title: The influence of the number and the type of magnetic attachment on the retention of mandibular mini implant overdenture.
abstract: OBJECTIVE
  The aim of this study was to compare the retention of mini implant overdenture by the number, the type of magnetic attachment, and the directions of applied dislodging force.
  
  
  METHODS
  The experimental groups were designed by the number and type of magnetic attachment. Twenty samples were tested with Magden implants. Each attachment was composed of the magnet assembly in overdenture sample and the abutment keeper in a mandibular model. Dislodging forces were applied to the overdenture samples (50.0 mm/min) in 3 directions. The loading was repeated 10 times in each direction. The values of dislodging force were analyzed statistically using SPSS at 95% level of confidence.
  
  
  RESULTS
  The retentive force of group 2 was greater than that of group 1 in both types of attachment in every direction (P< .05). Oblique retentive force of flat type magnetic attachment was higher than that of cushion type attachment in both groups (P< .05). In group 1, oblique retentive force showed the highest and anterior-posterior retentive force showed the lowest value in both attachment types (P< .05). In group 2, both types of attachment showed the lowest retentive force with anteriorposterior direction of dislodging force (P<.05).
  
  
  CONCLUSIONS
  Proper retentive properties for implant overdenture were obtained, regardless of the number and type of magnetic attachment. In both types of magnetic attachment, the greater retentive force was attained with more implants. Oblique retentive force of flat type magnetic attachment was greater than that of cushion type. Among all subgroups, anterior-posterior retentive force was the lowest among three different directions of dislodging force.
authors.affiliation: Department of Prosthodontics, College of Dentistry, Dankook University, Cheonan, Republic of Korea.
authors.forename: Eunjee
authors.identifier: 0000-0003-2843-3636
authors.initials: E
authors.lastname: Lee
authors.affiliation: Department of Prosthodontics, College of Dentistry, Dankook University, Cheonan, Republic of Korea.
authors.forename: Soo-Yeon
authors.identifier: 0000-0001-6160-7277
authors.initials: SY
authors.lastname: Shin
keywords: Dental mini implants; Magnets; Overdenture; Precision attachment