That One Dark Tooth You Can’t Stop Thinking About
She smiled with her lips closed. Every time. For three years.
A woman came into our Torrance office a while back. She’d had a root canal on one of her front teeth after a bike accident. The treatment went fine. The tooth was saved. But slowly, over the next year or so, it started turning dark. First a little yellowish. Then grayish. Then noticeably darker than every other tooth around it.
She told Dr. Phan she’d stopped smiling in photos. She covered her mouth when she laughed. She even looked into getting a veneer or a crown just to hide the color — but that felt like a lot of work and money for a tooth that was otherwise perfectly healthy.
Turns out, there was a much simpler fix.
What Is Internal Tooth Bleaching?
Internal bleaching is exactly what it sounds like. Instead of whitening the outside of a tooth like regular bleaching strips or trays do, we whiten it from the inside out.
Here’s why that matters. When a tooth darkens after a root canal, the staining comes from inside the tooth. Blood breakdown products soak into the dentin — that’s the layer just underneath your enamel. No amount of whitening toothpaste or external bleaching is going to fix that. You have to get the bleaching agent inside the tooth where the stain actually is.
The technique is sometimes called the “walking bleach” method. It’s been around for decades, and it works really well.
How It Works — Step by Step
The process is pretty straightforward. Since the tooth already had a root canal, there’s no nerve inside. That means no pain during the procedure. You won’t even need numbing in most cases.
Here’s what happens:
Visit 1: Dr. Phan opens a small access point on the back of the tooth — usually through the same spot that was used for the original root canal. He places a protective barrier over the root canal filling to seal it off. Then he puts a bleaching agent (sodium perborate mixed with water or a mild peroxide solution) inside the hollow chamber of the tooth. A temporary filling goes on top to seal everything in.
You go home. The bleaching agent sits inside the tooth and works over the next several days. That’s the “walking bleach” part — the whitening happens while you go about your life.
Visit 2 (about a week later): Dr. Phan checks the shade. If the tooth has lightened enough to match the surrounding teeth, great — he removes the bleaching agent and places a permanent filling. If it needs more time, he replaces the agent with a fresh batch and seals it back up for another round.
Visit 3 (if needed): Same check. Most teeth reach the right shade within 1-3 visits over a 2-3 week period.
That’s it. No drilling into healthy tooth structure. No lab work. No crowns. No veneers.
Who Is a Good Candidate?
Internal bleaching works best for teeth that darkened after:
- A root canal treatment
- Trauma to a front tooth (like getting hit in the mouth), even if the root canal was done years later
- A tooth where the nerve died on its own
The tooth needs to have a solid root canal already in place, and the structure of the tooth itself should be in good shape. If the tooth is cracked, heavily filled, or has signs of external root resorption, internal bleaching might not be the right call. Dr. Phan checks all of that before moving forward.
Front teeth are the most common ones we treat this way. They’re the ones that show when you smile, and they’re also the ones most likely to discolor after nerve damage.
What Kind of Results Can You Expect?
Most teeth lighten by 2-4 shades. That’s usually enough to blend back in with the teeth around it.
Some teeth respond faster than others. Teeth that darkened recently tend to lighten quicker than teeth that have been dark for 10 or 15 years. But even long-standing discoloration often responds well — it just might take an extra visit or two.
The results can last for years. Some patients see the color hold steady for 5-10 years or more. If it starts to darken again down the road, the procedure can be repeated.
See a real before-and-after in our discoloration case study.
Internal Bleaching vs. Crown vs. Veneer
This is where people get stuck. Your dentist tells you the tooth is dark, and the options on the table are usually a crown, a veneer, or internal bleaching. Here’s how they compare:
Internal bleaching costs a fraction of what a crown or veneer costs. It preserves all of your natural tooth structure. No grinding the tooth down. No lab fees. No temporary while you wait for the final restoration. For a tooth that’s structurally sound and just discolored, this is the most conservative option by a wide margin.
A veneer covers the front surface of the tooth with a thin shell of porcelain. It works great for color problems, but it requires shaving down the front of the tooth. Once you do that, you’ll need a veneer on that tooth for the rest of your life. And veneers typically run $1,000-$2,000 per tooth.
A crown covers the entire tooth. It’s the right choice when the tooth is weak, cracked, or heavily restored — but if the only issue is color, putting a crown on a structurally healthy tooth is overkill. Crowns require even more tooth reduction than veneers and cost $1,200-$2,500.
Dr. Phan’s philosophy is simple: start with the least invasive option. If internal bleaching can fix the problem, there’s no reason to cut into a perfectly good tooth. You can always do more later if needed. But you can’t undo a crown.
When Internal Bleaching Won’t Work
It’s not the right solution for every dark tooth. There are some situations where it has limits:
- Tetracycline staining — this type of discoloration affects the entire tooth structure from the inside and typically doesn’t respond well to internal bleaching alone
- External root resorption — if the root surface is breaking down, placing bleaching agents inside the tooth could cause further damage
- Very old, severe discoloration — teeth that have been extremely dark for decades may lighten but not fully match the surrounding teeth
- Teeth without root canals — internal bleaching requires access to the inside of the tooth, which means a root canal needs to already be in place
Dr. Phan will be straight with you about whether this is going to work for your specific situation. If it’s not a good fit, he’ll tell you and talk through the alternatives.
Why See an Endodontist for This?
You might wonder why an endodontist does tooth bleaching. It makes sense when you think about it. Endodontists specialize in the inside of teeth. They do root canals every day. They already know the anatomy, they have the tools, and they understand exactly how to protect the root canal filling while placing the bleaching agent.
Dr. Phan uses magnification to place the protective barrier precisely over the root canal seal. That barrier is what keeps the bleaching agent from leaking down into the root and potentially causing problems. Getting that placement right matters.
Torrance and the South Bay
Our office is in Torrance, and we see patients from all over the South Bay — Redondo Beach, Manhattan Beach, Hermosa Beach, Palos Verdes, Gardena, Carson, and Lomita. If your general dentist mentioned that your dark tooth might benefit from internal bleaching, they can send a referral our way. Or you can call us directly.
Ready to Smile Again?
If you’ve got a dark or gray tooth that’s been bothering you, it might be a simpler fix than you think. Internal bleaching is quick, painless, affordable, and it keeps your natural tooth intact.
Call our Torrance office or contact us online to set up a consultation. Dr. Phan will take a look, let you know if internal bleaching is right for your tooth, and walk you through exactly what to expect.
That tooth doesn’t have to stay dark.