INTRODUCTION:

Fluorine, which has been considered as one of the 14 physiologically most essential mineral for the normal development, growth and maintenance of the human body, does not exists in its elemental state [1]. It exists in its simplest anionic form 'fluoride' and is found in great abundance in a large variety of minerals like fluorspar, rock phosphate, fluorite [2]. Due to the unanimous presence of fluoride in the earths crust, all the water sources are enriched with varying concentration of fluoride content. It is found in seawater at a concentration of around 1.2 – 1.4 mg/litre, in ground waters at concentrations up to 67 mg/litre, and in most surface waters at concentrations less than 0.1 mg/litre. Hence all our water sources are willingly or unwillingly are sources of fluoride content.

FLUORIDE – DOUBLE EDGED SWORD:

The behavior of fluoride ions in the body is like that of a double edged sword [3]. Just as many other minerals and nutrients, optimum level of fluoride intake is essential for the normal growth and development of the body, whereas when taken in large amounts it becomes toxic leading to severe deformities in a person. Consumption of fluoride within the optimal levels proves to be an important factor in preventing dental caries, that is the reason due to which patients in the initial stages of dental caries are administered with fluoride gel, whereas on the other hand, intake of fluoride beyond the threshold concentration would result in deleterious effects of different parts of the body such as Dental Fluorosis and Skeletal Fluorosis.

EFFECT OF FLUORIDE ON TOOTH DEVELOPMENT:

It is a well known fact that fluoride can have both beneficial and detrimental effects on the dentition ever since Mc Kay and G. V. Black published the effect of fluoride on dentition in 1916 [4]. The beneficial effects of fluoride on dental caries are primarily due to the topical effect of fluoride on the teeth after it has erupted into the oral cavity [5].

There are three main mechanisms by which topical fluoride can prevent decay. It can:

(1) enhance demineralization of carious lesions before they become full-blown cavities

(2) inhibit demineralization, and

(3) poison the enzymes in the oral bacteria that produce the acids that erode The tooth Most importantly, none of the above three mechanisms are dependent on the concentration of fluoride content in the internal matrix of the tooth. Hence all three mechanism of topical action can take place even without ingestion of one drop of fluoride [6]. In contrast, detrimental effects are due to absorption of excessive fluoride during tooth development resulting in dental fluorosis that is one of the most common type of enamel demineralization [5].

DENTAL FLUOROSIS:

Dental fluorosis may be clearly defined as hypo-mineralisation of enamel resulting from excessive intake of fluoride during tooth development [7]. Excessive fluoride can come from fluoride pollution, inhalation of fluoride fumes from aluminium industry, highly fluoridated water, supplements, excessive consumption of tea, foods and beverages processed with fluoridated water, and through the usage of Teflon pans for cooking. In fluorosed enamel, fluoride decreases free calcium ion concentrations in the mineralizing matrix thus disturbing mineralization. The reduction in free calcium ions indirectly interfere with the proteinases which degrade matrix proteins during the maturation phase of amelogenesis. It results in the retention of matrix proteins and improper growth of crystals which accounts for increase porosities occupied by water and the following physical changes. The most important factors which determine the severity of fluorosis are duration, the frequency and timing of fluoride exposure during the period of tooth development. The appearance of the fluorosed teeth varies from white streaks (mild form) to brown (moderate form) to dark brown or black (severe form) discoloration. Severe fluorosis are sometimes characterized by enamel surface defects. The most common appearance of fluorosis is characterized by banding following the developmental lines of enamel. Most of the patients who are affected with mild or moderate fluorosis are unaware of their medical condition. Only a very few percentage of patients who are affected by severe fluorosis are aware of the fact and seek medical treatment for dental fluorosis to improve their aesthetic appearance [8].

FLUOROSIS IN INDIA:

Due to the inevitable presence of fluoride in the earths crust, all our water sources are rich in fluoride content. Eventually, groundwater which serves as the main sources of drinking water would be enriched with fluoride ions, which due to consumption during tooth development or over a long period of time would lead to dental fluorosis. In India, fluorosis has been considered as a major public health problem. More than 60 million people in India consume water having more than optimal required concentration of fluoride [9]. According to statistics, more than 15 States in India that is approximately 60 million people suffer from fluorosis. The most severely affected states are Andhra Pradesh (reported prevalence of fluorosis among young adults is 35%), Chhattisgarh (reported 8.2% prevalence of dental fluorosis) Uttar Pradesh, Gujarat, Tamil Nadu, Karnataka, Rajasthan Maharashtra and Haryana [10].

