Research on 50 faillure treatmant endodontic, base on clinical symptomer: pain, vestibular swollen 58 percent, vestibular fistula 8 percent, painless 34 percent. X-ray: signs missing not cannal detection 54 percent, mising root canal obturation root 30 percent, root canal instreatmant faillure 8 percent and 4 percent.One week after: Root canal retreatmant give a good rerult with 84 percent and a medium rerult 16 percent. 6 moths After root canal retreatment give a good rerult with 82.2 percent, faillure 6.7 percent, not certain 11.1 percent.