title: Soft and hard tissue histologic dimensions around dental implants in the canine restored with smaller-diameter abutments: a paradigm shift in peri-implant biology.
abstract: OBJECTIVE
  To evaluate the biologic width dimensions around implants with nonmatching implant-abutment diameters.
  
  
  METHODS
  Five canines had their mandibular premolars and first molars removed bilaterally and replaced with 12 implants that had nonmatching implant-abutment diameters. On one side, six implants were placed in a submerged surgical approach, and the other side utilized a nonsubmerged approach. Two of the implants on each side were placed either 1 mm above, even with, or 1 mm below the alveolar crest. Two months later, gold crowns were attached, and the dogs were sacrificed 6 months postloading. Block sections were processed for histologic and histomorphometric analyses.
  
  
  RESULTS
  The bone level, connective tissue length, epithelial dimension, and biologic width were not significantly different when the implants were initially placed in a submerged or nonsubmerged surgical approach. The bone level was significantly different around implants placed 1 mm above the crest compared to implants placed even with or 1 mm below the alveolar crest. The connective tissue dimension was not different for any implant level placement. The epithelial dimension and biologic width were significantly greater for implants placed 1 mm below the alveolar crest compared to implants placed even with or 1 mm above the alveolar crest. For five of six implant placements, connective tissue covered the implant/abutment interface.
  
  
  CONCLUSIONS
  This study reveals a fundamental change in the biologic response to implants with nonmatching implant-abutment diameters. Unlike implants with matching implant-abutment diameters, the connective tissue extended coronally past the interface (microgap). This morphologic tissue alteration represents a significant change in the biologic reaction to implant-abutment interfaces and suggests that marginal inflammation is eliminated or greatly reduced in these implant designs.
authors.affiliation: Department of Periodontics, The University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900, USA. Cochran@uthscsa.edu
authors.forename: David L
authors.initials: DL
authors.lastname: Cochran
authors.forename: Lian Ping
authors.initials: LP
authors.lastname: Mau
authors.forename: Frank L
authors.initials: FL
authors.lastname: Higginbottom
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Wilson
authors.forename: Dieter D
authors.initials: DD
authors.lastname: Bosshardt
authors.forename: John
authors.initials: J
authors.lastname: Schoolfield
authors.forename: Archie A
authors.initials: AA
authors.lastname: Jones
mesh_terms: D000539:Alveolar Process / Q000473:pathology / Q000601:surgery*; D000818:Animals; D001641:Bicuspid / Q000601:surgery; D003238:Connective Tissue / Q000254:growth & development / Q000473:pathology*; D003442:Crowns; D000044:Dental Abutments; D059605:Dental Implant-Abutment Design; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D004285:Dogs; D004848:Epithelium / Q000254:growth & development / Q000473:pathology; D005881:Gingiva / Q000473:pathology; D008297:Male; D008334:Mandible / Q000473:pathology / Q000601:surgery; D008963:Molar / Q000601:surgery; D014081:Tooth Extraction
chemical_list: D015921:Dental Implants