Target, Identify and Educate.
I think the beauty of your marketing is that:-
A) As a dental student your age gives credibility to door knocking. ( it might appear desperate if a middle aged dentist adopted the same approach?)
B) Cost effective.
C) Targets those close to the practice, that are more likely to need or make use of your dental praxtice.
D) Educates those people about the practice in a very open and friendly way.
E) Allows you to get informed on the competition. ( This can often give you the correct time frame to do a " return call")
Hope the exercise generates a great client base.