My cousin has to have metal chains put in her gums. what does that do?

Orthodontics?: I am assuming that your cousin is undergoing some orthodontic treatment. Normally, they use chains to pull impacted teeth into the arch of teeth. Cuspids or canines are the most common. The teeth are surgically exposed, then a bracket is bonded to tooth. The chain is attached to bracket and to the braces to encourage the tooth to move up into position. It appears that the chain is in the gums.

Move impacted teeth: Chains in the gum usually mean the patient has teeth that are stuck up in the gums and the chains will pull them down into position in the mouth.

Reposition teeth: Metal (usually gold) chains are used to pull an 'impacted' tooth (usually an upper canine) into position. The chain is attached to the impacted tooth by a surgeon and then an orthodontist guides the tooth into its' proper position.

Pull tooth down : If a permanent tooth is trapped under the gums and does not come down by itself, it is called an impacted tooth. To correct this problem, the gums are cut to expose the tooth, a hook is placed on the tooth, and a chain is extended from the hook and connected to orthodontic braces. The chain will slowly pull the tooth down from under the gums into the mouth into the tooth's normal position.