Important Medical Warning
If you are experiencing a dental emergency, difficulty breathing, severe swelling, or uncontrolled bleeding, call 911 or go to your nearest emergency room immediately.
The short answer: a black tooth under a fallen crown is almost never "just a stain," but it is also usually not the catastrophe it looks like. The black color is giving your dentist real diagnostic information about what was happening beneath that crown. In some cases it is harmless discoloration that will be hidden by a new crown. In others it signals active decay, a dead tooth, or a failing restoration — conditions that are treatable if you act now, but that get harder to fix the longer you wait.
This guide walks through the most common reasons a tooth turns black under a crown, what to do in the first 24 hours after your crown falls off, which scenarios are true emergencies, and what your realistic repair options and costs look like.
Why the Tooth Is Black: The Five Most Common Causes
1. Decay (the most common cause). Bacteria can sneak under a crown through a microscopic gap at the margin — the line where the crown meets the natural tooth. Once inside, they feed on sugars and slowly hollow out the tooth structure beneath the crown. Active decay often looks dark brown, black, or even greenish-black, and the tooth may feel soft when probed. This is the single most common reason crowns fall off in the first place — there is not enough solid tooth structure left to hold the crown in place.
2. A previously treated (root canal) tooth. Teeth that have had a root canal often darken over the years because blood breakdown products stain the dentin from the inside. If your crown was placed after a root canal, the "black" tooth may simply be the natural discoloration of a dead tooth — not new damage. This is usually not painful and not urgent, though it still needs a new crown.
3. Old metal post or cement staining. Many older crowns used metal posts or silver-based cements to attach to the tooth. Over the years, these materials can leach into the dentin and leave a dark gray or black tint on the remaining tooth stump. This is cosmetic, not dangerous, but it can make the tooth look dramatically worse than it actually is.
4. A cracked or fractured tooth. A vertical fracture that runs through the tooth can let saliva, blood, and food debris seep into the crack and stain the structure dark. Cracks often look like black hairlines on the exposed tooth. Fractured teeth under crowns are usually painful with chewing pressure and can be serious — sometimes the tooth is not savable.
5. Residual temporary cement or food debris. Occasionally what looks "black" is actually dark food residue (coffee, berries, dark sauces) or leftover temporary cement trapped in the cavity. A gentle rinse sometimes reveals that the tooth underneath is lighter than it first appeared. If color rinses away, this is the cause.
What the color itself can hint at — though only a dentist can confirm:
- Deep black, hard surface: often stained dentin from old metal or an endodontically treated tooth
- Black with a soft, "mushy" feel: active decay
- Black hairlines or stripes: possible fracture
- Blackish-green with a smell: active bacterial decay or infection
Is This a Dental Emergency?
Go to an ER or emergency dental clinic immediately if you have:
- Facial swelling near the jaw, cheek, or eye
- Fever above 101°F along with tooth pain
- Difficulty swallowing or breathing — this can indicate a deep-space infection that is closing the airway and is a true 911 call
- Severe, unrelenting pain that over-the-counter medication cannot touch
- Pus draining from the gums around the tooth
- A tooth that has snapped off at the gum line and is bleeding heavily
See a dentist within 24–48 hours if:
- The tooth is not currently painful but the crown has fallen off
- There is mild sensitivity to cold, heat, or sweet foods
- You can see visible black discoloration but no swelling
- A small piece of the tooth came off with the crown
- The tooth feels sharp or rough against your tongue or cheek
Why the urgency even without pain? The remaining tooth structure is now exposed to bacteria, food, and temperature changes. Decay can accelerate quickly when not protected, and the tooth may fracture further under normal chewing pressure. Every day without coverage makes the eventual repair more complicated.
What to Do in the First 24 Hours
1. Save the crown. Rinse it gently with warm water, dry it, and put it in a small container (a pill bottle, a plastic bag, a contact lens case). Do not wrap it in tissue — crowns get thrown away in tissue more often than you would think. Your dentist may be able to re-cement it if the underlying tooth is healthy enough.
2. Rinse your mouth gently. Use warm salt water (½ teaspoon salt in 8 oz water) to clean the exposed tooth. Do not scrub with a toothbrush or pick at the tooth with your fingers or a toothpick.
3. Inspect the underlying tooth in good light. Note the color, whether it feels smooth or soft, whether any sharp edges are present, and whether there is visible cracking. This information helps your dentist triage you over the phone.
