Sir, in relation to H. Keanie's letter (BDJ 2007; 202: 507–508) regarding one of his/her patient's potential fluoride allergy, I would also be very cynical at first. Over the last 40 years there have been a few documented cases of claimed potential fluoride allergy from toothpastes/gel, if searching with MEDLINE.1 Being a common enough agent, I presume that the potential for the body to produce an allergy to it is possible.

Personally I have not come across any patients in dental practice with this problem. But if I did, what I would recommend for improving oral hygiene and reducing the risk of dental caries would be a combination of chlorohexidine gel (to reduce the plaque load) and a toothpaste containing CPP-ACP (to help with remineralisation) in the absence of fluoride.

CPP-ACP, or casein phosphopeptide with amorphous calcium phosphate, is sold in the UK as 'Tooth Mousse' or as 'MI Paste' in USA and Japan. If some readers are not aware of this product, it consists of dissolved calcium and phosphate, bound to a cow's milk derivative called casein phosphopeptide, which acts like a carrier.2 CPP has the ability of keeping calcium and phosphate in the soluble form, but also has the ability to bind to tooth surfaces and the bacterial/plaque biofilm. This latter property allows high levels of calcium and phosphate to re-penetrate the biofilm following demineralisation to encourage active remineralisation. This may not be as good as fluoroapatite forming, but it's better than cavitation!

This product can also be used for dentine hypersensitivity in people with xerostomia and following bleaching of teeth. It can be applied in a tray, with toothbrush or finger. Leave in the mouth for one to two minutes, rinse gently and do not drink for 30 minutes.