Pain between the teeth usually signals that something is irritating or damaging the small triangle of gum tissue and ligament that fills the space between two neighboring teeth. The most common culprits are food wedged into that gap, early decay on the side surfaces of teeth, and gum inflammation from bacterial buildup. But the list of possible causes is longer than most people expect, ranging from a hairline crack in a tooth to problems with an old filling, and occasionally the pain points to something that has nothing to do with the teeth themselves.
Food Impaction and Trapped Debris
The single most frequent trigger for a sharp, sudden ache between teeth is food getting jammed into the contact point. Fibrous meat, popcorn husks, and seeds are classic offenders. When a piece of food is forced into the tight space between two teeth, it pushes against the gum papilla, the little peak of tissue that normally fills the gap. That pressure alone can hurt. If the debris stays put for hours, bacteria start breaking it down and the surrounding gum tissue gets inflamed, turning a minor annoyance into a throbbing ache. A comprehensive review of periodontal pain sources lists food impaction as a recognized cause of periodontal ligament strain and gum discomfort, alongside habits like clenching and grinding that stress the same structures.
Loose contacts between teeth make food impaction worse. As you age, teeth shift slightly, and the snug contact point that once kept food out can open up. Old fillings that have worn down or broken at the edges create the same problem. If you notice that one particular spot traps food every single meal, the contact between those two teeth has probably changed, and a dentist can often fix it by replacing or adjusting the restoration.
Decay on the Side Surfaces of Your Teeth
Cavities don’t just form on the chewing surfaces. Some of the sneakiest ones develop on the flat sides of teeth where two teeth press together, an area dentists call the interproximal surface. Because you can’t see these cavities in a mirror and they grow slowly, you might not notice anything until the decay gets deep enough to irritate the nerve or weakens the enamel to the point where hot, cold, or sweet foods send a jolt through the tooth. Bitewing X-rays, the ones where you bite down on a little tab, exist specifically to catch these hidden cavities early.
When interproximal decay progresses, it can also undermine the contact between two teeth, creating a gap that traps food. So what starts as a cavity problem quickly becomes a food-impaction problem too, and the pain between the teeth feels like it’s coming from the gum when the real issue is the tooth itself. This overlap is one reason interproximal pain can be tricky to self-diagnose.
Gum Disease and Periodontal Inflammation
If the pain is more of a dull, persistent soreness than a sharp jab, and your gums bleed when you brush or floss, gum disease is a strong possibility. In its early stage, gingivitis, bacterial plaque along the gumline triggers inflammation that makes the tissue between teeth tender and swollen. Left untreated, it can progress to periodontitis, where the infection works its way below the gumline and starts destroying the bone that holds your teeth in place. A detailed review of periodontal pain notes that periodontitis, gingival abscesses, and necrotizing periodontal disorders all cause mild to severe pain through tissue destruction and loss.1PubMed Central. The Periodontium as a Potential Cause of Orofacial Pain: A Comprehensive Review
Subgingival deposits, hardened tartar that forms below the gumline, play a direct role. One study using an endoscope to look beneath the gums found a clear link between bleeding on probing and the amount of subgingival deposits present, though bleeding alone wasn’t a highly sensitive indicator of exactly how much buildup existed underneath.2PubMed Central. The relationship between bleeding on probing and subgingival deposits. An endoscopical evaluation The practical takeaway: bleeding between your teeth isn’t “normal from flossing.” It usually means there’s enough bacterial buildup to cause inflammation, and a professional cleaning can remove deposits you can’t reach on your own.
A Cracked or Fractured Tooth
Cracked tooth syndrome is one of the more frustrating diagnoses in dentistry because the crack is often invisible to the naked eye and sometimes doesn’t even show up on X-rays. The hallmark symptom is a sharp, fleeting pain when you bite down on something hard, especially when you release the bite. The pain often feels like it’s coming from between two teeth because the crack runs along the side of one tooth, right where it contacts its neighbor.
A study of cracked tooth cases found that all patients responded positively to a bite test and had normal nerve-vitality readings, meaning the tooth was still alive and the nerve was intact, which is part of what makes the condition confusing. The study concluded that patients with unexplained pain in a vital, restored tooth, particularly maxillary molars, may have a crack that hasn’t been detected yet.3PubMed. Cracked tooth syndrome: characteristics and distribution among adults in a Nigerian teaching hospital If you have a large amalgam or composite filling, the remaining tooth structure around it is thinner and more crack-prone. Teeth that have been root-canal-treated but not crowned are also at higher risk.
