title: Constant strain rate and peri-implant bone modeling: an in vivo longitudinal micro-CT analysis.
abstract: BACKGROUND
  Strain, frequency, loading time, and strain rate, among others, determine mechanical parameters in osteogenic loading. We showed a significant osteogenic effect on bone mass (BM) by daily peri-implant loading at 1.600µε.s(-1) after 4 weeks.
  
  
  OBJECTIVE
  To study the peri-implant osteogenic effect of frequency and strain in the guinea pig tibia by in vivo longitudinal micro-computed tomography (CT) analysis.
  
  
  METHODS
  One week after implant installation in both hind limb tibiae, one implant was loaded daily for 10' during 4 weeks, while the other served as control. Frequencies (3, 10, and 30Hz) and strains varied alike in the three series to keep the strain rate constant at 1.600µε.s(-1) . In vivo micro-CT scans were taken of both tibiae: 1 week after implantation but before loading (v1) and after 2 (v2) and 4 weeks (v3) of loading as well as postmortem (pm). BM (BM (%) bone-occupied area fraction) was calculated as well as the difference between test and control sides (delta BM) RESULTS: All implants (n=78) were clinically stable at 4 weeks. Significant increase in BM was measured between v1 and v2 (p<.0001) and between v1 and v3 (p<.0001). A significant positive effect of loading on delta BM was observed in the distal peri-implant marrow 500 Region of Interest already 2 weeks after loading (p=.01) and was significantly larger (11%) in series 1 compared with series 2 (p=.006) and 3 (p=.016).
  
  
  CONCLUSIONS
  Within the constraints of constant loading time and strain rate, the effect of early implant loading on the peri-implant bone is strongly dependent on strain and frequency. This cortical bone model has shown to be most sensitive for high force loading at low frequency.
authors.affiliation: Department of Prosthetic Dentistry/BIOMAT Research Cluster, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, K.U. Leuven, Leuven, Belgium.
authors.forename: Els
authors.initials: E
authors.lastname: De Smet
authors.forename: Siegfried V N
authors.initials: SV
authors.lastname: Jaecques
authors.forename: Martine
authors.initials: M
authors.lastname: Wevers
authors.forename: Jos Vander
authors.initials: JV
authors.lastname: Sloten
authors.forename: Ignace E
authors.initials: IE
authors.lastname: Naert
mesh_terms: D000497:Alloys; D000818:Animals; D001696:Biomechanical Phenomena; D001853:Bone Marrow / Q000502:physiology; D016723:Bone Remodeling / Q000502:physiology*; D003722:Dental Alloys / Q000737:chemistry; D015921:Dental Implants; D017267:Dental Prosthesis Design; D006168:Guinea Pigs; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D016348:Osseointegration / Q000502:physiology; D010012:Osteogenesis / Q000502:physiology; D011897:Random Allocation; D013314:Stress, Mechanical; D013977:Tibia / Q000502:physiology / Q000601:surgery*; D013997:Time Factors; D014025:Titanium / Q000737:chemistry; D055114:X-Ray Microtomography / Q000379:methods
chemical_list: D000497:Alloys; D003722:Dental Alloys; D015921:Dental Implants; C031462:titanium alloy (TiAl6V4); D014025:Titanium