In a great world, brushing your teeth routinely could be enough to maintain your set of pearly whites, well, pearly and white between routine dentist appointments. But alas, for a lot of us (particularly those of us with a serious coffee habit), that is just not the case. We feel moved to hit up the local drugstore for whitening toothpaste and coverings to clean up our smiles — perhaps without giving much thought to what those products actually are and the way they work.

“Tooth enamel [is] a crystal,” Matthew J. MessinaDDS, a board-certified, Ohio-based dentist, and spokesperson for the American Dental Association (ADA), says. “When you were to take a look at tooth enamel under a extremely powerful microscope, [the structure] type of looks like chicken wire” (or wire mesh). He explains that removing stains inside the matrix of the tooth enamel is like getting out dirt stuck in chicken wire: “So what happens in whitening is we wish to…open the matrix and bubble out that color, the stain, after which close it back up.”

That is where peroxide is available in. Dr. Messina says peroxide causes that bubbling to occur, so the lively ingredient in whitening kits you purchase will probably be hydrogen peroxide or carbamide peroxide (a diluted version of hydrogen peroxide). “Carbamide peroxide is used since it’s a relatively stable compound,” Neil HadaeghDDS, a board-certified cosmetic and restorative dentist in Beverly Hills, California says. “This helps the manufacturer to make sure product quality and consistency at the patron’s end.” Dr. Messina notes that other than the peroxide, over-the-counter whitening products normally contain some additional ingredients to enhance the taste.

Peroxide is the most important lively ingredient within the products dentists use to do in-office whitening of their offices, too. The one difference is the concentration. “If we’re doing something where we will mask off the gum tissue…where the gum tissues are protected, we will use a stronger whitening agent…since it’s only touching the teeth,” Dr. Messina says. “Something you are using over-the-counter has the potential to the touch the gum tissues or be swallowed. So, we have now to make use of a much lower strength of the lively ingredient because…it would burn [the patient’s] gum tissues.”

Dentists carrying out skilled treatments, however, “can take all of the crucial precautions to be sure that the gum tissue is protected and guarded and the whitening agent is just getting on the tooth enamel that we wish whiter.” But ultimately, Dr. Messina says that every one over-the-counter, peroxide-based whiteners will deliver comparable results so long as you follow the manufacturer’s instructions to be used.