title: [The relationship between clasp retention and the depth of undercut].
abstract: OBJECTIVE
  To study the relationship between the depth of undercut and the retention of clasp, as a basic information in clinic designing of clasp.
  
  
  METHODS
  The Chatillon force measuring instrument was used to record the retention of 18 Co-Cr alloy casting Akers clasps when they were dislodging from undercuts of different depths (0.25 mm, 0.50 mm, 0.75 mm) on bicuspid and molar. All the data was analyzed by ANOVA.
  
  
  RESULTS
  It is showed that the deeper the undercuts the greater the retention is. The retention of the clasp on molar is greater than premolar in the same condition of undercut. The effect of the types of the abutment and the depths of the undercut are both obvious on the retention of clasp.
  
  
  CONCLUSIONS
  Within the elastic limit of the material, the retention of clasp and the depth of abutment undercut show a positive correlation.
authors.affiliation: Department of Prosthodontics, Ninth People's Hospital, Shanghai Second Medical University, Shanghai 200011, China.
authors.forename: Qi-Min
authors.initials: QM
authors.lastname: Ge
authors.forename: Fu-Qiang
authors.initials: FQ
authors.lastname: Zhang
mesh_terms: D016734:Dental Clasps; D003781:Denture Retention; D006801:Humans