Cavity treatment
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Cavity treatment
Hamille Tokyo Dental Office
Tooth decay is caused by bacteria in plaque producing acid that dissolves the tooth. In its early stages it can sometimes be reversed by brushing, but past a certain point it only gets worse and cannot heal on its own. To keep your teeth for the long term, it’s best to treat tooth decay while the nerve can still be saved.
About tooth decay
Tooth decay is caused by bacteria in plaque producing acid that dissolves the tooth. In its early stages it can sometimes be reversed by brushing, but past a certain point it only gets worse and cannot heal on its own. To keep your teeth for the long term, it’s best to treat tooth decay while the nerve can still be saved.
Symptoms of tooth decay
In its earliest stage, tooth decay has no symptoms — the tooth surface simply loses its shine or turns a light brown. Once acid from the bacteria dissolves the enamel, the area may discolour or develop a small hole, and you may notice some sensitivity, but there is still almost no pain at this stage.
Left unnoticed, decay will eventually reach the dentine and then the nerve, causing sharp pain even without any stimulus. Because the pain can disrupt sleep and daily life, this is often what brings patients to the clinic — but by this point the decay is usually too advanced to heal on its own, and treatment means removing the decayed tissue and placing a filling, or treating the nerve.
If decay is left untreated for longer still, the pain may ease for a time, but pus can collect at the root or gum, bringing even more severe pain, and in the worst cases extraction may be needed.
Causes of tooth decay
There are 4 main causes of tooth decay.
Bacteria in the mouth
There are several hundred species of bacteria in the mouth, and the one responsible for tooth decay is called Streptococcus mutans.
Sugar in your diet
Bacteria in plaque use the sugar in your diet to produce acid, and this acid dissolves the calcium and phosphate in your teeth, causing decay.
Time
The longer sugar stays in the mouth, the more active the bacteria become, and the further the decay progresses.
Tooth quality
Tooth quality varies from person to person, depending on the conditions during its formation and factors such as heredity, and some people’s teeth are simply more prone to decay. Tooth decay develops when these factors combine.
Stages of tooth decay
Tooth decay is classified into 5 stages, from CO to C4, according to how far it has progressed.
C0
CO is the earliest stage, before a hole appears: the surface loses its shine and looks cloudy, or turns a light brown. At this stage, fluoride treatment at the clinic plus careful daily brushing can stop it progressing, so in many cases we simply monitor it rather than treat it.
C1
At C1, a small hole has formed in the enamel. There is almost no pain or other symptom at this point, so the decay often progresses without you noticing. Treatment at this stage is to remove the decayed tissue and place a filling.
C2
At C2, decay has reached the dentine beneath the enamel and formed a larger hole. As it is now close to the nerve, cold or sweet food may cause a twinge, and you may feel some pain. Treatment involves removing the decayed tissue first, then fitting a filling or a crown depending on how far the decay has progressed and the size of the hole.
C3
At C3, decay has reached the nerve. Sharp pain can come and go even without any stimulus, disrupting sleep and daily life. A filling alone is no longer enough at this stage — the nerve needs treatment before a crown is fitted, so this usually takes more visits and more time.
C4
C4 is the most advanced stage. Decay has reached the root, and inflammation extends to the bone supporting the tooth and the surrounding gum; the risk of decay in other teeth also rises sharply, so extraction is usually needed. The pain may ease for a time once the nerve dies, but if pus collects at the root or inflammation reaches the bone, this brings even more severe pain and strong bad breath.
Treatment process
Booking
Please book in advance. You can book by phone or online.
Examination
We check how far the decay has progressed using dental instruments and X-rays.
Explanation and treatment plan
We explain the exact state of the decay and talk you through the treatment options.
Removing the decay
We remove the decayed tissue. If the infection has reached the nerve, we treat the nerve at the same time.
Fitting a filling or crown
We fit a filling or a crown, depending on how far the decay has progressed and the size of the hole.
Treatment complete
To keep the treated area clean, leave the follow-up care to us too.
Treatment costs
The first-visit fee is around ¥4,000 (30% co-payment). After that, the cost varies with how far the decay has progressed and what treatment is needed.
Early stage
￥3,000～6,000or so
(30% co-payment)
Moderate cases
￥3,000～10,000or so
(30% co-payment)
If you choose a self-pay material such as ceramic for the filling or crown, this is charged separately.
Severe cases
￥7,000～30,000or so
(30% co-payment)
If you choose self-pay treatment such as a ceramic crown or a dental implant, this is charged separately.
About insurance coverage
Dental treatment falls into 2 types: “insured treatment”, covered by health insurance, and “self-pay treatment”, paid entirely out of pocket. Basic treatment can use health insurance, and depending on your cover, you will usually pay 30% of the cost yourself.
However, insured treatment is limited to the minimum needed to relieve pain and restore function, using methods and materials approved under the insurance system. If you want better aesthetics, function, durability or a lower risk of further decay, we recommend self-pay treatment.
Examples of insured treatment
Procedures such as removing decay, nerve treatment and extractions, and materials such as silver fillings, silver crowns and insurance-approved dentures
Examples of self-pay treatment
Ceramic fillings, ceramic crowns, dental implants, metal-based dentures and clasp-free dentures
Preventing tooth decay
It matters to address each of the main causes of tooth decay — bacteria in the mouth, sugar in your diet, time and tooth quality — with the right measures for each.
- Brush your teeth soon after eating.
- Use floss, interdental brushes and mouthwash to remove what a toothbrush alone cannot.
- Avoid long, drawn-out meals and frequent snacking.
- Have regular check-ups at the dental clinic, and strengthen the enamel with fluoride treatment.
- Avoid passing decay-causing bacteria to infants and young children, for example by feeding them mouth-to-mouth.
Booking and enquiries
