Projects of Japanese Dental Science Federation in 2016
Investigation of materials with a high level of evidence and survey research

The Japanese Society of Magnetic Applications in Dentistry
Survey and Research on International Standardization and Clinical Evaluation of Magnetic Dental
Attachments

Prepared by:
Masayuki Hideshima (Medical Committee Chair; Tokyo Medical and Dental University), Shuji Okawa(President; Meikai University), Chikahiro Okubo (Vice Chair, Tsurumi University), Shinichi Masumi(Former Chair, Kyushu Dental College), Yukyo Takada (Chairperson of ISO Committee; Tohoku
University), Kazuhiro Nagata (Chairperson of Clinical Evaluation Committee; Nippon Dental
University at Niigata)

Related Committees:【Medical Committee】: Masayuki Hideshima1 (Chair), Yoshitada Umekawa2 , Shogo Ozawa3 , Toshihiro
Kawano4 , Mai Kono5 , Yasunori Suzuki6 , Joji Tanaka7 , Kan Nagao8，Akira Nishiyama1, Kazumoto
Hoshiai3.
【ISO Working Committee】: Yukyo Takada9 (Chair), Tomohiko Ishigami2, Yoshitada Umekawa2, Ryo
Kanbara3, Yoshinori Nakamura3, Eri Makihara4, Shinichi Masumi4【Clinical Evaluation Committee】: Kazuhiro Nagata10 (Chair), Tetsuo Oyama2 , Mineyo Sone11 ,Tatsuhiko Masuda3

1Tokyo Medical and Dental University, 2Nihon University School of Dentistry, 3Aichi Gakuin

University School of Dentistry, 4Kyushu Dental College, 5 Health Sciences University of Hokkaido,
6Tsurumi University School of Dentistry, 7Chiba Prefecture, 8Tokushima University, 9Tohoku

University School of Dentistry, 10 Nippon Dental University at Niigata, 11Meikai University School of
Dentistry,

Table of Contents

I. Introduction Preface

II. Evaluation of Magnetic Attachments for Clinical Application
1. Clinical evaluation of Hicorex (Prognosis after 1 year and 4 months)
2. Clinical evaluation of Magfit (Prognosis after 10 years)
3. Clinical evaluation of Magfit (Prognosis after 15 years, follow-up report of 2.(10years))
4. Clinical evaluation of Physio-magnet (Prognosis after 8-12 years)
5. Clinical evaluation of magnetic attachment abutment teeth in a multicenter setting
6. Clinical evaluation of magnetic attachment abutment teeth by multi-center (follow-up report of 5.)
7. References

III. International Standardization of Magnetic Attachment
1. History of International Standardization
2. Structure of ISO 13017 and outline of the supplemental version
3. References

IV. Development of Clinical Guidelines for Magnetic Attachments Development of Clinical Practice
Guidelines for Magnetic Attachments
1. Background of the development of practice guidelines
2. Survey and selection of clinical questions for magnetic attachments in dental practice
3. Evidence collection methods
4. Process and Criteria for Determining Recommendation Levels
5.Consensus method
6. Determination of recommendations and evaluation profile
7. References

Ⅴ．Clinical Questionnaire and Evaluation/Recommendation Profile of Clinical Guidelines

VI. Conclusion

1

Survey and Research on International Standardization and Clinical Evaluation ofMagnetic Dental Attachments
The Japanese Society of Magnetic Applications in Dentistry
Masayuki Hideshima (Chair, Medical Committee; Tokyo Medical and Dental University), Shuji Okawa(Chair, Meikai University), Chikahiro Okubo (Vice Chair, Tsurumi University), Shinichi Masumi(Former Chair, Kyushu Dental University), Yukyo Takata (Chair, ISO Committee; Tohoku University), ;Kazuhiro Nagata (Chair, Clinical Evaluation Committee; Nippon Dental College at Niigata)

I. Introduction
The Japanese Society of Magnetic Dentistry was founded in 1980 as a research group for new
denture attachments,

and was promoted to an academic society in 1991.

Since the establishment of the society, each organization affiliated with the society has conducted
prognostic studies on the clinical application of magnetic attachments, and after the promotion to
the society, a clinical evaluation committee has been established to accumulate data on thelong-term progress of magnetic dental attachments (hereinafter referred to as "magnetic
attachments") based on a common protocol.
On the other hand, the ISO task force committee was established in 2007 for the international
standardization of magnetic attachments,and has undergone examinations by the International

Organization for Standardization (ISO). As a result, Japanese magnetic attachments acquired
ISO13017 certification on July 15, 2010, achieving international standardization of magnetic
attachments.
In recent years, the need for evidence-based medicine and improvement in quality have prompted
various academic societies to develop guidelines for medical practice. For CQs with low levels ofevidence, a questionnaire survey was conducted among relevant experts, and a Delphi survey was
also conducted to converge opinions by feeding back the results. The "Clinical Practice Guideline for
Magnetic Attachments 2013" has been completed. It is now included in the Japanese Dental
Association's Dental Practice Guideline Library and posted on its website.
The purpose of this study was to summarize the research achievements of our society on magnetic
attachments in Japan, which have achieved international standardization, and to collect researchwith a high level of evidence and reliable clinical data.

2

We would like to report on the evaluation of the clinical application of magnetic attachments,
international standardization, and the formulation of medical practice guidelines, in this order, toassist in the selective treatment or insurance coverage of magnetic attachments currently underconsideration by our society.

II. Evaluation of magnetic attachments for clinical application
Since the inception of the study group, prognostic studies have been conducted at various
institutions, and the results have been presented at research meetings and academic conferences
and published in journals.
In 1990, magnetic attachments were approved as a medical device by the Ministry of Health,Labour and Welfare, and in 1991, after the Society of Magnetic Dentistry was promoted to theJapan Society of Magnetic Dentistry, a clinical evaluation committee was established, a protocol for
postoperative follow-up was formulated, and magnetic attachments from various institutions andmanufacturers were evaluated.