4. Call your dentist. Describe the situation — when the crown came off, what the tooth looks like, whether you have pain. Most general dentists reserve same-day or next-day slots for exactly this situation. If your regular dentist is unavailable, search for an emergency dentist near me — these practices are specifically equipped for walk-ins.
5. Protect the exposed tooth until you are seen.
- Avoid chewing on that side of your mouth
- Avoid very hot, cold, or sweet foods that may trigger sensitivity
- Brush gently around the area; floss very carefully so you do not catch and tear the gum
- If the sharp edge is irritating your tongue or cheek, dental wax (sold at most pharmacies near the toothpaste) can be molded over it as a temporary cover
6. Do not try to glue the crown back on with household glue. Super glue, nail glue, and craft adhesives are toxic to your pulp and can cause permanent damage. A temporary dental cement (sold over the counter as Dentemp or Recapit) is acceptable for a night or weekend, but is not a substitute for professional recementation.
What Your Dentist Will Look For
Tooth structure. Is there enough solid, healthy tooth above the gum line to hold a crown? Crowns generally need at least 2 mm of healthy tooth all the way around — what dentists call the ferrule. If decay or fracture has left less than this, a new crown alone will not stay on.
Active decay. The dentist will probe the tooth with a dental explorer to see if the black area is soft (decay) or hard (staining). X-rays confirm how deep any decay extends and whether it has reached the pulp. If decay has reached the pulp, a root canal is likely required before a new crown can be placed.
Cracks or fractures. A crack running into the root is often a death sentence for the tooth. The dentist may use a transillumination light or a dye to look for fracture lines. Vertical root fractures usually mean extraction; cracks limited to the crown portion can sometimes be rebuilt.
Pulp status. Does the tooth still have a live nerve? This is tested by tapping the tooth, applying cold, or (if the tooth is already dead or has had a root canal) by looking at X-rays for signs of infection at the root tip. A living, healthy pulp is good news; a pulp that has died since the crown was placed changes the treatment plan.
Periodontal health. The dentist will also check the gum and bone around the tooth. Bone loss from gum disease or chronic infection changes what is possible for the restoration.
Based on these findings, you will typically hear one of three outcomes: (a) the old crown can be recemented, (b) a new crown is needed but the tooth is savable, or (c) the tooth is not restorable and needs to be extracted.
Your Realistic Repair Options and Costs
Option 1: Recement the original crown. If the tooth is healthy and the crown is intact, a dentist can simply clean both surfaces and cement the crown back on. This is by far the cheapest outcome. $100–$300 with minimal time in the chair — sometimes same-visit. Insurance often covers recementation.
Option 2: New crown on existing tooth. If the crown is damaged, decay has been cleaned out, and enough healthy tooth remains, a new crown can be fabricated. This typically takes two visits over 2–3 weeks (or one visit at offices with same-day CEREC milling). $800–$2,500 per crown depending on material (porcelain, zirconia, metal) and your location.
Option 3: Core build-up plus new crown. If there is not enough tooth structure left but the pulp is still healthy, the dentist can rebuild the missing structure with a filling-like material (the core) and place a crown over it. $300–$500 for the core build-up plus the crown cost — total $1,100–$3,000.
Option 4: Root canal plus post and core plus crown. If decay has reached the pulp or the tooth is dead, a root canal is done first to clean out the infected pulp. A post (metal or fiber peg placed into the root) supports a core build-up, which then holds the crown. $1,000–$2,000 for the root canal, $200–$400 for the post and core, $800–$2,500 for the crown — total $2,000–$5,000. Root canal specialists (endodontists) often have higher success rates but charge more.
Option 5: Extraction and implant. When the tooth is cracked vertically into the root, or there is too little structure left, extraction is the only option. $150–$500 for the extraction, $500–$3,000 for any bone graft that is needed, and $3,000–$6,000 for the implant, abutment, and crown. Total: $4,000–$9,000 over 4 to 9 months of treatment.
Option 6: Extraction and bridge. A bridge uses the teeth on either side to anchor a replacement tooth. Faster than an implant (2–3 weeks vs several months) but involves filing down the adjacent teeth. $2,000–$5,000 for a 3-unit bridge.
Option 7: Extraction and partial denture. The cheapest replacement option at $500–$2,500. Less stable and less comfortable than an implant or bridge, but legitimate for patients who cannot tolerate surgery or want to spread costs.
