Baking soda whitens teeth primarily by physically scrubbing away surface stains, not by bleaching. It works as a mild abrasive that buffs discoloration from coffee, tea, wine, and tobacco off the outer layer of enamel. It also raises the pH inside your mouth, which helps prevent new stains from forming. But there’s an important distinction: baking soda removes stains sitting on top of your teeth, not the deeper discoloration embedded within enamel.
The Mild Abrasive Effect
Every toothpaste relies on some degree of abrasiveness to clean teeth. The standard measurement for this is called the Relative Dentin Abrasivity (RDA) scale, and plain baking soda scores a 7, which is about as gentle as it gets. For comparison, most commercial whitening toothpastes score between 45 and 90 on the same scale. Arm & Hammer Advanced Whitening scores 45, Colgate Whitening lands at 54, and Rembrandt Intense Stain hits 90.
That low abrasivity is actually the reason baking soda has a good safety profile for enamel. A review published in The Journal of the American Dental Association noted that baking soda has “an intrinsic low-abrasive nature because of its comparatively lower hardness in relation to enamel and dentin.” Its crystals are softer than tooth enamel, so they can dislodge plaque and surface stains without scratching the tooth underneath. The tradeoff is that it works slowly. You won’t see dramatic results after one use, and the whitening effect has a ceiling: once the surface stains are gone, baking soda can’t go further.
How pH Changes Help
Baking soda does something most abrasives don’t. When dissolved in saliva or water, it raises the pH in your mouth, shifting conditions from acidic toward neutral or slightly alkaline. A study in the National Journal of Maxillofacial Surgery found that using a baking soda rinse (about 3 grams dissolved in 50 milliliters of water) significantly increased salivary pH above the threshold where enamel starts to break down.
This matters for whitening because acidic conditions soften enamel over time, making teeth more porous and more likely to absorb pigments from food and drinks. By neutralizing acids after meals, baking soda helps protect the enamel surface and slows the cycle of new staining. The same research found a decrease in certain bacteria, including strains associated with cavities, though baking soda isn’t directly antimicrobial. It works more like a cleansing agent, dissolving mucus and loosening debris that bacteria cling to.
What Baking Soda Can’t Do
If your teeth are yellow because of aging, genetics, or deep stains from medications like tetracycline, baking soda won’t change the color. That kind of discoloration lives inside the tooth structure, and removing it requires a chemical bleaching agent, typically hydrogen peroxide or carbamide peroxide. These compounds release oxygen molecules that penetrate enamel and break apart the bonds in stain compounds at a molecular level.
The concentration the FDA and ADA consider safe and effective for at-home whitening is 10 percent carbamide peroxide, which breaks down to roughly 3.6 percent hydrogen peroxide. That’s a fundamentally different mechanism from scrubbing. Baking soda polishes the outside; peroxide bleaches the inside. Some commercial toothpastes combine both, which is why products like Arm & Hammer’s peroxide-based formulas score higher on the abrasivity scale (around 45) but also offer a mild chemical whitening effect.
One popular DIY method mixes baking soda with strawberries, mashed into a paste. Researchers at the University of Rochester specifically tested this and found no measurable whitening improvement. The theory is that the natural acids in strawberries would boost the effect, but in practice, applying acid directly to enamel before scrubbing can erode the tooth surface rather than whiten it.
Using It Safely
If you want to try baking soda as a surface stain remover, the simplest approach is mixing a small amount with water to form a paste and brushing gently for about two minutes. There’s no universally agreed-upon ratio in dental literature, but a thick, spreadable consistency (roughly two parts baking soda to one part water) is common in practice.
The low abrasivity score means baking soda is unlikely to damage enamel on its own, but the JADA review points out that wear on teeth is influenced by more than just the abrasive material. Brushing pressure, duration, and frequency all play a role. Scrubbing aggressively with any substance, even a gentle one, can wear down enamel over time, especially at the gum line where enamel is thinnest. A light touch matters more than the product you choose.
Baking soda also lacks fluoride, so using it as your only toothpaste means giving up the cavity-prevention benefit that fluoride provides. Many people use it as an occasional supplement to their regular toothpaste rather than a full replacement.
Realistic Expectations
Baking soda can make your teeth look brighter by stripping away the film of surface stains that builds up from daily eating and drinking. If you’re a heavy coffee or tea drinker, you’ll likely notice a difference over a few weeks of regular use. But the result is closer to “clean” than “white.” Your teeth will look more like their natural color, not the bleached shade you’d get from a peroxide-based whitening treatment.
For people whose natural tooth color is already fairly light, that might be all the whitening they need. For anyone looking for a more significant shade change, baking soda works best as one piece of a broader approach, keeping surface stains at bay between professional or at-home peroxide treatments that address the deeper discoloration.