1．Clinical evaluation of Hicorex (Prognosis after 1 year and 4 months)
In 1997, a survey (Table 1) of 1,123 cases with 1,719 teeth was conducted at 261 institutions from
November 1992 to March 1994, in which Hitachi Metals' Hicorex MD was applied, and the results
were published by the Tokyo Medical and Dental University in the Japanese Journal of
Prosthodontics, with the following findings1).
1) Distribution of cases:

By gender, 459 males (695 teeth), 616 females (945 teeth), and 48

unknown (79 teeth), and by age, the largest number of both males and females were in their 60s,
followed by those in their 50s and 70s (Figures 1, 2).
2) Abutment teeth: In the maxilla, canine teeth (44%), first premolars, second premolars, andcentral incisors were the most common, in that order. In the mandible, canine teeth (44%), firstbicuspids, second bicuspids, and lateral incisors were most common, in that order (Fig. 3).
3) Postoperative period: 3-6 months; 917 teeth (53.3%), in the order of 0-3 months, 6-12 months,
and 12 months or longer (Figure 4).
4) Postoperative problems: Gingival inflammation, pain of abutment teeth, and discoloration of
keepers were observed in 5 of 1123 cases.

3

Table 1: Medical Device Adverse Reaction Survey Card and Survey Items

Number of Teeth

Distribution by Age
500

421

400

299

300

198

200
100

107
7

42

24

23

2

0
Age
Fig 1: Distribution by gender and numberof abutment teeth for magnetic
attachments (all 1123 cases, 1719 teeth)

Figure 2: Age distribution of study subjects(all 1123 cases)

4Incisor

CaninePremolarMolar

Fig 4: Duration after Delivery of magnetic
Fig3：Distribution by Tooth Type（Maxilla & Mandible）

attachment (all 1719 abutment teeth)（All 1719 abutment teeth）

2．Clinical evaluation of Magfit (Prognosis after 10 years)
In 2004, an analysis of the postoperative course of Magfit applied to 105 metal dentures (240teeth) and 750 resin dentures (1133 teeth) (Table 2) over a 10-year period from May 1993 to May
2003 at Aichi-Gakuin University was published in the Japanese Journal of Magnetic Dentistry, andthe following results were obtained2,3).
1) The average number of magnetic attachments applied per denture: 2.3 teeth for metal denturesand 1.5 teeth for resin dentures (Table 2).
2) Age distribution of metal dentures: The most common age group was 60s, followed by 70s and50s (Figure 5).
3) Comparison of metal dentures in the upper and lower jaws: The number of abutment teeth in theupper jaw was about 1.5 times greater than that in the lower jaw, and application to the upper5

canine was the most common (Fig. 6).
4) Comparison of abutment devices in metal dentures: 42% of the abutment devices were magnetic
attachments only, and the remaining 58% were other devices (Table 3).
5) Longevity of abutment teeth in metal dentures: 95% after 5 years and 88% after 10 years (Table 4).
Number of
MA abutments

Metal plate

Number ofabutment
teeth

Resin plate

Number ofabutment
teeth

38
21
28
11
4
3
105

38
42
78
44
20
18
240

492
179
45
26
4
4
750

492
358
135
104
20
24
1133

1
2
3
4
5
6
Total
Average numberof abutment teeth
per plate

2.3

Total
numberof plates

530
200
73
37
8
7
855

Total
numberof abutment
teeth

530
400
213
148
40
42
1373

1.5

1.6

Table2：Number of abutment teeth and distribution bydenture plate type for magnetic attachments (MA)

Number of plates

Distribution of metal plates by age
40

34

32

30
23
20
10
2

4

3

30's

40's

5

0
under
30's

50's

60's

70's

over 80's
Age

Fig5：Age distribution of subjects (105 total cases)

Extructed teeth
Survival rate

After 5years

After 10
years

12
95.0%

28
88.3%

Combination
withother retainer

Number of
MA abutments

MA only

1
2
3
4
5
6

3
10
17
6
4
3
43

35
11
9
5

41.7%

58.3%

60

Table3： Number of abutment teeth of MA’s in metal
dentures and distribution of retainers by other devices

Table４：Survival rate of abutment teeth in metal
dentures (All 240 abutment teeth)6Incisor

CaninePremolarMolar

Fig6： Distribution of upper and lower jaw by
tooth type (total 1373 abutment teeth)

3. Clinical evaluation of Magfit (Prognosis after 15 years; continuation of 2 (after 10 years).)
In 2009, the progress of 252 teeth was analyzed over a 15-year period from May 1993 to May 2008
for the additional study described in 2. 4).
1) Survival rate of abutment teeth of metal dentures: Of the 252 teeth, 135 (54%) were available forinvestigation, of which 29 (12%) were lost (extracted) and 106 (42%) remained. Therefore, thesurvival rate over 15 years was 79% (Table 5, Fig. 7).
2) Survival rate of abutment teeth of resin dentures: Of the 111 dentures examined, 83 (75%) wereavailable, 16 (12%) were lost (extracted), and 67 (60%) remained.)
3) Comparison by tooth type: In the cases with Kennedy Class I and II free end defects, theabutment teeth were frequently extracted. On the other hand, extraction was less common in7

cases with all or none of the molar support zone in the A and C types of the Eichner classification(Fig. 8).
4) Comparison of the survival rate of abutment teeth: Metal denture patients aged 75 years or
younger had a longer survival rate of abutment teeth than resin denture patients aged 65 years orolder (Fig. 9).

