Hi Guest! D4263 – bone replacement graft – first site in quadrant can be crosscoded to: 21210 – graft, bone; nasal, maxillary, or malar areas or, 21215 – graft, mandibular **use modifier -52 for reduced services when bone is not obtained from patient D4266 – guided tissue regeneration – resorbable barrier, per site can be cross coded to: 41870 – Periodontal mucosal grafting Hope this helps!