title: EFFECT OF PILOT HOLE TAPPING ON PULLOUT STRENGTH AND INSERTION TORQUE OF DUAL CORE PEDICLE SCREWS.
abstract: OBJECTIVE
  To evaluate the influence of pilot hole tapping on pullout resistance and insertion torque of pedicle screws with a conical core.
  
  
  METHODS
  Mechanical tests using a universal testing machine were performed on pedicle screws with a conical core that were inserted into pedicles in the fifth lumbar vertebra of calves. The insertion torque was measured using a torque meter with a capacity of 10 Nm, which was considered to be the highest torque value. The pilot holes were prepared using a probe of external diameter 3.8 mm and tapping of the same dimensions and thread characteristics as the screw.
  
  
  RESULTS
  Decreased insertion torque and pullout resistance were observed in the group with prior tapping of the pilot hole.
  
  
  CONCLUSIONS
  Pilot hole tapping reduced the insertion torque and pullout resistance of pedicle screws with a conical core that had been inserted into the pedicle of the fifth lumbar vertebra of calves.
authors.affiliation: Postgraduate Student in the Department of Biomechanics, Medicine and Rehabilitation of the Locomotor Apparatus, Ribeirao Preto School of Medicine, University of Sao Paulo (USP), Ribeirao Preto, SP, Brazil.
authors.forename: Rodrigo César
authors.initials: RC
authors.lastname: Rosa
authors.affiliation: Postgraduate Student in the Department of Biomechanics, Medicine and Rehabilitation of the Locomotor Apparatus, Ribeirao Preto School of Medicine, University of Sao Paulo (USP), Ribeirao Preto, SP, Brazil.
authors.forename: Patrícia
authors.initials: P
authors.lastname: Silva
authors.affiliation: Postgraduate Student in the Department of Biomechanics, Medicine and Rehabilitation of the Locomotor Apparatus, Ribeirao Preto School of Medicine, University of Sao Paulo (USP), Ribeirao Preto, SP, Brazil.
authors.forename: Maurício José
authors.initials: MJ
authors.lastname: Falcai
authors.affiliation: Associate Professor in the Department of Biomechanics, Medicine and Rehabilitation of the Locomotor Apparatus, Ribeirao Preto School of Medicine, University of Sao Paulo (USP), Ribeirao Preto, SP, Brazil.
authors.forename: Antônio Carlos
authors.initials: AC
authors.lastname: Shimano
authors.affiliation: Titular Professor of the Department of Biomechanics, Medicine and Rehabilitation of the Locomotor Apparatus, Ribeirao Preto School of Medicine, University of Sao Paulo (USP), Ribeirao Preto, SP, Brazil.
authors.forename: Helton Luiz Aparecido
authors.initials: HL
authors.lastname: Defino
keywords: Biomechanics; Bone Screws; Spine