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Can you actually reverse a cavity?

Jun 16, 2026Dr. Dillon

Whether you can reverse a cavity depends on how far along the decay is.

Decay happens slowly, as a back-and-forth: acid from bacteria pulls minerals out of your enamel, and your saliva, fluoride, and a good clean push minerals back in. Dentists call those two halves demineralization and remineralization. Early on, the rebuilding side can still win.

What can re-harden, and what can't

A spot can re-harden until it becomes a hole.

An early spot — a chalky white mark or a soft patch where the enamel has lost minerals but hasn't broken open — can re-harden. The National Institute of Dental and Craniofacial Research puts it plainly: "Enamel can repair itself by using minerals from saliva and fluoride from toothpaste."1 Caught at that stage, a spot may never become a filling.

A cavitated hole is different. Once the surface has collapsed into a hole, it can't grow back, because enamel has no living cells to rebuild itself. As the Cleveland Clinic describes it, "Once a hole forms in your tooth, a dentist drills out the decayed tissue and fills the hole."2 No toothpaste or rinse changes that.

Does hydroxyapatite toothpaste reverse cavities?

Hydroxyapatite is the mineral your enamel is mostly made of, so a hydroxyapatite toothpaste is a fluoride-free way to deliver minerals to the tooth. One meta-analysis found "good evidence that hydroxyapatite in oral care products in the absence of fluoride effectively reduces caries."3

A more cautious review looked specifically at the clinical studies and found the evidence thin. It graded the certainty "very low," noted that many of the underlying trials were funded by the products' own makers, and found hydroxyapatite no better than fluoride.4 Hydroxyapatite is a reasonable option if you're avoiding fluoride. It isn't a cavity cure, and it isn't a reason to drop a proven fluoride toothpaste.

What helps, and what to skip

For an early spot you want to re-harden:

  • Cut back on how often you snack and sip on sugar and starch. Each time, bacteria turn it into acid, and frequent acid attacks pull minerals out of your enamel faster than saliva can put them back.5
  • Use a fluoride toothpaste — fluoride is one of the minerals enamel draws on to repair itself.1
  • Let us catch it early. That's what the check at a cleaning is for.

Skip the internet fixes that backfire. Swishing lemon juice or apple cider vinegar to "remineralize" does the opposite: the acid wears enamel away, and that erosion is permanent.6

If you think a spot is starting, catch it before it needs a filling. Point us to where you're worried, and we'll take a look.

References

  1. The National Institute of Dental and Craniofacial Research (NIH) describes early decay as reversible before a cavity forms: "Enamel can repair itself by using minerals from saliva and fluoride from toothpaste." NIDCR — Tooth Decay ↩ ↩2

  2. Cleveland Clinic, on what happens once decay breaks through: "Once a hole forms in your tooth, a dentist drills out the decayed tissue and fills the hole." Cleveland Clinic — Cavities ↩

  3. Limeback H, Enax J, Meyer F. Biomimetic hydroxyapatite and caries prevention: a systematic review and meta-analysis. Canadian Journal of Dental Hygiene. 2021;55(3):148–159. The review concluded there is "good evidence that hydroxyapatite in oral care products in the absence of fluoride effectively reduces caries." (Two of the authors are affiliated with a hydroxyapatite toothpaste maker.) PMID 34925515. ↩

  4. Wierichs RJ, Wolf TG, Campus G, Carvalho TS. Efficacy of nano-hydroxyapatite on caries prevention—a systematic review and meta-analysis. Clinical Oral Investigations. 2022. Looking at the clinical trials, the review found "the level of evidence was very low", that many studies "were funded/published by the manufacturers of the tested products", and that hydroxyapatite was no more effective than fluoride. doi:10.1007/s00784-022-04390-4 ↩

  5. The National Institute of Dental and Craniofacial Research (NIH), on how often you eat: "the repeated acid attacks will win the tug-of-war, causing the tooth to lose minerals." NIDCR — The Tooth Decay Process ↩

  6. American Dental Association (MouthHealthy), on acidic foods and drinks: "Foods and beverages that are high in acids wear away the enamel that protects your teeth, a process known as tooth erosion." It adds that "Tooth erosion is permanent." MouthHealthy — Dietary Acids and Your Teeth ↩

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