Toothpaste, making

In Chapter 5, you will find out about a chemical change that will dissolve that solid, and a similar change that dissolves the enamel on your teeth. Chapter 5 will also show you how fluoride in your toothpaste makes a minor chemical change in your mouth that can help fight cavities. 

Zinc oxide is a white powder that makes a very opaque paste when mixed with water or oils. It is used as a sunblock and as a colorant in toothpastes and cosmetics. Zinc oxide is used in many of the same products as titanium dioxide. 

But potassium nitrate is also used in toothpastes that are formulated to make teeth less sensitive to pain. As gums recede and the tooth root dentin becomes exposed, teeth can become hypersensitive to hot or cold foods. Potassium nitrate interferes with the transmission of pain signals in the nerves of the teeth. 

Toothpaste must have thickeners to help it squeeze out of the tube and stay on the toothbrush. It must have detergents to remove fatty films, water softeners to make the detergents work better, and sweeteners (preferably non-nutritive so as not encourage bacteria). 

Zeolites form a unique class of oxides, consisting of microporous, crystalline aluminosilicates that can either be found in nature or synthesized artificially [J.M. Thomas, R.G. Bell and C.R.A. Catlow in Handbook of Heterogeneous Catalysis (Ed. G. Ertl, H. Knbzinger and J. Weitkamp) (1997), Vol. 1, p. 206, VCH, Weinheim.]. The zeolite framework is very open and contains channels and cages where cations, water and adsorbed molecules may reside and react. The specific absorption properties of zeolites are used in detergents, toothpaste, and desiccants, whereas their acidity makes them attractive catalysts. 

Aluminum oxide is used to make synthetic rubies and sapphires for lasers beams. It has many pharmaceutical uses, including ointments, toothpaste, deodorants, and shaving creams. 

Probably the most common use of fluorine is its addition to municipal water supphes to help prevent tooth decay. Stannous (II) fluoride (SnFj) is added to the water in proportions of about one part per million (1 ppm). In addition, many brands of toothpaste add stannous fluoride or other fluoride compounds to their product to help prevent tooth decay. Tooth enamel degenerates overtime. Fluorine promotes remineralization, essentially making a form of new enamel called fluorapatite, which is resistant to decay. 

Toothpaste, toiletries, and cosmetics make up the largest sorbitol use (35%). Others uses include confections and food (30%), ascorbic acid (15%), industrial surfactants (10%), and pharmaceuticals (7%). 

The risk of fluorosis is only of concern for children below about 8 years of age, because enamel can no longer be affected once pre-eruptive maturation has occurred [89]. As far as cosmetic effects are concerned, the critical age is somewhat younger because at this age the central incisors are undergoing development, and hence are at a stage that makes them susceptible to fluorosis. For children at the age likely to be affected, the main sources of fluoride are drinking water, processed food and beverages, toothpaste and other dental products (i.e., tablets or drops). 

The wide variations in fluoride intake reported in the literature make its accurate estimation difficult. Our estimates show that the total intake of fluoride in infants and children from diet, fluoride supplements and use of fluoridated toothpaste is 0.008-0.111 (average 0.066) mg/day/kg body weight in non-fluoridated areas and 0.016-0.147 (average 0.063) mg/day/kg body weight in fluoridated areas. High intake of fluoride in non-fluoridated areas is ascribed to the use of fluoride supplements and in fluoridated areas to fluoride added into water. Both intakes exceed the lower threshold and are close to the upper threshold of 0.07 mg/day/kg body weight for the appearance of dental fluorosis. 

Most of the world production of phosphates goes into fertilizer, but some is used as detergent builders (Section 7.7). In toothpastes, calcium pyrophosphate has proved effective as a mild abrasive in eliminating tartar, while Na2[FP03], made by reaction of NaF with cyclic sodium metaphosphates (NaP03), is widely used as a fluoridating agent to suppress dental caries (Section 12.3). A minor amount of rock phosphate is used to make elemental phosphorus by reduction with coke in the presence of silica in the electric furnace (see Section 17.7) ... 

Sodium Lauryl Sulfate (SLS) This substance makes everything from shampoo to bubble bath to toothpaste foam. The Cosmetic Ingredient Review (the industry experts who test the safety of ingredients) reported that it caused enough changes in mouse skin to warrant further study. The Environmental Working Group says avoid SLS whenever possible. 

