Dip a cotton ball into the lemon juice and baking soda solution and apply it to your teeth. Let the lemon and baking soda solution sit on your teeth for around a minute. Brush your teeth to remove the acid. I saw results the first time I tried this.
I am not kidding you, this works better than the "clinical strength" deodorants Homemade Natural Deodorant. 3/4 C. Baking Soda, 1 TBSP. Melted Coconut Oil & approx 30 drop of essential oil of your choice. Mix and put into a tube.