TOO MUCH OF A GOOD THING
Toothpaste helps clean and protect your teeth in several ways. First of all it has a detergent component that breaks down oily substances (unauthorized cities of germs aka bacterial plaque) that adhere to teeth. Toothpaste has an antibacterial ingredient and a fluoride compound. The fluoride also has antibacterial properties but in addition it is absorbed into enamel during remineralization by the natural action of saliva on clean tooth surfaces. Finally, in addition to flavoring agents there is a mild abrasive to remove stains.
Using as much toothpaste as the images of ads suggest is necessary or customary is a waste of toothpaste. It is worse than just a waste of money. Over time excessive toothpaste use will erode enamel so that the yellow/orange dentin of your tooth will show through more as the enamel thins. That erosion may even make your teeth more sensitive to hot and cold. The companies that make toothpaste want you to use as much as possible. Some give the impression that the more you use the healthier your teeth and gums will be. The truth is that toothpaste doesn't do very much. It's the brush that does 98% of the job. The bacterial biofilm that grows on your teeth is similar to mayonnaise in that it is white and soft. Only the softest toothbrush bristles are necessary to disturb that biofilm so that it can then be rinsed away.
For information on different types of toothpaste, visit the WebMD website, they have great information on breaking down why maybe whitening toothpaste might not be the right choice for you. Click here for a direct link