Ingredients
Sodium bicarbonate in oral care
Baking soda neutralizes the acid that dissolves teeth, helps loosen the plaque biofilm that holds bacteria to tooth surfaces, and lifts surface stains while remaining unusually gentle. Concentrated baking soda can also inhibit or kill some oral bacteria in laboratory studies, although it is not a fast-acting antiseptic.
How it works against acid
Acidity is just loose hydrogen ions floating around. Baking soda mops them up and turns them into water and carbon dioxide, which raises the pH back toward neutral.
That matters because enamel dissolves once the acid level at the tooth surface passes a certain point, and the damage done by any snack mostly depends on how long it stays past it. Anything that shortens the acid episode means less mineral lost.
This is not some foreign chemical being imposed on your mouth, either. Bicarbonate is the main thing your own saliva uses to neutralize acid. Baking soda is the same substance.
Why it cleans without scratching
Toothpaste roughness is measured on a standard scale where a reference material scores 100 and the legal ceiling is 250. Baking soda sits right at the bottom of that scale.
Two reasons. Its crystals are soft, and it dissolves in water, so the particles start disappearing while you brush instead of staying as grit. What makes it unusual is that it still lifts coffee, tea and wine stains. Normally you only get stain removal by being rougher, and baking soda gets it without that trade.
For contrast, charcoal toothpastes are sold as gentle and natural, and when measured they land all over the scale, some of them high. The word on the box tells you nothing here. The number does.
What it does to plaque and bacteria
Plaque is a biofilm: bacteria embedded in a sticky matrix that helps them cling to teeth. Laboratory studies show that concentrated baking soda can break apart mature plaque biofilm, making it easier for brushing to remove.
Baking soda can also slow or kill some oral bacteria, but the amount used and the contact time matter. Several common plaque organisms needed much longer exposure than a normal two-minute brushing session. Its antimicrobial effect is therefore real but limited; its ability to loosen biofilm may matter more in everyday toothpaste use.
What the research shows
A formal review of the trials found that baking soda toothpastes removed plaque better than toothpastes without it. A newer twelve-week trial also found less plaque, gum inflammation and bleeding than with a conventional fluoride toothpaste.
The picture is not one-sided. An independent study that applied toothpaste without brushing found no special plaque-inhibiting effect, suggesting that baking soda works best by helping the toothbrush disrupt biofilm rather than by sitting on teeth like a lasting antiseptic. Much of the positive research was also manufacturer-funded, and plaque scores do not prove fewer cavities over a lifetime.
Does it add salt to your diet?
No. You spit toothpaste out, and what stays behind after rinsing is tiny next to the sodium in food. Deliberately swallowing baking soda as an antacid is a completely different thing and a question for a doctor.
What baking soda does not do
- It does not bleach teeth. Taking surface stain off can make them look lighter, but that is cleaning, not changing the color of the tooth.
- It does not replace a cavity-preventing ingredient if you are prone to cavities. Soaking up acid and rebuilding enamel are two different jobs.
- It does not sterilize the mouth. Concentrated baking soda can kill some bacteria in the laboratory, but ordinary brushing is brief and its biofilm-disrupting action may be more important than direct killing.
- It does not treat gum disease. Established gum disease needs professional treatment.
Read the full evidence review Buffering, biofilm disruption, antimicrobial activity, abrasivity, and the clinical evidence.
Baking soda is an unglamorous ingredient with an unusually good evidence base. It buffers the acid that dissolves enamel, helps physically disrupt mature plaque biofilm, and has antimicrobial activity that depends on concentration and contact time. It also removes surface stain while being one of the least abrasive cleaning agents in common use, and unlike most things in a toothpaste tube it has been through formal systematic review. None of that makes it a sterilant or a treatment for established dental disease.
Key points
- Sodium bicarbonate is a buffer. It resists change in pH, which is directly relevant to the acid episodes that drive tooth demineralization.
- Bicarbonate is also the body's own principal salivary buffer, so this is not a foreign mechanism being imposed on the mouth.
- Concentrated sodium bicarbonate can inhibit or kill selected oral bacteria in vitro, but the effect depends strongly on species, concentration, contact time and the rest of the formula.
- Its more clinically relevant action may be physical disruption of the plaque biofilm, which helps brushing detach bacteria from tooth surfaces.
- It is highly soluble and its crystals are soft, giving it very low relative dentin abrasivity while still lifting surface stain.
- A systematic review found baking soda dentifrices more effective than non-baking-soda dentifrices for plaque removal, with effects on gingivitis less consistent.
