title: Crestal bone loss related to immediate implants in crestal and subcrestal position: a pilot study in dogs.
abstract: OBJECTIVE
  The aim of the present study was to compare crestal bone loss with different implant designs inserted immediately in crestal or subcrestal position in post-extraction sockets in a dog model.
  
  
  METHODS
  The mandibular second, third, fourth premolars, and the first molars of six adult fox hound dogs were extracted bilaterally, and 48 implants were placed immediately in both hemi-arches of each dog. Randomly, eight implants (sky classic (®) and blue sky (®) ) were inserted, four crestally (control group) and four 2 mm subcrestally (test group). Both groups were treated with a minimal mucoperiosteal flap elevation approach. After a 12-week healing period, the animals were sacrificed, and samples were obtained. Biopsies were processed for ground sectioning. Histomorphometric analysis was carried out to compare buccal and lingual bone height loss.
  
  
  RESULTS
  All implants were clinically and histologically osseointegrated. Healing patterns examined microscopically at eight and 12 weeks for both groups (crestal and subcrestal) yielded similar qualitative bone findings. At 12 weeks, the distance from the top of the implant collar to the first BIC (ISBc) showed significant difference between implant positions (crestal or subcrestal) in the buccal aspect (P = 0.1253), values for the crestal group being higher (1.79 ± 0.3 mm) in comparison with the subcrestal group (0.89 ± 0.5 mm). Better results were achieved by both implant designs when implants were placed in the deeper position. No significant differences were found in BIC values (P > 0.05). The total BIC at 8 weeks was (46.22 ± 4.29%) for the crestal group and (49.72 ± 2.21%) for the subcrestal group; at 12 weeks, it was (41.54 ± 3.87%) for the crestal group and (56.87 ± 3.46%) for the subcrestal group.
  
  
  CONCLUSIONS
  Within the limitations of this study, the findings suggest that apical positioning of the top of the implant does not jeopardize bone crest and peri-implant tissue remodeling. However, less resorption of the lingual and buccal crest may be expected when implants are placed 2 mm subcrestally, but this is not related to implant design. Moreover, implants placed subcrestally produced better bone-to-implant contact measurements.
authors.affiliation: Department of General and Implant Dentistry, Faculty of Medicine and Dentistry, University of Murcia, Murcia, Spain.
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: Calvo-Guirado
authors.affiliation: Department of General and Implant Dentistry, Faculty of Medicine and Dentistry, University of Murcia, Murcia, Spain.
authors.forename: Patricia Jara
authors.initials: PJ
authors.lastname: López-López
authors.affiliation: Department of General and Implant Dentistry, Faculty of Medicine and Dentistry, University of Murcia, Murcia, Spain.
authors.forename: Jose Eduardo
authors.initials: JE
authors.lastname: Mate Sanchez
authors.affiliation: Department of Implant Dentistry, International University of Catalonia, Barcelona, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Gargallo Albiol
authors.affiliation: Department Of General Dentistry, Faculty of Dentistry, University of Seville, Seville, Spain.
authors.forename: Eugenio
authors.initials: E
authors.lastname: Velasco Ortega
authors.affiliation: Department of Prosthodontics and Digital Technologies, Stony Brook University, New York, NY, USA.
authors.forename: Rafael
authors.initials: R
authors.lastname: Delgado Ruiz
mesh_terms: D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology; D000818:Animals; D016723:Bone Remodeling / Q000502:physiology; D000069343:Bone-Implant Interface / Q000000981:diagnostic imaging / Q000473:pathology; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants / Q000009:adverse effects; D017267:Dental Prosthesis Design; D004285:Dogs; D008334:Mandible / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D023421:Models, Animal; D016348:Osseointegration / Q000502:physiology; D010865:Pilot Projects; D011859:Radiography; D011897:Random Allocation; D013524:Surgical Flaps / Q000601:surgery; D013997:Time Factors; D014081:Tooth Extraction; D020390:Tooth Socket / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D014945:Wound Healing / Q000502:physiology
chemical_list: D015921:Dental Implants
keywords: crestal; immediate implant; subcrestal