Evaluation of Testing Procedure Accuracy Described for the Measurementof Magnetic Attachment Attractive Force in ISO 13017
R. Kanbara, K. Shoji, Y. Nakamura, M. Takahashi1, Y. Takada1, S. Tanaka, Y. Ohno, Y. Tanaka
Department of Removable Prosthodontics, School of Dentistry, Aichi-Gakuin University
1

Division of Biomaterials, Tohoku University Graduate School of Dentistry

Introduction
A dental magnetic attachment International Standard of (ISO 13017) was published in2012. However the basic methods and techniques for the uniform measurement of magneticattachments was amended and covered in 2013.
The uniform measurement of magnetic attachments attractive force as applied to an
International Standard requires several considerations including, the attractive force measuringmethod repeatability, measurement accuracy, ease of use and availability. The Japanese Societyof Magnetic Applications in Dentistry performed a reevaluation of previous measurement jig andmeasuring techniques (fixation method) for the measurement of magnetic attachment attractiveforce.

A proposed revision of the written standards was submitted for consideration in April, 2013.

A review of the validity, versatility, and accuracy of the document revision contents should beevaluated to confirm attractive force measurement procedures according to the specific written
universal standard.

Objective
The present study investigated if the written instructions for attractive force measuringmethods specified in the revision of the ISO 13017 written standards can be understood andperformed for the first time use.

Further, the accuracy and validity of first time use measurements

will be examined to determine written standard accuracy and use.

Materials and Methods
1． The proposed revision of the ISO 13017 written standards
Since the proposed revision of the written standards does not contain diagrams, only thedocuments were distributed. The following are the contents of the proposed revision.
1 The lateral surface is positioned so that the centers of the upper and lower stages installed on○
the attractive force measuring device are in line.
2 A magnet or attractive surface of a magnet is temporarily bonded to the center of the lower○

stage using double-faced tape.
3 Cyanoacrylate adhesive is carefully applied on top of the temporarily bonded magnet or magnet○
assembly.
4 The upper stage is moved downward to press against a temporarily-bonded magnet or○
magnetic assembly. A joint part is reinforced using autopolymerizing resin if necessary.
5 After a magnet or magnetic assembly is completely bonded to the upper stage, the upper stage○
was moved upward, and double-faced tape is removed.
6 A magnet or keeper is accurately positioned to the attractive surface of a magnet or magnetic○
assembly bonded on the upper stage, and attach.
7 Cyanoacrylate adhesive is dropped in the center of the lower stage. The upper stage is moved○
downward, and the bottom part of a magnet or a keeper is fixed to the lower stage so that theattractive surface is perpendicular to the move axis. The joint part is reinforced using autopolymer
resin if necessary.
8 Do not move a magnet or keeper until the adhesive is completely cured. Do not remove the○upper and lower stages from the device to maintain the proper position.
9 When the attractive force is extremely smaller than 85% (manufacturer’s indicated value), the○positional relationship between a magnet and keeper, and magnetic assembly and keeper isadjusted, and remeasurement is performed.
2． Verification method of the contents

1) Measurer
Five measurers (A, B, C, D, and E) with no attractive force measurement experience
were selected.
2) Verification method
The proposed revision of the ISO 13017 written standards were distributed to eachmeasurer, and was evaluated according to the following procedure.
Stage 1: Measurement was performed only by reference to the proposed revision of the ISO
13017 written standards.
Stage 2: Questions were asked to experts, and remeasurement was performed.
Stage 3: Remeasurement was performed after observing the measurement by experts.
Feedback was performed after the completion of Stage 1 measurement to elucidate unclear pointsof the proposed revision.
3． Sample and measurement conditions

1) Sample
Dental magnetic attachment (GIGAUSS C600, GC) was used as a measurement sample. The
public value of this sample was 5.88 N.(fig. 1)

2)

Measurement conditions
A simplified attractive force measuring device was used for the measurement. (fig. 2) The

crosshead speed was 4.4 mm/min. The number of a sample was one, and measurement was
performed 10 times. The number of attachment and removal was 5 times for each stage.

Fig. 1GIGAUSS C600

Fig. 2

Simplified attractive force
measuring machine

Results
1. Attractive force measurement value by each measurer
Fig. 3 shows the attractive force measurements of measurers A, B, and C.
Consistent attractive force measurements were obtained from Stage 1 to 3. Standard deviation
became smaller from Stage 1 to 3.
Fig. 4 shows the attractive force measurements of measurers D and E.
The average of measurement results of Stage 1 were lower than the public value of 85%.
Consistent attractive force measurement values were obtained for Stage 2 and 3.
Fig. 5 shows five measurements of Stage 1 by measurers D and E whose measurements
showed a high standard deviation. Although the second measurement of the measurer D reached
85% of the public value, the results were higher error was observed after the third measurement.
For the measurer E, measurements became consistent after the third measurement by repeating
the measurement.
2. The contents of the proposed revision of the written standards that measurers could notunderstandThe following show the points in the written standards where measurers did not understand afterStage 1.
○
1 The description about a magnet or magnetic assembly, and magnet or keeper is complex.
○2 Cure time and the amount of adhesive are unclear.
○
3 The positional adjustment of a magnetic assembly and keeper is unclear.
○
4 The removal method of a magnetic assembly and keeper is unclear.

Fig. 3Fig. 4

Attractive force measurements of measurers A, B, C

Attractive force measurements of measurers D, E

Fig. 5

Five measurements of Stage 1 by measurers D and E

Discussion
1. Measurement results
Measurement results of the measurers A, B, and C were consistent, showed small
standard deviation, and exceeded 85% of the public value, suggesting that the measurers A, B,and C understood the contents of the proposed revision of the written standards before performing
attractive force measurement (Fig. 3).
Stage 1 measurements of the measurers D and E showed high standard deviation. Thiswas considered to be due to the fact that measurers did not fully understand the contents of theproposed revision. The more a measurement was repeated, the more consistent measurements
became. This was considered to be due to the fact that measurers understood the contents after
repeating the procedure.
Although the second measurement of the measurer D reached 85% of the public value,
the results were back to low after the third measurement. It was found that the measurer damaged
a magnetic assembly and keeper during the second removal, causing unstable results (Figure 4and 5).
2. The contents of the proposed revision of the written standards
A feedback from measurers after the measurement showed that although the contents ofthe proposed revision of the written standards that are difficult to understand directly influence on
the attractive force measurement value, they were understood by repeating the measurement. To
improve the understanding, diagrams should be included in the proposed revision.

Conclusion
The results of the present study showed that a proposed revision of the written standards appears
sufficient to standardize the attractive force measurement of a magnetic attachment internationally,suggesting an efficiency with revision of measurement instruction document contents.

References
1. ISO13017 Dentistry-Magnetic attachments, International Organization for standardization,2012
2. Yoshinobu T.: The Caterpillar turns into the Butterfly. J J mag dent 2013;22(1):1-12.
3. Yukyo T.: A commission report of the ISO corresponding committee working toward international
standardization of dental magnetic attachments -ISO/TC106 meeting in Paris- . J J mag dent
2013;22(1):65-68.