After 15
years
Extructed teeth

29

Survival rate

78.5%

Table5：Survival rate of abutment teeth inmetal plate dentures (135 of a total of 252
abutment teeth were eligible for the survey)
Fig7：Comparison of the life extension rate of abutment teeth
between metal and resin dentures (all 83 abutment teeth)

Fig8：Comparison of the life extension rate of abutment teeth by defect type (all 83 abutment teeth)Fig 9：Comparison of the survival rate of abutment teeth of metal and resin dentures by
age group (all 83 abutment teeth)

84. Clinical evaluation of Physio-magnet (After 8-12 years)
In 2015, the long-term course of patients wearing Physio-magnets (Hitachi Metals) at Tsurumi
University was published in the Journal of the Japanese Society of Magnetic Dentistry, with thefollowing results5,6) .
1) A survey was conducted on 46 people (mean age 65.4 years) with detailed records of 80 teeth whowore magnetic attachments during the 5-year period from 2002 to 2006 (Fig. 10), of which 19
people and 34 teeth were analyzed (Table 6).
2) Canine teeth were the most common abutment teeth, followed by first bicuspids and second
bicuspids (Fig. 11).
3) The average age since implantation was 10.3±1.4 years, 11 (32.4%) of the abutment teeth werelost, and 15 (44.1%, including 4 missing teeth) of the magnetic structure were lost.
4) After approximately 10 years of implantation, 67.6% of the abutment teeth and 55.9% of themagnetic structures were long-lived (Table 7).
5) Comparison of the life expectancy of the abutment teeth after approximately 10 years of
implantation by denture base showed that the life expectancy of the metal base was 70.4% andthat of the resin base was 57.1%. The metal base showed a better survival rate.
6) Regarding the progress of the periodontal tissues of the abutment teeth, an increase inperiodontal pocket depth was observed in approximately 60% of the patients, with 35% having
an increase of 1 mm at the deepest point and 26% having an increase of 2 mm (Figure 12).
7) In the survey of abutment teeth at the time of magnetic attachment, 42% of the abutment teeth
were upset and about half of the abutment teeth had pocket depths of 3 mm or greater,
indicating that the condition of the abutment teeth was not good.

Numberof Cases
Rate

Male

FemaleTotale

1

18

19

2.2%

39.1%

41.3%

(In 43 total
surveyed cases)

Table 6：Number of cases that responded to theinvestigation among the recalled cases withcomplete progress records (43 cases in total)
Fig10：Number of MA denture cases and abutment teeth during the study period

9Incisor

CaninePremolar

Molar

Number ofabutment
teeth
Rate

Extructed
teeth

Loss ofmagnetstructure

Totale

11

4

15

32.4%

11.8%

44.1%

(In 34 abutment
teeth of 19 cases)

Table 7：Progress of abutment teeth(34 teeth in 19 cases in total)

Fig 11：Distribution of upper and lower jaw by tooth type(total 34 teeth)

Fig12：Progress of periodontal pocket depth (mm) for eachabutment tooth (all 34 teeth)

5. Clinical evaluation of magnetic attachment abutment teeth at multiple institutions
In 2003, the Japanese Society of Magnetic Dentistry began postoperative analysis at each
institution using a common protocol developed by the Clinical Evaluation Committee, especiallythe analysis of periodontal pocket depth of abutment teeth.)
1) Probing values (PD values) of abutment teeth after 5 years of magnetic attachment were10

measured using the 6-point method, and cases with a 5-year follow-up by June 2009 wereanalyzed.
2) At the start of the study, 44 cases were included, but 12 cases were censored, and finally 29 cases,
62 teeth, 16 maxillary and 19 mandibular rests were included (Table 8).
3) The abutment tooth types were 12 incisors, 24 canines, 17 bicuspids, and 9 molars, and thedenture bases were 21 resin bases and 14 metal bases (Table 9).
4) The percentage of patients with free end defects was about 90%, and the percentage of patientswith loss of occlusal support was about 70% (Fig. 13).
5) PD values of abutment teeth increased significantly after 5 years (Figure 14). In pre- andpostoperative comparisons, the PD value of the deepest pocket significantly increased in the
maxillary, female, resin-floored abutment teeth (Figs. 15-17).

Number of cases

Number of
denture plates

Number ofabutment
teeth

Base line at start

44

Maxilla16

32

suspension of
investigation

12

Mandible

19

30

35

62

32
Extructed teeth

14

Table 8：Process of the investigation and comparison of all 29 cases
analyzed, 35 dentures, and 62 teeth by upper and lower jaws
Tooth type

IncisorNumber ofabutment teeth

12

Canine Premolar Molar
24

17

9

Number of
denture plates

Metal plate
dentures

14

Resin plate
dentures21
35

Table 9：Distribution by tooth type and comparison by floor (all 29 cases)

11

Fig13：Comparison of the survival rate of abutment teeth by defect type of remaining dentition (all 29 cases)

Fig14：Change in pocket depth after 5 years(all 29 cases, 62 abutment teeth)

Fig15：Comparison of pocket depth in upper andlower jaws (all 29 cases, 62 abutment teeth)Fig 16：Comparison of pocket depth by gender(all 29 cases, 62 abutment teeth)Fig 17：Comparison of pocket depth by denture type(all 29 cases, 62 teeth)

12

6.

Multicenter clinical evaluation of magnetic attachment abutment teeth (continuation of 5.)

Additional survey of 5. was published in 20128,9).
1) At the beginning of the survey, 70 cases were included, but 28 cases were censored, and finally 42
cases, 75 teeth, 24 maxillary abutments and 21 mandibular abutments were included (Table 10).
2) The abutment tooth types were 12 incisors, 29 canines, 25 bicuspids, and 9 molars, and thedenture bases were 23 resin and 22 metal (Table 11).
3) The PD values of the abutment teeth increased significantly after 5 years (Figure 17). In pre- andpostoperative comparisons, the PD values of the deepest pockets significantly increased in the
maxillary, female, and resin-bed abutment teeth, and also significantly increased in the canine
abutment teeth and female resin-bed abutment teeth (Figures 18-20).

