Multi-select problem: How does the next paragraph end?

How to whiten teeth
Use whitening toothpaste if you're on a tight budget.
A tube of whitening toothpaste typically costs less than $10 at the drugstore or local supermarket.
Look for a toothpaste with the american dental association (ada) seal of approval.

Available choices: -- This means the toothpaste you use to whiten is positive for your teeth. For many people, it doesn't matter if your mouth looks clean or not.. -- Ada-approved whitening toothpastes use abrasive particles to polish teeth along with chemicals that bind to stains and remove them. Studies have proven that these toothpastes are no harder on your enamel than other toothpastes.. -- Ada seals of approval will denote that whitening toothpaste has not been used for up to four decades. The ada seals of approval will generally have a different seal over the results of whitening purposes.. -- This seal of approval means the product does not contain sulfates, which can taint or cause tooth decay. Look for a denture seal that is made of a harder substance known as enamel..
Ada-approved whitening toothpastes use abrasive particles to polish teeth along with chemicals that bind to stains and remove them. Studies have proven that these toothpastes are no harder on your enamel than other toothpastes.