But that update changed how on page optimization works. Keyword density is an ineffective measure of relevancy, so rough repetition is not an effective SEO strategy. Many pages and sites that use keywords too aggressively end up getting filtered out of the search results.
Your on page SEO strategy should use semantically related phrases and mix up your keyword usage. If your page title is "Chicago Dentist & Dental Care : Business Name" then your on page heading tag should be something like "Your Friendly Dentists in Chicago".
This spreadsheet offers examples of how you might want to mix up your keyword usage
A cool tool called Quintura helps you visualize related phrases.
Type in some of your keywords and find out what keywords and keyword modifiers they think are related.