title: Comparative study of buccal dehiscence defects in immediate, delayed, and late maxillary implant placement with collagen membranes: clinical healing between placement and second-stage surgery.
abstract: BACKGROUND
  Implants can be placed at the time of tooth extraction (immediate), after several weeks (delayed), or after complete healing (late). The purpose of this study was to evaluate clinical bone healing of buccal dehiscence-type defects around maxillary implants placed together with bioabsorbable collagen barrier membranes and bone graft at the 3 time points.
  
  
  METHODS
  Three implant placement protocols were compared: immediate procedures primarily closed by a rotated split palatal flap (19 patients, 23 implants; group 1); delayed sites closed by a rotated (full-thickness) palatal flap at the time of tooth extraction (25 patients, 39 implants; group 2); and late implantation (22 patients, 40 implants; group 3). One to 3 proximal implants were simultaneously placed. Defect height and width were measured at the time of implant placement and at second-stage surgery. Surface area was calculated as half ellipses.
  
  
  RESULTS
  The best results were obtained with delayed implantation. The mean percentage of the reduced defect height for groups 1, 2, and 3 was 77.4%+/-16.92%, 88.8%+/-15.29%, and 75.2%+/-17.99%, respectively, and the mean percentage area of the reduced defect was 90.2%+/-9.15%, 95.6%+/-8.73%, and 87.6%+/-11.48%, respectively. Differences between groups were statistically significant. The mean percentage of the reduced defect height and area was significantly smaller when there was spontaneous implant cover screw exposure. Single rather than multiple implant placement led to significantly better results.
  
  
  CONCLUSIONS
  Timing of placement, number of simultaneously placed implants, and spontaneous implant exposure significantly influence clinical bone healing around maxillary implants placed together with augmentation procedures.
authors.affiliation: Department of Periodontology, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Israel. carlos@post.tau.ac.il
authors.forename: Carlos E
authors.initials: CE
authors.lastname: Nemcovsky
authors.forename: Zvi
authors.initials: Z
authors.lastname: Artzi
mesh_terms: D020341:Absorbable Implants; D016301:Alveolar Bone Loss / Q000209:etiology* / Q000601:surgery; D000540:Alveolar Ridge Augmentation; D000704:Analysis of Variance; D001861:Bone Regeneration; D016025:Bone Transplantation; D003094:Collagen; D003758:Dental Implantation, Endosseous / Q000009:adverse effects* / Q000379:methods*; D016557:Guided Tissue Regeneration, Periodontal / Q000379:methods*; D006801:Humans; D008437:Maxilla / Q000601:surgery; D008566:Membranes; D008875:Middle Aged; D013524:Surgical Flaps; D013997:Time Factors; D014081:Tooth Extraction
chemical_list: D003094:Collagen