Problems With Old Fillings and Restorations
A filling that extends slightly past the edge of the tooth, known as an overhang, creates a ledge that traps plaque and food right at the gumline between teeth. Over time, that ledge irritates the gum tissue and can even cause localized bone loss. One study examining restored teeth found that about one in ten had iatrogenic changes linked to overhanging restorations, including bone reduction in the area between adjacent teeth.4Acta Medica Bulgarica. Frequency of Iatrogenic Changes Caused from Overhang Restorations
The pain from a restoration overhang tends to be chronic and low-grade rather than acute. You might notice that one spot between your teeth always feels sore after eating, or that floss shreds in a particular area. Both are clues that the filling’s margin isn’t smooth. The fix is usually straightforward: the dentist can reconture or replace the restoration to eliminate the ledge.
Wisdom Teeth Pushing Against Their Neighbors
If the pain is toward the back of your mouth and you still have your wisdom teeth, pressure from an erupting or impacted third molar is worth considering. Wisdom teeth often don’t have enough room to come in straight, and as they push against the second molar, they create pressure that feels like deep, aching pain between the two rearmost teeth. Partially erupted wisdom teeth also commonly cause pericoronitis, an acute inflammation of the gum flap that partially covers the crown, and can contribute to decay or root damage on the adjacent second molar.5PubMed Central. Problems with erupting wisdom teeth: signs, symptoms, and management
There’s an evolutionary angle here too. Modern human diets are much softer than what our ancestors ate, and the reduced wear on our teeth means less natural space is created at the back of the jaw. Research has tied the prevalence of dental crowding and third molar impaction directly to the soft, processed diet modern humans eat, which doesn’t wear the teeth down enough to make room.6American Journal of Orthodontics. The adaptive value of dental crowding: A consideration of the biologic basis of malocclusion Your jaw may simply be too short for all 32 teeth.
Flossing the Wrong Way
This one surprises people. Flossing is supposed to prevent interproximal pain, but aggressive or improper technique can actually cause it. Snapping floss hard into the gum, sawing it back and forth against the tissue, or using a sawing motion at the base of the papilla can create gingival clefts, small cuts or notches in the gum tissue that become chronically sore. A case report documented a 33-year-old patient with excellent oral hygiene who had developed gum clefting and angular bone loss at multiple sites, all traced to a long-standing habit of improper flossing.7PubMed. Periodontal bone loss associated with an improper flossing technique: a case report
Another case report described a patient with unusual notch-like lesions on the surfaces between teeth, caused by incorrectly angling the floss so it cut into the tooth’s neck rather than sliding gently against the side.8PubMed. Interproximal cervical lesions caused by incorrect flossing technique Physical trauma from flossing is well-recognized alongside other gum injuries from oral piercings, ill-fitting dentures, and even aspirin placed directly on tissue.9PubMed. Traumatic lesions of the gingiva: a case series The correct technique is to gently guide the floss between teeth, curve it into a C-shape against one tooth, and slide it up and down rather than forcing it straight into the gum.
Gum Recession and Exposed Roots
When gum tissue recedes, the root surface of the tooth becomes exposed. Root surfaces aren’t covered by enamel; they’re covered by cementum, which is thinner and softer. That exposed root is far more sensitive to temperature, touch, and the acidity of certain foods. Gingival recession is associated with thermal and tactile sensitivity, a tendency toward root cavities, and cosmetic concerns.10PubMed Central. Gingival recession: review and strategies in treatment of recession
When recession happens between two teeth, the triangular gap where the papilla used to be opens up, creating what dentists call a “black triangle.” Food gets trapped easily, the exposed root surfaces sting when cold air or drinks hit them, and the area becomes harder to keep clean. Recession can be caused by aggressive brushing, gum disease, tooth grinding, or simply thin gum tissue that was prone to pulling back over time. Depending on the severity, treatment ranges from desensitizing toothpaste to surgical grafting.
When No Physical Cause Can Be Found
Sometimes the pain between teeth persists despite thorough exams, clean X-rays, and even multiple dental procedures. If no local source of infection, inflammation, or structural damage explains the pain, the problem may be neuropathic rather than dental. Patients with unrelenting tooth or gum pain sometimes see multiple dentists and undergo irreversible procedures like root canals or extractions without relief; in those cases, a neuropathic alteration of the trigeminal nerve should be considered.11PubMed. Persistent orodental pain, atypical odontalgia, and phantom tooth pain: when are they neuropathic disorders?
