title: Influence of the cutting edge angle of a titanium instrument on chip formation in the machining of trabecular and cortical bone.
abstract: OBJECTIVE
  The placement of self-tapping implants is associated with microfractures and the formation of bone chips along the cutting flutes. This study was conducted to investigate the effect of different cutting edge angles on chip formation during the machining of trabecular and cortical bone using instruments with a rough titanium surface.
  
  
  METHODS
  Mandibular cortical and trabecular bone specimens were obtained from freshly slaughtered domestic pigs. A predefined thrust force was applied to the specimens. Four specially designed cutting instruments that simulated dental implants and had a rough titanium surface were allowed to complete one full revolution at cutting edge angles of 55, 65, 75, and 85 degrees, respectively. Torque and thrust were measured during the cutting process. Bone chips were measured and weighed under a microscope.
  
  
  RESULTS
  Different cutting edge angles did not lead to significant differences in torque. The lowest torque values were measured when the cutting edges were positioned at 65 degrees in trabecular bone and at 85 degrees in cortical bone. Bone chips were significantly larger and heavier at angles of 55 and 65 degrees than at angles of 75 and 85 degrees in trabecular bone.
  
  
  CONCLUSIONS
  Instruments with a rough titanium surface show considerable angle-dependent differences in chip formation. In addition to bone density, the angle of the cutting edges should be taken into consideration during the placement of dental implants. Good results were obtained when the cutting edges were positioned at an angle of 65 degrees. This angle can have positive effects on osseointegration.
authors.forename: Constantin
authors.initials: C
authors.lastname: von See
authors.forename: Marcus
authors.initials: M
authors.lastname: Stoetzer
authors.forename: Martin
authors.initials: M
authors.lastname: Ruecker
authors.forename: Max
authors.initials: M
authors.lastname: Wagner
authors.forename: Paul
authors.initials: P
authors.lastname: Schumann
authors.forename: Nils-Claudius
authors.initials: NC
authors.lastname: Gellrich
mesh_terms: D000818:Animals; D015519:Bone Density; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D003762:Dental Instruments; D008334:Mandible; D063168:Mandibular Osteotomy / Q000295:instrumentation*; D055595:Mechanical Phenomena; D034421:Sus scrofa; D014025:Titanium; D019415:Torque
chemical_list: D015921:Dental Implants; D014025:Titanium