Periapical radiographs of implant site and exfoliation. (a) Implant placement, (b) exfoliation three years later, and (c) progression of bone loss two years after implant exfoliation at the site of the left mandibular second premolar. (d) Implant placement, (e) exfoliation three years later, and (f) progression of bone loss two years after implant exfoliation at the site of the right mandibular first molar.