Cavities between teeth can only be reversed if they’re caught early enough, before the decay breaks through the enamel surface. Once a cavity has formed an actual hole, no home remedy or toothpaste will fix it. You’ll need a dentist to restore the tooth. But if the decay is still in its earliest stage, a non-cavitated lesion, you have a real window to stop and even reverse it with the right daily habits and products.
Why Cavities Form Between Teeth
The spaces between your teeth are some of the hardest spots to keep clean, and bacteria know it. Plaque, a sticky film of bacteria, builds up on the surfaces where two teeth touch. When you eat or drink anything with sugar, those bacteria feed on it and produce acid as a byproduct. That acid sits against the enamel and slowly dissolves it. Over time, the weakened enamel breaks down into a cavity.
What makes these interproximal cavities especially tricky is that your toothbrush bristles can’t physically reach the contact points between teeth. If you’re not flossing or using interdental cleaners, plaque in those spots goes completely undisturbed, sometimes for months or years. By the time you feel pain or see a dark spot, the decay has often progressed well into the tooth.
Signs You Might Have One
Cavities between teeth are notoriously hard to spot on your own. Most are found on dental X-rays before you ever notice symptoms. But there are physical clues worth paying attention to:
- Floss snagging or shredding at the same spot consistently, which can indicate a rough, decayed edge on the tooth surface.
- Food getting trapped between the same two teeth repeatedly, suggesting a gap created by decay.
- Sensitivity to hot, cold, or sweet foods in a specific area, especially if it’s new.
- Sharp pain when chewing or biting down on one side.
- Swollen or bleeding gums around a particular tooth, which can signal decay irritating the nearby tissue.
If your floss catches in a spot it never used to, don’t ignore it. That’s often one of the earliest signs something has changed on the tooth surface.
How Dentists Find Hidden Decay
Bitewing X-rays are the standard tool for detecting cavities between teeth. These small images show the contact points where your molars and premolars meet, revealing decay that’s invisible to the naked eye. The ADA and the American Academy of Oral and Maxillofacial Radiology published updated guidelines in 2026 recommending how often you need them based on your risk level.
If you have no active cavities and aren’t at increased risk, adults typically need bitewing X-rays every 24 to 36 months. But if you’ve had recent cavities or are considered high risk (frequent sugar intake, dry mouth, history of decay), that interval drops to every 6 to 18 months. For children and adolescents at higher risk, the recommendation is every 6 to 12 months. These intervals exist because interproximal decay can progress silently for a long time before symptoms appear.
When a Cavity Can Still Be Reversed
There’s a critical distinction between a cavity that has broken through the enamel surface and one that hasn’t. Early decay starts as a demineralized area, a weak spot where minerals have been lost but the enamel is still intact. At this stage, remineralization is possible. Your body can actually rebuild that weakened enamel if the conditions are right: enough fluoride exposure, reduced acid attacks, and consistent plaque removal.
Once the surface collapses and a physical hole forms, you’ve crossed a threshold. No amount of fluoride, special toothpaste, or dietary change will fill that hole back in. The shift in modern dentistry has been toward catching decay at that non-cavitated stage, when prevention can replace drilling. This is why regular X-rays matter so much for between-teeth cavities. They’re the only reliable way to catch decay while it’s still reversible.
What You Can Do at Home for Early Decay
If your dentist identifies an early lesion that hasn’t broken through the surface, several strategies can help halt or reverse the damage.
Prescription-Strength Fluoride Toothpaste
Standard toothpaste contains around 1,000 to 1,500 ppm of fluoride. Prescription toothpastes contain 5,000 ppm, more than three times the concentration. The ADA supports using these high-fluoride toothpastes for cavity prevention in at-risk adults and children six and older. They work by inhibiting mineral loss from the enamel and promoting the redeposit of calcium and phosphate back into weakened areas. Your dentist can write a prescription if they see early decay forming.
Toothpaste With Arginine
A newer approach targets the bacteria themselves. Arginine is a naturally occurring amino acid that feeds beneficial bacteria in your mouth. Those bacteria convert arginine into ammonia, which neutralizes the acid that causes decay. While fluoride strengthens the tooth directly, arginine shifts the bacterial community in your mouth toward one that produces less acid in the first place. Clinical studies have shown that toothpaste combining 1,450 ppm fluoride with arginine produces better cavity prevention results than either ingredient alone. Some over-the-counter toothpastes now include arginine as an active ingredient.
Flossing the Right Way
This sounds obvious, but technique matters enormously for between-teeth cavities. You need to wrap the floss into a C-shape around each tooth and slide it below the gum line, scraping the side of the tooth as you pull up. A quick snap-and-go between the teeth barely disrupts the plaque that’s causing the problem. If traditional floss is difficult for you, interdental brushes or water flossers can help reach those contact points, though floss remains the most effective tool for tight spaces.
Reducing Acid Attacks
Every time you eat or drink something with sugar or starch, bacteria produce acid for roughly 20 to 30 minutes afterward. Frequent snacking means your teeth spend more total time under acid attack. Reducing snacking between meals, drinking water instead of sugary or acidic beverages, and rinsing your mouth with water after eating all limit the amount of acid exposure your enamel faces each day. This is especially important for between-teeth surfaces where plaque is hardest to remove.
Treatment Options When a Filling Is Needed
If the decay has progressed past the enamel surface and into the softer layer underneath, your dentist will need to remove the damaged tooth structure and fill the space. For cavities between teeth, this typically involves one of a few approaches.
A standard composite (tooth-colored) filling is the most common treatment. Your dentist numbs the area, removes the decayed material, and fills the space with a resin that bonds to the tooth. Because the cavity is between two teeth, the dentist has to carefully shape the filling to recreate the natural contact point so food doesn’t get trapped there afterward. This is technically more demanding than filling a cavity on a chewing surface, but it’s still a routine procedure.
For larger cavities that have destroyed a significant portion of the tooth, an inlay or crown may be necessary instead of a simple filling. This happens when there isn’t enough healthy tooth structure left to support a standard restoration. Your dentist will let you know which option fits your situation based on what they see on the X-ray and during the procedure.
A Non-Drilling Option for Some Cases
Silver diamine fluoride (SDF) is a liquid treatment that can arrest active decay without any drilling. It kills cavity-causing bacteria, hardens weakened tooth structure, and has been shown to remineralize demineralized enamel and the layer beneath it. A dentist paints it directly onto the affected area. For between-teeth cavities, it can be delivered using floss soaked in the solution.
SDF is most commonly used in children’s baby teeth with early interproximal decay. Clinical trials have evaluated its ability to stabilize or reverse cavities that are still within the enamel or just reaching the boundary with the next layer. The main drawback is cosmetic: SDF permanently stains decayed areas black. On baby teeth or back teeth where appearance matters less, this trade-off is often worth it to avoid a filling. For visible front teeth in adults, most people find the staining unacceptable.
Preventing the Next One
If you’ve already had a cavity between your teeth, your risk of developing another one is higher. The same conditions that led to the first, whether that’s plaque buildup patterns, diet, saliva flow, or bacterial composition, are still in play. Daily flossing is the single most important habit for preventing interproximal cavities, because it’s the only way to physically disrupt plaque at the contact points between teeth. Pairing that with a fluoride toothpaste (and a prescription-strength one if your dentist recommends it), limiting between-meal snacking, and keeping up with regular bitewing X-rays gives you the best chance of catching any new decay while it can still be reversed.