DIAGNOSIS OF FLUOROSIS:

Dental fluorosis is identified mainly on the basis of its typical clinical appearance, that is, hypoplastic teeth with pitted enamel, usually combined with a history of consuming fluoride-rich water during childhood (tooth development). Fluorosis is often confused with hypo maturation type of amelogenesis imperfecta. Mainly, its patient history of being the resident of an area that is rich in fluoride in water supply helps in the diagnosis of dental fluorosis. Dean, in 1942, proposed Dean's Fluorosis Index that classifies fluorosis on the basis of clinical appearance which is widely used for the classification of fluorotic teeth [11].

Radio-graphical appearances also show great variability for skeleton fluorosis. Some of the other indices available are:

The tooth surface fluorosis index

Fluorosis risk index

TREATMENT AVAILABLE FOR FLUOROSIS:

Management and treatment of dental fluorosis depends on the severity of the condition as well as patients’ motivation towards the treatment. The most common reason for which the patients come seeking treatment for fluorosed teeth is the discolouration of tooth. For mild fluorosis discolouration and for moderate fluorosis discolouration, treatment to change the aesthetic appearance of the teeth can be accomplished with minimally invasive procedure using micro-abrasion. Micro and macro-abrasion, which is used as an option for mild-to-moderate fluorosis is a faster procedure but it involves the use of high-speed hand piece. If proper coolants are not used or if the operator is not skilled and experienced, it can even result in damage to the tooth structure. In case of severe fluorosis, micro-abrasion in combination with bleaching can be used as a treatment to provide acceptable results. Bleaching in other words known as tooth whitening is restoration of natural tooth shade. Techniques which are used in bleaching are bleaching strips, bleaching pen, bleaching gel and laser tooth whitening. Bleaching is considered as the least invasive option, but it is also associated with sensitivity in some cases.

Other alternatives may be veneers or full coverage crowns. Full coverage restoration requires very careful planning as well as execution of the procedure. For more severe fluorosis with dark discolouration and surface pitting, adhesive restorative dentistry may be necessary to fulfill a patient’s aesthetic desires. As such, there is no

standard treatment for skeletal fluorosis; but there are assumptions that it can be reversible in some instances. After fluoride ingestion is stopped, existing fluoride level in the bone starts to recede and is excreted via urine [12]. But this usually shows negligible results, and is accompanied with very disastrous side effects, hence is not widely accepted .

PREVENTION IS BETTER THAN CURE:

Dental fluorosis is irreversible in nature and its treatment requires skilled technicians, complex and expensive procedures which are extremely time consuming and are not accessible to all sections of the society. There is no specific or particular treatment measures for skeletal fluorosis. Therefore, due to lack of proper treatment measures for dental as well as skeletal fluorosis, prevention of dental fluorosis through appropriate measures is found to be the best method to combat this endemic disease - FLUOROSIS. As we already saw the most common way through which fluoride ions enters our body is through the heavily fluoridated groundwater (drinking water) due to the universal presence of fluoride in the earth crust. Hence the first step in prevention of dental fluorosis is provision of safe and no fluoridated drinking water.

Maximum Fluoride levels in different waters have been prescribed by various authorities which help in prevention of fluorosis through drinking water [13].

PROVISION OF SAFE DRINKING WATER:

The most common and easy method to provide safe drinking water is by removing fluoride from drinking water sources which is otherwise called as defluoridation using suitable techniques.

DEFLUORIDATION:

Defluoridation refers to methods of water treatment that reduce the concentration of fluoride in the water, normally, in order to make it safe for human consumption. Defluoridation can be achieved through two major ways,1) removal of fluoride content at the water source (large scale) 2) treatment of water in the household level (small scale). Treatment at the source is best suited for developed countries as it can be carried out on a large scale under direct supervision of skilled personals [14]. On the other hand, treatment of the water at point of use level i.e. at household level can be preferred in less than developed countries as it will be more cost effective.

