title: Immediate versus delayed loading of dental implants in the maxillae of minipigs: follow-up of implant stability and implant failures.
abstract: OBJECTIVE
  To assess the course of the stability and the failure rate of dental implants placed in the partially edentulous maxillae of minipigs.
  
  
  METHODS
  Three months after tooth removal, implants were placed in 9 minipigs. Six implants (XiVE; Friadent, Mannheim, Germany) were placed on each side of the posterior maxilla after preparation of the implant sites either by an osteotome technique or with spiral drills. Implant stability was assessed by resonance frequency analysis (RFA) at the time of placement, at second-stage surgery (which took place after a healing periods of 1, 2, 3, 4, or 5 months), and after a loading period of 6 months.
  
  
  RESULTS
  Implant stability was significantly influenced by the healing period (P = .007). Implant stability decreased after 1 to 3 months of healing for both of the placement techniques and increased after a healing period of 4 months. After implant site preparation by an osteotome technique, 6 of 12 immediately loaded implants, 18 of 24 implants loaded after healing periods of 1 to 3 months, and 1 of 18 implants loaded after a healing period of 4 or 5 months were lost. After implant site preparation using spiral drills, 7 of 12 immediately loaded implants, 12 of 24 implants loaded after healing periods of 1 to 3 months, and 2 of 18 implants loaded after healing periods of 4 or 5 months were lost. Broad overlapping of confidence intervals for the number of implant failures revealed that there was no relevant difference between immediate and early functional loading for either of the 2 techniques.
  
  
  CONCLUSIONS
  Implant loading after healing periods of 1 to 3 months did not improve implant survival compared to immediate loading in the posterior maxillae of minipigs. Not until a healing period of 4 months was reached did implant stability begin to increase. Only when functional loading was started at this point in time was maximal implant survival achieved.
authors.affiliation: Department of Oral and Maxillofacial Surgery, University of Erlangen-Nuremberg, Germany. emeka.nkenke@mkg.imed.uni-erlangen.de
authors.forename: Emeka
authors.initials: E
authors.lastname: Nkenke
authors.forename: Bernhard
authors.initials: B
authors.lastname: Lehner
authors.forename: Matthias
authors.initials: M
authors.lastname: Fenner
authors.forename: Fidel San
authors.initials: FS
authors.lastname: Roman
authors.forename: Ulf
authors.initials: U
authors.lastname: Thams
authors.forename: Friedrich Wilhelm
authors.initials: FW
authors.lastname: Neukam
authors.forename: Martin
authors.initials: M
authors.lastname: Radespiel-Tröger
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D003758:Dental Implantation, Endosseous / Q000295:instrumentation / Q000379:methods*; D015921:Dental Implants; D017268:Dental Prosthesis Retention; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003831:Denture, Partial, Immediate; D005260:Female; D020007:Implants, Experimental; D008437:Maxilla; D013552:Swine; D013556:Swine, Miniature; D013997:Time Factors; D019415:Torque; D014732:Vibration; D016474:Weight-Bearing
chemical_list: D015921:Dental Implants