title: Bone healing following immediate versus delayed placement of titanium implants into extraction sockets: a prospective clinical study.
abstract: OBJECTIVE
  The aim of this study was to compare bone healing and crestal bone changes following immediate (Im) versus delayed (De) placement of titanium dental implants with acid-etched surfaces (Osseotite) in extraction sockets.
  
  
  METHODS
  Forty-six patients were randomly allocated to the Im or De group (n = 23 per group) and received 1 implant at the incisor, canine, or premolar region of the maxilla or the mandible. The implants were placed an average of 10 days following tooth extraction in the Im group and approximately 3 months after extraction in the De group. The widths (parallel and perpendicular to the implant) and the depth of marginal bone defects around the implants were measured clinically just after placement and 3 months later at the abutment surgery. The crestal bone changes mesially and distally to the implants were evaluated radiographically by linear measurements.
  
  
  RESULTS
  The survival rates were 91% in the Im group and 96% in the De group. In the Im group, the mean reductions in parallel width, perpendicular width, and depth of the largest defect of each implant amounted to 48% (from 4.4 to 2.3 mm), 59% (from 2.2 to 0.9 mm), and 48% (from 6.9 to 3.6 mm), respectively. The corresponding mean reductions in the De group amounted to 39% (from 3.1 to 1.9 mm), 77% (from 1.3 to 0.3 mm), and 34% (from 4.4 to 2.9 mm). The reduction over time was statistically significant in both groups (P < .04). For both groups, a higher degree of bone healing was achieved in the infrabony defects (> 60% for depth) than in dehiscence-type defects (approximately 25%). Furthermore, 70% of the 3-wall infrabony defects with a parallel width of up to 5 mm, a depth of maximum 4 mm, and a perpendicular width of maximum 2 mm had a capacity of spontaneous healing within a period of 3 months.
  
  
  CONCLUSIONS
  New bone formation occurs in infrabony defects associated with immediately placed implants in extraction sockets.
authors.affiliation: Department of Oral Radiology, University of Aarhus, Arhus, Denmark. lschropp@odont.au.dk
authors.forename: Lars
authors.initials: L
authors.lastname: Schropp
authors.forename: Lambros
authors.initials: L
authors.lastname: Kostopoulos
authors.forename: Ann
authors.initials: A
authors.lastname: Wenzel
mesh_terms: D000328:Adult; D000368:Aged; D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D001861:Bone Regeneration; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D019232:Dental Restoration Failure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016348:Osseointegration; D011859:Radiography; D013997:Time Factors; D014025:Titanium; D014081:Tooth Extraction / Q000009:adverse effects; D020390:Tooth Socket
chemical_list: D015921:Dental Implants; D014025:Titanium