title: Dimensional ridge alterations following immediate implant placement in molar extraction sites: a six-month prospective cohort study with surgical re-entry.
abstract: OBJECTIVE
  To assess dimensional ridge alterations following immediate implant placement in molar extraction sites.
  
  
  METHODS
  Twelve subjects received 12 immediate transmucosal implants in molar extraction sites. Peri-implant defects were treated according to the principles of Guided Bone Regeneration by means of a deproteinized bone substitute and a bioresorbable collagen membrane. Changes in vertical (IS-BD, CREST-BD) and horizontal distances (EC-I, IC-I) of alveolar bony walls to the bottom of the defects (BD) and to the implant surfaces (I) were compared between implant placement and surgical re-entry at 6 months.
  
  
  RESULTS
  The implant survival rate at 6 months was 100%. Statistically significant differences (P<0.01) were observed in the mean changes in vertical distances IS-BD and CREST-BD between baseline and re-entry. At re-entry, all peri-implant marginal defects assessed from the internal socket wall to the implant surface (IC-I) were healed. The residual combined thickness of the buccal wall with the newly formed peri-implant bone at sites with an initial thickness of 1 mm was statistically significantly smaller (P<0.05) compared with that of sites with an initial buccal thickness of 2 mm (2.50 +/- 0.76 vs. 4+/-0 mm).
  
  
  CONCLUSIONS
  The marginal defects around immediate implants placed in molar extraction sites were completely filled after 6 months of healing through de novo bone formation. Bone resorption was observed from the external aspects of the buccal and oral socket walls. Dimensional changes of the external socket walls were mostly pronounced at the buccal aspects.
authors.affiliation: Department of Dental and Maxillofacial Sciences, University of Naples 'Federico II', Naples, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Matarasso
authors.forename: G E
authors.initials: GE
authors.lastname: Salvi
authors.forename: V
authors.initials: V
authors.lastname: Iorio Siciliano
authors.forename: C
authors.initials: C
authors.lastname: Cafiero
authors.forename: A
authors.initials: A
authors.lastname: Blasi
authors.forename: N P
authors.initials: NP
authors.lastname: Lang
mesh_terms: D000328:Adult; D016301:Alveolar Bone Loss / Q000517:prevention & control; D000539:Alveolar Process / Q000502:physiology*; D000540:Alveolar Ridge Augmentation / Q000379:methods*; D001861:Bone Regeneration / Q000502:physiology*; D015331:Cohort Studies; D003442:Crowns; D003758:Dental Implantation, Endosseous / Q000009:adverse effects / Q000379:methods*; D019250:Dental Implants, Single-Tooth; D019094:Dental Prosthesis, Implant-Supported; D005260:Female; D005500:Follow-Up Studies; D016557:Guided Tissue Regeneration, Periodontal / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008963:Molar / Q000601:surgery; D016348:Osseointegration; D011446:Prospective Studies; D013997:Time Factors; D014081:Tooth Extraction / Q000009:adverse effects; D020390:Tooth Socket / Q000601:surgery*; D016896:Treatment Outcome