Decaying teeth and unhealthy gums can give off unpleasant odour. Up to 90% of halitosis (bad breath) comes from oral causes. The primary sites for odour causing bacteria are the tongue and gums. Elimination of halitosis involves bacterial removal and destruction of sulphur compounds. Over the counter mouthwashes, toothpastes and mints only cover up bad breath with stronger more pleasant odour but does not eliminate the cause. The dentist will check the mouth thoroughly for any factors causing the bad breath and he may recommend you to see a hygienist to get your mouth up to scratch and improve your cleaning.