- The sodium content of toothpaste is not a meaningful dietary sodium source, because it is not swallowed in quantity.
What a buffer actually does
A buffer is a solution that resists changes in pH. Sodium bicarbonate dissociates into sodium and bicarbonate ions, and the bicarbonate reacts with free hydrogen ions to form carbonic acid, which then breaks down into water and carbon dioxide. Hydrogen ions are what acidity consists of, so removing them raises pH.
This matters because of the mechanism described in how cavities form: enamel dissolves when the pH at the tooth surface falls below roughly 5.5, and the damage done by any given sugar exposure is largely a function of how long pH stays down there. Anything that shortens the acid episode reduces the mineral lost during it.
Bicarbonate is not a novel intervention here. It is the principal buffer system in saliva itself, and salivary bicarbonate concentration rises sharply with flow rate, which is a large part of why a fast-flowing mouth is more resistant to caries. That relationship is covered in our article on saliva and oral health.
Antimicrobial activity and biofilm disruption are different
Sodium bicarbonate does have direct antibacterial activity under laboratory conditions. In one classic study, a 1.0 mol/L solution killed selected periodontal pathogens within 30 to 120 minutes, while supragingival plaque organisms required at least six hours for a 99% reduction. Bicarbonate salts were more active than equivalent sodium chloride, indicating that the effect was not simply high salt concentration.7
A separate study found substantial growth inhibition of Streptococcus mutans from baking soda alone. Its short-exposure killing became stronger when baking soda was combined with sodium dodecyl sulfate, a detergent, showing why the behavior of a complete toothpaste cannot be predicted from one ingredient in isolation.8 These experiments establish genuine antimicrobial potential, but their contact times and formulations do not justify describing ordinary two-minute brushing as disinfection.
Biofilm disruption is a separate mechanism. In a saliva-derived laboratory plaque model, two-minute exposure to a 67% sodium bicarbonate slurry reduced the organisms remaining in mature biofilm by about three orders of magnitude. Confocal and electron microscopy showed substantial removal of the biofilm from its surface.9 The result is best read as physical detachment of the sticky biofilm matrix, not proof that every removed bacterium was killed.
Human evidence is limited but informative. A small crossover trial of ten adults found fewer salivary mutans streptococci after four weeks with either of two bicarbonate dentifrices than with a bicarbonate-free placebo; the authors explicitly called for larger, longer studies.10 Conversely, an independent 2023 split-mouth study that applied a high-bicarbonate toothpaste without brushing found no significant reduction in plaque formation or gingival inflammation.11
The most defensible conclusion is that baking soda has real but context-dependent antimicrobial activity. In normal toothpaste use, its better-supported benefit is helping the toothbrush detach mature biofilm, while buffering makes the oral environment less favorable to acid-producing, acid-tolerant bacteria. It should not be presented as a broad-spectrum or long-lasting antiseptic.
Abrasivity, and the interesting tension
Toothpaste abrasivity is measured as relative dentin abrasivity, or RDA, covered at length in toothpaste abrasivity. It is a standardized index in which a reference abrasive is assigned a value of 100. Regulatory and ISO limits set the ceiling for a marketable dentifrice at 250, and the methodology itself has known reproducibility problems that are worth knowing about when comparing published figures.1
Sodium bicarbonate sits at the very bottom of the range. Its crystals are comparatively soft and, critically, it is highly soluble in water, so the particles begin dissolving during brushing rather than persisting as hard grit. Comparative in vitro work on commercial dentifrices places baking soda formulations among the least abrasive measured.2
The tension worth noticing is that baking soda is nonetheless effective at removing extrinsic stain, the surface discoloration left by coffee, tea, wine and tobacco. Most stain removal in toothpaste is bought with abrasivity, and the two normally trade off. Bicarbonate is unusual in delivering reasonable stain removal at the low end of the abrasivity scale.
For contrast, charcoal dentifrices, frequently marketed as gentle and natural, have been measured across a wide abrasivity range with some products scoring high.3 "Natural" says nothing about abrasivity. The number does.
Enamel is hard enough that no compliant dentifrice meaningfully abrades it under normal brushing. The tissue actually at risk is exposed dentin and cementum on root surfaces, which are far softer and become exposed with gum recession. Abrasivity is therefore a concern that scales with age and periodontal history rather than a universal one.