These common uses only hint at all the things that transition metals can do. The copper penny, for instance, is mostly made of zinc, another transition metal. Chromium provides the shiny, mirror-like metal coating on chrome car bumpers, but is also added to some lasers to make their light shine red. Nickel and chromium combine in an alloy that can be coiled into the wires that heat toasters and hair dryers. Titanium dioxide is a very white reflective compound used in toothpaste and paints. The transition metal cadmium is used in brilliant and permanent colors such as cadmium yellow, red, and orange. Artists have used cadmium-based paints for hundreds of years, and manufacturers used the colors more recently in plastic products. However, the colors are rarely used now that scientists have discovered that cadmium pollution can cause cancer and other health problems. 

Of course there is no such product as LoveSmile toothpaste, at least a search of the Internet failed to reveal one. What the above news item suggests is that a trip to the dentist is likely to become a rare event in the life of children bom today, unlike the regular visits to the dentist that most people have had to make in the past if they wanted to keep their teeth in good condition. The new ingredients mentioned in the... 

Are you still thinking Consider each room in your home. Think about the bathroom, for example. Does soap involve chemistry Do toothpaste, cosmetics, and shampoo involve chemistry Think about the light in the bathroom. Without chemistry, there is no glass to make lightbulbs. 

Follow this procedure Straighten the toothpaste tube. With the scissors, cut off the flat bottom end of it. Rinse the tube out very carefully, including the cap. Replace the cap but pull the other end apart to make a wider opening. Set the tube aside to dry. In the small bowl, mix 2 teaspoonfuls of powdered calcium carbonate and 2 teaspoonfuls of powdered orris root. Add teaspoonful of sodium bicarbonate and 3 drops of essence of peppermint. Add water to this mixture, a drop at a time, stirring it constantly until a paste forms. Put the paste into the empty tube by the teaspoonful. Before trying to squeeze the toothpaste from the tube, close the open end by folding it up several times. 

You will find your toothpaste inexpensive and pleasant to use. You may have to try making it several times, however, before you learn just the right amount of water to use to get the right consistency. 

The use of HPLC need not be limited to the analysis of nonvolatile flavor components. HPLC can be coupled with GC/MS to form an extremely powerful separation system. The unique separation properties of HPLC can be used to separate complex flavor mixtures to simplify later GC/MS separation and identification. This approach can be somewhat tedious to use in that a separate GC/MS run must be made for each HPLC fraction - but for very complex flavor systems there is often no other choice. Grob et al. (61 ) devised a direct transfer for HPLC fractions into a capillary GC to make this approach more convenient to use. They demonstrated the practical workability of the system by separating and Identifying two components in a toothpaste using both HPLC/GC and HPLC/GC/MS. 

The first list of metrics will look like that in Figure 6-4. Each metric has a number and a name. It will be associated with one or more needs. In this first list, need and specification numbers coincide, but later you may add or delete metrics. Note that some metrics have a straightforward unit. However, others may be given in terms of a list, or a binary (yes/no pass/fail). One of the units is given as subj or subjective this one is measured by a panel of users. You will want to avoid these, because it takes a long time to measure them. Some metrics have the unit RDA these use the Radioactive Dental Abrasion test, a standard test used in the toothpaste world. When such tests exist, you should use them. This makes comparison with measurements from others easier. Also it is often a large job to develop a test. The rank of a metric is determined by the rank of the need it describes - this may require some discussion in the team. 

The numerical models are usually implemented on a computer while the physical models can be test versions of the actual product. Both types of models help in estimating part of the product properties without making a complete product. One can seldom model all properties of a product in one go. An example of such a model is that for flow properties of the toothpaste given in Appendix 6-2. We used it for the first guesses of the yield stress and viscosity. 

Uses fluoride compounds are used in making steel, chemicals, ceramics, lubricants, dyes, plastics, and pesticides fluorine and hydrogen fluoride are used to make certain chemical compounds hydrofluoric acid is used for etching glass fluorides are also added to drinking water, dental products, toothpaste, and mouth rinses... 

Toothpastes are effective as vehicles to deliver fluoride and Triclosan to the tooth surface, and although fluoride may have some effect against plaque bacteria and their enzymes, its major effect is to make the tooth surface more resistant to destruction by plaque bacteria. With the exception of Colgate Total, other toothpastes are accepted by the ADA for their fluoride... 

A familiar use of some fluoride compounds is in toothpastes. Studies show that small amounts of fluorides can help reduce tooth decay. Fluorides are deposited as new tooth material is formed, making it strong and resistant to decay. 

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