Number of Number ofdentureabutment
platesteeth

Number of cases
Base line at start

70

Metal plate
dentures24

45

Suspension of
investigation

28

Resin plate
dentures

21

30

45

75

42
Extructed teeth

18

Table 10：Process of the investigation and comparison of all 42 cases analyzed,
45 dentures, and 75 abutment teeth by upper and lower jaws

Tooth type

IncisorCaninePremolar

Molar

Number ofabutment teeth

12

29

25

9

Number of
denture plates

Metal plate
dentures22

Resin plate
dentures23

Table 11：Distribution by tooth type andcomparison by floor (all 42 cases)

45

13

Fig 17：Change in pocket depth after 5 years (all 42 cases, 75
abutment teeth). Comparison between the deepest point of

Fig 18：Comparison of pocket depth in upper andlower jaws (total 42 cases, 75 abutment teeth)

the 6-point method and all measurement points

Fig19：Comparison of pocket depth by gender and denture type(all 42 cases, 75 abutment teeth)Fig 20：Comparison of pocket depth by tooth type(all 42 cases, 75 abutment teeth)

147. References
1) Mizutani A, Nakamura K, Ai M. A Follow-up Study of Dentures with Magnetic Attachments Using a
Surgeon's Questionnaire (in Japanese). Journal of the Japan Prosthodontic Society. 1997; 41:902-909.
2) K. Hoshiai, T. Tanaka, N. Hasegawa, M. Kawakita, W. Fujinami, K. Wakayama, T. Hikosaka, H. Hirai,
T. Miyata, K. Kumano, R. Sakane. Postoperative survey of magnetic attachments in metal dentures(in Japanese). Journal of Magnetic Dentistry. 2004; 13(1): 1-8.
3) Hoshiai K, Tanaka Y, Hasegawa N, Kawakita M, Fujinami W, Wakayama K, Imaizumi Y, Matumoto T,
Sakane M. Longitudinal Study of Metal Plate Denture with Magnetic Attachments. JJ Mag Dent.
2004; 13(2): 26-29.
4) Ito R, Hoshiai K, Hasegawa N, Muraji N, Kaaguchi T, Noda K, Watanabe N, Tanaka Y.: Longitudinal
Study on Metal Plate Denture with Magnetic Attachments. J J Mag Dent. 2009; 18(2): 8-14.
5) Shigeko Takayama: Special feature: Reexamination of magnetic attachments based on long-term
follow-up, Current status of magnetic attachments from the viewpoint of prognosis study (in Japanese),
Journal of Magnetic Dentistry., 24(1): 30-31, 2015.
6) Shuji Okawa: Special feature: Reexamination of magnetic attachments after long-term follow-up Summary of the symposium (in Japanese) -, Journal of Magnetic Dentistry 24(1): 30-31, 2015.
7) Ito R, Hoshiai K, Tanaka Y, Ishigami T, Ishibashi T, Bando E, Sasaki H. Longitudinal Study ofMagnetic Attachments -Investigation ob Probing Depth on J J Mag Dent. 2010; 22(3):321-322. J J Mag
Dent. 2010; 19(2): 35-39.
8) Miwata M, Ito R, Hoshiai K, Tanaka Y, Ishigami T, Ishibashi K, Bando E, Sasaki H. Mizutani H,
Hosoi T: Longitudinal Study of Magnetic Attachments - Investigation ob Probing Depth on Abutment
teeth-. J J Mag Dent. 2010; 20(2): 73-78.
9) Ito R, Miwata M, Hoshiai K, Tanaka Y, Ishigami T, Ishibashi T, Bando E, Sasaki H. Longitudinal
Study of Magnetic Attachments -Investigation ob Probing Depth on Abutment teeth Part.2-. Depth on
Abutment teeth Part.3-. J J Mag Dent. 2011; 20(2): 69-72.

15

Ⅲ． International Standardization of Magnetic Attachments
1. History of International Standardization
In 2005, the Japanese Society of Magnetic Dentistry, led by the Japan Society of Magnetic
Dentistry, obtained a grant from the New Energy and Industrial Technology Development
Organization (NEDO) under the research theme of "Optimization of Magnetic Attachments for
Dental Use and Creation of International Standards" and launched an effort toward international
standardizationofmagnetic

attachmentsbyestablishingtheMagnetic

Attachment

Standardization Committee. The efforts toward the international standardization of magnetic
attachments began with the establishment of the Magnetic Attachment Standardization
Committee (Fig. 1).

Optimization and International Standardization of the Magnetic Dental Attachment
by New Energy and Industrial Technology Development Organization (NEDO)

Fig 1: Participating organizations at the time of the establishment of the Magnetic Attachment Standardization Committee

In 2007, at the ISO/TC106 Berlin meeting, a New Work Item Proposal (NP) was submitted to
Subcommittee 2 (SC2), which develops standards for prosthetic materials. At the following meeting of
ISO/TC106 in Gothenburg in 2008, WG22 (Working group 22) Magnetic attachments was newly
organized in SC2. Japan became the chairing country of WG22, and the Magnetic Attachments
Standardization Committee produced a convener (chairperson) and a Japanese expert. At this meeting,
the Japanese draft standard (Dentistry - Magnetic Attachments) was adopted as a working draft (WD)and approved as ISO/ WD 130171). In the same year, the NEDO support was terminated, and an ISO
task force committee was established in the Japan Society of Magnetic Dentistry to take over the16

development of the ISO standard (Figure 2).
In May 2009, the NEDO-supported follow-up project was selected as the next grant, and theStandardization Committee for Magnetic Dental Attachments was reorganized with the members of the
ISO task force committee. At the ISO/ TC106 Osaka meeting in September of the same year, the CD(committee draft) ballot for ISO/ WD 13017 was approved, and the committee was promoted to ISO/CD
13017 in the CD ballot held in March 2010. The DIS (draft International Standard) ballot for ISO/CD
13017 was approved at the ISO/ TC106 General Assembly, and the standard was promoted to ISO/DIS
13017 in the June 2011 DIS ballot without any negative votes. Furthermore, ISO/ FDIS 13017 wasapproved through FDIS (Final Draft International Standard) balloting in June 2012, and ISO 13017
was published as an international standard on July 15, 2012, thus achieving the international
standardization of magnetic attachments2) (Figure 3).

