title: High versus low implant insertion torque: a histologic, histomorphometric, and biomechanical study in the sheep mandible.
abstract: OBJECTIVE
  The purpose of this study was to analyze, in an animal model, the histologic and biomechanical phenomena at the bone-implant interface of implants inserted with high torque (HT) as compared to low torque (LT) during the first 6 weeks of healing.
  
  
  METHODS
  Forty tapered-screw-form implants were placed in five hybrid sheep. The implant sites were placed in the mandible, using an extraoral approach; four were placed with HT (test: mean 110 Ncm) on one side and four were placed with LT (control: mean 10 Ncm) on the contralateral side. After 1, 2, 3, 4, and 6 weeks of healing, removal torque testing and resonance frequency analysis were performed and the animals were sacrificed for histologic examination.
  
  
  RESULTS
  Implants from the HT group showed significantly higher bone apposition than implants from the LT group at all examined healing times. Similarly, removal torque was consistently higher for the HT as compared to the LT group. A significant loss of primary stability in the HT group was evident 7 days after placement. Implants from the LT group achieved a significant increase in stability after 4 weeks. Resonance frequency analysis was unable to detect these histologic and biomechanical modifications of the bone-implant complex.
  
  
  CONCLUSIONS
  The results of the study showed that high implant insertion torque in dense cortical bone does not induce bone necrosis or implant failure, but it does increase the primary stability of implants, which is extremely important in immediate loading protocols.
authors.affiliation: Biomaterials Clinical Research Association, Lucca, Italy. paulbioc@tin.it
authors.forename: Paolo
authors.initials: P
authors.lastname: Trisi
authors.forename: Marzio
authors.initials: M
authors.lastname: Todisco
authors.forename: Ugo
authors.initials: U
authors.lastname: Consolo
authors.forename: Domenico
authors.initials: D
authors.lastname: Travaglini
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D015519:Bone Density; D019245:Compressive Strength; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D017268:Dental Prosthesis Retention; D003799:Dental Stress Analysis; D020878:Device Removal; D005260:Female; D008334:Mandible / Q000502:physiology / Q000601:surgery*; D016348:Osseointegration; D016062:Porosity; D012756:Sheep; D019415:Torque; D014732:Vibration; D014945:Wound Healing
chemical_list: D015921:Dental Implants