Apple Cider Vinegar
Soak your toothbrush in apple cider vinegar, then brush your teeth as usual and rinse your mouth afterward. Use this remedy no more than 1-2 times per week, and be careful not to leave the apple cider vinegar on your teeth for too long.

Fruit
Red fruits, such as strawberries and tomatoes, can be rubbed on your teeth to help remove tartar. Let the juice stand on your teeth for about 5 minutes to soften the buildup, then rinse your mouth with baking soda and warm water for a bright, shiny smile. You can also use red bell peppers, berries, lemons or oranges.

Baking Soda
Instead of using your regular toothpaste, mix a little bit of baking soda with a pinch of salt to remove tartar buildup.

You can also make a mouthwash using:

1/2 cup of water
2 teaspoons of baking soda
2 drops of tea tree essential oil
2 drops of peppermint essential oil

Mix the ingredients into a glass jar and use this remedy 1-2 times per day. The essential oils will work their anti-bacterial magic to help prevent buildup.