How to get rid of bad breath if I brush my teeth regularly?

Tartar is a common cause, and you need to have it removed by a hygienist, not just brush at home. But if the smell comes and goes, I'd recommend checking your stomach and throat first - sometimes the problem has nothing to do with your teeth at all, I've seen plenty of cases like that in 27 years working at the clinic. Also pay attention to your tongue, plaque builds up there and that smells too - try brushing it with a toothbrush or scraper. And it wouldn't hurt to consult with a dentist in person to rule out cavities under fillings or gum inflammation.