How do injectable fillers work?

Injecting dermal filler into different levels of the dermis is similar to filling a jelly doughnut, in that a hole is pierced into a pressurized system. The extracellular matrix is the dough that holds the filler in place. Fillers are derived from four sources. Synthetic materials are silicone, calcium hydroxylapatite, poly-l-lactic acid, and polymethylmethacrylate (PMMA). These are the heavyweights, not just because of their permanent or semipermanent aspect but because they can be very dense, like calcium hydroxylapatite, or offer high volume, like poly-l-lactic acid acid (Sculptra). Sculptra is a solution - (more watery than other gel fillers) - that provides a great fill effect on a large area, but the downside is that the extra fluid dissipates quickly and requires refilling every three to five months for three to five treatments until it builds up and stimulates the body to build its own collagen.