I had a Porex chin implant last year but I want more projection. What are my options? Can another implant be added on top of it?

One can add some moderate projection to an existing chin implant but it has to be placed under it. This is known as the wafer chin implant revision technique. Whether this would be appropriate depends one exactly what type of chin augmentation change you seek from the implant you currently have. From a nose standpoint, the result is usually pretty stable after one year and certainly by two years after surgery. Whether a revision rhinoplasty is warranted depends on exactly what changes you wanted to see.

 It is probably best to return to your original surgeon who put the Porex chin implant in place to have it removed. Your  Original surgeon should have the specific screwdriver needed to remove the titanium screw that is present, since there are many different manufacturers of titanium screws and each have their own hex head  shape and sizes. There is no sense in placing one implant on top of another, just put the appropriate sized implant in place. For many examples of Silastic chin implants, please see the link below

You can increase your chin projection with either a larger implant or an advancement genioplasty.  The old implant needs to be removed which whatever you decide.   For the nose, you are probably where you will be at 2 years post op and very little if any change is likely to occur.  A revision may be done depending on the problem concerning you.  This could possibly be done along with chin surgery.  Good luck. Donald R. Nunn MD, DDS  Atlanta Plastic Surgeon.