title: An Evaluation of Retentive Ability and Deformation of Acetal Resin and Cobalt-Chromium Clasps.
abstract: OBJECTIVE
  To compare the retentive ability and deformation of Acetal resin with Cobalt-Chromium clasps via Insertion Removal apparatus after subjecting them to stimulate clinical use.
  
  
  METHODS
  Materials used for this study are commercially available Cobalt-Chromium alloy namely Wironit, Bego, Germany and Acetal resin namely Biodentaplast, Bredent, Germany. The test samples were divided into two major groups based on the type of materials used in the study. Each major group is further subdivided into two sub groups based on the retentive undercut depths used to engage the clasps. So a total of 20 specimens were prepared, comprising of 5 specimens in each sub group. Then the specimens were tested for retention force and deformation.
  
  
  RESULTS
  The results of this study indicate that acetal resin clasps are resistant to deformation and may offer a clinical advantage over the conventional metal clasps. The retentive force of acetal resin clasps did not decrease over the cycling periods. This would be attributed to the resilient nature of acetal resin. Under the conditions of the present study cobalt chromium clasps lost retentive force within 730 cycles of placement and removal and continued to lose retentive force during the remaining test period.
  
  
  CONCLUSIONS
  This invitro study demonstrated that retentive force of cobalt chromium clasp is superior to that of Acetal resin for removable partial dentures. As acetal resin clasps exhibits greater flexibility and long term retentive resiliency, it can be used for removable partial dentures where aesthetics or periodontal health is a primary concern.
authors.affiliation: Professor, Department of Prosthodontics, Tamil Nadu Government Dental College and Hospital , Chennai, India .
authors.forename: A
authors.initials: A
authors.lastname: Meenakshi
authors.affiliation: Prosthodontics, Private Practitioner.
authors.forename: Ranjana
authors.initials: R
authors.lastname: Gupta
authors.affiliation: Post Graduate Student, Department of Prosthodontics, Tamil Nadu Government Dental College and Hospital , Chennai, India .
authors.forename: Vinay
authors.initials: V
authors.lastname: Bharti
authors.affiliation: Associate Professor, Department of Prosthodontics, Tamil Nadu Government Dental College and Hospital , Chennai, India .
authors.forename: G
authors.initials: G
authors.lastname: Sriramaprabu
authors.affiliation: Dean and Head, Department of Orthodondics, Thai Moogambigai Dental College and Hospital , Chennai, India .
authors.forename: Ramachandra
authors.initials: R
authors.lastname: Prabhakar
keywords: Aesthetics; Direct retention; Insertion removal apparatus; Removable prostheses