 Hello everyone, welcome back to a new session on dentistry and more. So today we have a new topic that is flu rights. So flu rights will be covered under different sessions. So today's sessions will be covering about history of flu rights. So what is so much special about flu rights in dentistry was nowadays we see flu rights in almost all the dental products like toothpaste or mouth washes or gels, everything has fluoride because it has proven that fluoride can prevent dental caries to an extent and fluoride is the most significant element which prevents dental caries. So how we know that the fluoride can prevent dental caries, it is like almost a centurion that put by the scientist and epidemiologist which has ultimately reached the conclusion that fluoride can prevent dental caries. So we have to study the history of fluoride, how the element was invented, how it was found out that fluoride causes fluorosis then it was used to prevent dental caries and all this will be covered in this chapter. And today's section will be covering about the history of flu rights, the scientist and their inventions, their contribution and the significant contribution by new scientist ultimately that contributions leads to the conclusion that fluoride prevent dental caries. So let's see the some basic things about fluoride. It has atomic weight 19 atomic number nine and it is derived from a Latin word fluoro that means to flow and it is very electronegative element. So it cannot exist as an element and it always stays like with the compound. It combines with some other element and like calcium fluoride fluoride, sodium fluoride. So it always exists as compounds. So let's see the historical evolution of fluoride. So we have to start with a famous dentist named Frederick McKay. So in 1901 he finished his dental graduation from Pennsylvania dental school and started practicing in a city known as Colorado Springs in USA. So there he found out in many patients some peculiar enamel markings and he could not find any scientific literature to substantiate this peculiar enamel markings and the discoloration or hypomentalization or the brown discoloration on the teeth and he called this enamel as motile enamel. So it looked like white flex, yellow or brown spots which are scattered irregularly and streaked over surface of the tooth. So Dr. Frederick McKay was the first name you should remember. He was the pioneer in the fluorosis or the fluorine identification or fluoride and dental caries or fluorine and fluorosis identification. So Dr. Frederick McKay in 1901. So he identified the Colorado Stains or Colorado motile enamel. Then came Dr. G. V. Black. So he approached another doctor or dentist named G. V. Black. He was that time Dean of Northwestern University Dental School. So he did not actually believe it the theory of all the findings of Dr. Frederick McKay but what he did was he collected some motile enamel samples and agreed to attend the Colorado State Dental Association 1901, 1909 and spend some time in Colorado. So agreed to visit Colorado Springs for further investigation but meanwhile what our Frederick McKay did was he did a study with the help of Isaac Burton, a flaming. He did examination among almost 3,000 children in public schools of Colorado Springs and found out that almost 88% of children's were with motile enamel and he published the same findings along with G. V. Black as an entemic imperfection of enamel of teeth here to for unknown in literature of dentist. This was the first published a finding of dental fluorosis or motile enamel but still they were not able to find out what was the first. So in 1916 McKay and G. V. Black conducted studies on individuals that is from 26 different communities in USA and concluded that a particular factor in the water causing this motiling of the enamel and that was affecting during the tooth calcification. So similar motilings were seen in the city of Britain. So it was sitting in the USA not in United Kingdom. So Britain where the water supply people's drinking water supply was changed from shout out to deep wells in 1898. So it was found that people were born before 1898 were having normal teeth and people who went after 1898. In another word we can say that people who started drinking the deep well water are started showing enamel motilings. So it made them believe that it was due to the particular factor in the water which causing enamel motilings. The same thing was also happened in Bauxite because in 1909 this water changed from shout out to deep water. Then came another scientist H. V. Churchill. He was a chief chemist in Alcova Company in Pennsylvania. So that time in USA people were using aluminum for aluminum were for cooking but they mentioned that aluminum utensils cause poisoning because most of the aluminum product that Alcova Company taking from Bauxite area because aluminum just taken from Bauxite and in Bauxite there were a lot of dental enamel motiling. So they thought this problem with aluminum because in Bauxite region there are people