I have changed my mind on dental implants and have already been charged for them. Can I be reimbursed?

When you say charged for them - were you billed and remitted a check as cash payment or did you use a credit card and the charge appears there? Did you pay upfront for them and they were not implanted yet? If so, then yes since no services were performed.

If you have had the base of the implant implanted I doubt it since you still need to pay for that procedure and the implants - if you paid upfront for everything such as the crown, bridge or denture that would attach to it - you would only be entitled to a partial refund for servise not provided.