In many cases, the reason a single front tooth looks dark is that the nerve (dental pulp) of that tooth has been lost. A tooth that has had its nerve removed, or a tooth whose nerve has died after being hit, can darken from the inside over time. This discoloration can sometimes be made less noticeable by a method that whitens the tooth from the inside (walking bleach). However, cavities and fillings can also be the cause, so there is more than one reason a tooth can look dark. Let's start by finding out the cause.
In this article, we explain in order why only one front tooth discolors, how to tell the possible causes apart, how to whiten the tooth, costs and risks, and when to see a dentist.
Why Does Only One Front Tooth Turn Dark?
At the center of a tooth, there is a space through which the nerve and blood vessels run. When the nerve in this part is lost, nutrients no longer reach the tooth. In addition, substances produced when the nerve and blood vessels break down soak into the inside of the tooth. As a result, the color of the tooth gradually darkens from the inside and begins to look gray, brown, or blackish.
How long it takes to notice the discoloration differs from person to person. Some people notice it within a few months of treatment, while others notice it only after several years. Because the surrounding teeth stay white, just one tooth tends to stand out. Have you ever suddenly noticed it when smiling or looking back at a photo?
Main Causes of Discoloration
- A tooth that has had nerve removal treatment (root canal treatment): The nerve is gone, and the tooth may darken from the inside over time.
- A tooth whose nerve died after being hit or after a fall: An injury from the past may show up as discoloration several years later.
- The effect of old fillings or crowns: A metal filling may show through, making the tooth look dark.
- Cavities: A cavity that has progressed on the tooth surface or under a filling may look black or brown.
How Can You Tell a Dark Tooth's Cause? What to Check Before Your Visit
You may think, "Can't the cause be told by how it looks?" In fact, the cause cannot be determined from color alone. The following points can be clues during an examination.
- Have you ever had nerve removal treatment on that tooth?
- Do you remember hitting that tooth?
- Is there any hole or roughness on the surface?
- Does it hurt with cold or hot things, or hurt when you bite?
- Is the gum swollen, or does it hurt when pressed?
If there is pain or swelling, inflammation may have developed at the tip of the tooth root after the nerve died. In this case, the inflammation needs to be treated before whitening. We check the condition of the root with an X-ray and then decide the order of treatment.
How to Whiten a Darkened Tooth
Depending on the cause and degree of discoloration, the following 3 methods are mainly possible.
Method | Description | Suitable condition |
|---|---|---|
A bleaching agent is placed inside the tooth through a small hole on the back of the tooth, gradually whitening it | Discoloration from the inside of a tooth whose nerve has been removed or has died | |
The agent acts from the tooth surface | Yellowing of teeth with a living nerve. It may not work well on teeth discolored from the inside | |
The tooth is trimmed and covered with a white artificial tooth | A tooth that is largely chipped, or that does not become white enough with bleaching |
For yellowing of teeth with a living nerve, whitening, in which the agent acts from the tooth surface, is suitable. On the other hand, because the cause of color in a tooth whose nerve has been removed lies inside, methods from the surface may not make it white easily. In that case, walking bleach, which whitens from the inside, is an option.
The Flow of Walking Bleach
- Examination and tests: We use an X-ray to check whether the root canal treatment has been properly completed. If the root canal treatment is insufficient, it may be redone first.
- Placing the agent: A small hole is made on the back of the tooth, the bleaching agent is placed inside, and the hole is sealed.
- Changing the agent: You visit the clinic once every few weeks, and the agent is changed while checking the color.
- Finishing: When the color blends in with the surrounding teeth, the agent is removed and the hole is filled.
The number of visits until the tooth becomes white depends on the degree of discoloration. We will tell you the outlook at the time of your examination. A feature of this method is that it does not require trimming the tooth much.
What to Check Before Whitening
The method of whitening from the inside requires that root canal treatment has been completed and that there is no inflammation at the tip of the tooth root. If bacteria remain inside the root, pain or swelling may appear later even after whitening. That is why we first check the condition of the root with an X-ray.
Also, a tooth with thin walls breaks more easily. The size of the hole for placing the agent, and whether reinforcement is needed after whitening, are also decisions made after checking at the examination. We value not only whitening, but also making sure you can keep using that tooth for a long time.
Estimated Cost
The cost of walking bleach is ¥33,000 (tax included). Our clinic offers self-pay (not covered by Japanese health insurance) treatment only and does not provide insurance-covered treatment. If other treatment is needed first, such as redoing root canal treatment, we will explain the details and cost beforehand. Please check the latest fees on the price list.
Risks to Be Aware Of
- A tooth whose nerve has been removed is brittle to begin with, and may break easily even after treatment. Please be careful when biting hard foods.
- It has been reported, though rarely, that the outer side of the tooth root is resorbed (dissolves). Our policy is to keep checking with regular X-rays even after treatment.
- The degree of whitening differs from person to person, and the color may return over time.
- Depending on the cause of discoloration, the tooth may not become white enough. In that case, we will suggest other methods such as a crown.
When to See a Dentist Early
- Your front tooth has started to turn dark, or its color has suddenly changed
- The dark tooth has pain, swelling, or a bump on the gum
- The dark area has a hole or roughness
- The color began to change some time after you hit the tooth
Even without pain, discoloration can be a sign that the nerve has been lost. If you would like to check the condition of your whole mouth in detail, you can also have the thorough examination, the Oral Dock (comprehensive dental check-up).
Frequently Asked Questions
Is a single dark front tooth a cavity?
It may be a cavity, but often it is a tooth whose nerve has been removed, or whose nerve died after being hit, darkening from the inside. Because it cannot be told apart by appearance alone, we check the cause with X-rays and other means. If there is a hole on the surface, cavity treatment may come first.
Can whitening make a dark tooth white?
Whitening is suitable for yellowing of teeth with a living nerve. Teeth discolored from the inside may not become white easily with methods from the surface, and we may suggest walking bleach. Which one suits you is determined at the examination.
Does walking bleach hurt?
Because it is performed on a tooth without a nerve, you rarely feel strong pain when the agent is placed. If you feel any discomfort in the gum or when biting, please let us know right away.
Will a whitened tooth stay white forever?
The color may gradually return over time. If it starts to bother you, please talk to us about repeating the treatment.
If You Want to Consult About a Darkened Front Tooth in Shibuya
Halulu Shibuya Dental Clinic is on the 4th floor of the Toyama Building in Jinnan, Shibuya-ku, a 5-minute walk from Shibuya Station (JR and other lines). The director is Dr. Kazuya Shiho, a dentist who graduated from Tokyo Medical and Dental University (now Institute of Science Tokyo). We focus on prevention and value care that protects your existing teeth as much as possible. Even if only one tooth is discolored, please feel free to consult us.
Our hours are 10:00 to 18:00 on weekdays. On weekends, public holidays, and evenings, we see patients by appointment only on days when a doctor is in. Please check the calendar at the time of booking for details. You can make a reservation online (accepted 24 hours a day), and also by LINE or phone (03-5422-3518). If it is your first visit, please start with the first-visit counseling (initial consultation fee ¥5,500), where we listen to your concerns.
Book online at Halulu Shibuya Dental Clinic here
This article was supervised by Dr. Kazuya Shiho, Director and dentist at Halulu Shibuya Dental Clinic.