title: In vitro comparison of the retentive properties of ball and locator attachments for implant overdentures.
abstract: OBJECTIVE
  To compare the retentive properties of ball and locator attachments during 5,000 insertion-separation cycles, corresponding to approximately 4.5 years of clinical use.
  
  
  METHODS
  Four dental implants (diameter, 3.8 mm; length, 12 mm) were inserted into the prepared beds of two polyethylene blocks. Twenty acrylic prosthetic components were fabricated and connected to the ball and locator abutments. Tensile force was applied to the prosthetic components until the attachments were separated from the abutments. All samples were subjected to 5,000 insertion-separation cycles. Retention forces were measured after 10, 100, 200, 300, 400, 500, 1,000, 1,500, 2,000, 3,000, 4,000, and 5,000 insertion-separation cycles. Additionally, the wear of the attachments was measured using scanning electron microscopy. Data were analyzed to determine statistical equivalence among the two different attachments using the Student t test procedure and the Mann-Whitney U test procedure (α = .05).
  
  
  RESULTS
  Ball attachments showed significant retention loss after 100, 200, 400, 500, 1,500, and 4,000 cycles, and the locator attachments showed significant retention loss after 100, 200, 300, 500, and 3,000 cycles as compared with the previous cycle (P < .05). Retention loss after 5,000 cycles was detected significantly more often for ball attachments than for locator attachments (P = .049). No significant difference was detected between the retention losses of the two attachment systems during the other cycles as compared with the initial retention values (P > .05). No significant difference was detected between the wear on the two attachment systems after 5,000 cycles (P > .05).
  
  
  CONCLUSIONS
  Both attachment systems showed decreased retentive forces after 5,000 insertion-separation cycles. However, after 5,000 insertion-separation cycles, locator attachments showed better retentive properties than ball attachments.
authors.forename: Pinar Eren
authors.initials: PE
authors.lastname: Türk
authors.forename: Onur
authors.initials: O
authors.lastname: Geckili
authors.forename: Yasin
authors.initials: Y
authors.lastname: Türk
authors.forename: Volkan
authors.initials: V
authors.lastname: Günay
authors.forename: Tayfun
authors.initials: T
authors.lastname: Bilgin
mesh_terms: D000044:Dental Abutments; D015921:Dental Implants; D019094:Dental Prosthesis, Implant-Supported; D019554:Dental Restoration Wear; D003799:Dental Stress Analysis; D003779:Denture Design; D003781:Denture Retention / Q000295:instrumentation* / Q000379:methods; D003828:Denture, Overlay; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D013314:Stress, Mechanical; D013499:Surface Properties; D019415:Torque
chemical_list: D015921:Dental Implants