How much baking soda and lemon juice would I use to whiten teeth?

Bad idea. Do not put lemon juice on your teeth. These acidic juices can cause irreversible damage to your enamel. The baking soda is ok to use to brush your teeth.
Serious damage. Please please for the love of all that is holy, don't do that. Use either professional whitening or over the counter products like crest white strips. You can cause serious damage to your teeth and end up in a world of hurt. Go see a dentist.

Related Questions

Can baking soda and lemon juice be used as a tooth whitener?

Not so much. Hydrogen peroxide is the most important whitener. It's the basic ingredient in most home whitener kits. While baking soda is an excellent dentifrice (tooth cleaner), and having clean teeth is paramount in having white teeth to be sure, it's not specifically useful for whitening. As for the lemon juice, not recommended! it has lots of acid, which is very hard on your teeth. Read more...
No, don't do it. Do not put lemon juice on your teeth for any period of time. It is highly acidic and will wear away the tooth enamel quickly. Baking soda is ok to brush with and it will polish away some stains, but it is pretty abrasive and can also wear away tooth enamel. The best tooth whitener is custom made mouth trays and dentist prescribed whitening gel. Read more...
No. Get a professional whitening. Experiment and you may end up with some ugly cosmetic results. Read more...

Is it good to use lemon juice with baking soda for whitening of teeth?

Professional bleach. For optimum results have your dentist do professional bleaching only. The dentist will calibrate the percentage of bleaching material based on individual need. Read more...
No. Lemon juice is very acidic and will eat away at your enamel. Baking soda is abrasive so that will also wear away your enamel. You are better off using products specifically designed to whiten teeth. Read more...
No. A combo of an acidic & abrasive nature is not a good idea....will it work for those with hard stains, sure, but so will using activated charcoal for 5min. Now I do not advise doing these things to my patients, I would always suggest a more proven/predictable route with professional bleaching treatments. Of course that doesn't stop them from trying YouTube things like lemon/baking soda;) Read more...

I rubbed lemon juice on my teeth twice this week to whiten them. Is that a good idea?

NO Never. This chemically destroys the enamel of the tooth. The resulting erosion will later cost you thousands of dollars of reconstruction or the loss of your teeth. Have a dentist examine you and give you the correct pathway to follow now. Read more...