Cosmetic Dentistry · Last reviewed May 2026
One Dark Tooth: The Treatment That Actually
Lightens It From Inside.
Internal bleaching at Picasso Dental is, for a single tooth that has darkened after a root canal or trauma. A peroxide-based gel is placed inside the tooth, through a sealed access cavity, and works on the dentine from within. Surface whitening cannot fix internal discoloration, the gel never reaches it. Most cases finish in 3 sessions over 3 weeks.
What is Internal Bleaching?
Internal bleaching is a technique where a peroxide-based bleaching gel is placed inside the pulp chamber of a non-vital tooth (a tooth that has had a root canal) and sealed with a temporary restoration. The gel works on the internal dentine over several days. Multiple sessions may be needed. It is also called the "walking bleach" technique, because the bleach continues to work between appointments while you go about your normal day.
Why You Can't Just Use Regular Whitening
External whitening lightens the front enamel surface. When a tooth has darkened from inside, after a root canal, or from old blood pigments after trauma, the discoloration is in the dentine, under the enamel. External peroxide cannot reach it. Internal bleaching addresses the source.
Why Picasso for Internal Bleaching
Cosmetic Dentist Supervises Shade-Matching
A dedicated cosmetic dentist supervises shade-matching to your natural neighbours. The goal is not maximum whiteness, it is for the treated tooth to disappear into the smile.
Sealed Cavity, Protective Barrier
A protective barrier is placed over the root canal filling before any bleach is introduced. This prevents leakage below the gum line, which is the root cause of cervical resorption (the rare but documented risk in the literature).
Professional Dosing and Stop Criteria
Bleach is replenished only at scheduled review visits, with controlled volumes and clear stop criteria. We do not over-bleach a tooth to the point it looks chalky or whiter than its neighbours.
Follow-Up and Re-Treatment
Reviews at 1 week, with re-treatment built into the protocol if the first round does not reach the target shade. We do not declare it done until your tooth blends into the smile.
Combined With Surface Whitening
If your other teeth could also use lightening, internal bleaching is sequenced alongside in-office or at-home whitening on the rest of the smile. Blended results, single visit plan.
Honest About When It Won't Work
Long-standing tetracycline staining, dark posts under the gum line, and severe years-old discoloration may not respond. We say so on day one, and quote a veneer as the alternative rather than charging for treatment that will not deliver.
When Internal Bleaching Is the Right Tool
Single Darkened Front Tooth After Root Canal
The classic case. One tooth had a root canal, sometimes years ago, and has slowly turned grey, yellow or brown while the others stayed normal.
Tooth Darkened From Old Trauma
A blow to a front tooth in childhood or sport can leave blood pigments inside the dentine. Even after a root canal seals the tooth, the colour stays. Internal bleach lifts those pigments out.
Gradually Darker Than Its Neighbours
Some non-vital teeth darken slowly over years. If the tooth is otherwise sound, with no need for a crown, internal bleaching is the most conservative way to bring it back into the smile.
You Don't Want a Veneer or Crown
Internal bleaching removes no enamel and adds no porcelain. If you would prefer to keep the tooth as natural as possible, this is the conservative route to try first.
When It's Not the Right Tool
The Tooth Still Has Live Pulp
Internal bleaching is only for non-vital teeth. If your tooth has live pulp, surface whitening is the answer, do not have a root canal just to internally bleach.
Fractures or Large Cavities
Structural problems are restored first. Bleach should never be sealed inside a tooth that is leaking.
Discoloration From a Metal Post
If the dark colour is coming from a metal post sitting under the gum, bleach will not change it. A more complex restoration, removing the post and rebuilding, is needed.
You Want All Teeth Lightened
Internal bleaching treats one tooth. If your goal is general whiteness across the smile, in-office or at-home whitening is the right tool.
Severe Long-Term Discoloration
Decades-old grey teeth, heavy tetracycline staining or a tooth previously bleached and rebounded multiple times, these often will not lighten enough. A veneer is the more reliable answer.