Fig 2. International standardization of magnetic attachments (2005-2011)

Fig 3: ISO/FDIS 13017 voting results

17However, it was developed in a short period of four years after the ISO task force was established, andin addition, there were points that were unsatisfactory as a provision for measuring retentive force thatcan fully evaluate the uniqueness of domestic magnetic attachments that show strong retentive force
even though they are small in size. Therefore, based on the progress of international standardization of
the maintenance force measurement method for magnetic attachments, which we have been working onin parallel since 2010, we started activities to apply for the supplemental version of ISO 13017 at thesame time as the publication of the international standard. The draft standard was submitted with ahigh degree of completeness due to the preparations that had been made since 2010, and therefore, it isusually considered as a work in progress.
Although deliberation would be made from the Draft WD, the wish for deliberation from the Draft
International Standard (DIS) was also passed at the same time (Figure 4).

Figure 4: International standardization of magnetic attachments (2011-2015)

The draft Amendment was subsequently revised, and after the 2013 Inchon meeting, it was elevatedto ISO13017: DAM.1 (Draft International Standard as supplement) through DAM ballot (DIS ballot as
supplement) 4). During the DAM ballot, Germany objected that the amendments made at the Inchon
meeting were not fully reflected in the draft Amendment. However, it turned out that the draft
Amendment circulated for DAM balloting before the Inchon meeting was a systemic deficiency causedby the fact that it was circulated before the Inchon meeting, and the German approval was obtained. In
addition, Australia proposed a request for additional friction provisions, which was revised with
sufficient evidence and approved for FDAM (draft final international standard for addendum) ballot at18

the Berlin meeting in 2014. At the Berlin meeting, the results of interlaboratory tests conducted in three
countries (Japan, Germany, and China) were reported (Figure 5) and discussed on the improvement of
the specimen fixation method, the definition of maintenance force and its calculation method, and thedefinition of friction force during vertical specimen movement. After returning to Japan, we revised andadded to the current DAM.1 according to the points raised and submitted the draft FDAM.1 to the SC2
secretariat5).

(a)

Japan

(b) China(c) Germany

Fig 5. Interlaboratory testing (specimen table and fixation method for post-keeper)

FDAM registration was completed in 2015, and in September, FDAM ballot elevated it to FDAM.1(the final draft International Standard for the addendum). At that time, the integration of ISO 13017
and Amd.1 (the supplemental version) was pointed out by Germany, and a slight modification of theformat was pointed out by the UK, but the revised version of FDAM was submitted after the Bangkok
meeting in September 2015. The integration of ISO 13017 and Amd.1 (supplemental version) was
proposed and approved at the time of the periodic review in 2017, which is conducted every five years
after the publication of an international standard6). Thus, ISO 13017:2012/Amd.1 (the supplement to
ISO 13017) was published in November 20157) (Figure 6).

19Fig 6

International standardization of magnetic attachments in dentistry (2012-2016)

The international standardization of magnetic attachments, which started in 2005, has beenaccomplished after 11 years with the publication of two international standards, ISO 13017 andISO 13017:2012/Amd.1 (supplemental version). The two international standards will be integrated
for the periodic review in 2017 (Figure 7) .

ＩＳＯ １３０１７ （Original standard version）

ＩＳＯ １３０１７ （Amendment1）

Fig 7 ISO 13017and Amendment 1(Supplemental ed.)20

2. Structure of ISO 13017 and outline of the supplemental edition
Figure 8 shows the structure of ISO 13017 and the supplement to the standard by Amd. 1(supplement). Underlines indicate the parts supplemented by Amd.1.
ISO 13017 consists of items 1 to 8, and is mainly supplemented by Amd. 1, which covers the
preparation of specimens (5.1 Maintenance force) in 5. and test methods (6.3 Maintenance force, 6.4
Corrosion resistance) in 6.
In 3. Terms and definitions, terms and definitions related to dental magnetic attachment types,
magnets and magnetic structures, keepers, magnetic circuits, etc. are given. For example, magnetic
attachments without a magnetic circuit are defined as "magnet" and those with a magnetic circuitas "magnet structure (magnet) assembly" to clarify that magnetic attachments in Japan aremagnet structures.

Contents of ISO 13017 and compensation by the Supplement edition
1. Scope
2. Normative references
3. Terms and definitions
4. Requirements
4.1 Material
Declaration of composition
4.2 Hazardous elements
Ni＜0.1％, Cd, Be＜0.02％
4.3 Risk analysis
Compliant with ISO14971
4.4 Magnetic flus leakage
Display obligation if it is 40ｍT or more

4.5 Retentive force
Not less than 85％ of the standard value

4.6 Corrosion resistance

5. Preparation

6. Test methods

5.1 Retentive force

6.1 Information, Instructions

Pre-treatment of specimen

5.2 Static immersion test
5.3 Anordic polarization
curve

and making

6.2 Magnetic flux leakage
6.3 Retentive force
Apparatus(device)
Fixing materials
Fixing procdure
Methods and evaluation

Definition of retentiveforce
6.4 Corrosion resistance
Minimum limit of determination

7. Information and instruction for use

Eluted ion amount according to ISO22674
Not less than breakdown potential of 316L

Fig 8

8. Marking and labellingContents of ISO 13017 and compensation by the Supplement edition.

The requirements in Section 4 consist of 4.1 Materials, 4.2 Hazardous Elements, 4.3 Risk Analysis,
4.4 Leakage Field, 4.5 Maintenance Force, and 4.6 Corrosion Resistance. 4.1 Materials uses the21ISO standard classification that defines magnets, and only major constituent elements areindicated to prevent leakage of trade secrets. 4.6 Corrosion resistance: Corrosion resistance ofstainless steel 316L or higher for orthopedic use for biological use was specified to maintain quality
and to prevent distribution of pirated copies.
In 5. Preparation of specimens, preparation of specimens at the time of testing is specified, andin 5.1 Sustaining force, the pretreatment method is added according to Amd. 1.
Amd. 1 specified in detail the method of measuring 6.3 maintenance force, the jig to be used (Figs.
9 and 10), the method of calculating the maintenance force (Fig. 11), and the measurement methodwith high accuracy and reproducibility (Fig. 12). 6.4. In corrosion resistance, in order to clarify thequantitative analysis of impurity element ions in static immersion tests, the lower limit ofquantification and detection limit of the chemical analysis method were introduced, and accuratequantification was specified.
7. and 8. specify descriptions and labeling contents to support the product.