Defluoridation technique can be broadly classified as [15]

Precipitation – Nalgonda Technique:

The first community defluoridation plant for removal of fluoride from drinking water was constructed in the district of Nalgonda in Andhra Pradesh. Nalgonda Technique involves addition of Aluminium salts, lime and bleaching powder followed by rapid mixing, flocculation, sedimentation, filtration and disinfection. Aluminium salt may be added as aluminium sulphate (alum) or aluminium chloride or combination of these two. It is responsible for removal of fluoride from water . This can be considered to be a versatile technique as it can be used for both large scale as well as small scale treatments.

Adsorption Technique:

This technique functions on the adsorption of fluoride ions onto the surface of an active agent. In the adsorption method, raw water is passed through a bed containing defluoridating material. The material retains fluoride either by physical, chemical mechanisms.

1. Activated Alumina [14]

Activated alumina (Al2O3), which has been used since 1934 for Defluoridation is prepared by low temperature dehydration (300-600°C) of aluminum hydroxides. The legend exchange reaction at the surface of activated alumina is thought to be the probable mechanism of fluoride removal. The advantages of this domestic defluoridation units are: it serves as a cost effective treatment as only a limited volume of water is required (for cooking and drinking) to be treated and the lower requirement of treated water correspondingly lowers the need of chemicals and generates lower volume of sludge.

2. Bone Char[14]:

Bone char is ground animal bones, charred at optimum temperature (5000C) to remove organics. The fluoride removal mechanism involves the replacement of carbonate of bone char by fluoride ion.

3. IISc Method [16]:

The Indian Institute of Science (IISc), Bangalore developed this simple defluoridation technique. The method uses magnesium oxide, calcium hydroxide and sodium bisulfate. Magnesium oxide removes dissolved fluoride ions from water samples by precipitating fluoride as insoluble magnesium fluoride;

4. Other methods of defluoridation include reverse osmosis, electro dialysis and electrolysis [12]

OTHER METHODS TO PREVENT FLUOROSIS:

Reduce the consumption of foods processed with fluoridated water Reduce the consumption of tea:

Tea plants absorb fluoride from the soil due to which tea leaves contain high levels of fluoride. Numerous studies have linked excessive consumption of tea to skeletal fluorosis.

Reduce the use of dental products with high fluoride content:

Many dental products now contain fluoride, including over 95./. of toothpaste. Studies show that significant number of children swallow more fluoride from toothpaste which exceed the recommended levels.

Workplace Exposure:

fluoride is a common air contaminant in industrial workplaces. As a result, workers in many heavy industries including the aluminum, fertilizer, steel industries will be exposed to high levels of fluoride.

DISCUSSION:

Dental fluorosis which is also called as mottling of tooth enamel is a developmental disturbance of dental enamel ,due to the excessive consumption of fluoride during tooth development. Patients with mild or moderate fluorosis are usually unaware of their medical condition and only patients with severe fluorosis approach the dentist seeking treatment for the discolouration of teeth to fulfil their aesthetic needs. The various treatment options for dental fluorosis include micro abrasion, macro abrasion, bleaching, veneer and full coverage crowns. Dental fluorosis is irreversible in nature and its treatment requires complex and expensive procedures which are time consuming and are not easily available to all sections of the society [12]. As we discussed earlier, excessive consumption of fluoride is through fluoridated water, foods processed with fluoridated water, tea leaves and fumes from industries.

It is difficult to draw any conclusion for this multi-faceted problem of fluorosis or to propose a universal strategy to mitigate fluorosis, which would be acceptable by all. Therefore, due to lack of sustainable treatment measures for any form of fluorosis ( including dental and skeletal fluorosis) prevention and control through interventions and appropriate measures (provision of safe water and safe food) is said to be the best approach to manage this endemic disease and proves to be the ultimate solution to put an end to this fluorosis menace.

REFERENCES:

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16. Eswar P, Devaraj CG. Water defluoridation: Field studies in India. Indian Journal of Dental Advancements. 2011; 3 (2): 526–33.

Received on 30.03.2016 Modified on 22.04.2016

Research J. Pharm. and Tech. 2016; 9(7):967-971.

DOI: 10.5958/0974-360X.2016.00185.2