title: Six-month performance of implants with oxidized and machined surfaces restored at 2, 4, and 6 weeks postimplantation in adult beagle dogs.
abstract: OBJECTIVE
  The purpose of this study was to compare machined-surface implants (control) and oxidized-surface titanium screw-type implants (test) loaded with fixed partial dentures at 2, 4, and 6 weeks postplacement in terms of implant survival and stability.
  
  
  METHODS
  The beagle model was chosen for the study. Four mandibular premolars were extracted bilaterally from each dog. After 2 months of healing, 4 implants were placed in each dog. Half of the dogs (n = 6), the test group, received oxidized-surface implants; the other half (n = 6), the control group, received machined-surface implants. In each group, 2 dogs were randomly assigned to a 2-week preloading healing period, 2 to a 4-week period, and 2 to a 6-week period. Three implants were loaded in each dog; 1 was left unloaded as a control. Clinical stability and survival were monitored every 2 weeks for 6 months.
  
  
  RESULTS
  Failures were noted only among the implants assigned to the 2- and 4-week groups. Failures accounted for 9.4% (9/96) of the implants--12.5% (6/48) of the control implants and 6.3% (3/48) of the test implants. One hundred percent prosthesis stability was noted for the test-surface implant group. Stability of the test implants was significantly better than stability of the control implants (-2.6 vs -1.7, P < .05). Mean Periotest values at loading were 3.7 for the group loaded at 2 weeks, 1.6 for the group loaded at 4 weeks, and 0.6 for the group loaded at 6 weeks. Fifty percent of the 6-week group, 25% of the 4-week group, and 12.5% of the 2-week group had a Periotest value < 0 at loading.
  
  
  CONCLUSIONS
  The results reveal a qualitative difference in performance between the implant groups. Twice as many failures occurred in the control group, few failures occurred following loading, and no failures occurred after 4 weeks postplacement. The survival curves for both implants were flat after 4 weeks; however, the duration of follow-up may hide effects of time-dependent factors on survival and poses a concern for clinical inference.
  
  
  CONCLUSIONS
  Early loading of both implant types was well tolerated, as only 2 failures occurred following loading. A subsequent report will review these outcomes along with histomorphometric data collected at 6 months to better understand the significance of tissue-level implant-surface interaction for survival and stability.
authors.affiliation: Ohio State University College of Dentistry, Department of Restorative Dentistry, Prosthodontics, and Endodontics, Columbus, Ohio, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Knobloch
authors.forename: Peter A
authors.initials: PA
authors.lastname: Larsen
authors.forename: Bob
authors.initials: B
authors.lastname: Rashid
authors.forename: Alan B
authors.initials: AB
authors.lastname: Carr
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D003775:Dental Polishing; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003830:Denture, Partial, Fixed; D004285:Dogs; D005260:Female; D008297:Male; D010084:Oxidation-Reduction; D011897:Random Allocation; D013499:Surface Properties; D013997:Time Factors; D016474:Weight-Bearing
chemical_list: D015921:Dental Implants