title: Resistance to wear of four matrices with ball attachments for implant overdentures: a fatigue study.
abstract: OBJECTIVE
  The study evaluated in vitro the retention force and the wear resistance over simulated function of four matrix components of ball attachments for implant-retained overdentures.
  
  
  METHODS
  Four types of matrices for ball attachments were evaluated in a fatigue study simulating 5500 cycles of insertion and removal. The matrices used were (1) a Teflon matrix supported by a metal housing, (2) a titanium matrix, (3) a gold alloy matrix, (4) an O-ring matrix using the red color ring for medium retention. Dimensional changes of the ball attachments were investigated with a profilometer.
  
  
  RESULTS
  The Teflon matrices showed an increase of 27% in retention at 5500 cycles while the gold alloy matrices showed an increase of 50% in retention in the first 500 cycles and remained relatively stable up to 5500 cycles. On the other hand, titanium matrices and O-ring matrices exhibited progressive loss of retention ending with 68% and 75% of retention loss, respectively, at 5500 cycles. Dimensional analysis by profilometer revealed significant wear on the ball attachment only for titanium matrixes.
  
  
  CONCLUSIONS
  Gold alloy and Teflon matrices showed the highest retention values without retention loss after 3 years of simulated function. Titanium and O-ring matrices presented a continuous loss of retention with the highest wear on the ball attachments when combined with the titanium matrix.
authors.affiliation: Department of Prosthetic Dentistry, University of Florence, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Branchi
authors.forename: Dario
authors.initials: D
authors.lastname: Vangi
authors.forename: Antonio
authors.initials: A
authors.lastname: Virga
authors.forename: Genevieve
authors.initials: G
authors.lastname: Guertin
authors.forename: Giovanni
authors.initials: G
authors.lastname: Fazi
mesh_terms: D000044:Dental Abutments; D003722:Dental Alloys / Q000737:chemistry; D015921:Dental Implants; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry; D019094:Dental Prosthesis, Implant-Supported; D019554:Dental Restoration Wear; D003799:Dental Stress Analysis / Q000295:instrumentation; D003781:Denture Retention / Q000295:instrumentation*; D003824:Denture, Complete; D003828:Denture, Overlay; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D011138:Polytetrafluoroethylene / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry
chemical_list: D003722:Dental Alloys; D015921:Dental Implants; D003764:Dental Materials; D006047:Gold Alloys; D011138:Polytetrafluoroethylene; D014025:Titanium