title: Carbon film coating of abutment surfaces: effect on the abutment screw removal torque.
abstract: OBJECTIVE
  To evaluate the effect of diamond-like carbon (DLC) coating of prefabricated implant abutment on screw removal torque (RT) before and after mechanical cycling (MC).
  
  
  METHODS
  Fifty-four abutments for external-hex implants were divided among 6 groups (n = 9): S, straight abutment (control); SC, straight coated abutment; SCy, straight abutment and MC; SCCy, straight coated abutment and MC; ACy, angled abutment and MC; and ACCy, angled coated abutment and MC. The abutments were attached to the implants by a titanium screw. RT values were measured and registered. Data (in Newton centimeter) were analyzed with analysis of variance and Dunnet test (α = 0.05).
  
  
  RESULTS
  RT values were significantly affected by MC (P = 0.001) and the interaction between DLC coating and MC (P = 0.038). SCy and ACy showed the lowest RT values, statistically different from the control. The abutment coated groups had no statistical difference compared with the control. Scanning electron microscopy analysis showed DLC film with a thickness of 3 μm uniformly coating the hexagonal abutment.
  
  
  CONCLUSIONS
  DLC film deposited on the abutment can be used as an alternative procedure to reduce abutment screw loosening.
authors.affiliation: *PhD Student, Department of Dental Materials and Prosthodontics, Institute for Science and Technology at São Jose dos Campos, São Paulo State University, São José dos Campos, Brazil. †Collaborating Professor, Department of Physics, Technologic Institute of Aeronautics, São José dos Campos, Brazil. ‡Postdoctoral Student, Department of Dental Materials and Prosthodontics, São Paulo University, São Paulo, Brazil. §Professor, Department of Dental Materials and Prosthodontics, Institute for Science and Technology at São Jose dos Campos, São Paulo State University, São José dos Campos, Brazil. ‖Adjunct Professor, Division of Prosthodontics, Department of Dentistry, Federal University of Rio Grande do Norte (UFRN), Natal, Brazil.
authors.forename: Pedro Henrique
authors.initials: PH
authors.lastname: Corazza
authors.forename: Alecsandro
authors.initials: A
authors.lastname: de Moura Silva
authors.forename: José Renato
authors.initials: JR
authors.lastname: Cavalcanti Queiroz
authors.forename: Susana María
authors.initials: SM
authors.lastname: Salazar Marocho
authors.forename: Marco Antonia
authors.initials: MA
authors.lastname: Bottino
authors.forename: Marcos
authors.initials: M
authors.lastname: Massi
authors.forename: Rodrigo Othávio
authors.initials: RO
authors.lastname: de Assunção e Souza
mesh_terms: D001863:Bone Screws; D002244:Carbon; D000044:Dental Abutments; D006801:Humans; D008855:Microscopy, Electron, Scanning; D013499:Surface Properties; D019415:Torque
chemical_list: D002244:Carbon