This condition goes by several names, including atypical odontalgia and phantom tooth pain. It can occur after dental procedures like root canal therapy or extractions, even in sites that look completely normal on clinical and radiographic examination. These pain states are thought to involve neuropathic changes, vascular factors, and sometimes psychiatric comorbidities, and they can overlap with conditions like burning mouth syndrome and TMJ dysfunction.12Journal of Nepalese Prosthodontic Society. Atypical Odontalgia or Phantom Tooth Pain: Current Evidences for Better Understanding, Diagnosis and Management If you’ve had teeth worked on or removed and the interproximal pain just won’t quit, pushing for more dental procedures may not be the answer. A referral to an orofacial pain specialist is more likely to help.
Why the Spaces Between Teeth Are So Vulnerable
The area between two teeth is a uniquely sheltered environment for bacteria. It’s warm, moist, hard to reach with a toothbrush, and shielded from the natural rinsing action of saliva. Bacterial communities in the mouth live as biofilms: highly organized, surface-attached colonies embedded in a protective matrix. Both cavities and gum disease are not caused by some invading germ you picked up, but rather by a breakdown in the normal balance of the microbial communities already living in your mouth.13PubMed Central. The Structure of Dental Plaque Microbial Communities in the Transition from Health to Dental Caries and Periodontal Disease When the ecology shifts, certain acid-producing or tissue-damaging species gain the upper hand, and the interproximal space is where they thrive best because it’s the area that gets cleaned least often.
This is why dentists keep pushing interdental cleaning even though most people find it annoying. A systematic review comparing water flossers to string floss found that most studies favored water flossers for plaque reduction, and they were particularly effective at reaching inaccessible interproximal surfaces.14PubMed Central. Comparing the effectiveness of water flosser and dental floss in plaque reduction among adults: A systematic review Another study in children found that both water flossers and interdental brushes were significantly more effective than brushing alone at removing plaque, though no single interdental tool dramatically outperformed the others.15PubMed Central. Efficiency of Three Interdental Plaque Control Aids (Dental Floss, Water Flosser, and Interdental Brush) as an Adjunct to Toothbrushing in Children The evidence around implants is even more dramatic: one systematic review found that a water flosser paired with a manual toothbrush was roughly two and a half times more effective than floss at reducing bleeding around implant sites.16BDJ Open. Efficacy of oral irrigators compared to other interdental aids for managing peri-implant diseases: a systematic review
The bottom line on tools: the best interdental cleaner is the one you’ll actually use consistently. If you hate string floss, a water flosser or an interdental brush is a perfectly valid substitute. The goal is to physically disrupt the biofilm between your teeth before it matures and causes trouble.
How to Tell Which Cause Applies to You
The character of the pain gives you clues. A sharp sting that shows up during or right after eating and goes away once you dislodge food is probably impaction. A lingering ache that worsens with hot or sweet foods points toward decay. Soreness and bleeding when you clean the area suggest gum inflammation. A sharp, fleeting jolt when you bite down hard, then release, is the classic signature of a cracked tooth. And persistent, burning, or bizarre pain that doesn’t respond to any treatment at all should raise the question of a neuropathic origin.
Timing matters too. Pain that started gradually over weeks and keeps getting worse usually involves a progressive process like decay or gum disease. Pain that appeared suddenly after a meal might be food impaction or a crack that finally propagated. Pain that began after a dental procedure and never went away could be a restoration issue or, if nothing structural explains it, a nerve-related problem.
None of this replaces an actual exam. The spaces between teeth are nearly impossible to inspect yourself, and interproximal cavities are often invisible without X-rays. But understanding the patterns helps you give your dentist better information, and better information leads to a faster, more accurate diagnosis.
Referred Pain and Sinus Pressure
Your upper premolars and molars sit close to the floor of the maxillary sinus. When you have a sinus infection or severe congestion, the pressure and inflammation in the sinus can produce an aching pain that feels exactly like a toothache between those upper back teeth. The giveaway is usually that multiple adjacent teeth feel sore at once, the pain worsens when you bend forward or lie down, and you have other sinus symptoms like congestion and facial pressure. This kind of referred pain resolves when the sinus infection clears, but people sometimes end up in a dental chair first because the tooth pain is so convincing.
Heart problems can also refer pain to the jaw and teeth, though this is rarer and more of a concern if the pain comes on with exertion and you have other cardiovascular risk factors. The take-home point is that not all pain felt between teeth originates in the teeth or gums. When a dentist examines the area and finds nothing wrong, it’s worth thinking about what else sits nearby anatomically.