You Want a Guaranteed Final Shade
Bleaching results vary tooth by tooth. If you need a specific colour match for a planned smile makeover, a porcelain veneer is more predictable.
Internal Bleaching Pricing
All pricing. Internal bleaching is priced per tooth.
| Service | Price |
|---|---|
| Internal bleaching (per tooth) | |
| Initial root canal if not already done (incisor / canine) | |
| In-office whitening, per jaw (if combining with surface whitening) | |
| Veneer if internal bleaching is not enough (Emax Press) |
See also teeth whitening, root canal treatment and porcelain veneers.
Are You a Candidate?
Internal bleaching is a narrow tool. Here is who benefits, and who is better served by a different treatment.
You're a Strong Candidate If
You have one tooth that is noticeably darker than its neighbours.
The tooth has had a root canal that is still well-sealed (confirmed by X-ray).
The dark tooth is otherwise sound, no large cavity, no fracture, no metal post under the gum.
You want a conservative option before considering a veneer.
You have realistic expectations, the goal is to blend the tooth back into the smile, not to bleach it whiter than its neighbours.
Internal Bleaching May Not Be Right If
The tooth still has live pulp, surface whitening is the answer.
The root canal seal is leaking or compromised, re-treatment first.
The discoloration is caused by a dark metal post under the gum line.
The tooth has a large filling, fracture or existing crown, restoration is the better path.
You want every tooth lightened, do in-office whitening instead.
How Internal Bleaching Works
Five steps over 3 weeks.
Examination + X-Ray
Confirm the existing root canal is well-sealed and intact. If not, root canal re-treatment is done first.
Reopen Access Cavity
The access cavity at the back of the tooth is reopened, and a protective barrier is placed over the root canal filling.
Bleaching Gel Sealed Inside
Peroxide gel is placed inside the pulp chamber and sealed with a temporary restoration. You leave with the gel working from inside.
Review at 1 Week
Shade is checked. If further lightening is needed, fresh gel is placed and resealed. Repeat 2 times.
Permanent Seal
Once target shade is reached, the access cavity is permanently restored with composite. Avoid staining foods for 48 hours.
Internal Bleaching vs Veneer for a Single Dark Tooth
An honest comparison. Both work, the trade-offs are different.
Internal Bleaching,
Conservative, no enamel removal, no porcelain bonded on. Takes 3 short sessions. Result depends on the underlying cause and may need top-ups over time. Re-treatment is straightforward if it rebounds. The right starting point if you would prefer to keep the tooth natural.
Veneer,
Permanent, predictable shade-matching, masks any underlying discoloration regardless of cause. But removes 0. 0.5 mm of front-surface enamel and the tooth will need a veneer (or replacement) for life. The right answer if internal bleaching fails or if you want guaranteed colour stability.
Aftercare
Avoid Staining Foods 48 Hours
After the access cavity is permanently sealed, avoid coffee, tea, red wine, curry and dark sauces for 48 hours. The fresh composite is more receptive to staining in this window.
Brush Gently Around the Access Site
The access site is on the back of the tooth. Brush normally but gently in the first week, the temporary or final composite needs time to fully bond.
Follow-Up at 1 Week
Review at 1 week to confirm shade and check the seal. Most second sessions, if needed, happen at this visit.
Expect Some Shade Rebound
Slight darkening over months is normal, the tooth often re-equilibrates a fraction of a shade. A short top-up application can refresh the result if and when this happens.
Risks & Honest Tradeoffs
Internal bleaching is conservative, but not zero-risk. Here is what we tell every patient before starting.
Cervical Resorption (Rare)
Cervical resorption is documented in the dental literature when bleach leaks below the gum line and irritates the root surface. It is rare. Picasso minimises this with a protective barrier over the root canal filling and controlled dosing, but the small residual risk is real and we disclose it.
Shade Rebound Over Months
Some tooth-by-tooth rebound is normal. The result is not as permanent as a veneer. Top-ups are simple but not free.