Insurance notes. Most dental insurance covers crowns at 50% after the deductible, with annual maximums ($1,000–$2,000) that often do not cover the full crown plus any other treatment you need. If cost is a concern, ask about CareCredit financing, dental school clinics (30–60% discounts with supervision), and payment plans.
What If You Cannot Get to a Dentist Right Away?
Use over-the-counter temporary dental cement. Brands like Dentemp and Recapit are sold at most pharmacies for around $10. Clean and dry the crown and the tooth, apply a small amount of the cement to the inside of the crown, seat it firmly over the tooth, and bite gently for a few minutes. This is a genuine fix for a few days, not a few weeks.
If the crown is lost or broken, dental wax can be molded over any sharp edges to protect your tongue and cheek. A tea bag (wet it and hold it over the tooth) can help with minor bleeding. Cloves, clove oil (applied sparingly with a cotton swab), and over-the-counter toothache gels containing benzocaine can numb the area temporarily.
For pain management, alternating ibuprofen (400–600 mg every 6 hours) and acetaminophen (500–1000 mg every 6 hours) is more effective than either alone. Avoid aspirin placed directly on the tooth — it causes chemical burns on the gum.
Protect the area when eating. Soft foods (yogurt, scrambled eggs, mashed potatoes, smoothies) let you eat without disturbing the tooth. Avoid anything sticky (caramel, gum, dried fruit), hard (nuts, popcorn, chips), or extreme in temperature.
What to avoid: super glue, nail glue, and craft adhesives on the crown. These are toxic to the pulp and can cause permanent nerve damage. Picking at the tooth with metal tools. Ignoring the tooth and hoping it will "settle" — decay does not pause.
When to stop managing at home and seek help: any new swelling, any fever, any pain that wakes you up at night, any pus or bad taste. These signs mean infection is developing, and waiting for a regular appointment is no longer safe.
Why Crowns Fall Off in the First Place — And How to Prevent It Next Time
Decay under the crown. The most common reason. Microscopic gaps at the crown margin let bacteria in. Fluoride toothpaste, daily flossing under and around the crown, and 6-month dental cleanings to catch margin problems early are the best defense.
Cement failure. Crowns do not last forever — the cement typically lasts 10 to 15 years, though high-quality crowns can go 20+. If your crown is older than 15 years, it is overdue for evaluation even if it "feels fine."
Loss of tooth structure. Every time a crown comes off and is recemented, a little more tooth can be lost. At some point there is not enough to hold a new crown without a post and core or root canal.
Clenching and grinding (bruxism). Night grinding can exert 250+ pounds of pressure per square inch on a crown and slowly fatigue the cement bond. If you grind, a custom night guard (around $300–$800) is much cheaper than replacing crowns.
Sticky or hard foods. Caramels, taffy, hard candy, ice, and popcorn kernels are the most common direct causes of crowns popping off. After a new crown, being mindful of these for the life of the crown pays off.
Poor-fit crowns. Some crowns come off because they were not well-made in the first place. If your previous crown had a history of repeatedly coming off, ask about getting the new one made at a different lab or with a different material.
Gum disease and bone loss. If the gum recedes or bone is lost around the tooth, the crown's support changes and it can loosen. Treating gum disease protects your crowns too.
Most of these factors are manageable. A well-maintained crown on a healthy tooth with good oral hygiene can last 20–25 years or more.
Red Flags That Change the Plan
The tooth was already dead and you did not know. A significant number of crowned teeth harbor silent dead pulps that were missed when the crown was placed. When the crown comes off and the tooth is visibly black, the chronic infection may have been simmering for years. X-rays typically show a dark periapical lesion at the root tip.
The tooth has a vertical root fracture. A fracture running down into the root cannot be repaired. Signs include a narrow black line extending below the gum, a "J-shaped" radiolucency on X-ray, and pain when biting on a specific point. Vertical root fractures almost always require extraction.
There is active infection. A fistula (small bump draining pus on the gum), a bad taste, or facial swelling means the infection has organized at the root tip. Antibiotics may be prescribed before definitive treatment, but antibiotics alone do not cure the problem — the infected tooth must be treated or extracted.
The tooth is mobile. A crown tooth that wiggles under finger pressure has likely lost substantial bone support. Depending on the cause, periodontal treatment, splinting, or extraction may be needed.