Fig 9

Overview of the jig for measuring retention force (left) and the low-friction linear slider (right)

22

Fig 10. Retentive Force Measuring Jig

Fig 11. Retentive Force Curve

Fig12: Dynamic frictional force and change in the jig for measuring maintenance force

3. References
1) ISO 13017: 2012(E), Dentistry -Magnetic attachments.
2) Y. Takada: ISO Task Force Report: Toward International Standardization of Magnetic
Attachments for Dental Use (in Japanese), Journal of Magnetic Dentistry, 20(1): 81-85, 2011.
233) Y. Takada: Report of the ISO Task Force Committee: Toward the International Standardizationof Magnetic Dental Attachments, - ISO/TC 106 Paris Conference - (in Japanese), Journal ofMagnetic Dentistry, 22(1): 65-68, 2013.

4) Takada, Y.: Report of the ISO Task Force Committee: Toward International Standardization ofMagnetic Dental Attachments, - ISO/TC 106 Inchon Meeting -, (in Japanese). Journal of Magnetic
Dentistry, 23(1): 72-76, 2014.

5) Takada, Y.: Report of the ISO Task Force Committee: Toward International Standardization ofMagnetic Dental Attachments, - ISO/TC 106 Berlin Meeting , (in Japanese) . Journal of Magnetic
Dentistry, 24(1): 48-53, 2015.

6) Y. Takada: Report of the ISO Task Force Committee Toward International Standardization ofMagnetic Dental Attachments, - ISO/TC 106 Bangkok Conference (in Japanese)-, Journal ofMagnetic Dentistry 25(1): 39-44, 2016.

7) ISO 13017: 2012(E)/Amd.1, Dentistry -Magnetic attachments.

24IV. Development of Clinical Practice Guidelines for Magnetic Attachments
1. Background of the development of medical practice guideline
In recent years, rapid changes in the composition of the population and the structure of disease,
as well as the need for evidence-based medicine and improvement in the quality of medical care asa social accountability for clarifying human rights and the right to choose medical care, haveprompted various academic societies to develop guidelines for medical practice. In the JapaneseSociety of Magnetic Dentistry, the Medical Committee has been playing a central role in theformulation of practice guidelines for magnetic attachments since 2009.
However, unlike general dentistry, the application of magnetic attachments to complete
dentures is not covered by insurance, so there are various restrictions on the conditions andselection of applicable cases, and on the facilities where they are used. Therefore, the Medical
Committee first conducted a questionnaire survey on the pros and cons of introducing magnetic
attachments to the insurance system, mainly among those who had served on the board of
directors of academic societies. As a result, of the 116 responses, 26 were in favor, 29 wereconditionally in favor, and 37 were opposed, indicating that many were both in favor and opposed1).
In Phase I, the Medical Committee surveyed CQs that raised clinical questions and collected
147 questions, from which 14 representative CQs were selected: 4 on implants, 3 on defect styles,
3

onocclusion/periodontal

disease,2

onabutment

placement/form,

and

2

on

management/others1-4). In the second year of the project, eight courses were asked to develop
guidelines in accordance with the GRADE system5,6). In addition, in order to inform the public
about the significance of medical practice guidelines and the steps involved in their development,
we requested lectures at the 21st Annual Meeting on the theme of "Development of Medical
Practice Guidelines for Magnetic Attachments" by persons with experience in developing clinicalpractice guidelines in various specialties, introducing how to proceed with evidence collection andthe Delphi method7-9) when evidence is insufficient, as well as discussion. The speakers introduced
and discussed how to proceed with evidence collection and the Delphi method7-9) when there is alack of evidence. At the 22nd Annual Meeting, an educational symposium was held by the former
Vice President and the former President on the merits of magnetic attachment application,
failures due to magnetic attachment application, and countermeasures against them under thetheme of "If you have a problem with magnetic attachments "9) . Furthermore, at the 23rd Annual
Conference, a practice guideline symposium was held under the theme of "Application of25

Magnetic Attachments to Implants vs. Natural Teeth "10).
Through the above process, we have raised awareness of the issue of practice guidelines among
the members of the society and have tried to spread awareness of the significance of the practiceguidelines.
“Clinical practice guidelines" are practice guidelines based on Evidence Based Medicine (EBM),
which support dentists in general dental practice in making appropriate choices and decisions
about prevention and treatment of dental diseases under specific clinical circumstances11).
Therefore, they are different from procedural instructions or insurance guidelines, and they are
not intended to regulate the discretion of dentists.
In recent years, the mainstream in the formulation of medical practice guidelines has been toevaluate evidence and determine recommendations using the system devised by the GRADE(Grading of Recommendations Assessment, Development and Evaluation) Group5,6) , and theJapan Medical Evaluation Organization (JMEDO) has been working on the development of
medical information guidelines. The MINDS (Medical Information Network Distribution
Service)12) of the Japan Medical Evaluation Organization and the Japanese Dental Association
also recommend the GRADE system. This method takes into account 3 factors: the physician's
expertise, experience, and skills; patient factors; and quality of evidence. Recommendations are
determined by comprehensively judging four major factors: quality of evidence, balance of benefits
and disadvantages, values and preferences, and cost and resource utilization3,4).
However, because of the special nature of prosthetic dentistry and the lack of evidence inmagnetic dentistry, which is a new field, we have incorporated evaluation methods that takeadvantage of the characteristics and originality of our society while referring to the GRADE
system. For example, in the medical field, epidemiological verification is essential, but in the fieldof prosthodontics and magnetic attachments, model experiments and simulation experiments are
more reproducible and can be cited as sufficient evidence for the maintenance and durability ofoutcomes, etc. Therefore, as one of the levels of evidence, S (very low), B (low) and C (very high)were added in addition to A (high), B (low) and C (very low). S (Simulated or model experiment)
was added to A (high), B (low), and C (very low) as one of the levels of evidence13).
In addition, when evidence was insufficient or conflicting, a questionnaire survey including theDelphi method was conducted to supplement the evidence. Furthermore, a consensus group wasformed for each clinical question (CQ: Clinical Question) and asked to review the description of26

the practice guideline for each CQ, which was finally summarized by the medical committee8,9) .
At present, there are many CQs for which there is insufficient evidence, and we believe that not
only the Magnetic Dentistry Society but also the dental community as a whole should urgently
address these as research themes. It is necessary to continue to make many reorganizations, suchas adding CQs, revising recommendations, and developing a system to accept users' opinions andsuggestions on the contents of recommendations.

