Polydioxanone, a modern sutural material is used to produce PDO threads. This material is normally used by surgeons for sewing together soft tissues. It diffuses inside the tissues within 180-210 days, does not cause any allergic reactions, and is not toxic.
Polydioxanone has high-tensile strength. During the diffusion it stimulates formation of fibrous connective tissue.
These PDO screws are absolutely amazing. They do the job of a filler without the dangers associated with it. I tied them on my neck, double chin and jawline. There was not much change at first but in a couple of weeks they really looked better than the expensive skin tightening treatments that I had tried years earlier. Make sure to use enough threads and get the right length.