There are certain developmental disorders in which the teeth form without enamel, abnormally large nerves, or abnormally small nerves which can lead to discoloration.usage of certain medications during tooth em development, tetracyclines for example, or high fevers during tooth development may lead to discoloration as well.
Can be exposure to too much fluoride during childhood or chipped teeth which can cause discoloration due to nerve or enamel damage
Discoloration you mean decay? Discoloration can be many things, it can be decayed, can be stain, can be own teeth color, can be non-vital tooth, can be fluorosis, etc.
1. Tooth decay:
Tooth become brownish/black color due to surface/acid intake. Yes, juice can cause tooth decay, but the main reason for that to happen is long-term exposed to acidic environment.
After a sip of juice, our pH value of our mouth will drop, study shows that tooth decay process begin when pH value is below 5.5. However, our saliva will neutralize the acidity within time, so after 45min, pH value will come up again. Therefore the frequency of food intake is the key.
For example: if you drink a 2L coke now and finished it within 5 min, your mouth is only be acidic for a short while, then the chance of getting tooth decay is low. But if you have a sip now, 5min later another sip, 10min later another sip, and you finished the coke in 1 hour, your mouth is constantly in an acidic situation, the chance of getting tooth decay is very high.
Stain is something externally attached to the teeth, can be removed by going to a dentist or hygienist to do a dental cleaning
3. Own tooth color
Some people has more yellowish color than others, it’s genetic
4. Non-vital tooth
If the child had injury before (knocked/fall on the floor), the tooth might be injured, and the nerve of the tooth become non-vital, then the tooth will get darker and darker within time. Need to go to a dentist for treatment (it can cause infection and may affect the permanent tooth)
Excess intake of fluoride can cause fluorosis. Tooth become either whitish spots or brownish color.
My advice to you is take your child to a dentist for a check up, get a proper diagnosis, and then have treatment if necessary.
Dr. Chun-I Lee
You do not mention how they are discolored or what color they are, so it is hard to pinpoint the reason with the information given.