Dental cysts are not dangerous and usually will go away on their own.
However you should get treatment for the dental cyst if possible because when a dental cyst is left untreated it can lead to infection of the gums and teeth.
The tooth infection and gum infection can cause serious complications.
So it would be best to see a dentist to get the dental cyst taken care of before it potentially causes any further infection.
Dental cysts are non cancerous so there's no worry about that.
Just like most other cysts on arms etc are not cancerous it's still a good idea to get it checked out just in case.