The answer depends on the age of the horse.
From Foaling to 5-years the oral cavity should undergo a veterinary exam every 6-months. This is because of the huge amount of change that occurs in the mouth during this time frame with the loss of the deciduous teeth “caps” and the eruption of the permanents.
The first “Official” dental is usually at 9-months of age where the deciduous teeth have erupted. This can be a good time to remove “wolf teeth” if present, a vestigial tooth, that can cause problems with biting. Wolf teeth can also be removed at castration in colts taking advantage of the anaesthetic that is already on board.
It is highly recommended that the horse undergoes a dental examination before breaking to minimize potential pain and stress that could affect a horse’s behaviour and association with the bit for the rest of its life.
Older horses are generally able to be maintained with an oral examination every year. If this does not happen large overgrowths occur that can be difficult to correct and may require several visits over the course of 6-months to bring the mouth into balance.
Just like people horses can suffer from periodontal disease and this condition is more common in the older horse. It is an important condition to identify and address as it is painful and can have an effect on whole body health. The chronic shedding of bacteria into the blood stream from periodontal disease in broodmares for example is a known cause of reproductive losses.