NEWCASTLE UPON TYNE, England, June 20 (TNSjou) -- Northumbria University issued the following news release: * * * Smoking leaves lasting mark on teeth, research reveals Evidence of the permanent impact of smoking on people's teeth has been uncovered by researchers for the first time. Researchers from Northumbria University have discovered that smokers have tell-tale signs of their smoking habits ingrained deep within their teeth, which remain even after a person has quit. Their findings, wh more PR