Signs Of A Tooth Infection In Kids: A Pediatric Dentist's Guide

Written By: Logan Grover, Content Writer

Reviewed By: Dr. Alison Grover, Board-Certified Diplomate Pediatric Dentist

Last Reviewed: September 14, 2026

The signs of a tooth infection in kids are a gum pimple, a gray or dark tooth, face or jaw swelling, bad breath, pain that wakes them at night, chewing on one side, a loose tooth that shouldn't be loose, and fever. But pain is the least reliable sign on that list. The Scottish Dental Clinical Effectiveness Programme tells dentists to treat an abscessed baby tooth even when the infection is asymptomatic. No pain does not mean no infection. It sometimes means the nerve already died.

I'm Dr. Alison Grover. I've been treating these in Erie for years, and the visit I dread is the one where a parent tells me the toothache finally went away last week.

What Is a Tooth Infection in Kids?

A tooth infection in a child is a bacterial infection that starts in a cavity, spreads through the enamel into the pulp (the nerve inside the tooth), then out through the root tip into the surrounding bone. Dentists call the result a dental abscess. It happens in baby teeth and adult teeth, but faster in baby teeth.

That's the 30-second version. The part that changes what you do is the sequence, because each stage looks different from the outside.

The 3 Stages, and What You Can Actually See

Stage 1, reversible pulpitis. The nerve is irritated but alive. Cold and sweets sting, then the sting stops when you take the cold away. This is fixable with a filling.

Stage 2, irreversible pulpitis. The nerve is dying. The American Academy of Pediatric Dentistry describes this as "sharp, unprovoked, lingering pain (including nocturnal pain)." Translation: it hurts for no reason, it keeps hurting after the ice cream is gone, and it wakes your kid up. This is the loudest stage.

Stage 3, necrosis and abscess. The nerve is dead. Per the same AAPD guideline, this stage shows up as a "sinus tract, soft tissue pathology, or gingival swelling." Notice what's missing from that list. Pain.

Most articles on this topic list "sensitivity to cold" as a sign of infection. It isn't. Cold sensitivity means the nerve is still alive in there. Once the pulp dies, the tooth usually stops answering cold altogether. If your child had a tooth that hurt with ice water for 2 weeks and now feels nothing, that's not recovery.

The 8 Signs of a Tooth Infection in Kids

Watch for these 8. I've ordered them by how often I actually see them walk through the door, not by how dramatic they sound.

1. A pimple on the gum. A white, yellow, or red bump on the gum above or below a tooth. This is a parulis, the drainage point for an abscess that found its way out through the bone. It's the single most common thing parents show me on their phone. It often doesn't hurt, because draining relieves the pressure. It may shrink and come back. It is not a canker sore and it will not resolve on its own.

2. A gray, dark, or pink-tinged tooth. A baby tooth that changes color compared to its neighbors usually means the nerve inside died, either from decay or from an old fall nobody thought much about at the time. Dark gray is the common one.

3. Pain that wakes them at night. Daytime pain has distractions competing with it. Night pain doesn't. A child who wakes crying and holding their face, or who won't lie flat, is telling you the pressure inside the tooth is high.

4. Swelling in the cheek, jaw, or under the eye. Facial swelling means the infection left the tooth and got into soft tissue. This is the one that stops being a dental problem and starts being a medical one.

5. Bad breath or a bad taste they keep mentioning. Pus draining into the mouth tastes and smells like exactly what it is. Parents often describe it as breath that doesn't improve after brushing.

6. Chewing on one side, or suddenly refusing food they like. Younger kids frequently can't localize dental pain or name it. They just stop using that side. A 3-year-old who abruptly won't eat crunchy food is worth a look.

7. A loose tooth at the wrong time or in the wrong place. Bone loss around an infected root loosens the tooth. If a molar is wobbly, or a front tooth is loose years before its neighbors, that's not exfoliation.

8. Fever with any of the above. Fever on its own is a hundred things. Fever plus facial swelling plus a sore tooth is one thing.

Signs 1, 2, 5, and 7 can all show up with no pain at all.

Why "It Stopped Hurting" Is the Sign I Take Most Seriously

When the pain stops on its own without treatment, the most common reason is that the nerve finished dying. The pressure sensor got destroyed. The infection didn't go anywhere; it just lost its ability to complain.

This is why I push back on the standard advice to watch and wait for a few days. The waiting period is exactly the window in which the tooth goes quiet and the parent relaxes.

One number should end the "they're just baby teeth" argument. A 2022 study in Scientific Reports reviewed 912 children hospitalized for dentoalveolar infection, ages 0 to 18. A baby tooth was the source of the infection in about 70% of cases (70.2% and 68.2% across the study's 2 groups). The median hospital stay was 4 days. That's Israeli hospital data rather than US, so I won't claim it's the American rate. But the mechanism doesn't change at the border. Baby teeth put children in hospital beds.

