title: Effects of implant design and surface on bone regeneration and implant stability: an experimental study in the dog mandible.
abstract: BACKGROUND
  Previous experimental studies have shown a higher degree of bone-implant contact for surface-enlarged implants compared with machined implants. Yet, there is insufficient evidence that such implants show higher stability and an increased survival rate.
  
  
  OBJECTIVE
  The purpose of this investigation was to study the integration and stability of grit-blasted implants with retention elements on the implant neck, with and without marginal bone defects, compared with machined implants without retention elements.
  
  
  METHODS
  After tooth extraction of the mandibular premolars in six dogs, two grit-blasted, partly microthreaded Astra Tech implants and one standard Brånemark implant were bilaterally placed in each dog. On one side, 3 x 3 mm large buccal defects were created, to expose three to four implant threads. The contralateral side served as control, and no defects were made. The animals were sacrificed after 4 months of healing. Implant stability was measured using resonance frequency analysis at implant installation and after 4 months of healing. Histologic and histomorphometric evaluation was made after 4 months of healing.
  
  
  RESULTS
  Resonance frequency analysis indicated that all implants in the test and control groups were osseointegrated after 4 months, with a tendency toward higher implant stability for the Astra Tech implants. There was a statistically significant higher increase in resonance frequency for the Astra test implants compared with their corresponding controls. Histology and histomorphometry showed well-integrated implants with varying degrees of bone repair at the defect sites. The greater bone-implant contact for the Astra implants was statistically significant. No significant difference between the implants in amount of bone filling the threads was recorded.
  
  
  CONCLUSIONS
  The Astra Tech implants tested showed a higher degree of bone-implant contact and higher level of bone regenerated at defect sites compared with the Brånemark implants. Resonance frequency analysis demonstrated a significantly higher increase in the Astra test implants compared with their control groups than did the Brånemark test implants versus their controls.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Göteborg University, Box 450, SE-405 30 Göteborg, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Rasmusson
authors.forename: K E
authors.initials: KE
authors.lastname: Kahnberg
authors.forename: A
authors.initials: A
authors.lastname: Tan
mesh_terms: D016301:Alveolar Bone Loss / Q000503:physiopathology / Q000601:surgery; D000818:Animals; D001861:Bone Regeneration; D015921:Dental Implants; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D004285:Dogs; D005260:Female; D005500:Follow-Up Studies; D008297:Male; D008334:Mandible / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D016348:Osseointegration; D018709:Statistics, Nonparametric; D013499:Surface Properties; D020390:Tooth Socket / Q000503:physiopathology / Q000601:surgery; D014159:Transducers; D014732:Vibration; D014945:Wound Healing
chemical_list: D015921:Dental Implants