Primary Care Dental Academic Workforce Development Act of 2008 - Amends the Public Health Service Act to authorize the Secretary of Health and Human Services to make grants to, or enter into contracts with, programs of general dentistry or pediatric dentistry to plan, develop, and operate a loan repayment program to pay student loans in exchange for service as full-time faculty members. Requires the Secretary to: (1) encourage participating programs to use support to broadly recruit diverse faculty; and (2) establish appropriate financial penalties for individuals not completing their service obligations.