title: Effect of abutment angulation in the retention and durability of three overdenture attachment systems: An in vitro study.
abstract: OBJECTIVE
  This in vitro study investigated and compared the durability and retention of three types of attachments.
  
  
  METHODS
  Three commercially available attachments were investigated: Clix®, Dalbo-Plus® and Locator®. In total, 72 samples of these attachments were placed in the acrylic resin forms and subjected to mechanical testing (5400 cycles of insertion and removal) over the respective ball or Locator abutments immersed in artificial saliva at pH 7 and 37℃. The abutments were placed at angulations of 0°, 10° and 20°. The retention force was recorded at the beginning and after 540, 1080, 2160, 3240, 4320 and 5400 insertion-removal cycles.
  
  
  RESULTS
  The results revealed that there were significant differences in the average values of the insertion/removal force due to angulation (F (2.48) = 343619, P<.05) and the type of attachment (F (7.48) = 23.220, P<.05).
  
  
  CONCLUSIONS
  Greater angulation of the abutments was found to influence the retention capacity of the attachments, and the fatigue test simulating 5 years of denture insertion and removal did not produce wear in the metal abutments.
authors.affiliation: Department of Oral Rehabilitation, Instituto Universitario de Ciencias da Saude (IUCS), Portugal.
authors.forename: Carlos
authors.initials: C
authors.lastname: Aroso
authors.affiliation: Department of Oral Rehabilitation, Instituto Universitario de Ciencias da Saude (IUCS), Portugal.
authors.forename: Antonio Sergio
authors.identifier: 0000-0002-1718-0744
authors.initials: AS
authors.lastname: Silva
authors.affiliation: Industrial Engineer, Chairman of Idearum, Enginyeria i Innovació de Producte, Igualada, Barcelona, Spain.
authors.forename: Raul
authors.initials: R
authors.lastname: Ustrell
authors.affiliation: Department of Oral Rehabilitation, Instituto Universitario de Ciencias da Saude (IUCS), Portugal.
authors.forename: Jose Manuel
authors.initials: JM
authors.lastname: Mendes
authors.affiliation: Department of Production and Systems Engineering, University of Minho (UM), Braga, Portugal.
authors.forename: Ana Cristina
authors.initials: AC
authors.lastname: Braga
authors.affiliation: Department of Endodontics, Faculty of Odontology, University of Barcelona, Barcelona, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Berastegui
authors.affiliation: Department of Rehabilitation and Maxillofacial Prostheses, Faculty of Odontology, University of Barcelona, Barcelona, Spain.
authors.forename: Tomas
authors.identifier: 0000-0002-7515-6064
authors.initials: T
authors.lastname: Escuin
keywords: Attachments; Dental implants; Edentulous patients; Overdentures