title: Cutting torque measurements in conjunction with implant placement in grafted and nongrafted maxillas as an objective evaluation of bone density: a possible method for identifying early implant failures?
abstract: BACKGROUND
  Bone grafts are frequently used to enable the placement of dental implants in atrophied jaws. The biomechanical properties of bone grafts used in one- or two-stage implant procedures (in comparison with the use of nongrafted bone) are not well known.
  
  
  OBJECTIVE
  The purpose of this study was (1) to measure cutting torques during the placement of self-tapping dental implants in nongrafted bone and in bone grafts, either as blocks or in a milled particulate form, in patients undergoing implant treatment in an edentulous maxilla and (2) to identify implants with reduced initial stability and to correlate these findings with a clinical classification of jawbone quality.
  
  
  METHODS
  The study included 40 consecutive patients with edentulous maxillas, 27 of whom were subjected to bone grafting prior to or in conjunction with implant placement (grafting group) and 13 of whom received implants without grafting (nongrafted group). Grafted bone from the iliac crest bone was used (1) as onlay blocks, (2) as maxillary sinus inlay blocks, or (3) in particulate form in the maxillary sinus. Implants were placed after 6 to 7 months of healing, except in the maxillary sinus inlay blocks, where implants were placed simultaneously. Cutting torque values were obtained from 113 grafted implant sites and from 109 nongrafted implant sites.
  
  
  RESULTS
  Significantly lower cutting torque values were assessed in grafted regions than in nongrafted regions, irrespective of grafting technique. Lower values were also seen for implants placed in block grafts after 6 months when compared to other grafting techniques used. The cutting torque values revealed an inverse linear relation to the Lekholm and Zarb bone quality index.
  
  
  CONCLUSIONS
  The cutting torque values correlated well with the Lekholm and Zarb index of bone quality. Significantly lower cutting torque values were seen in grafted bone than in nongrafted bone.
authors.affiliation: Department of Surgical Sciences, Oral and Maxillofacial Surgery, University Hospital of Uppsala, Uppsala, Sweden. bjorn.johansson@kus.se
authors.forename: Björn
authors.initials: B
authors.lastname: Johansson
authors.forename: Tomas
authors.initials: T
authors.lastname: Bäck
authors.forename: Jan-Michael
authors.initials: JM
authors.lastname: Hirsch
mesh_terms: D016301:Alveolar Bone Loss / Q000601:surgery*; D000540:Alveolar Ridge Augmentation; D001696:Biomechanical Phenomena; D015519:Bone Density; D016025:Bone Transplantation; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D017268:Dental Prosthesis Retention; D019232:Dental Restoration Failure; D005500:Follow-Up Studies; D006245:Hardness Tests; D006801:Humans; D007575:Jaw, Edentulous / Q000534:rehabilitation / Q000601:surgery*; D008437:Maxilla / Q000601:surgery; D008439:Maxillary Diseases / Q000601:surgery*; D011237:Predictive Value of Tests; D013314:Stress, Mechanical; D019415:Torque; D014945:Wound Healing
chemical_list: D015921:Dental Implants