For scale on how common the starting point is: 15% of US children ages 5 to 11 have untreated tooth decay, and that climbs to 23% among children in families below the poverty line, per federal NHANES data collected through March 2020.

Is a Tooth Infection in a Child an Emergency?

Sometimes tonight, sometimes tomorrow, and occasionally the emergency room instead of us. Use this.

What you're seeing	What to do	Why
Trouble breathing or swallowing, drooling, can't open mouth, swelling closing an eye, confusion or lethargy	Emergency room now	Swelling has reached the airway or spaces around the eye. This is beyond a dental chair.
Face or jaw swelling that is growing, with fever	Same day. Call (303) 500-3202 and press 2 after hours	Infection is in soft tissue and moving
Pain waking them at night, or pain not touched by children's ibuprofen	Same day or next morning	Irreversible pulpitis. It won't settle on its own
Gum pimple, no pain, no swelling	This week, not "sometime"	An active abscess draining. Quiet, not resolved
Gray tooth, no other symptoms	Next 1 to 2 weeks	Needs an x-ray to grade it, but it isn't tonight

Current patients can reach our on-call dentist after hours by calling (303) 500-3202 and pressing 2. If your child isn't a patient here yet and it's the middle of the night, the top row of that table still applies: go to the ER, not to a waiting room chair. Our emergency dental page for Erie families has the after-hours details, and if you're trying to sort out whether tonight's toothache is urgent at all, we wrote a separate walkthrough of pediatric dental emergencies for that decision.

Can an Infected Baby Tooth Damage the Permanent Tooth Underneath?

Yes, and this is the argument I have most often. The permanent tooth develops in a follicle sitting directly beneath the root of the baby tooth above it. An abscess at that root tip is inflammation happening a couple of millimeters from a tooth that is still being built.

Cordeiro and Rocha documented the outcomes in the Journal of Clinical Pediatric Dentistry in 2005: permanent successors affected by inflammation from the primary tooth above showed "hypoplasia, morphological alteration on the dental crown or total arrest of radicular formation." A permanent tooth can erupt with defective, chalky, pitted enamel because of an infection in the baby tooth that preceded it. Dentists call that a Turner's tooth.

I'll be straight about the limits of that citation: it documents the mechanism and the types of damage, not an incidence rate. I can't tell you what percentage of infected baby teeth produce a damaged adult tooth, and anyone who quotes you a number should show you where it came from. What I can tell you is that "it's going to fall out anyway" ignores the tooth that hasn't come in yet.

Getting the X-Ray Is the Real Bottleneck in 2026

I can't diagnose an abscess by looking at it. Bone loss at a root tip is invisible from the outside; it shows on a radiograph. Which means the actual obstacle in most of these visits isn't the diagnosis or the treatment. It's getting one usable image of a molar in a scared 4-year-old's mouth while they're in pain.

That's a specific problem, and we built the office around it. We take x-rays in the treatment room on a handheld, camera-style unit, so your child stays in the chair and keeps watching their movie while we do it. There's no walk to a separate radiology room, no standing against a wall in a lead apron. Every sensor and instrument we use is sized for a child's mouth, not scaled down from an adult set. Every operatory is plumbed for nitrous oxide, and we offer mild, moderate, and deep sedation for kids who need it.

That sounds like a comfort feature. It's a diagnostic one. The child who can't tolerate the x-ray is the child who gets sent home undiagnosed and comes back with a swollen face.

How an Infected Baby Tooth Gets Treated

The treatment depends entirely on whether the nerve is still alive, which is what the x-ray settles. The honest comparison, including where the odds sit:

Situation	Treatment	What it involves	Evidence
Deep decay, nerve still healthy	Indirect pulp therapy	Remove decay, leave a thin protective layer, seal it	97% success at 24 months (AAPD, 2024)
Decay into the nerve, root portion still alive	Pulpotomy	Remove the whole coronal pulp, medicate the living nerve left in the canals, crown it	94% success at 24 months with calcium silicate cement (AAPD, 2024)
Nerve dead, abscess present	Pulpectomy or extraction	Clean the canals and fill them, or remove the tooth	Depends on remaining root and bone
Tooth removed early	Space maintainer	Holds the gap so the permanent tooth has room	Standard of care after early loss

Two corrections to what you'll read elsewhere. First, a pulpotomy is vital pulp therapy. The AAPD defines it as "removal of the entire coronal portion of the pulp (nerve) and placement of a medicament to cover the vital portion of the nerve remaining in the pulp canals." Vital means living. A pulpotomy is not the fix for a tooth that's already dead and abscessed. Several pediatric dentistry blogs describe it that way, and it's wrong.

Second, antibiotics are not the treatment. They can knock down swelling and buy time before a procedure. They do not reach the dead tissue inside a tooth, because there's no blood supply left in there to carry them. A course of amoxicillin with no procedure afterward is a delay, not a cure. The infection comes back.

