What can be used to keep the surgical incision of a tummy tuck flat and thin?

Hello!
First it is important to support the healing process in conjunction with your surgeon. I typically use moisture between surgery and first visit, and switch to tape to incision 1 week after surgery for several weeks, with Aquaphor to the belly button. Then I encourage moisture and massage, using products like Cocoa Butter, Shea Butter or Coconut Oil, twice a day. With scars that look like they might thicken I recommend Biocorneum which has silicone in it. 
Your surgeon should be active in your quest for the optimal scar! Best of luck!

Dear Kcunnin,
In addition to scar cream, I would recommend silicone adhesive strips.  Hope this helps and good luck!  

How a tummy tuck scar ends up has to do with a few factors such as surgical closure, skin quality and skin color.  We all (or should) close the incision in multiple layers.  Scarpa's fascia being the most important.  If tension is taken off the skin edges then the scar will be thin.  I use a "superglue" tape on the incision to take additional tension off of the skin edges.  After the dressings come off I recommend patients use anything with silicone.  Silicone is the only substance proven to help the appearance of scars.