A Comparative Study on the Retention of Implant Overdenture According to the Shape and the Number of Magnetic Attachment

자성 어태치먼트의 형태와 수에 따른 하악 임플란트 피개의치의 유지력에 대한 비교 연구

  • Seo, Min-Ji (Department of Prosthodontics, College of Dentistry, Dankook University) ;
  • Lee, Joon-Seok (Department of Prosthodontics, College of Dentistry, Dankook University) ;
  • Cho, In-Ho (Department of Prosthodontics, College of Dentistry, Dankook University)
  • 서민지 (단국대학교 치과대학 치과보철학 교실) ;
  • 이준석 (단국대학교 치과대학 치과보철학 교실) ;
  • 조인호 (단국대학교 치과대학 치과보철학 교실)
  • Received : 2008.03.10
  • Accepted : 2008.06.25
  • Published : 2008.06.30


The aim of this study was to compare the retention and stability of implant overdenture according to the shape and the number of magnetic attachment. The experimental groups were designed for the number of implants(1, 2, 4) and shape of magnetic attachments(flat, cushion, dome type) resulting in 9 subgroups. 45 attachments were tested attached to $Br{\aa}nemark$ system implants which were planted on a mandibular model. Each attachment was composed of the magnet assembly embedded in a overdenture sample and the abutment keeper screwed into the implants. Dislodging tensile forces were applied to the overdenture samples using an Instron(cross-head speed 50.80mm/min) in 3 directions simulating function: vertical, oblique, and anterior-posterior. The loading was repeated 10 times in each direction for 45 samples. The values of maximum dislodging force of each subgroup were processed statistically using SPSS V. 12.0 at the 0.05 level of significance. The results of this study were as follows: 1. Flat type magnetic overdenture was the most retentive when subjected to vertically directed forces and dome type was the lest retentive when subjected to obliquely directed forces(p<0.05). 2. In case of planting one implant, flat type had a higher vertically retentive force than anterior-posteriorly retentive force. In case of planting two implants, flat type and dome type had a higher vertically retentive force and in case of planting four implants, flat type and cushion type had a higher vertically retentive force than anterior-posteriorly retentive force(p<0.05). 3. The incremental number of dental implant, without regards to the three types of magnetic attachment shapes, showed higher retention of overdenture(p<0.05). From the results, if a patient need much more retention of implant overdenture, flat type magnetic overdenture would be a good treatment. In case of the bruxism where excessive lateral forces are already present, dome type could be expected to produce better results. In case of planting one implant, flat type is more stable than the other shape of magnet and in case of two implant, flat type and dome type are more stable and in case of four implants, flat type and cushion type are more stable. Planting more than two implants and using flat type magnetic attachment would provide better retention and stability of implant overdenture


  1. Gunne HS, Bergman B, Enbom L, Hogstrom J. Masticatory efficiency of complete denture patients. Acta Odontol Scand 1982;40:289-97 https://doi.org/10.3109/00016358209024072
  2. Haraldson T, Karlsson U, Carlsson GE. Bite force and oral function in complete denture wearers. J Oral Rehabil 1979;6:41-48 https://doi.org/10.1111/j.1365-2842.1979.tb00403.x
  3. Parel SM. Implants and overdentures: The osseointegrated approach with conventional and compromised applications. Int J Oral Maxillofac Implants 1986;1:93-99
  4. chikawa T, Horiuchi M, Matsmoto N. In vitro study of mandibular implant-retained overdentures: The influence of stud attachment on load transfer to implant and soft tissue. Int J Prosthodont 1996;9:394-99
  5. Kenney R, Richards MW. Photoelastic stress patterns produced by implant retained overdentures. J Prosthet Dent 1996;80:559-64
  6. Engquist B, Bergendal T, Kallus T, Linden U. A retrospective multicenter evaluation of osseointegrated implants supporting overdentures. Int J Oral Maxillofac Implants 1988;3:129-34
  7. Mensor MC Jr. Attachment fixation for overdentures. Part I. J Prosthet Dent 1977;37:366-373 https://doi.org/10.1016/0022-3913(77)90137-8
  8. Miller PA. Complete dentures supported by natural teeth. Text Dent J 1965;83:4-8
  9. Preiskel HW. Overdentures made easy. A guide to implant and root supported prostheses. 1st ed. London UK, Quintessence. 1996:105-138
  10. Mensor MC Jr. Removable partial overdenture with mechanical (precision) attachments. Dent Clin North Am 1990;34:669-81
  11. Gendusa NJ. Magnetically retained overlay dentures. Quint Int 1988;19:265-71
  12. Kroone HB, Bates JF. Overdenture with magnetic retainers. British Dental J. 1982;152:310-13 https://doi.org/10.1038/sj.bdj.4804808
  13. Jackson TR. The application of rare earth magnetic retention to osseointegrated implants. Int J Oral Maxillofac Imp 1986;17:571-86
  14. Walmslely AD. Magnetic retention in prosthetic Dentistry. Dent Update 2002;29:428-33 https://doi.org/10.12968/denu.2002.29.9.428
  15. Highton R, Caputo AA, Matyas M, Matyas J. The interaction of a magnetically retained denture with osseointegrated implants. J Prosthet Dent 1988;60:486-90 https://doi.org/10.1016/0022-3913(88)90255-7
  16. Burns DR, Unger JW, Elswiok RK Jr, Beck DA. Prospective clinical evaluation of mandibular implant overdenture: Part I - Retention, stability, and tissue response. J prosthet Dent 1995;73:354-63 https://doi.org/10.1016/S0022-3913(05)80331-2
  17. Walmsley AD, Brady CL, Smith PL, Frame JW. Magnet retained overdentures using th Astra dental implant system. Br Dent J 1993;174:399-404 https://doi.org/10.1038/sj.bdj.4808185
  18. Magnet Attachment for Esthetic Prosthetics. Shin JW. Myungmoon. 1st ed. 2001:10-24
  19. The Academy of prosthodontics. Glossary of prosthodontic terms. J Prosthet Dent 1994;71:50-107
  20. Gillings BR. Magnetic denture retention systems. In: Prieskel HW. Precision attachments in prosthodontics. 2nd ed. Quintessence book. 1986:191-241
  21. Sarnat AE. The efficiency of cobalt samarium magnet as retentive unit for overdentures. J Dent 1983;11: 324-33 https://doi.org/10.1016/0300-5712(83)90117-3
  22. Lewandowski JA, White KC, Moore D, Johnson C. An investigation of two rare earth magnetic systems by measuring grip force and reseating force. J Prosthet Dent 1988;60:705-11 https://doi.org/10.1016/0022-3913(88)90404-0
  23. Akaltan F, Can G. Retentive characteristics of different dental magnetic systems. J Prosthet Dent 1995;75:422-27
  24. Hur KS, Hur SJ, Cho IH. A comparative of retentive force of various overdentures using several magnet. The Journal of Korean Prosthetics 1991;29:11-20
  25. Petropoulos VC, Smith W. Maximum dislodging force of implant overdentures stud attachments. Int J Oral Maxillofac Implants 2002;17:526-35
  26. Ma PS, Shin SW. Three dimensional finite element analysis on the madibular implant-supported overdentures depending upon the type of magnetic attachments and number of fixtures. MS thesis 2005(1), Department of prosthodontics, Graduate School of Clinical Dentistry, Korea University