May Not Fully Match Neighbours
Bleaching depends on the cause and age of the discoloration. Sometimes the tooth lightens significantly but not completely. A veneer remains the fallback for a perfect match.
Root Canal Seal Must Be Intact
If the original root canal is leaking or incompletely sealed, internal bleaching cannot proceed safely. Re-treatment is done first, which adds cost and time.
Not a Whole-Smile Solution
Internal bleaching treats one tooth. If you also want surface whitening across the rest of the smile, that is a separate treatment, sequenced alongside.
What We Will Tell You No To
If the cause is a dark metal post, severe tetracycline staining or decades-old discoloration that has resisted prior bleaching, we will say internal bleaching is unlikely to work, and quote a veneer or crown instead.
Your Cosmetic Team
Internal bleaching at Picasso is supervised by our cosmetic dentist alongside the founding clinical director, who sets the protocol group-wide.
Dr. Rosie Nguyen
Cosmetic Dentist. Supervises internal bleaching cases, shade-matching to natural neighbours and combined whitening plans across the smile.
Dr. Emily Nguyen
Founding Clinical Director. Founded the original clinic in Hanoi in 2013 and sets clinical standards for case selection and prosthetic delivery group-wide.
Frequently Asked Questions
How is internal bleaching different from regular teeth whitening?
Regular whitening lightens the front enamel surface using gel applied outside the tooth. Internal bleaching places gel inside the tooth, in the pulp chamber, after a root canal. It treats discoloration that comes from within the dentine and which surface whitening cannot reach.
Will internal bleaching work on my dark tooth?
It depends on the cause and how long the tooth has been discoloured. Discoloration from old blood pigments after trauma, or from the root canal procedure itself, generally responds well. Very long-standing discoloration, or discoloration caused by a metal post, may not fully lighten. We assess realistic outcomes before starting.
How many sessions will I need?
Most cases need 3 sessions, spaced about a week apart. The bleaching gel works inside the tooth for several days between visits. Some cases reach the target shade in a single sealed application; others need two or three top-ups.
Does internal bleaching hurt?
No. The tooth being treated has already had a root canal, so it has no live nerve. Reopening the access cavity does not cause pain. There may be brief mild sensitivity in the surrounding gum, which settles within a day.
Will the result last?
Many cases hold their shade for years. Some shade rebound over months is normal, and a brief top-up application can refresh the result. If long-term colour stability is the priority, a porcelain veneer is the more permanent alternative.
Can I have internal bleaching if I have not had a root canal?
No. Internal bleaching is only performed on non-vital teeth, meaning teeth that have already had a root canal. If your tooth still has live pulp, surface whitening or a veneer is the right approach instead.
Can the bleach harm the tooth root?
Cervical resorption is a rare but documented risk in the dental literature, where bleach leaks below the gum line and irritates the root. Picasso minimises this by placing a protective barrier over the root canal filling before any bleach is introduced, and by using controlled dosing and stop criteria.
What if internal bleaching does not work?
If the tooth does not lighten enough to match its neighbours, the next step is a porcelain veneer at or a crown if the tooth is heavily restored. Internal bleaching is conservative, so trying it first does not preclude these alternatives.
Can I have internal bleaching on multiple teeth?
Yes, if more than one tooth is non-vital and individually discoloured, each can be treated. Pricing is per tooth at. However, if you want general lightening across all your teeth, surface whitening on the rest of the smile is usually combined with internal bleaching on the dark tooth.
What is the alternative if internal bleaching fails?
A porcelain veneer (Emax Press,) is the standard alternative. It removes 0. 0.5 mm of front-surface enamel and bonds a thin porcelain layer in a chosen shade. The result is permanent and predictable, but it is more invasive than bleaching.
Start Here
One Dark Tooth, Back In The Smile.
Book a free consultation. We will X-ray the tooth, confirm the root canal seal, and tell you on day one whether internal bleaching is likely to work or whether a veneer is the better tool. Quoted in writing before any clinical work.