Failed Root Canal Symptoms and What to Do
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Most root canals hold for life. When one does not, the tooth usually tells you: pain on biting that will not settle, a bump on the gum that keeps coming back, swelling, or a tooth that slowly turns gray. A failed root canal can often be saved with retreatment at $1,620, but not if it is ignored for a year. Here is what to watch for.
Seen in Midtown Houston, Saturday hours: Book an appointment · (713) 322-7474 · Endodontics in Houston
The Signs of a Failed Root Canal
Roughly in the order we see them.
• Pain on biting or pressure. After a normal root canal, tenderness fades within days. Pain that comes back weeks, months or years later, especially a specific ache when you bite down on that one tooth, is the most common first sign.
• A pimple or boil on the gum near the tooth. This is a sinus tract, a channel the body opens to drain pus. It often drains, shrinks and comes back. It usually does not hurt, which is exactly why people ignore it. Do not ignore it.
• Swelling of the gum, cheek or face on that side.
• Sensitivity returning. A properly treated tooth has no nerve left in it, so new sensitivity to hot or cold in that tooth means something is going on inside or beside it.
• A bad taste or persistent bad breath coming from one spot.
• The tooth darkening to gray or brown compared with its neighbors.
• Sinus symptoms from an upper back tooth: one sided congestion, pressure and facial ache that does not behave like a cold.
• Nothing at all. Some failures are found only on a routine X ray, which is a plain argument for keeping your checkups.
Why Root Canals Fail
Four causes account for nearly all of them, and only one is about the root canal itself.
The seal broke down. This is the most common. The permanent filling or crown that was supposed to go on top was delayed, or it cracked, or decay crept in underneath the margin. Bacteria get back into canals that were perfectly clean when they were sealed. A root canal without its crown on a back tooth is an unfinished job.
A canal was missed or not fully cleaned. Molars can have four or five canals, some so narrow or sharply curved that they are genuinely hard to find. Untreated tissue left in a canal is a reservoir for bacteria. This is where the difference between an endodontist with a surgical microscope and a general practice with a standard X ray actually shows up.
A crack in the root. Sometimes present before treatment, sometimes developing afterward in a tooth that never got its crown. Cracks below the gumline are the one category that often cannot be fixed.
New decay or new trauma reopened the tooth to bacteria years later.
How Fast You Need to Be Seen
Same day if you have facial swelling, a fever, swelling that is closing your eye or spreading toward your neck, or any difficulty swallowing or breathing. That is a spreading infection and it is treated as an emergency. Call (713) 322-7474 or go to an emergency room if you cannot reach us.
Within a few days for pain on biting, a gum pimple that keeps returning, or localized swelling that is not spreading. It is not an emergency but it will not resolve on its own.
At your convenience, but do book, for a tooth that is only discoloring with no other symptoms.
One thing to be clear about: antibiotics do not cure a failed root canal. They can knock down an acute infection and buy a few days, which is useful, but the bacteria live inside a tooth with no blood supply and antibiotics do not reach them. Any dentist who gives you a course of antibiotics and no follow up plan has treated the swelling, not the tooth.
Retreatment: What It Involves and What It Costs
Retreatment is $1,620 at our Midtown Houston office. A first time root canal starts at $1,500.
The appointment: the tooth is numbed, the crown or filling is opened, and the old filling material is removed from the canals. Under a microscope the canals are re-cleaned, any missed canal is located, and the whole system is disinfected and resealed. A temporary filling goes in, and you come back for the permanent restoration.
It takes one or two visits, usually 60 to 90 minutes each. Anesthesia works the same way it did the first time, and most patients are back to normal the following day.
Success rates for retreatment are good, though not quite as high as for a first treatment, and they are meaningfully better when the tooth is restored promptly afterward. If your crown has to be replaced as part of the process, that is quoted separately at the consultation.
We verify your insurance benefits before treatment and give you your share in writing. Cherry, Affirm and Sunbit spread the balance monthly.
When Retreatment Is Not the Answer: Apicoectomy
Sometimes the infection sits at the very tip of the root, in an area that cannot be reached by going back down through the canal, or the tooth carries a post and crown that would be destroyed by re-entering it. That is when an apicoectomy makes sense. It is $1,400 here.