with motiling of enamel so it could affect us also because of this particular aluminum product. So Alcova Company had to answer for this poisoning theory by the people of USA because of the Bauxite region people showing enamel motiling and they thought that it was due to the aluminum and Churchill took sample from Bauxite and did analysis and found out that 13.7 parts per million of fluoride was present in Bauxite water. So Churchill was the first person who found out the presence of fluorine in water and later he started collecting samples from various regions like Colorado Spring had 2 ppm and Bauxite as I mentioned 13.7 well near Kiddur 12 ppm then 11 ppm and 6 ppm. So various regions where this motiling were recorded are having high amount of fluorine in the drinking water setup but still there was no precise correlation between fluoride content and this motiled enamel. They could not establish a proper parcel link between this fluoride and motiling of the enamel thereby this company proved that it was not due to the aluminum or aluminum is not a poison it was due to the amount of fluorine in the water which is causing fluorosis or the motiling of the enamel at Bauxite region. So it was to protect their company but accidentally they found out the element fluorine. So next came the famous epitomologist or public health scientist Dr. H. D. Dean or H. Trendley Dean. He conducted some landmark survey in the history of evolution of fluorides that is the Schu Leather Survey it is commonly asked question and it is very interesting the name is very interesting Schu Leather Survey. So he was appointed by United State Public Health to continue the work of McKay. So they wanted to continue the work of Dr. McKay what was the reason for this motiling of the enamel and what is the connection between fluoride and this motiling of the enamel because by the time fluoride was already into picture and they wanted to show or prove that this could be reason for the fluoride could be the reason for fluorosis or motiling of the enamel. So Schu Leather Survey was done by Trendley H. Dean. So his first task was to continue McKay's work to find the extent and geographic distribution of motile enamel. So he wanted to see how far it is distributed how much area it was affected. So what he did was he started posting lectures to local and state and society in country local physicians asking if motile enamel existed in their area. So almost 1200 letters he sent and 632 replies were received. Then he started his famous Schu Leather Survey. Dean and his colleagues started Schu Leather Survey among the 22 cities in 10 states of USA and collected 5,824 children and gave a report and why it was known as Schu Leather Survey because it was a door to door survey because he started walking to each place or his friends started walking asking questions. So it was involving a lot of walking hence it was called as Schu Leather Survey because of this door to door survey and a lot of walking and what they found out was a striking feature. You can see that this blank one is normal enamel and this black one is motile enamel. So you can see as the PPM of fluoride is increasing the motiling also started increasing. So you can see 0.6 ppm there is no motiling 0.9 there is very little or very mild motiling 1.7, 2.5, 2.9, 3.9 and for 6 the high motiling seen. So they could found out that the presence of fluoride is directly proportional to the motiling of the enamel that was the biggest conclusion of this Schu Leather Survey directly proportional fluoride and motiling. Then this gave the report like a high concentration of fluoride water is directly related to the motiling enamel motiling was widespread in areas with water content more than 3 ppm with a discrete pitting if it is more than 4 ppm whereas motiling was less where it is 2.5 or 3 and no motiling was present where it is around 1 ppm. So these were the conclusions of Schu Leather Survey. So motile enamel gave way to more exact terms. So they started calling this motiling of enamel as dental fluorosis because the perfection imperfection was caused by fluorine. So they started calling as dental fluorosis and in 1934 Dean's standardized a classification of fluorosis and it is known as Dean's fluorosis index. We have already learned it in a practical session and it was modified later in 1942. And in 1942 he found out that drinking 1 ppm of water it would reduce carries by 60 percentage then he conducted another study 21 cities study. This is different from Flu Leather Survey. This was done by Dean Arnoldt and Elvov in 1942. So what he wanted to prove that there is a inverse relationship between this fluorosis and dental carries because what he observed was wherever this fluorosis is present the dental carries was very less. So he wanted to prove that the fluorine and carries are inverse relationship sorry not the carries and fluorine fluorosis and dental carries. So what he did was carries experience was investigated among 7257 children that is between 12 to 14 years from the 21 