Where (in terms of skin depth) are dermal fillers injected?

Good question. As the name implies, most fillers are injected into the dermal layer of the skin.

Dermal fillers such as Restylane and Juvederm are injected into the dermal layer of the skin which is the layer beneath the epidermis.  Voluma is injected deeper in the skin.  Please consult an experienced injector for the best cosmetic results.  Best, Dr. Green