The Document Center allows you to view documents for a single patient or an entire family. Use Views to see a list that contains all documents for every member of the family without having to select a new patient and switch between patients.
via Dentrix Tip Tuesdays: Viewing Documents for an Entire Family in the Document Center.
I believe Document Center is one of the most useful features of Dentrix and yet it is very often not used by offices or else used very inefficiently.