title: Effect of insertion torque on titanium implant osseointegration: an animal experimental study.
abstract: OBJECTIVE
  To evaluate the effect of implant insertion torque on the peri-implant bone healing and implant osseointegration.
  
  
  METHODS
  Bilaterally in the tibia of five adult New Zealand white rabbits, 20 implants were installed, subdivided into four groups, corresponding to two insertion torque conditions (low, < 10 Ncm vs. high > 50 Ncm) and 2 experimental periods (2 weeks vs. 4 weeks of healing). The implant insertion torque was determined by the surgical drill diameter relative to the implant diameter. Implant osseointegration was evaluated by quantitative histology (bone-to-implant contact with host bone [BIC-host], with neoformed bone [BIC-de novo], with both bone types [BIC-total], and peri-implant bone [BA/TA]). Every response was modelled over time using GEE (general estimation equation) with an unstructured variance-covariance matrix to correct for dependency between the measurements from one animal. The statistical significance level of α = 0.05 was applied.
  
  
  RESULTS
  Significantly, more BIC-host and BIC-total were recorded for H implants compared with L implants after 2 week of healing (P = 0.010 and P = 0.0001, respectively). However, this result was no longer found for the extended healing period. Furthermore, BIC-total significantly increased over time for L implants (P < 0.00001). In contrast, the significant increase in BA/TA over time was found for H implants (P < 0.01). Finally, H insertion torque led to an increased BA/TA after 4 week of healing (P < 0.02) compared with the L insertion protocol.
  
  
  CONCLUSIONS
  L insertion torque implants installed in the rabbit tibial bone osseointegrate with considerable de novo bone formation. This bone neoformation enables L implants to catch up, already during the early osseointegration stage, the initial inferior amount BIC contact compared with that of H implants. A negative impact of the created strain environment accompanying H insertion torque implant installation on the biological process of osseointegration could not be observed, at least not at tissue level.
authors: Department of Oral Health Sciences & Dental Clinic, KU Leuven & University Hospitals Leuven, BIOMAT KU Leuven & Prosthetics Unit, Leuven, Belgium.
authors: Joke
authors: J
authors: Duyck
authors: Rutger
authors: R
authors: Roesems
authors: Marcio V
authors: MV
authors: Cardoso
authors: Toru
authors: T
authors: Ogawa
authors: Germana
authors: G
authors: De Villa Camargos
authors: Katleen
authors: K
authors: Vandamme
mesh_terms: D000818:Animals; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D020007:Implants, Experimental; D008297:Male; D016348:Osseointegration; D010012:Osteogenesis; D011817:Rabbits; D013314:Stress, Mechanical; D013977:Tibia / Q000473:pathology / Q000601:surgery*; D014025:Titanium; D019415:Torque
chemical_list: D015921:Dental Implants; D014025:Titanium
keywords: animal experiments; bone implant interactions; insertion torque; surgical techniques