There are a lot of dentists in MKE, many of them reputable. You could start by looking through Milwaukee Magazine's listing of top doctors. I can't post a link here, but find the magazine's home page, then go to Local Search > Physician Search and select "Dentistry" under the Specialty pull-down. Or you can search according to insurance, if you have dental insurance.
I know people who go to Dr. Mykleby (on Watertown Plank Rd.) but he seems a little too eager to do expensive procedures. Dr. Tongas (on 124th & North) is someone I've heard good things about.
Speaking of insurance, Delta Dental is pretty reasonable. Good luck!