The inferior alveolar nerve block (IANB) is a dental anesthetic injection that is critical to the performance of many dental procedures. Dental students typically learn to administer an IANB through videos and practice on silicone molds and, in many dental schools, on other students. This causes significant stress for both the students and their early patients. To reduce discomfort and improve clinical outcomes, we created an anatomically informed virtual reality headset-based educational system for the IANB. It combines a layered 3D anatomical model, dynamic visual guidance for syringe position and orientation, and active force feedback to emulate syringe interaction with tissue. A companion mobile augmented reality application allows students to step through a visualization of the procedure on a phone or tablet. We conducted a user study to determine the advantages of preclinical training with our IANB simulator. We found that in comparison to dental students who were exposed only to traditional supplementary study materials, dental students who used our IANB simulator were more confident administering their first clinical injections, had less need for syringe readjustments, and had greater success in numbing patients.