title: The Effects of Subcrestal Implant Placement on Crestal Bone Levels and Bone-to-Abutment Contact: A Microcomputed Tomographic and Histologic Study in Dogs.
abstract: OBJECTIVE
  Implant design and the implant-abutment interface have been regarded as key influences on crestal bone maintenance over time. The aim of the present study was to determine crestal bone changes around implants placed at different depths in a dog model.
  
  
  METHODS
  Thirty-six two-piece dental implants with a medialized implant-abutment interface and Morse taper connection (Ankylos, Dentsply) were placed in edentulous areas bilaterally in six mongrel dogs. On each side of the mandible, three implants were placed randomly at the bone crest, 1.5 mm subcrestally, or 3.0 mm subcrestally. After 3 months, the final abutments were torqued into place. At 6 months, the animals were sacrificed and samples taken for microcomputed tomographic (micro-CT) and histologic evaluations.
  
  
  RESULTS
  Micro-CT analysis revealed similar crestal or marginal bone loss among groups. Both subcrestal implant groups lost significantly less crestal and marginal bone than the equicrestal implants. Bone loss was greatest on the buccal of the implants, regardless of implant placement depth. Histologically, implants placed subcrestally were found to have bone in contact with the final abutment and on the implant platform.
  
  
  CONCLUSIONS
  Implants with a centralized implant-abutment interface and Morse taper connection can be placed subcrestally without significant loss of crestal or marginal bone. Subcrestal placement of this implant system appears to be advantageous in maintaining bone height coronal to the implant platform.
authors.forename: Michael
authors.initials: M
authors.lastname: Fetner
authors.forename: Alan
authors.initials: A
authors.lastname: Fetner
authors.forename: Theofilos
authors.initials: T
authors.lastname: Koutouzis
authors.forename: Emanuele
authors.initials: E
authors.lastname: Clozza
authors.forename: Nick
authors.initials: N
authors.lastname: Tovar
authors.forename: Alvin
authors.initials: A
authors.lastname: Sarendranath
authors.forename: Paulo G
authors.initials: PG
authors.lastname: Coelho
authors.forename: Kathleen
authors.initials: K
authors.lastname: Neiva
authors.forename: Malvin N
authors.initials: MN
authors.lastname: Janal
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Neiva
mesh_terms: D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging / Q000473:pathology; D000539:Alveolar Process / Q000000981:diagnostic imaging* / Q000473:pathology; D000818:Animals; D000069343:Bone-Implant Interface / Q000000981:diagnostic imaging* / Q000473:pathology; D059605:Dental Implant-Abutment Design; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D004285:Dogs; D005260:Female; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008334:Mandible / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D023421:Models, Animal; D016348:Osseointegration / Q000502:physiology; D010012:Osteogenesis / Q000502:physiology; D011897:Random Allocation; D013997:Time Factors; D055114:X-Ray Microtomography / Q000379:methods*
chemical_list: D015921:Dental Implants