cities of four states. Okay this Schu Leather Survey was different it was done among the 22 cities of 10 states whereas 21 city studies were done in four states. Okay so it was done in four states but 21 cities it was to prove the relationship of dental fluorosis and dental carries but Schu Leather Survey was done to prove that enamel, modeling and the amount of fluorine in water there is no carries in Schu Leather Survey. So in 21 cities concluded that there is an association between the increasing fluoride concentration in the drinking water and decreasing carries experience. So that was the landmark conclusion which created history in public health because they found out that maximal reduction in carries experience occurred with the concentration of 1 ppm of fluoride drinking water and this became the foundation of fluoridation of water, fluoridation of toothpaste, fluoridation of all the other products to get a net effect of 1 ppm. So 1 ppm was approved by the World Health Organization in later times so as to provide fluorides to people with less or more carries area and less fluoride in drinking water. WHO only recommended to start water fluoridation to get the benefit of fluorine to prevent dental carries. So it is like double A spot if it goes very higher it creates problem like fluorosis. If it is very less it has no benefit and there will be carries. So it has to be at an optimal level that is 1 ppm. So this was the graph where they found out after the 21 cities studies. So we can see that the ppm is on the x axis and the carries experience on the y axis. So you can see there is an inverse relationship as the fluoride content is going high there is a significant reduction in the carries. You can see this curve is going downward as the fluoride is going on the x axis. So there is an inverse relationship between carries experience and fluoride. So that's all about history of fluorides. So in next session we will be seeing about systemic fluoride where they started water fluoridation studies. After this World Health Organization or the not World Health Organization after this US public health service started giving permission to water fluoridation in certain cities and it has all proved that there was a reduction of around 50 to 60 seconds. So that was a different story of the water fluoridation studies and it was among some six, seven cities in Canada and USA. So they all proved that water fluoridation was effective in preventing dental carries. So that's all about history of dental fluorosis and its effect with dental carries. And just for your information fluorides are present all over the lithosphere, biosphere and atmosphere. So it is an organic fluoride compound and it is this lake you have to remember highest natural fluoride concentration is Nakuru Lake in Kenya almost 2800 ppm. So we were talking about 345 ppm and this is 2800 ppm that is Lake Nakuru in Kenya and 15 states in India are affected with fluorosis. Some states almost 5200 states these all are coming in fluoride toxicity. So I just want to show that some natural products which is having high amount of fluoride that is tea leaves having high amount of fluoride that is 3.22400 ppm and the fish products like salmons, sardines and fluoride content cereals, banana, sweet potatoes. That's all about history of fluorides. It started from Dr. Frederick McKay, then G.V. Black, then Churchill, then came our famous friendly SD. He conducted 21 city studies and shoo leather survey. Finally found out that giving one ppm fluoride in drinking water could prevent dental caries. So US public health adopted this concept and started giving permission for water fluidations. So after that 1945 the first artificial fluidation started in USA. So in next video I will be explaining more about this water fluidation studies under systemic water fluidation. So this video mainly introduce the history of fluorides and various scientists, various surveys and landmark achievements by the scientists. So the next sessions will be having systemic topical fluoride toxicity and de-fluidation techniques. But in India there is no scope for water fluidation because as I told you 15 out of 30 states including the unitary trees are affected with endemic fluorosis. So we are into the action of de-fluidation but this community water fluidation is a great moment and a great invention in the public health sector and it was started in USA and they continued this water fluidation for at least 30 to 40 years and then around 1970 since this toothpaste started into the market which provide equal effect of caries protection. It slowly started disappearing almost of the plants were closed around 1970s because the same benefit could be obtained by the toothpaste. So why to waste so much money the installation charges for water fluidation but this was so this was how fluoride came into our dentistry and how it protected dental caries this was one of the landmark invention or achievement by the public health. So I'll come with a system of fluidation in my next video.