Eat Strawberries( lots and lots of them) or brush your teeth with them.
There is evidence that strawberries can help whiten teeth due to containing an enzyme called malic acid and vitamin C. The astringent found in strawberries helps to remove surface stains, while vitamin C washes away plaque. Mashing a few strawberries and brushing with the mixture once or twice a week can have positive results. You could also just eat strawberries, making sure to chew really well and allowing them to do the brushing on their own.
Baking Soda and Lemon juice
This may be one of the most popular of the natural teeth whitening home remedies. The chemical reaction of baking soda with the citrus of lemon juice has a smile-brightening effect. Either one of these ingredients works well, but together they are super-effective. If you’re worried about damaging tooth enamel, you could try some of the other solutions. I would suggest only doing this 1-2 times a week as it can be very harsh on the teeth and gums if used too much.
Coconut Oil Pulling
Oil pulling is an Indian remedy used primarily to enhance oral health and cleanse the body. The process is actually quite simple, harmless, and very inexpensive. Simply take one tablespoon of a pure, organic coconut oil and swish it around in your mouth for 10-15 minutes. Move the oil around your mouth,After rinsing, spit out the oil, thoroughly rinse your mouth out with water, and consume 2-3 glasses of water (purified if possible). Ensure to do this method at least once every day for effective results.
Charcoal powder
Activated charcoal has a number of different uses such as removal of water impurities. When it comes to teeth whitening, its powerful crystals will remove all the yellow stains from your teeth.
Also, you can combine activated charcoal with your regular toothpaste and brush your teeth twice a day. However just make sure you rinse your mouth clean after every use.
Turmeric
This is a potent teeth whitening agent that can whiten your teeth naturally. First, add a table spoon full of organic tumaric into a bowl along with a teaspoon of coconut oil and then lastly add some lime juice and salt to the turmeric.
This combination won’t only whiten your teeth naturally but it will keep your gums healthier.
You could also combine orangic tumaric to your everyday toothpaste. Just ensure you rinse your teeth & mouth after every use because it's a very vibrant yellow/orange colour.