2. Survey and selection of clinical questions for magnetic attachments in dental practice
For the selection of clinical questions (CQ: Clinical Question) for magnetic attachments (MA), a
questionnaire survey was sent by e-mail to experienced officers of the society, requesting a wide
range of responses from dentists at their facilities and general clinicians in the community1 ).. Inaddition, we distributed the questionnaire to the participants of the 19th Annual Meeting,published it on the website of the Society and in the Journal of the Society2), and mailed thesurvey to the academic members of the dental associations in each prefecture.
The CQs consisted of Patient, Intervention, Comparison, and Outcome. The survey was
conducted in accordance with the PICO format, with examples provided and multiple responses
requested (Table 1).
In case of ～is ～(intervention：I)

compared to～(comparison：C)

effective?
(outcome：O)

1) In case of few remaining mandibular teeth

is a magnetic attachment

effective?

2) In case of implant-supported overlay dentures,is a magnetic attachment

3) When applying a magnetic attachment to aremaining abutment tooth

is a flat-type keeper

compared to applying
claspscompared to othertypes of retainers
compared todome-shaped keepers(patient or problem：P)

effective?
effective for stabilityof the denture?

①②③
Table 1: Questionnaire regarding clinical questions

The results of the survey revealed that 117 respondents responded to the questionnaire, and a
total of 147 CQs were collected1-4). Of the 117 respondents, 77 had more than 10 years of clinicalexperience, 18 had 5 to 10 years, 21 had 2 to 5 years, and 1 was a resident. Sixty-seven respondents
were working in general dentistry or clinics, and 50 were working at university hospitals. Fifty-two
were members of the university, 64 were non-members, and one was not listed. Fifty-eight patients27

had more than 10 cases of magnetic attachments, 12 had 5 to 10 cases, 24 had less than 5 cases,
and 23 had no experience.
The number of CQs categorized into five groups according to content is as follows.
1) Implant-related: 21
2) Comparison with other systems in terms of defect style: 51
3) Comparison with other systems in terms of occlusion and periodontal disease: 174) Placement and form of abutment teeth: 275) Management and others: 31
From the above CQs, a total of 14 CQs were selected as representative CQs: 4 on implants, 3 on
deficiency styles, 3 on occlusion/periodontal disease, 2 on abutment placement/form, and 2 onmanagement/others. The CQs were reviewed and discussed during the formulation process, andresponses to the 12 CQs were finally prepared8-10) (Table 2).
Ⅰ． Implant
1．In case of implant-supported overlay dentures, is magnetic attachments (MAs) more effective than applying other type of retainers?
2．In implant-supported overlay dentures, are applying MAs to implant abutments more successful than applying them to natural teeth?
3．Applying MAs to implant-supported overlay denture cases, are maxillary cases more successful than mandibular ones?
4．Applying MAs to implant-supported overlay denture cases, are multiple abutments with MAs more effective than a single abutment?
Ⅱ． Defects
5. In few remaining mandibular teeth, are applying MAs more effective than other type of retainers?
6. In free-end saddle removable partial dentures, are applying MAs more effective than other type of retainers?
Ⅲ．Occlusion/Periodontics
7. In partially edentulous without occlusal contact, are applying MAs more successful than other type of retainers?
8. In partially edentulous with undulating occlusal planes, are applying MAs more effective than other type of retainers?
9. When remaining abutments are with periodontal disease, are applying MAs more successful than other type of retainers?
Ⅳ．Arrange / Form
10.Applying MAｓ to multiple abutment teeth, are symmetrical arrangements more effective than asymmetrical ones?
11.Applying MAｓ to remaining abutment teeth, is flat type keeper more effective than dome-shaped keeper for stability of the denture?

Ⅴ．Manage/etc
12. When setting MAs to removable partial dentures, is the applied pressure method more successful than the minimum pressure ones?

Table 2： 12 CQs (Clinical Questions) and the formulating process(MA：Magnetic Attachment，DM：Delphi Method)
Other devices refer to various attachments other than clasps and magnetic attachments28

3. Methods of evidence collection
Literature searches were conducted using MEDLINE, Medical Journal Web (Ver. 4), Cochrane Oral
Health Group Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE,
UMIN Clinical Trials Registry (UMIN-CTR), etc. The search principle was to search for references thatwere searchable in the databases by October 2012. Randomized controlled trials (RCTs), cohort studies,case-control studies, cross-sectional studies, observational studies, and case reports were searched, andtheir citations were hand-searched.

4. Process and criteria for determining the level of recommendation
The most important role of a guideline is to clearly state the level of recommendation. In this guideline,
the GRADE system was used as a reference, and the following process was used to determine the level ofrecommendation, taking into consideration the special characteristics of prosthodontics.

Process for determining the level of recommendation

Factors Considered in Making Recommendations
Level of evidence in terms of study design
Level of Evidence

Research Design

A（High）

Randomized controlled trials, Systematic review

B（Low）

observational study

29

C（Very Low）

Case Reports, Case Studies

S

Model experiments and demonstrations using engineering methods

Quality of Evidence
Quality of Evidence

Meaning

H（High）

Little to no change in estimated effects

M（Midle）

There may be a possibility of changing in estimated effect

L（Low）

Possible change in estimated effect

VL（Very Low）

Estimated effects are very uncertain

In the case of evidence from engineering methods, the possibility of changing the estimatedeffect was evaluated based on whether the environment was fully realized in vivo and whether
the estimation was based on an understanding of the problems with engineering methods13).

