title: Bone remodeling at implants with different configurations and placed immediately at different depth into extraction sockets. Experimental study in dogs.
abstract: OBJECTIVE
  This study evaluated the effect of implant macrodesign and position, related to the bone crest, on bone-to-implant contact (BIC) and crestal bone (CB) in immediate implants.
  
  
  METHODS
  The study comprised of six foxhound dogs in which 48 immediate implants were placed. Three types of implants from the same manufacturer with similar surface characteristics but different macrodesigns were randomly placed: Group A (external hex with no collar microthreads), Group B (internal hex and collar microrings), and Group C (internal conical connection and collar microrings). Half of the implants were placed leveled with the bone crest (control) and the remaining, 2 mm subcrestally (test). Block sections were obtained after 12 weeks and processed for mineralized ground sectioning. Statistical analysis consisted of nonparametric Friedman and Wilcoxon test.
  
  
  RESULTS
  All implants were clinically stable and histologically osseointegrated. Mean BIC percentage within the control group was as follows: A: 42.52 ± 8.67, B: 35.19 ± 18.12, and C: 47.46 ± 11.50. Within the test group: A: 47.33 ± 5.23, B: 48.38 ± 11.63, and C: 54.88 ± 11.73. Differences between each subgroup in the test and the control groups were statistically significant. BIC was statistically significantly higher in the test (50.588 ± 8.663) than in the control (43.317 ± 9.851) group. Within both groups, differences between group C and the other 2 were statistically significant. Distance from the implant shoulder to the buccal CB was statistically significantly larger in the control than in the test group and between subgroups B and C in the control and test groups. Within the test groups, relative bone gain was noticed.
  
  
  CONCLUSIONS
  Subcrestal immediate implant positioning may lead to a relatively reduced CB resorption and increased BIC. Implants macrodesign with crestal microrings may enhance BIC in post-extraction implants.
authors.affiliation: Department of General & Implant Dentistry, Faculty of Medicine and Dentistry, University of Murcia, Murcia, Spain.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Calvo-Guirado
authors.forename: Gerardo
authors.initials: G
authors.lastname: Gomez Moreno
authors.forename: Antonio
authors.initials: A
authors.lastname: Aguilar-Salvatierra
authors.forename: Jose Eduardo
authors.initials: JE
authors.lastname: Mate Sanchez de Val
authors.forename: Marcus
authors.initials: M
authors.lastname: Abboud
authors.forename: Carlos E
authors.initials: CE
authors.lastname: Nemcovsky
mesh_terms: D000818:Animals; D016723:Bone Remodeling; D003758:Dental Implantation, Endosseous; D017267:Dental Prosthesis Design; D004285:Dogs; D020007:Implants, Experimental; D008334:Mandible / Q000601:surgery; D008422:Materials Testing; D023421:Models, Animal; D011897:Random Allocation; D014081:Tooth Extraction; D020390:Tooth Socket / Q000502:physiology
keywords: crestal bone loss; histological analysis; implant design; implant stability