Hello, your question is a good one. It is hard to tell exactly what is going on just by the images alone but there are several options to re-contour the chin. Some involve modifying the bony structure while others involve the use of custom silicone chin implants versus soft-tissue fillers. I would suggest the least invasive option first. Sounds like the injury was quite some time ago and the bone defect may or may not be relevant. Would need to see the images and evaluate the chin to make proper call.
Your photo appears to show that your right lower chin is higher than your left. Even though this may be due to previous bone-fracture, a well-performed injectable filler procedure may be helpful. We prefer to use Silikon-1000, an off-label filler for permanent results. Photo below.
Hope this helps you.