Bad breath can be due to several factors .we need to know the cause and treat the cause so that it will not occur repeatedly.
Bad breath may be because of
1.Lot of deposits(tartar) on the teeth
2.severe gum inflammation.
3.gaps inbetween teeth where food can get stuck and the decomposed food can cause bad breath.
4. cavities in the teeth.
5.less saliva in the mouth due to intake of some medicines.
6.Habits :food(garlic,onion) regular intake
....these are few it can also be due to some systemic conditions
1.In most cases mere cleaning the teeth(scaling) will solve the problem.
2.In case of cavities they can be filled.
3.In case of less saliva artificial saliva substitute s can be given
4.In case bad breath still persists even after dental treatment then you may need to consult physician for upper respiratory tract assessment to rule out any infections.
please contact your dentist for clinical assessment and get appropriate treatment.