What the clinical evidence shows
A systematic review examining baking soda dentifrices for plaque and gingivitis control found that they removed plaque more effectively than dentifrices without baking soda. The effect on gingivitis was less consistent, and the authors noted heterogeneity across the included studies.4
More recent randomized work continues in the same direction. A twelve-week randomized controlled trial comparing a sodium bicarbonate toothpaste against a conventional fluoride toothpaste reported benefits on gingivitis measures.5 A separate randomized trial of an experimental formulation containing sodium bicarbonate also reported gingivitis improvements.6
Two honest caveats. Much of this literature is manufacturer-funded, which is typical for dentifrice research and a reason for measured interpretation rather than dismissal. And plaque and gingivitis indices are surrogate outcomes: they are reasonable proxies, but they are not the same as demonstrating fewer cavities or less tooth loss over a lifetime.
The sodium question
People on sodium-restricted diets sometimes ask whether a bicarbonate toothpaste contributes meaningfully to sodium intake. In normal use it does not. Toothpaste is spat out rather than swallowed, and the residual quantity retained after brushing and rinsing is very small relative to dietary sodium from food.
The exception is deliberate ingestion. Baking soda taken orally as an antacid or supplement is a different exposure entirely, and is a matter for a physician rather than a toothpaste label.
What baking soda does not do
- It does not bleach teeth. Removing extrinsic surface stain can make teeth look lighter, but that is cleaning, not bleaching. Intrinsic tooth color is not changed by an abrasive or a buffer.
- It is not a substitute for a caries-preventive agent in a high-risk mouth. Buffering acid and delivering a remineralizing agent are different jobs, and the evidence base for bicarbonate concerns plaque and gingivitis rather than caries increment.
- It is not a substitute for an antiseptic. Concentrated bicarbonate has direct antibacterial activity, but many oral bacteria require more contact time than brushing provides. Its everyday value is more plausibly a combination of biofilm disruption, easier plaque removal and an ecological shift away from persistent acidity.
- It does not treat gum disease. Established periodontitis involves attachment and bone loss and requires professional treatment.
References
- González-Cabezas C, Hara AT, Hefferren J, Lippert F. Abrasivity testing of dentifrices: challenges and current state of the art. Monographs in Oral Science. 2013;23:100-107. PMID 23817063.
- Schemehorn BR, Moore MH, Putt MS. Abrasion, polishing, and stain removal characteristics of various commercial dentifrices in vitro. Journal of Clinical Dentistry. 2011;22(1):11-18. PMID 21290981.
- Zoller MJ, Bidra AS, et al. Relative dentin and enamel abrasivity of charcoal toothpastes. International Journal of Dental Hygiene. 2023;21(1):149-156. PMID 36303293.
- Valkenburg C, Kashmour Y, Dao A, Van der Weijden GAF, Slot DE. The efficacy of baking soda dentifrice in controlling plaque and gingivitis: a systematic review. International Journal of Dental Hygiene. 2019;17(2):99-116. PMID 30734996.
- West NX, Davies M, et al. A randomised, controlled trial investigating the effect of tooth brushing with a sodium bicarbonate toothpaste for 12 weeks compared to a conventional fluoride toothpaste on gingivitis. Journal of Dentistry. 2025;160:105886. PMID 40482904.
- Axe A, Patel R, et al. Efficacy of an experimental toothpaste containing sodium bicarbonate, sodium hyaluronate and sodium fluoride on gingivitis. BMC Oral Health. 2024;24(1):209. PMID 38336635.
- Newbrun E, Hoover CI, Ryder MI. Bactericidal action of bicarbonate ion on selected periodontal pathogenic microorganisms. Journal of Periodontology. 1984;55(11):658-667. PMID 6094783.
- Drake D. Antibacterial activity of baking soda. Compendium of Continuing Education in Dentistry Supplement. 1996;17(19):S17-S21. PMID 11524862.
- Pratten J, Wiecek J, Mordan N, et al. Physical disruption of oral biofilms by sodium bicarbonate: an in vitro study. International Journal of Dental Hygiene. 2016;14(3):209-214. PMID 26198308.
- Legier-Vargas K, Mundorff-Shrestha SA, Featherstone JDB, Gwinner LM. Effects of sodium bicarbonate dentifrices on the levels of cariogenic bacteria in human saliva. Caries Research. 1995;29(2):143-147. PMID 7728829.
- Abrahamsen S, Koldsland OC, Preus HR. The anti-plaque effect of high concentration sodium bicarbonate dentifrice on plaque formation and gingival inflammation, irrespective to individual polishing technique and plaque quality. BMC Oral Health. 2023;23:281. PMID 37170260.
This article is educational and describes published research on sodium bicarbonate as an ingredient class. It is not medical or dental advice, not a diagnosis, and not a claim about any product. If you have a specific concern about your teeth or gums, ask a dentist.
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