title: Impact of implant overloading on the peri-implant bone in inflamed and non-inflamed peri-implant mucosa.
abstract: OBJECTIVE
  To assess the impact of overloading on peri-implant bone level and the bone-to-implant contact (BIC) in the presence of healthy or inflamed peri-implant tissues.
  
  
  METHODS
  Four screw-shaped machined implants were placed bilaterally in the mandible of four beagle dogs and left submerged for 3 months. Prosthetic abutments were connected either in supra-occlusal contact with the opposite teeth (overloaded) or in infra-occlusal position (unloaded). In each dog, cotton floss ligatures were placed unilaterally around abutments to promote plaque accumulation; the contralateral side was brushed three times a week. There were four experimental sites, two implants in each: loaded uninflamed (LU), loaded inflamed (LI), unloaded uninflamed (UU), and unloaded inflamed (UI). Clinical and radiographic parameters were recorded at baseline and every 3 months throughout the observation period. At 12 months, the dogs were sacrificed and histomorphometric analysis was performed.
  
  
  RESULTS
  Implants with ligature-induced peri-implantitis presented high inflammatory indices throughout the observation period. Clinical parameters did not change from baseline for both LU and UU. Loading significantly increased the percentage of BIC (BIC%) (P<0.05) and slightly increased crestal bone resorption, but not apical to the implant neck. Both LI and UI groups showed significant peri-implant bone loss (P<0.01), mostly horizontal on the buccal aspect and angular on the lingual aspect, which exposed implant threads. Loading significantly (P<0.05) increased implant thread exposure due to buccal and lingual vertical bone resorption.
  
  
  CONCLUSIONS
  In the presence of uninflamed peri-implant mucosa, overloading of implants in the dog model increased BIC% and slightly reduced marginal bone level. However, resorption did not progress beyond the implant neck. Overloading aggravated the plaque-induced bone resorption when peri-implant inflammation was present.
authors.affiliation: Department of Periodontology, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel. kavital@post.tau.ac.il
authors.forename: Avital
authors.initials: A
authors.lastname: Kozlovsky
authors.forename: Haim
authors.initials: H
authors.lastname: Tal
authors.forename: Ben-Zion
authors.initials: BZ
authors.lastname: Laufer
authors.forename: Roy
authors.initials: R
authors.lastname: Leshem
authors.forename: Michael D
authors.initials: MD
authors.lastname: Rohrer
authors.forename: Miron
authors.initials: M
authors.lastname: Weinreb
authors.forename: Zvi
authors.initials: Z
authors.lastname: Artzi
mesh_terms: D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D000539:Alveolar Process / Q000000981:diagnostic imaging / Q000503:physiopathology*; D000818:Animals; D000891:Anti-Infective Agents, Local / Q000627:therapeutic use; D002710:Chlorhexidine / Q000031:analogs & derivatives / Q000627:therapeutic use; D000044:Dental Abutments; D015921:Dental Implants; D003769:Dental Occlusion, Traumatic / Q000150:complications* / Q000503:physiopathology; D003773:Dental Plaque / Q000150:complications / Q000503:physiopathology; D004195:Disease Models, Animal; D004285:Dogs; D008334:Mandible / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D016348:Osseointegration / Q000502:physiology; D010512:Periodontal Index; D010518:Periodontitis / Q000150:complications* / Q000503:physiopathology; D011859:Radiography; D013997:Time Factors; D014099:Toothbrushing
chemical_list: D000891:Anti-Infective Agents, Local; D015921:Dental Implants; C010882:chlorhexidine gluconate; D002710:Chlorhexidine