title: Removal torque and physico-chemical characteristics of dental implants etched with hydrofluoric and nitric acid. An experimental study in Beagle dogs.
abstract: OBJECTIVE
  To study the composition, surface characteristics and response to removal torque of an implant surface subjected to hydrofluoric acid etching and posterior passivating with hydrofluoric and nitric acid.
  
  
  METHODS
  Twelve implants were initially selected and their physico-chemical characteristics were evaluated by means of energy-dispersive X-rays (EDS), scanning electron microscopy (SEM) and photoelectron spectroscopy (XPS). In addition, 24 implants - 12 measuring 8 mm and 12 measuring 10 mm in length - were implanted in 6 Beagle dogs. Twelve implants were removed after a recovery period of 6 weeks, followed by removal of the remaining 12 implants after 12 weeks, using a torque calibrator (Gauge Tonichi model BGT150CN-S) with a force registry range of 0-150 Ncm.
  
  
  RESULTS
  EDS analysis of the surface chemical composition only revealed the presence of titanium in the etched surfaces. In the same way as with the surfaces of other dental implants, XPS analysis revealed traces of other elements present in the surface, fundamentally carbon. Following dual acid etching, the surface showed the roughness resulting from acid action, with a morphology that proved to be quite homogeneous. The roughness values obtained exceeded 1 mm. The mean removal torque values after 6 weeks were 79.7 Ncm for the 8 mm implants and 115 Ncm for the 10 mm implants. After 12 weeks, these values increased to 101.2 Ncm and 139.7 Ncm, respectively.
  
  
  CONCLUSIONS
  Hydrofluoric and nitric acid etching affords optimum surface characteristics comparable to those of other surfaces. The recorded removal torque values raise the possibility of human clinical application for early or immediate loading procedures.
authors.affiliation: Madrid Complutense University, Dental School, Spain. jmargo@odon.ucm.es
authors.forename: José María
authors.initials: JM
authors.lastname: Martínez-González
authors.forename: Francisco
authors.initials: F
authors.lastname: García-Sabán
authors.forename: Javier
authors.initials: J
authors.lastname: Ferrándiz-Bernal
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Gonzalo-Lafuente
authors.forename: Jorge
authors.initials: J
authors.lastname: Cano-Sánchez
authors.forename: Cristina
authors.initials: C
authors.lastname: Barona-Dorado
mesh_terms: D000134:Acid Etching, Dental; D000818:Animals; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D015921:Dental Implants; D004285:Dogs; D006858:Hydrofluoric Acid; D017942:Nitric Acid; D013499:Surface Properties; D019415:Torque
chemical_list: D015921:Dental Implants; D017942:Nitric Acid; D006858:Hydrofluoric Acid