Dr Kit Barnfather, of the Leeds Dental Institute, and his team have created a saliva test giving smokers immediate feedback on how their habit is affecting the levels of nicotine in their bodies. 'Dentists are in an ideal position to give this kind of health advice because most people regularly visit their dentist, but would only see their doctor once they already have a health problem,' said Dr Barnfather. Using a patient's saliva sample, dentists and doctors can measure the level of nicotine and breakdown products. If harmful chemicals are present the sample will change colour - from yellow to brown depending on the level of chemicals. 'From this the clinician can show a patient they are absorbing high amounts of carcinogenic chemicals like tar, benzenes and so on, which could lead to oral health problems including oral cancer and gum diseases,' Dr Barnfather said.

When general health counselling on the effects of smoking is combined with this visual feedback, patients are far more likely to be successful in giving up smoking. Four in five smokers who took part in the original trial found it a helpful test. Dr Barnfather - along with researchers from the University of Birmingham - has published his findings in the BMJ. He is now recruiting volunteers to take part in a second trial to discover whether high nicotine levels reduce the effectiveness of the antioxidant immune system in the mouth.