In the UK we say 'tooth filled' for having the action done in the sense of the activity of carrying out the work. I.e. I've had my tooth filled. We say 'filling' (meaning tooth filling) for the actual metal in the tooth. We can also say 'I'm having a filling done'. Therefore, 'It costs about 500 to have a tooth filled' is correct, but we could also say 'It costs about 500 to have a filling' as well. Filled is the activity, Filling is the metal, except on the rare occasion when a dentist is actually in the process of 'filling' the tooth when they would be carrying out a filling! This latter sense would be rare.

They are equally good. "Filling" is a noun. "Fill" is a verb. When you have a cavity, the dentist first removes the decay. That creates a hole that that needs to be "filled". Once he does that, the tooth has been "filled". The entire process is called "filling". It is the same with the words "cleaning" and "cleaned". You may pay someone to have your house "cleaned". The whole process is called "cleaning". So you can say either "I paid Jack and Mary $100 to have my house cleaned" or "I paid Jack and Mary $100 for a house cleaning."

Filled

“… to have a tooth filled” is how one would complete your sentence here. To have something done means to have arranged for someone else to do it for you, and the expression always ends with the past participle, I believe - to have the party catered, to have her hair done, to have the lawn mowed, for example.