1. How Dentists Decide on Treatment by Checking How Far Tooth Decay Has Progressed
When people hear "tooth decay," many imagine a scene with a drill. However, the Ministry of Health, Labour and Welfare’s e-Health Net explains tooth decay treatment by stages of progression. In the very first stage, which is early decay limited to the tooth surface, the approach is to not drill and instead rely on remineralization. [1]
Remineralization is the process where calcium and other substances in saliva return to the tooth surface that has been dissolved by acid. The important point here is that "tooth decay does not always mean drilling." Therefore, in treating tooth decay, it is more important to determine what stage you are currently at than to look for places to drill. [1]
Once the assessment is complete, the next step is treatment appropriate for that stage. How do they fix the parts that have progressed?
2. How Small Cavities Are Filled in One Visit and Large Cavities Need a Mold
For small cavities, the affected part is removed and filled with resin (synthetic resin). This often finishes in one treatment. [1] According to an explanation by a dentist, this resin hardens when special light is applied, so it can be filled directly in the mouth without taking a mold. [9] Hardening with light applies to small fillings, not all treatments.
If the cavity is large, the situation changes. A mold of the tooth is taken, plaster is poured into that mold to make a model of the tooth, and the filling or crown is made outside the mouth and then attached. [1] This process differs from filling small cavities directly in the mouth.
If it progresses further and reaches the pulp, which contains nerves and blood vessels, the pulp is removed, a post is placed, and a crown is attached. [1] As the stage progresses, the treatment becomes more extensive. All of this so far has been treatment "after tooth decay has occurred." So, what can be done at the dentist to prevent or manage tooth decay?
3. What Tartar Is and How Dental Hygienists Remove It
Plaque on the tooth surface contains many bacteria. When these bacteria combine with calcium and phosphate in saliva, they become tartar and stick to the tooth surface. [2] In other words, tartar is plaque that has combined with components in saliva and hardened like stone. Once it hardens, it cannot be removed by rubbing with a toothbrush.
Therefore, tartar is removed at the dentist. For gingivitis or mild periodontitis, improvement is said to be seen with just brushing instruction and tartar removal. [2]
One person who handles this procedure is the dental hygienist. The Dental Hygienist Law states that dental hygienists are licensed by the Minister of Health, Labour and Welfare and perform preventive procedures for mouth and tooth diseases under the direction of a dentist. This includes mechanically removing deposits and sediments on the tooth surface and applying medicine. They can also assist in dental treatment and provide dental health guidance. [6] Dental hygienists are specialists who handle preventive procedures, assistance in dental treatment, and dental health guidance.
However, removing tartar is not the end. There are also procedures to apply medicine to the teeth.
4. How Fluoride Application and Sealants Protect Teeth Before Drilling Is Needed
Fluoride application is a method where dentists or dental hygienists apply a relatively concentrated fluoride solution or gel to the teeth. It can be done from age 1 to prevent cavities in baby teeth. It is important to continue this at least twice a year. There are reports that continuing this in infants and young children reduced cavities by nearly half. On the other hand, reports often state the preventive effect for permanent teeth is 20–30%. [3] Please do not mix the "nearly half" for baby teeth with the "20–30%" for permanent teeth, as they are different numbers.
Fluoride is said to make teeth resistant to dissolving in acid and to help with remineralization, which restores calcium to dissolved parts. You can view this as a fluoride treatment that supports the "relying on remineralization" mentioned in Section 1.
The other method is sealants. Sealant material is poured into the grooves of newly erupted molars to block them, preventing plaque and food debris from entering. However, it does not last forever; it can chip or fall off, so regular checks at the dentist are necessary. Even with sealants, brushing is still needed. [4]
So, how much radiation do you receive from dental X-rays taken during an examination?
5. How Much Radiation You Receive from Dental X-Rays
Dentists sometimes take X-ray photos. This is to check for cavities that cannot be seen by eye or to examine the condition inside the gums.
According to materials from the Tokyo Dental Association (modified from materials by the National Institute of Radiological Sciences), the radiation dose for a dental X-ray of one tooth is about 0.01 mSv, and for a panoramic X-ray of the entire jaw, it is about 0.03 mSv. The materials explain that both values are extremely small compared to one year's worth of natural radiation. [5] We receive natural radiation in our daily lives, and these numbers serve as a benchmark for comparison.
However, these are approximate figures based on one source. These numbers are to help understand the approximate dose, not to definitively state that it is safe.
6. Where the 8020 Movement's Goal of Keeping 20 Teeth at Age 80 Came From
The 8020 Movement is a campaign to "keep at least 20 of your own teeth at age 80." It was proposed in 1989 (the first year of the Heisei era) by the Ministry of Health (then) and the Japan Dental Association. It is based on a survey from Aichi Prefecture. At the time it started, fewer than 1 in 10 people had achieved it, but in a 2016 survey, 51% of people aged 75–84 had achieved it. [7]
Why 20 teeth? Excluding wisdom teeth, there are 28 teeth, but it is said to be based on research that if you have 20 or more, you can chew most foods. The number 80 is explained as being close to the average life expectancy at the time of its proposal in 1989 (75.9 years for men, 81.8 years for women). [8] However, this explanation is based on a municipal page, and the original source has not been traced.
Monitoring early cavities without drilling, removing tartar, and protecting with fluoride and sealants. If you connect the dentist's treatments into one line, they are all directed toward preserving your own teeth.
7. What You Can Do at Home and Ask Your Dentist Next Time
Things you can do at home: Look at the grooves of your back teeth with a mirror and a bright light. The sealants in this article are exactly a procedure to block these grooves. It is enough to just observe the grooves. Be careful not to shine the light into your eyes.
Things you can do at the dentist: Next time you go, ask, "What did we do today?" Assessment, filling, removing, applying, taking photos. If you know which of the five things in this article applies, what is happening in the examination room becomes concrete.
Official materials: The Ministry of Health, Labour and Welfare’s e-Health Net has explanations such as "stages of tooth decay treatment" and "fluoride application." You can open them from the source column. [1]