What is the risk of screw fixation causing degradation of a silicone chin implant?

My silicone chin implant has drifted up and I want to try another implant. I've seen some dentists (plastic surgery docs too?) who advocate screw fixation for stability. Current doc says using a screw is not good because over time the implant could degrade with small movements / chance of silicone particles loose in the body. Says only alternative (besides cutting bone) is - remove implant, suture pocket down smaller, wait 6 mos (weak chin with saggy skin - no!) to try implant again. Help