title: Influence of underpreparation on primary stability of implants inserted in poor quality bone sites: an in vitro study.
abstract: OBJECTIVE
  The purpose of this present study was to investigate the relation between implant site underpreparation and primary stability in the presence of poor-quality bone.
  
  
  METHODS
  A study was performed on fresh humid bovine bone; samples presented no cortical layer with a cancellous structure inside and were obtained from the hip. The bones were firmly attached to a base device. Sixty sites were prepared according to the protocol provided by the manufacturer: a 2-mm pilot drill was introduced to the proper depth and then twist drills of 3 and 3.4 mm were used. After site preparation, 20 3.4- × 11-mm (standard protocol group), 20 3.8- × 11-mm (10% undersized group), and 20 4.5- × 11-mm (25% undersized group) implants were inserted at a calibrated maximum torque of 70 N-cm at the predetermined speed of 30 rpm. After implant insertion, variable torque work (VTW), maximum insertion torque (peak IT), and resonance frequency analysis (RFA) values were recorded.
  
  
  RESULTS
  The standard protocol group showed a mean VTW of 565.77 ± 219.12 N-cm, a peak IT of 11.3 ± 4.44 N-cm, and an RFA of 69.35 ± 7.35 implant stability quotient (ISQ). The 10% undersized group showed a mean VTW of 1,240.24 ± 407.78 N-cm, a peak IT of 20.26 ± 7.03 N-cm, and an RFA of 73.40 ± 2.33 ISQ. The 25% undersized group showed a mean VTW of 1,254.96 ± 727.49 N-cm, a peak IT of 17.15 ± 10.39 N-cm, and an RFA of 72.30 ± 6.70 ISQ. For VTW, the difference between the standard and undersized protocol values was statistically significant; for peak IT, the difference between the standard and 10% undersized protocol values was statistically significant; no other statistical differences were found between mean values.
  
  
  CONCLUSIONS
  In the presence of poor-bone quality, a 10% undersized protocol is sufficient to improve the primary stability of the implant; additional decreases do not seem to enhance primary stability values.
authors: Private Practice, Bologna, Italy.
authors: Marco
authors: M
authors: Degidi
authors: Private Practice, Bologna, Italy.
authors: Giuseppe
authors: G
authors: Daprile
authors: Full Professor, Department of Medical, Oral and Biotechnological Sciences, University of Chieti-Pescara, Chieti, Italy. Electronic address: apiattelli@unich.it.
authors: Adriano
authors: A
authors: Piattelli
mesh_terms: D000818:Animals; D015519:Bone Density / Q000502:physiology*; D002417:Cattle; D003758:Dental Implantation, Endosseous / Q000295:instrumentation / Q000379:methods*; D015921:Dental Implants; D017267:Dental Prosthesis Design; D010027:Osteotomy / Q000295:instrumentation; D013499:Surface Properties; D019415:Torque; D014732:Vibration
chemical_list: D015921:Dental Implants