The teeth grinding sound is produced when the rabbit’s teeth rub against each other. It could be normal purring, clicking or chattering if it is less audible, and has a higher frequency. This is a sign of contentment common during petting.
However, in this discussion, we are talking about the louder, more audible teeth grinding and not purring. Let us look at the meaning of this dental vocal cue.
Reason for rabbit teeth grinding
An effective deciphering of any rabbit body language as well as vocal sounds requires you to consider the circumstances under which it occurs. This will ensure you always correctly interpret and understand what your furry friend is trying to tell you or other bunnies.
Some of the common reasons for this dental rubbing behavior include the following:
Your rabbit is in pain and discomfort
Teeth grinding often signifies pain. Your bunny is trying to tell you that he or she is in pain or hurting. This should not be confused for purring which shows contentment. You will notice other pain symptoms including “hunched and tense, doesn’t show any interest in moving or eating, or shows aggression” 
Your bunny has dental problems
It could be a sign of malocclusion and elongation of molars and premolars. Some of the common symptoms of this condition include rabbit teeth grinding , not eating (reduced appetite), preferring softer foods, drooling excessively, producing excessive tears, nasal discharges, and signs of pain such as a hunched posture, lethargy, depression, among others.
In case of overgrown teeth, your vet may consider filing them and recommended a diet that is high in fiber to help wear them down as well as recommend chew toys among other treatment options. Always ensure you provide your rabbits unlimited amounts of grassy hay brands like Small Pet Select 2nd Cutting "Perfect Blend" Timothy Hay Pet Food, Kaytee Timothy Hay, Standlee Premium Western Forage Timothy Grass, among many others.
If your rabbit does not eat, you should be worried since it can lead to other digestive related problems including GI stasis.
He or she is stressed, terrified or anxious
The third common cause of teeth grinding in bunnies is stress. If he or she has emotional distress, anxiety, nervousness, panic, and so on. Wrong and rough handling, sight, smell or noises of predators, sudden environment change, confinement in a small cage among others can often make these pets show this behavior.
Seek for treatment
If you are not certain about the causes of pain in your rabbit, call a rabbit savvy vet for diagnosis and treatment. Some causes of pain can be life-threatening and they may cause death.
When caused by pain, discomfort, or dental problems, some bunnies may have other symptoms including screaming, not eating, hiding, not moving, hunched posture, lethargy, decreased grooming among others.