There is no study that I know of on this.  But I do have considerable experience over the past five years with both products.   I have my patients wait until 6 months after the last Sculptra treatment before doing Thermage and have had no problems with Sculptra "bumps" occurring.   Ideally, when you do your yearly maintenance (usually one treatment), you would do your Thermage in the month prior because your fibroblasts (cells that make collagen) should be more active.  Theoretically, you should get more response from your Sculptra but there are no studies to prove this.   Dr. I