title: Effect of Platform Shift on Crestal Bone Levels and Mucosal Profile Following Flap Surgery and Subcrestal Implant Placement in Presence/Absence of Gap Defects.
abstract: BACKGROUND
  Physiologic remodeling resulting in crestal bone loss appears a common corollary to dental implant surgery. Several hypotheses and clinical strategies have been advanced to explain and avert crestal remodeling; however, causative mechanisms remain unclear and the efficacy of clinical protocols uncertain.
  
  
  OBJECTIVE
  The objective of the present study was to provide a histologic account of crestal bone levels and mucosal profile at implant sites receiving platform shift/switch and standard abutments following conventional flap surgery and subcrestal implant placement in presence or absence of crestal gap defects using a dog model.
  
  
  METHODS
  Four dental implants were placed into the left/right edentulated posterior mandible in five adult male Hound Labrador mongrel dogs using flap surgery including subcrestal placement with/without a 1 × 5 mm (width × depth) gap defect, and using platform shift/switch and standard abutments. Block biopsies were collected for histological/histometric analysis following an 8-week healing interval.
  
  
  RESULTS
  No significant differences in crestal resorption were observed among experimental groups; crestal resorption being significantly more advanced at buccal than at lingual sites (p < .001). Similarly, crestal bone-implant contact was not significantly different among groups; crestal bone-implant contact being consistently below the implant platform at buccal sites (p < .01). Moreover, the peri-implant mucosal profile was not statistically different among groups, the mucosal height being significantly greater at buccal than at lingual sites (p < .001). Also, no significant differences among groups were observed for the apical extension of the epithelial attachment, the epithelial attachment being arrested more than 2 mm above the implant platform at both platform shift/switch and standard abutments.
  
  
  CONCLUSIONS
  Using a clinical strategy including flap surgery and subcrestal implant placement, implant technology comparing platform shift/switch with standard abutments, surgical approach, and abutment selection seems to have a limited impact on crestal remodeling, associated bone loss, and mucosal profile.
authors.affiliation: Laboratory for Applied Periodontal & Craniofacial Regeneration (LAPCR), Georgia Regents University, Augusta, GA, USA.
authors.forename: Brent A
authors.initials: BA
authors.lastname: Wenzel
authors.affiliation: Laboratory for Applied Periodontal & Craniofacial Regeneration (LAPCR), Georgia Regents University, Augusta, GA, USA.|Clinica Dental Gamborena, San Sebastian, Spain.
authors.forename: Inãki
authors.initials: I
authors.lastname: Gamborena
authors.affiliation: Laboratory for Applied Periodontal & Craniofacial Regeneration (LAPCR), Georgia Regents University, Augusta, GA, USA.
authors.forename: Jaebum
authors.initials: J
authors.lastname: Lee
authors.affiliation: Laboratory for Applied Periodontal & Craniofacial Regeneration (LAPCR), Georgia Regents University, Augusta, GA, USA.|Section of Periodontology, School of Dentistry, Federal University Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Tiago
authors.initials: T
authors.lastname: Fiorini
authors.affiliation: Laboratory for Applied Periodontal & Craniofacial Regeneration (LAPCR), Georgia Regents University, Augusta, GA, USA.|Peter Schüpbach Ltd, Horgen, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Schüpbach
authors.affiliation: Laboratory for Applied Periodontal & Craniofacial Regeneration (LAPCR), Georgia Regents University, Augusta, GA, USA.
authors.forename: Ulf M E
authors.initials: UM
authors.lastname: Wikesjö
authors.affiliation: Laboratory for Applied Periodontal & Craniofacial Regeneration (LAPCR), Georgia Regents University, Augusta, GA, USA.
authors.forename: Cristiano
authors.initials: C
authors.lastname: Susin
mesh_terms: D000539:Alveolar Process; D000818:Animals; D016723:Bone Remodeling; D015921:Dental Implants; D004285:Dogs; D004846:Epithelial Attachment; D008297:Male; D008334:Mandible
chemical_list: D015921:Dental Implants
keywords: alveolar bone; animal models; crestal resorption/remodeling; dental implants; platform shift/switch