Inside the Watterson and outside the Gene Snyder are two different accounts
The ring roads mark a real change in competition, patient behavior and what a click is worth.
Inside the Watterson, practices sit close together and a patient has a dozen credible options within ten minutes. Clicks are contested, brand recognition matters, and the deciding factor is often availability rather than distance.
Out past the Gene Snyder and into Oldham and Bullitt counties, the picture inverts. Fewer practices, longer drives, and patients who expect to travel. Auction pressure is generally lighter and the same daily budget goes further, but the volume is thinner and the account takes longer to learn.
Split them. Separate campaigns, separate budgets that cannot borrow from each other, separate landing pages. A shared campaign will spend the outer-county money in the dense inner ring, because the algorithm goes where the clicks are cheapest to win, not where the chairs need filling.
Set the targeting to people regularly in the location, not people showing interest in it. Left on the default, a dental account in a metro with this much through traffic will buy clicks from people who are not here.