For the teeth we can save, we use crowns sized for children, including Hall crowns and white crowns on back molars. A Hall crown seals a decayed baby molar under a stainless steel cap with no drilling, no removal of tooth structure, and no numbing shot. That matters when the patient is 4 and already frightened. When a tooth can't be saved, extraction with a space maintainer is the better outcome than leaving an infected root in a growing jaw.

What Actually Prevents the Next One

Every article ends with brush and floss. Fine, but 2 things about how that advice is usually written are wrong.

The fluoride toothpaste amount matters more than the brushing schedule. The AAPD's published guidance for parents is a "tiny smear" from the first tooth, moving to a "pea-size dollop" between ages 3 and 6. Most families I see are using too little, not too much.

On supervision: you'll see "supervise until age 10 or 11" repeated across dental blogs. It isn't in AAPD's parent guidance, which addresses ages 3 to 6 and says parents should "perform or assist" brushing. The honest answer is that it depends on the kid's coordination, not the birthday. Watch them brush. If the back molars are still dry when they finish, they aren't ready.

Six-month checkups are the standard recommendation, and AAPD notes your pediatric dentist can adjust that based on your child's own risk. A child who has already had one abscess is not average risk. We usually shorten the interval after that. Our preventive care page covers what those visits include, and if you want the earlier warning signs, we've written about early childhood tooth decay separately.

One thing I'd add that nobody lists: look in your child's mouth with a phone flashlight once a week. Cheeks pulled back, look at the gumline above and below the back teeth. That's 20 seconds, and it's how the gum pimple gets caught in week 1 instead of week 6.

When to Call Us in Erie

Call (303) 500-3202 if your child has a gum pimple, a gray tooth, face or jaw swelling, night pain, or a tooth that hurt for a week and then went quiet. After hours, press 2 to reach the on-call pediatric dentist. Mini Miners Pediatric Dentistry is at 61 Erie Pkwy, Unit 101, in Erie Commons at Briggs and Erie Parkway, and we see families from Lafayette, Louisville, Broomfield, Boulder, Longmont, Westminster, Thornton, Brighton, and Arvada.

If your child can't breathe, can't swallow, can't open their mouth, or has swelling closing an eye, go to the emergency room first and call us after.

FAQs

Can a child have a tooth infection without pain? 

Yes, and it's common. Once the nerve inside the tooth dies, the tooth loses its ability to signal pain even though the infection continues in the bone around the root. The SDCEP clinical guidance directs dentists to treat an abscessed baby tooth even when it's asymptomatic. A gum pimple, a gray tooth, or bad breath with no pain still means infection.

What are the first signs of a tooth infection in kids? 

The earliest reliable signs are a pimple-like bump on the gum, a tooth that turns gray or dark, and pain that wakes a child at night or lingers after cold food is gone. The AAPD describes that lingering, unprovoked, nighttime pain as the marker of irreversible pulpitis, the stage just before the nerve dies. Cold sensitivity that stops as soon as the cold does is a different, earlier problem.

Is a tooth infection in a child an emergency? 

It depends on where the swelling is. Trouble breathing or swallowing, an inability to open the mouth, swelling closing an eye, or lethargy means the emergency room now. Growing facial swelling with fever means a same-day dental visit. A painless gum pimple means this week rather than tonight, but it does not mean it can be ignored.

Will a tooth infection in a child go away on its own? 

No. The pain can stop on its own, which is different, and it usually means the nerve died rather than that the infection cleared. Antibiotics alone don't cure it either, because the dead tissue inside the tooth has no blood supply to carry the drug. The tooth needs a pulpectomy, a pulpotomy if the nerve is still partly alive, or removal.

Can an infected baby tooth damage the permanent tooth underneath? 

Yes. The permanent tooth develops directly beneath the root of the baby tooth above it. Research published in the Journal of Clinical Pediatric Dentistry documented permanent successors affected by inflammation from the primary tooth showing "hypoplasia, morphological alteration on the dental crown or total arrest of radicular formation." That result is known as a Turner's tooth.

How is a tooth infection in kids treated? 

Treatment depends on whether the nerve is alive, which an x-ray determines. If the nerve is healthy under deep decay, indirect pulp therapy seals it, with 97% success at 24 months in AAPD's 2024 review. If decay reached the nerve but the root portion is alive, a pulpotomy plus a crown runs 94% success at 24 months with calcium silicate cement. If the nerve is dead, it's a pulpectomy or an extraction with a space maintainer.

What does a pimple on my child's gum mean? 

It's a parulis, the point where an abscess has drained through the bone and out into the mouth. It often doesn't hurt, because draining relieves the pressure, and it may shrink and return over weeks. It is not a canker sore, it will not clear up on its own, and it means the tooth above or below it needs an x-ray.