The endodontist lifts a small flap of gum, removes the last few millimeters of the root tip along with the infected tissue around it, seals the cut end with a filling, and places a few stitches. It is done under local anesthetic and takes about an hour.
Recovery is a day or two of swelling and soreness. Stitches come out in about a week. The bone fills in over several months, which is confirmed on a follow up X ray.
We use a CBCT scan to see the root tip and its relationship to the sinus or the nerve before planning any of this.
When the Tooth Cannot Be Saved
A vertical root fracture below the gumline, a root that has resorbed away, or too little tooth structure left to restore all mean the tooth comes out. Our endodontists will tell you that directly rather than sell you a retreatment that will not hold.
What that path costs here:
• Extraction: $250.
• Bone graft to preserve the socket for a future implant: $600. Worth doing at the same appointment if an implant is in your plan, because the bone starts shrinking as soon as the tooth is gone.
• Single implant with its crown: $2,800 to $6,000, and the surgeon can often plan it the same day the tooth comes out.
Compare that with $1,620 to retreat and keep your own tooth, and the case for saving it usually makes itself, when saving it is possible.
Seeing an Endodontist in Midtown Houston
An endodontist is a dentist with two to three additional years of training in exactly this: root canals, retreatment, and surgery on root tips. Published data show noticeably higher success rates when endodontists do the treatment, which matters a great deal on a tooth that has already failed once.
Ours are Dr. Pedram Bohluli, Columbia trained with a PhD in dental sciences and more than 20 years in practice, and Dr. Parastou Terrany. They work with surgical microscopes and CBCT imaging, which is how a missed fourth canal in a molar gets found.
We are at 106 W Gray St in Midtown, close to Montrose, River Oaks, Downtown and the Texas Medical Center. Saturday appointments are available, and we hold same day slots for dental emergencies. You do not need a referral from your general dentist.
Bring any X rays you have. Call (713) 322-7474 or book online.
Frequently asked
What are the symptoms of a failed root canal?
Pain when biting on the treated tooth, a pimple or boil on the gum near it that keeps coming back, swelling of the gum or face, sensitivity returning to a tooth that should have no nerve, a bad taste from one spot, or the tooth darkening. Some failures cause no symptoms at all and are only found on a routine X ray, which is one reason not to skip checkups.
How much does root canal retreatment cost in Houston?
Root canal retreatment is $1,620 at Omega Dental Specialists in Midtown Houston, compared with $1,500 for a first time root canal. An apicoectomy, which treats the tip of the root surgically when retreatment cannot reach the problem, is $1,400. If the crown has to be replaced as part of the work, that is quoted separately. We verify your insurance benefits and give you your share in writing before we start.
Can a failed root canal be fixed?
Usually yes. Retreatment reopens the tooth, removes the old filling material, cleans and disinfects the canals under a microscope including any canal that was missed, and reseals them. When the problem sits at the root tip or the tooth carries a post that should not be disturbed, an apicoectomy treats it surgically instead. The cases that cannot be saved are mainly vertical root fractures below the gumline.
How long after a root canal can it fail?
Any time. Failures show up weeks later when a canal was missed or the seal was never completed, and years later when a crown cracks, decay creeps under a margin, or a tooth that never got its permanent restoration finally fractures. A gum pimple or biting pain on a tooth treated a decade ago is worth the same appointment as one treated last month.
Will antibiotics cure a failed root canal?
No. Antibiotics can reduce an acute infection and swelling and buy you a few days, which is genuinely useful before treatment, but the bacteria live inside a tooth that no longer has a blood supply, so the drug does not reach them. The infection returns once the course finishes. Antibiotics are a bridge to treatment, never a substitute for it.
Is a failed root canal an emergency?
It becomes one with facial swelling, fever, swelling that is spreading toward the eye or neck, or any trouble swallowing or breathing. Call us immediately at (713) 322-7474, or use an emergency room if you cannot reach us. Pain on biting, a recurring gum pimple or localized swelling should be seen within a few days but is not an emergency.
Should I just have the tooth pulled instead of retreatment?
Usually not, when retreatment is possible. Retreatment is $1,620 and keeps your own tooth with its own root and ligament. Extraction is $250, but replacing the tooth properly means an implant that runs $2,800 to $6,000 all included, grafting and crown among it, and no replacement is quite the same as the tooth you were born with. Where the root is cracked below the gumline, extraction is the honest answer and we will say so.