title: Effect of using a titanium washer on the removal torque of an abutment screw in the external connection type of dental implant.
abstract: OBJECTIVE
  The aim of this study was to determine the effect of using a washer on the removal torque of an abutment screw in the external connection type of dental implant and abutment complex.
  
  
  METHODS
  Four experimental groups with titanium washers of different types (CP titanium or Ti6Al4V titanium alloy) and thicknesses (1.0 or 2.0 mm) included between the abutment and external connection type of implant were investigated. No washer was applied in the control group. The removal torque was measured with a resolution of 0.1 Ncm. One-way analysis of variance (α = 0.05) and Scheffé's post hoc test were used for statistical analysis.
  
  
  RESULTS
  The removal torque was higher in all the groups with a washer than in the control group (α = 0.05), higher with a CP titanium washer than with a titanium alloy washer of the same thickness, and higher with a 2.0-mm-thick washer than with a 1.0-mm-thick washer (α = 0.05).
  
  
  CONCLUSIONS
  Inclusion of a washer between the titanium screw and the abutment seems to increase the removal torque. A 2.0-mm-thick CP titanium washer might provide the largest increase in the removal torque.
authors.affiliation: Department of Prosthodontics, College of Dentistry, Yonsei University, Seoul, Republic of Korea.
authors.forename: Otgonbold
authors.initials: O
authors.lastname: Jamiyandorj
authors.forename: Sungtae
authors.initials: S
authors.lastname: Kim
authors.forename: June-Sung
authors.initials: JS
authors.lastname: Shim
authors.forename: Keun-Woo
authors.initials: KW
authors.lastname: Lee
mesh_terms: D000497:Alloys; D000044:Dental Abutments; D003722:Dental Alloys / Q000737:chemistry; D059605:Dental Implant-Abutment Design / Q000295:instrumentation*; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D055119:Elastic Modulus; D006801:Humans; D008422:Materials Testing; D018583:Pliability; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D019415:Torque
chemical_list: D000497:Alloys; D003722:Dental Alloys; D003764:Dental Materials; C031462:titanium alloy (TiAl6V4); D014025:Titanium