These Are HORSE Teeth, Not HUMAN Teeth
Cavities do occur in horses, but they usually resolve by themselves either by self repair (but also with the removal of starch / grain) or a piece of tooth breaks off with no harm to the horse.
There are some equine dentists “filling” horse cavities saying that the horse will live on average 5 additional years because of the treatment. This is just a play on your emotions based on your fear of cavities in your own mouth.
Just as a reminder, these are HORSE teeth and not HUMAN teeth. They are completely different. Since 1983 I have not had 1 horse come to me with a complaint of a cavity causing him not to eat or causing any other issue.
What is happening is decay of one or more of the pulp chambers of a tooth which will eventually cause a fracture of a part of that tooth. Think of a wedge splitting a log into fire wood. The upper 9’s are the most commonly affected.
In 2013 at the AAEP meeting, it was mentioned that the dental acrylics used in the repair of these decaying areas is not effective. They usually fall out. Remember that horse teeth continually erupt with chewing and ware.
What I have found is that about 1 in every 40 horses (or more) I see has a tooth fracture which causes no problem in the horse other than occasionally the tooth fragment creates a painful rubbing ulcer in the cheek or tongue. The tooth fragment is easily removed and the sharp edges are then smoothed.