Objective: How can you use banana peels on your teeth?

Which of the following solutions is more sound in terms of naive physics reasoning?

Available options: (i) Simply peel a ripe banana, and rub your teeth with the insides of the peel for about two minutes. After three weeks, your teeth will have whitened. Banana peel can act as a gentle exfoliator for your teeth.; (ii) Simply peel a ripe banana, and rub your teeth with the outside of the peel for about two minutes. After three weeks, your teeth will have whitened. Banana peel can act as a gentle exfoliator for your teeth.;
(i)