Influence of Thermal Cycle on Attractive Force of Magnetic by pptfiles


									             Comparison of Retentive Force of Diff

              Overdenture Stud Attachments in Var

                     Dislodgements. In Vitro Study

                  Part 2 Changes after Fatigue Test

        H.Mizutani, D.Destine, V.Rutkunas*, A.B

        K.Nakamura**, S.Ishikawa, H.Sasaki, S.M

        C.Tsuda, Y.Ogasawara, H.Kazama, T.Mat


           Graduate School, Tokyo
Medical and Dental University
           *Lithuania Vilnius University
Institute of Odontology
         ** International University of
Health and Welfare
          1-5-45 Yushima Bunkyo-ku
Tokyo Japan 113-8549



     1. Various attachments are used for retaining overdentures. Due to simplicity
     and good servicing resilient attachments have gained popularity.
     Two-implant supported mandible overdentures were qualified as first-choice
     standard of care for edentulous patients. Various attachments are used for
     retaining overdentures. Direct relationship exists between retention
     and patient satisfaction. Wear induced material losses at the attachment
     surfaces, dimensional changes and reduction of resiliency occur during
     insertion and removal of the overdenture as well as during minimal movements
     under functional load. As a result, with time overdenture attachments loose
     their retentive properties. Therefore, servicing are required.

     2. Aims of our study was:
     To evaluate quantitative (reduction in maximum retentive force) fatigue
     characteristics of overdenture attachments.

     3. Fatigue characteristics of 7 commercially available attachments were tested
     Era Overdenture orange and white (Sterngold, Attleboro, MA, USA), Locato
     Root pink, white and blue (Zest Anchors, Escondido, CA, USA), O-P anchor #
     (Inoue attachment Co., Ltd, Tokyo, Japan) and Magfit DX600W (Aichi Ste

     4.   Fivespecimens of each type of attachment were used. Specimens wer
     mounted in the testing machine , Micro Material Testing 250N made b
     Shimadzu Corporation.,( Kyoto, Japan).
     For Magfit DX600W, consecutive loadings were 0-2000 cycles and for th
     others 15000 insertion-removal cycles performed in 37oC demineralized water
     Maximum retentive force (N) was measured initially and after each 100 cycles.


     5.   Statistical analysis was made by SPSS for Windows software. The means
     and standard deviations were calculated, and statistical comparison was made
     using a one-way analysis of variance. Significance of differences between each
     group had been evaluated.


     6.   Fatigue test revealed attachment type dependent changes in maximum
     retentive force values. As for Era Orange and Era White sudden decrease
     follow by a constant curve was characteristic. All 5 specimens showed on this
     slide accused the same curve’s shape during 15000 insertion-removal cycles. 

     7.   Retentive force for LP, LW and LB increased after initial decrease. LP, LW
     and LB attachments had relatively wide variability among the different

      8.   As for Magfit DX600W during consecutive loading (0-2000 cycles), if we
      compared it with OP we observed that both are slightly increasing on their
      retentive force and keep the same retentive force after 1000 cycles. And with the
      other specimens as for LP, EW, and EO they retentive force fall sharply before
      to continue on the same level.


     9. This   diagram shows the average retentive force values after 15000 cycles.
     Era overdenture decreased sharply and continued to the same level during the
     15000 cycles. The Locator Root overdenture decreased also at the beginning but
     rise slowly during the insertion-removal cycles.. However, O-P Anchor after a
     slight increasing persist on the same level.


      10.   After 2000 insertion-removal cycles for Magfit and 15000 for the other
      attachments, the retention was constant only for O-P anchor and Magfit
      However, with Era Orange and Era White statistically significant decrease in
      retention was observed.

      11.   Value    of Era Orange and Era White retentive force after fatigue
      simulation was comparable to that obtained by other studies.For Magfit after
      2000 cycles the retentive force did not change. For O-P anchor, there was a
      slight moification. The differences from the others specimens, Locator and Era
      ,are hugely proved by the graph. Maximum retentive force for Magfit and O-P
      are fairly the same. Retention of O-P unexpectedly increased to 117% of initial


      12.   In conclusion:
      1) Decrease in retention of overdenture attachments is found for most of the
         specimens after fatigue test.
      2) Different color coded plastic males does not necessarily provide different
         levels of retention.
      3) With some types of attachments increase in retention could be expected.
      4) Retentive force values for different overdenture attachments test have high
      5) Magnetic attachments showed constant retentive force throughout the cycle.

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