susceptibility of the population residing in high-fluoride areas to periodontal disease can be ascertained from both medical and dental literature:

  • Fluoride also had a toxic effect on the alveolar bone of permanent teeth that eventually lead to osteonecrosis and recession of the alveolar crest. [28]
  • The fluorosed teeth radiographically presented the features like osteosclerosis, cementosis and periapical root resorption. [29]
  • Reddy et al. [30] reported calcification of muscular attachments, ligaments and ossification histopathologically, which interferes with the functional movement of the skeletal system. This data is supported by our institutional study, [9] which showed that periodontally healthy fluorosed teeth exhibited a higher percentage of partial/initial mineralization of connective tissue fibers and globular mineralized deposits than NFH teeth. Would these SEM changes indicate calcification of periodontal ligament fibers requires to be elucidated histopathologically.


The direct evidence of toxic effect of fluoride in medical and dental literature theoretically convinces the possibility of toxic effect of fluoride such as cemental necrosis, osteosclerosis and calcification of ligament in human periodontal region as a consequence of the life time exposure to high-fluoride water levels. The toxic effect of fluoride on cementum and bone is not dispensable for the fluorosed human teeth leading to destruction of periodontal structures through a noninflammatory process, which may compound the regular plaque induced inflammatory destruction in the high-fluoride areas. The use of the term "noninflammatory process" gives a better explanation of the deleterious effects of fluorides on the periodontium. Based on the above hypothesis presently the prevalence of periodontitis significantly observed in our study is well-reported. However, the toxic effect of fluorides on human periodontal tissues remains to be researched extensively to confirm the data. [27]

The effect of various periodontal treatment procedures on the periodontal tissues in the fluorosed teeth has also shown significant differences as compared to nonfluorosed teeth.


   Summary Top


In a nutshell, these studies conducted in our institution were a preliminary attempt to investigate any possible relationship between fluorosis and periodontal disease and to evaluate and compare the effect of various periodontal treatment procedures between fluorosed and nonfluorosed teeth. Results indicated that:

  • A strong association of occurrence of periodontal disease in highfluoride areas.
  • Healthy fluorosed teeth exhibited a higher percentage of partial/initial mineralization of connective tissue fibers and globular mineralized deposits than NFH teeth.
  • Fluorosed enamel (5.06 ± 2.88 μ) and cementum (3.80 ± 1.72 μ) specimens exhibited more tooth surface roughness than non fluorosed teeth enamel (2.77 ± 1.69 μ) and cementum (3.93 ± 2.14 μ).
  • Fluorosed enamel (346 ± 52.89VHN) and cementum (48.90 ± 6.85 VHN) demonstrated higher VHN values than nonfluorosed teeth enamel (322.6 ± 46.23 VHN) and cementum (45.22 ± 8.07 VHN).
  • There was a significant increase in surface roughness values for cementum in the Manual Brush and Ultrasonic Brush groups, a significant difference in surface roughness for enamel and cementum in only the Ultrasonic Brush group and increased surface roughness values in fluorosed teeth when compared to nonfluorosed teeth (3.58 ± 0.75 μm v/s 2.93 ± 0.38 μm).
  • There was a significant increase in surface roughness values for both enamel and cementum in the ultrasonic scaler group. A comparison of the mean Ra values for the untreated fluorosed control specimens vs. those for the nonfluorosed group indicated relatively equal topographical characteristics (3.90 ± 1.04 μm and 6.18 ± 1.16 μm v/s 4.97 ± 2.81 μm and 4.02 ± 1.74 μm).
  • Root bio-modification procedure brings in definite difference between fluorosed and nonfluorosed dentin and cementum specimens. The amount of smear layer removal and exposure of collagen matrix in dentin specimens were variable in different groups. The exposure of fibrillar structures on cementum specimens were seen significantly on healthy specimens as compared to diseased specimens.
  • Root bio-modification brings about definite change in dentinal and cemental changes.SRP proves yet to be standard requirement for fibroblast attachment to occur both in fluorosed and non fluorosed teeth, and EDTA does not seem to be a promosing agent for root bio-modification in fluorosed teeth in given concentration and time.
  • Relatively greater root conditioning (in terms of comparison between the number of dentinal tubules, tubular width 1.71 μ and surface area) of fluorosed teeth compared to nonfluorosed teeth (tubular width1.56 μ).
  • Following Er:YAG laser irradiation, except for melting of root surface, other undesirable morphological changes were found to be more common in nonfluorosed than fluorosed root specimens.
  • Following ND:YAG laser irradiation the percentage expression of melting, charring and open pdl insertion sites were maximum in both fluorosed and FH root specimens. The percentile occurrence of smear layer open and closed pdl insertion sites was maximum in fluorosed diseased specimen.
  • Fluorosis is one of the factors that bring about mineralization changes in a dentinal structure leading to dentin hypersensitivity. Application of desensitizing agents demonstrated higher number of dentinal tubular occlusion and diameter reduction in nonfluorosed dentin compared to fluorosed dentin.
  • A preliminary study to find out the genetic susceptibility of an individual to periodontal diseases showed no evidence of the association between polymorphisms in the COL1A2 gene with dental fluorosis in high-fluoride exposed populations.
  • Diode laser-aided CSF procedure is free from thermal hazard on nonfluorosed root surfaces, but may provoke some thermal changes on fluorosed root surfaces.


We only hope that these studies will encourage further research in this direction and help in better understanding of the relationship between the fluorosis and periodontal disease. A great deal of time has been spent in studying population comparing periodontal conditions between high and low fluoride areas without actually focusing on the destructive effects of fluoride on the human periodontium. Considering our institutional report, the fluorosis can be regarded as an environmental risk factor in the causation of periodontitis. Groundwater with fluoride concentration above the permissible limit set by WHO that is, 1.5 mg/l have been recorded in several parts of the world. In 1984, WHO estimated that more than 260 million people living all over the world consume water with fluoride concentration above 1 mg/l (WHO, 1984). Based on WHO studies the fluoride effect on the periodontium requires to be studied globally. If we turned our attention to populations susceptible to disease, it might be a fruitful area of research in understanding the etiology and pathogenesis of periodontitis, and whether fluorosis is a bane or boon to periodontal structures?


   Acknowledgments Top


I express my profound thanks to Dr. Charles M Cobbs, Professor, Department of Periodontology, University of Missouri, USA, for interpretation of Scanning Electron Microscope photographs and for his valuable suggestions and inputs for the conductance of the studies.

My heart fills with fond gratitude as I reminisce the cherishable moments of benevolence and co-operation I received from my postgraduate students Pauline George, Kunal Dhingra, Sesha Reddy, Sanjeevkumar Reddy, Sadanand K, Jayashree, Roopa Patil, Pragya Goswami, Neha Mahajan, Saubhik Ghosh, Haneet Kaur and Priyanka Dalvi.

Special thanks to Priyanka Dalvi, my postgraduate student for helping me in the making of this paper.

 
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   Authors Top

About the Author Dr. Vandana K L received her B.D.S. from Govt. Dental College, Banglore in 1984 and her M.D.S.(Periodontics) from Bapuji Dental College 1988. She has an excellent academic career spanning over 28 years. She has contributed vastly to field of Periodontics through various innovative research projects with high citation index of 212 at College of Dental Sciences, Davangere where she is currently Sr Professor, Department of Periodontics and Asso. Dean Of Academics. She is a reviewer for many national and international journals with high impact factor also an invited editor of International dental journal. She has been invited as guest speakers for many national and international conferences.



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