Dean entered his plea during an arraignment hearing at the Evans courthouse.
A grand jury indicted him Feb. 2 on two counts of molesting one of five children he and his wife, Renee, adopted from Guatemala in 2008.
According to the indictment, Dean exposed himself and inappropriately touched the girl.
On Thursday, Superior Court Judge James G. Blanchard Jr. appointed a child advocate to guard against potential undue influence on the girl that might sway her testimony. She currently lives with Renee Dean in their Harlem home.
Scott Dean has not lived at the home since the state Division of Family and Children Services temporarily removed the adopted children in October.
Dean resigned from his post as District 4 county commissioner on the day of the indictment. Two days later, the commission formally accepted his resignation and set March 15 as the date for a special election to replace him.