The adjacent or opposing teeth are involved. Sometimes the issue extends beyond the one crowned tooth. Adjacent teeth may have decay, the opposing tooth may have over-erupted (grown down into the now-empty space), or the bite may have shifted. All of this needs to be factored into the treatment plan.
None of these findings are catastrophic on their own — but they change the timeline, cost, and treatment path, and they are much easier to address at the first visit than after you have already committed to recementing the old crown.
Key Takeaways
The most common scenarios are all treatable: staining from an old root canal tooth can be hidden under a new crown, decay can be cleaned and the tooth rebuilt, a fractured tooth can sometimes still be saved, and even a tooth beyond repair can be replaced with an implant or bridge. The single most important thing you can do right now is save the old crown, rinse the tooth gently, call a dentist, and avoid chewing on that side until you are seen.
Do not use household glue. Do not ignore the tooth. Do not assume that a lack of pain means there is no problem — teeth under crowns can decay silently for years before the crown finally fails. The faster you get a professional look, the more likely your tooth can be saved, and the less expensive the final repair will be.
This article is for informational purposes only and is not a substitute for professional dental or medical advice. If you have facial swelling, fever, trouble breathing or swallowing, or severe pain, seek emergency dental or medical care immediately.
Frequently Asked Questions
Is it an emergency if my crown fell off and my tooth is black?
Usually not a 911-level emergency, but it does need dental attention within 24 to 72 hours. The black color most often indicates decay, staining from a previous root canal, or old metal leaching from the original crown — all of which are treatable if addressed quickly. However, seek immediate emergency care if you have facial swelling, fever above 101°F, difficulty swallowing or breathing, severe pain unrelieved by over-the-counter medication, or visible pus draining from the gums. These signs point to a spreading infection that cannot wait.
Can a dentist still save a tooth that looks black after the crown comes off?
In most cases, yes. A black appearance alone does not mean the tooth is beyond saving — it usually means the pulp died years ago, decay has developed under the crown, or old metal has stained the dentin. If enough healthy tooth structure remains above the gum line (at least 2 mm all around, which dentists call a ferrule), the tooth can typically be cleaned up, rebuilt with a core or post-and-core, and covered with a new crown. A root canal is often needed if decay has reached the pulp. The tooth is usually unsavable only when it is cracked vertically into the root or when too little structure remains for a stable restoration.
Can I glue my crown back on at home?
Use over-the-counter temporary dental cement such as Dentemp or Recapit — these are sold at most pharmacies for around $10 and are safe for short-term use (a few days). Never use super glue, nail glue, craft glue, or any household adhesive. These products contain chemicals that are toxic to the pulp and can cause permanent nerve damage, chemical burns on the gum, and make the crown impossible for a dentist to remove cleanly. Temporary dental cement is only a bridge to a real appointment, not a long-term fix — see a dentist within a few days.
How much does it cost to fix a tooth that looks black under a fallen crown?
Costs vary widely based on what the dentist finds. If the tooth is healthy and the original crown is intact, recementation is $100–$300. A new crown runs $800–$2,500. A core build-up plus new crown totals $1,100–$3,000. If a root canal is needed, expect $2,000–$5,000 total for the root canal, post and core, and crown. If the tooth cannot be saved, extraction is $150–$500, and a replacement implant totals $4,000–$9,000 including any bone graft. Dental insurance typically covers 50% of crowns after the deductible, and payment plans, CareCredit, and dental school clinics can reduce out-of-pocket costs significantly.
Why did my crown fall off in the first place?
The most common reason is decay under the crown that has eaten away the supporting tooth structure. Other causes include age-related cement failure (most crowns last 10 to 15 years), tooth fracture from biting on something hard, night grinding or clenching that stresses the cement bond, and sticky foods like caramel or taffy that physically pull the crown off. If your crown came off with a black tooth underneath, decay is by far the most likely culprit. Preventing future failures means daily flossing around crowns, regular 6-month cleanings to catch problems early, and a night guard if you grind your teeth.
Medical Disclaimer
The information provided on Urgent Dental Helper is for general informational and educational purposes only. It is NOT intended to be a substitute for professional medical or dental advice, diagnosis, or treatment. Always seek the advice of your dentist, physician, or other qualified health provider with any questions you may have regarding a dental or medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
