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Gum control My dentist has suggested I buy a mouthwash to help keep my gums, or specifically the junction between gums and teeth, healthy. The mouthwash is quite expensive, so before I hand over my money I’d like to know what the two active ingredients do. Just what effect will stabilised chlorine dioxide and sodium monofluorophosphate have on the health of my mouth?

n Chlorine dioxide is an antiseptic and sodium monofluorophosphate strengthens tooth enamel. But how do they perform in the lab? Raw chlorine dioxide gas decomposes violently in air, but is safe in mouthwash as a 5 per cent buffered aqueous solution with a pH of 9. In the US it is an approved and widely used disinfectant in food and water processing. It works by oxidation, which removes damaging chemicals but, unlike chlorine, it produces no harmful by-products.

Two other common antiseptic mouthwashes are hydrogen peroxide, which also oxidises, and chlorhexidine, which attacks a broad spectrum of microbes and can work through the soft plaque that clings to teeth and gums. But peroxide is a potential irritant that can aggravate symptoms. Chlorhexidine works by breaking down bacterial cell membranes but the brown remnants can discolour teeth, so is unsuitable for frequent use. Chlorine dioxide also penetrates plaque, but being a more potent oxidiser it works at

a lower concentration. And it kills a vast spectrum of bugs, including gram-positive and gram-negative bacteria, aerobes and anaerobes, viruses, fungi, spores, cysts and protozoa – all by dismantling their enzymes. Even bacterial spores with their multiple tough outer layers are dead in 5 minutes.

Tooth enamel is mostly made of hydroxyapatite, a complex of calcium, phosphate and hydroxide. Acids from food and sugars broken down by microbes strip away the hydroxide part, leaving the enamel more soluble, softer and hence prone to wear. Alkaline saliva provides hydroxide ions that gradually replenish it, though.

Sodium monofluorophosphate, like the sodium fluoride often used in toothpaste, provides fluoride ions that bind more tightly to the calcium-phosphate base of tooth enamel, making it more resistant to acid attack.Len WinokurLeeds, UK

n Mouthwashes clean and disinfect the mouth and gums, particularly if you are prone to gum diseases such as gingivitis. Dentists recommend floss or interdental brushes, followed by brushing for 2 minutes. If this is followed by a mouthwash for 30 to 60 seconds, then any remaining bacteria will be significantly reduced, or eliminated.

Mouthwashes also have a significant cleaning effect, and

will help to remove minor food traces that even determined brushing fails to dislodge.

Sodium monofluorophosphate protects tooth enamel from attack by bacteria that cause dental cavities. Stabilised chlorine dioxide mouth rinses contain a chemical called sodium chlorite, which is a salt used in the manufacture of chlorine dioxide. Both of these materials have an antibacterial role, but there is no point in buying expensive mouthwashes since cheaper products will also contain

antibacterial chemicals and perform the same function.

Diluted hydrogen peroxide is a powerful cleaning and antibacterial mouth rinse, and is recommended by my own dentist. However, it tends to leave a metallic taste in the mouth. I get round this by adding about half a teaspoonful of the concentrate to a standard quantity of the cheapest ordinary mouthwash. Having used this for about a year now, both myself and my dentist have seen a general improvement in my dental health.J. A. CroftsNottingham, UK

n I don’t argue with dentists, but the ingredients mentioned are harmless, and the mouthwash should be dirt cheap.

Monofluorophosphate supplies fluoride and inhibits some microbes, but many toothpastes contain plenty anyway; just don’t rinse too soon after brushing. Chlorine dioxide (stabilised or not) is powerfully germicidal and compatible with bodily defences, but unless combined with silver it too is cheap.

Some 20 years ago mouthwash prices so insulted my intelligence that I checked their active ingredients and found that I had been paying way over the odds, so I bought some chlorhexidine concentrate and cheap vodka. Then I prepared a formulation of 0.2 per cent active ingredient in 6 per cent ethanol, adding a drop of clove oil and some saccharine tablets to mask the taste.

Since then a nightly rinse between flossing and brushing has worked miracles. I have no more ulcers, remarkable cleansing between teeth, no bad breath, and tartar reduction so drastic as to excite remark from successive dentists. Whitening toothpaste removes the harmless brown chlorhexidine stains. The cost is a small fraction of mouthwashes that don’t work like my own. Jon RichfieldSomerset West, South Africa

This week’s questionGrouT GripeWhy does white bathroom grouting turn black? And what can be done to prevent it?Jane BrookesGlasgow, UK

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“i don’t argue with dentists, but the recipe described is harmless and it should be dirt cheap”

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