We have claims that are rejecting through DentalXChange due to the Taxonomy number not matching. Where in Denticon do I enter each providers Taxonomy number?

The Taxonomy Code is selected by the providers specialty.

To select the provider specialty go to Set Up>Providers>Providers Set Up>Select the provider>Edit Provider>Under Provider Settings> Select the specialty from the drop down>Save:

 
The setup for Type Records for Specialties (taxonomy codes) is found at: Setup>Misc Setup>Advance>Provider Specialties>Edit: