title: Fate of the buccal bone at implants placed early, delayed, or late after tooth extraction analyzed by cone beam CT: 10-year results from a randomized, controlled, clinical study.
abstract: OBJECTIVE
  To present 10-year cone beam CT (CBCT) data on the fate of buccal bone at single-tooth implants placed early, delayed, or late after tooth extraction.
  
  
  METHODS
  Sixty-three of 72 patients, originally randomly allocated to three equal-size groups, received a single-tooth implant on average 10 days (Ea; N = 22), 3 months (De; N = 22), or 1.5 years (La; N = 19) after tooth extraction. Healing abutments were mounted after a 3-month period of submerged healing and metalceramic crowns were cemented after one additional month. At the second stage surgery, presence of buccal bone defects (dehiscences or intrabony) and their dimensions were registered. CBCT scans recorded with a Scanora(®) 3D unit and standardized periapical (PA) radiographs of the implants were obtained at the 10-year control. Interproximal bone levels (i.e., the distance from the implant platform to the first bone-to-implant contact; BIC) measured in CBCT image sections and PA were compared, and the buccal bone level was determined in the CBCT images.
  
  
  RESULTS
  Two Ea and one De implants failed to osseointegrate. Forty-nine patients attended the 10-year control and due to poor quality of 5 CBCT scans, useful CBCT images were available from 44 patients (Ea:12, De:17, La:15). No significant differences between CBCT and PA images in measurements of the interproximal bone levels were observed. Ten years after implant placement, BIC at the buccal aspect was located on average 2 mm apically to the implant platform (2.39 ± 1.06 mm [median = 2.36] for Ea, 2.22 ± 0.99 mm [median = 2.16] for De, and 1.85 ± 0.65 mm [median = 1.95] for La implants) with no significant difference among the groups (P = 0.20). Mean buccal bone level (bBL) for implants with an intrabony or a dehiscence defect at second stage surgery was 2.51 ± 1.12 mm [median = 2.70] and 2.84 ± 0.70 mm [median = 2.79], respectively, while 1.78 ± 0.74 mm [median = 1.93] for the implants with no defect. The difference in bBL between the implants without a defect and those with a dehiscence was significant at 10 years (P = 0.0005).
  
  
  CONCLUSIONS
  Time of placement of single-tooth implants after tooth extraction did not significantly influence the peri-implant buccal bone level, while presence of a buccal bone dehiscence at second stage surgery resulted in significantly more apically located BIC buccally at 10 years.
authors.affiliation: Prosthetic Dentistry, Department of Dentistry, Aarhus University, Aarhus C, Denmark; Oral Radiology, Department of Dentistry, Aarhus University, Aarhus C, Denmark.
authors.forename: Lars
authors.initials: L
authors.lastname: Schropp
authors.forename: Ann
authors.initials: A
authors.lastname: Wenzel
authors.forename: Rubens
authors.initials: R
authors.lastname: Spin-Neto
authors.forename: Andreas
authors.initials: A
authors.lastname: Stavropoulos
mesh_terms: D000328:Adult; D000368:Aged; D000539:Alveolar Process / Q000000981:diagnostic imaging*; D054893:Cone-Beam Computed Tomography; D003758:Dental Implantation, Endosseous / Q000379:methods*; D019250:Dental Implants, Single-Tooth; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016348:Osseointegration; D010514:Periodontal Pocket / Q000000981:diagnostic imaging / Q000209:etiology; D013997:Time Factors; D014081:Tooth Extraction
keywords: buccal bone; cone beam CT; delayed implantation; dental implant; early implantation; late implantation; randomized controlled trial; single-tooth