title: Loosening torque of Universal Abutment screws after cyclic loading: influence of tightening technique and screw coating.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the influence of tightening technique and the screw coating on the loosening torque of screws used for Universal Abutment fixation after cyclic loading.
  
  
  METHODS
  Forty implants (Titamax Ti Cortical, HE, Neodent) (n=10) were submerged in acrylic resin and four tightening techniques for Universal Abutment fixation were evaluated: A - torque with 32 Ncm (control); B - torque with 32 Ncm holding the torque meter for 20 seconds; C - torque with 32 Ncm and retorque after 10 minutes; D - torque (32 Ncm) holding the torque meter for 20 seconds and retorque after 10 minutes as initially. Samples were divided into subgroups according to the screw used: conventional titanium screw or diamond like carbon-coated (DLC) screw. Metallic crowns were fabricated for each abutment. Samples were submitted to cyclic loading at 10(6) cycles and 130 N of force. Data were analyzed by two-way ANOVA and Tukey's test (5%).
  
  
  RESULTS
  The tightening technique did not show significant influence on the loosening torque of screws (P=.509). Conventional titanium screws showed significant higher loosening torque values than DLC (P=.000).
  
  
  CONCLUSIONS
  The use of conventional titanium screw is more important than the tightening techniques employed in this study to provide long-term stability to Universal Abutment screws.
authors.affiliation: Meridional Faculty - IMED, School of Dentistry, Prosthodontics and Dental Materials, Brazil.
authors.forename: Atais
authors.initials: A
authors.lastname: Bacchi
authors.affiliation: Meridional Faculty - IMED, School of Dentistry, Prosthodontics and Dental Materials, Brazil.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Regalin
authors.affiliation: Piracicaba Dental School, Campinas State University, Prosthodontics and Periodontics, Brazil.
authors.forename: Claudia Lopes Brilhante
authors.initials: CL
authors.lastname: Bhering
authors.affiliation: University of Passo Fundo, Post-graduate Program in Dentistry, Dental School, Brazil.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Alessandretti
authors.affiliation: Meridional Faculty - IMED, School of Dentistry, Prosthodontics and Dental Materials, Brazil.
authors.forename: Aloisio Oro
authors.initials: AO
authors.lastname: Spazzin
keywords: Dental prosthesis retention; Implant-supported dental prosthesis; Prosthesis loosening; Single-tooth dental implant