title: Implementation of the "loaded implant" model in the rat using a miniaturized setup--description of the method and first results.
abstract: OBJECTIVE
  To miniaturize the "loaded implant" model to permit its application to small rodents. In this model, two titanium implants are placed 8 mm apart with their heads protruding from the skin and are forced together by a dedicated actuator. To assess the effect of (i) the post-implantation healing period and the duration of stimulation and (ii) the intratissular strain level on the microtomographical bone parameters BV/TV, Tb.N., Tb.Th. and BIC.
  
  
  METHODS
  Implants, 1 × 8 mm, were machined, inserted into the tibiae of rats and activated. A total of 123 animals were used. In series 1, the implants were left to heal for 2/4 weeks and then loaded to generate intratissular strains of 1125 ± 5% με for 4/8 weeks. Series 2 had their implants loaded to 750, 1500 and 2250 ± 5% με, respectively.
  
  
  RESULTS
  Bone to implant contact increased upon loading. In series 1, no difference was observed regarding the duration of healing or the stimulation period. In series 2, at 750 με, the bone parameters did not differ from baseline. At 1500 με, all four parameters increased. At 2250 με, three of four parameters decreased relative to 1500 με.
  
  
  CONCLUSIONS
  (i) The loaded implant model can be miniaturized to the millimeter range; (ii) in the present model, implant activation beyond 4 weeks did not affect the bone parameters; (iii) mechanical stimulation increased bone to implant contact by up to 20%; (iv) the results obtained are consistent with the concept of an anabolic effect from 750 to 1500 με and deleterious effects at strains in the 2250 με range; and (v) strains at 2250 με did not lead to implant dis-integration.
authors.affiliation: Laboratory of Biomaterials, University of Geneva, Geneva, Switzerland. anselm.wiskott@unige.ch
authors.forename: H W Anselm
authors.initials: HW
authors.lastname: Wiskott
authors.forename: Philippe
authors.initials: P
authors.lastname: Bonhote
authors.forename: Joel
authors.initials: J
authors.lastname: Cugnoni
authors.forename: Stéphane
authors.initials: S
authors.lastname: Durual
authors.forename: Giovanna
authors.initials: G
authors.lastname: Zacchetti
authors.forename: John
authors.initials: J
authors.lastname: Botsis
authors.forename: Susanne S
authors.initials: SS
authors.lastname: Scherrer
authors.forename: Patrick
authors.initials: P
authors.lastname: Ammann
mesh_terms: D000818:Animals; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis; D057893:Immediate Dental Implant Loading; D020007:Implants, Experimental; D008904:Miniaturization; D023421:Models, Animal; D016348:Osseointegration; D051381:Rats; D017207:Rats, Sprague-Dawley; D013977:Tibia / Q000601:surgery; D014025:Titanium
chemical_list: D015921:Dental Implants; D014025:Titanium