Probuphine (buprenorphine implant) is an investigational implant placed just below the skin containing buprenorphine (BPN). BPN is an approved treatment for opioid dependence. This is a 6-month, open-label, re-treatment study that will confirm the safety and efficacy of Probuphine in patients who have previously completed the 6-month PRO-806 study with either Probuphine, placebo or sublingual buprenorphine.