The Chemistry of Toothpaste

Introduction

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Toothpaste is paste used on a tooth brush for cleaning teeth and a product well known by Americans and used frequently each day.  I chose to research toothpaste because I wanted to show people how much chemistry is involved in something as simple and commonly used as toothpaste.  Toothpaste affects everyone's life and it is something I use twice a day to keep my teeth shining, my gums healthy,and my breath fresh.


Composition of ...

The only two active ingredients in toothpaste are Sodium Fluoride (NaF) and Triclosan (C12H7Cl3O2) ;however, these two ingredients are found in very small amounts each accounting for only .2-.3% of the toothpaste.  The most abundant ingredient in toothpaste which, accounts for 50% of it, are abrasives such as silica gels or Silicon Dioxide (SiO2). There are generally several different abrasives that account for small amounts of the toothpaste as well. Water (H20) is 20 to 40% of the ingredients in toothpaste.  The rest of the ingredients include sorbitol (C6H14O6) for flavor and as a humectant to keep the toothpaste smooth and wet.



Main Chemicals, Compounds, Components

The first active ingredient in toothpaste that plays a large role in keeping your teeth clean is Sodium Fluoride.  Sodium Fluoride or NaF, discovered in the early 1900s by Frederick Sumner McKay, is a white odorless solid that accounts for only .24% in all colgate toothpastes.  NaF is an ionic compound that crystallizes in a cubic structure and has octahedral molecular structure meaning there are 6 atoms arranged symmetrically around a center atom like the vertices of a octahedron.  The mineral form of sodium fluoride is villiaumite however it is not obtained from villiaumite.  It was first used in toothpaste in 1914 and still is in toothpaste today as it keep your teeth hard and healthy.  The second active ingredient in toothpaste is Triclosan or C12H7Cl3O2. First patented in 1964 in sweden by the company Ciba- Geigy. Triclosan is .30% of all colgate toothpastes.  In toothpaste it works as antifungal and antibiotic preventing gingivitis. Other than toothpaste it is also used in many other cleaners as well as shampoo, bedding,and garbage bags. It is a solid white powder that is classified as a chlorinated aromatic ether.  There is much controversy over the safety concerns of triclosan; however, production still continues through synthesis.


Chemistry's Role


 Everyday items, such as toothpaste, revolve around chemistry.  Lets first start off with toothpaste’s most well known ingredient Sodium Fluoride. The compound Sodium Fluoride is  found naturally in this world in the mineral villiaumite; however, Sodium Fluoride or NaF is not produced commercially from this source.  Sodium Fluoride is mass produced through two different man made processes.  The first way it is made is during the manufacturing of phosphate fertilizers.  To make phosphate fertilizers they crush apatite and soak it in sulfuric acid.  This reaction gives off phosphoric acid, calcium sulfate, hydrogen fluoride, and Silicon tetrafluoride. Then the hydrogen fluoride and Silicon tetrafluoride have the sodium fluoride separated by basically scrubbing the compounds with water or fluosilicic acid.  The other way is by neutralizing hydrofluoric acid with sodium carbonate(HF + Na2CO3= NaF + H2O + CO2)or sodium hydroxide (HF + NaOH = NaF + H2O).  This is not the only chemistry involved, once in toothpaste Sodium Fluoride goes to work.  Not only does Sodium Fluoride prevent further tooth decay, it can repair previous minor tooth decay.  Sodium Fluoride repairs your teeth by replacing the lost calcium and phosphorus.  When it reaches your teeth the enamel absorbs it and the lost minerals are replaced in the process called remineralization keeping the teeth hard.This helps slow down the dissolution of the minerals in the demineralization phase and the strengthening of the teeth protects them from the bacteria in your mouth that produce decaying acids.

The second active ingredient in toothpaste is Triclosan.  Triclosan or C12H7Cl3O2 is not naturally occurring. Instead, Triclosan is synthesized through a several step process. First, 1-(2-hydroxyethyl)pyrrolidin-2-one is desiccated using Zinc or calcium oxide turning it into 1-vinylpyrrolidin-2-one. This product can then be reacted with 5-chloro-2-(2,4-dichlorophenoxy)phenyl acrylate in the chemical heptane to form triclosan.  In toothpaste triclosan works as antifungal and antibiotic protecting your gums from gingivitis. Triclosan is bacteriostatic and targets bacteria in fatty acid synthesis.  Triclosan virtually releases the ENR enzyme that prevents the fatty acids from doing damage to your gums and it does not affect your body because you don't have the ENR enzyme.  So every morning and night when people are brushing their teeth there is tons of chemistry going on.


Background Research


The history of toothpaste goes way back to the Egyptians in 5000 BC who were the first ones to use a paste to clean their teeth, keep their gums healthy and their breath fresh. Greeks and Romans used a paste as well to clean their teeth and in China and India they started to use toothpaste about 500 BC. In beginning the components of the paste differed.  Some of these ancient pastes contained ox hooves’ and eggshells mixed with pumice. The Greeks and Romans preferred more coarse paste using ground bone and oyster shells. To refresh their breath, they used anything from charcoal to bark and the chinese even used ginseng, salt, and herbal mints. In the 1800s was when toothpaste really developed as common ingredients in toothpaste were soap, chalk, and even nuts.  Most of people did not buy toothpaste but rather made it at home using makeshift charcoal recipes.  It was not until the 1850’s that toothpaste became a liquid. Previously, all toothpaste was powder, but now it was a liquid sold in jars.  In 1873 Colgate became the first to commercially sell toothpaste and they called it Creme Dentifrice. In the late 1890’s Colgate came out with the collapsible toothpaste tube that was invented by Dr. Washington Sheffield. During the 1900’s specific types of toothpaste came out and the soap in toothpaste was changed to sodium lauryl sulphate.  The new types of toothpastes included types for people with sensitive teeth and fluoride toothpaste to slow decay were a few.  More modern improvements include whitening toothpaste and toothpaste with Triclosan.  Now present toothpastes are composed of all sorts of flavoring, sweeteners, and other ingredients to preserve it.


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About the Author


Alex is a Junior at Billings Senior High School.  He enjoys learning about science and understanding chemistry and its impact on life.  He is in all honors classes and a state AA football champion. Alex also enjoys hunting, fishing, and the outdoors.









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