5. Consensus method
Due to the clinical specificity of prosthetic dental practice, there is not always a high level ofevidence for many CQs. When the quality of evidence is not sufficiently high for a guideline foreach CQ, or when there are conflicting opinions, recommendations and opinions based on expert
consensus were appended.
The consensus was formed by choosing between the Delphi method for the consensus group(determined by the subcommittee for each CQ, taking into account the areas of expertise) and astandard questionnaire survey of members.
*About the Delphi method
Questionnaire surveys using the Delphi method were conducted in the following cases7-10) .
As a result of collecting evidence by the aforementioned methods･When no references could be found at all･When the number of references is small and the quality of evidence is very low (VL)･When the literature search results in conflicting opinions and it is difficult to make a judgment.

30

The Delphi method was conducted in the following steps.
･Phase 1: Questionnaires were solicited from guideline developers for each CQ for which noevidence could be obtained from the literature search. The questionnaires were compiled and thefirst questionnaire was prepared.
･Phase 2: Questionnaires were distributed to the consensus group, who were asked to predict
the numerical value of each item and to indicate their level of agreement by giving a score. The
second questionnaire was prepared by tabulating the scores and expressing them in afrequency distribution for each question, as well as improving the points raised by theconsensus members.
･Phase 3: The results of the first questionnaire (results for the consensus group as a whole, with
the questions distributed by frequency distribution) and the second questionnaire were
distributed to the consensus group, and the respondents were asked to indicate their level ofagreement with the content of each item again by giving a score. Here, respondents wereallowed to change their scores based on the results of the first survey. The scores weretabulated, and the degree of convergence of the responses and the degree of agreement
between the first and second responses were used as references to examine the overall degreeof agreement.
Following the above procedure, the effectiveness of magnetic attachments was evaluated foreach of the 9 CQs for which no relevant literature was found or the quality of evidence was low,using an 11-point scale from -5 to +5 for the following 11 outcomes: maintenance, mastication,
pronunciation, esthetics, comfort, responsiveness, durability, periodontal health, burden, harm,and cost. A Delphi questionnaire was used to evaluate the 11 outcomes on a scale of -5 to +5.
Thirty-six members and 35 non-members of the consensus group were selected for the survey,
and questionnaires were sent by e-mail or mail. A total of 38 respondents, 25 of whom answered
all questions including implants and 13 of whom answered only general prosthetics, wereobtained in two surveys8-10).

Selection of recommendations by the Delphi method
median≦−２−２＜median＜＋２＋２≦median31Degree of convergence：High

NN

U

PP

Degree of convergence：Middle

N

U

P

Degree of convergence：Low

U

U

U

Convergence: High Distribution range of 3 or less after excluding those with frequencies of 2 or less
Convergence: Medium The distribution range is 4-6 when the frequencies less than or equal to 2 are excluded.
Convergence: Low The distribution range is more than 7 when those with a frequency of 2 or less are excluded

Outcome Factors for Magnetic Attachment
Treatment OutcomesClassification among the primary factors in determining the level of recommendation

Retentive force

Effectiveness (denture maintenance and stability)

Masticatory function

Effectiveness (Treatment Outcome)Pronunciation

Effectiveness (Treatment Outcome)

Aesthetics (appearance)

Effectiveness (Treatment Outcome)Comfort (fit)Downsides

Repairability (Repair)Downsides (ease of repair)

Durability (prolongation of

Downsides (ability to maintain prosthetic dentition)

abutment teeth, etc.)
Periodontal healthDownsides (Does it induce gingival inflammation?)

Overload

Downsides (burden on abutment teeth, periodontal tissues, etc.)

Harm (tooth damage, pain)

Downsides (treatment time, discomfort and pain associated with treatment)

Expression of degree of recommendation
PP：Recommended (positive strong recommendation)
P: Recommendable (weak positive recommendation)
N: Not recommended (negative weak recommendation)
NN: Not recommended (negative strong recommendation)
U: Unable to determine

32

6. determination of recommendation and evaluation profile
Evaluation profile
OutcomeQuality of

Evaluation

Delphi method

Evidence(validity, etc.)

evaluation

1.Retentive force
2.Masticatory function
3.Pronunciation
4.Aesthetics (appearance)
5.Comfort (fit)
6.Repairability (Repair)
7.Durability (prolongation ofabutment teeth, etc.)
8.Periodontal condition
9.Overload
10. Harm (tooth damage, pain)
11.CostRecommendation

Judgment as a whole

As for the overall recommendation, as mentioned above, clinical decisions and outcomes of
prosthodontic practice are greatly influenced by the patient's own values and other factors, so thatin practice it is necessary to match this recommended profile with the profile of the patient's values.
However, in this guideline, an overall recommendation level was purposely presented after
consultation by the guideline development committee to provide suggestions to users. Therefore, it
must be understood that the above assumptions must be made when using this overall
recommendation.
In addition, when multiple recommendations are described in the overall recommendation (e.g.,
N to P), it indicates that the importance of each treatment outcome based on the evidence iscompeting and that it is difficult to select a single recommendation. In this case, it means that the33

decision should be based on a thorough understanding of the patient's own values, medical
resources, and the skill of the practitioner.
7. References
1) Hideshima M, Igarashi Y, Ichikawa T, et al: Preliminary Questionnaire Survey for formulating
Clinical Practice Guidelines for Magnetic Attachments Applications - Analysis and Selection of theClinical Questions (CQ) -. J J Mag Dent 19: 29-34, 2010.
2) Medical Committee of the Japanese Society of Magnetic Dentistry: Request for Preliminary
Questionnaire Survey for Formulating Clinical Practice Guidelines for Magnetic Attachments
Applications - Analysis and Selection of the Clinical Questions (CQ) - (in Japanese), Journal ofMagnetic Dentistry, Vol. 19, No. 1, 119-120, 2010.
3) Hideshima M, Igarashi J, Ichikawa T, et al: Questionnaire survey on practice guidelines formagnetic attachments - Survey and selection of clinical questions (CQ) (in Japanese). Journal ofMagnetic Dentistry, Vol. 20, No. 1, 114, 2011.
4) Hideshima M, Igarashi Y, Ichikawa T, et al: Questionnaire Survey for Formulating Clinical
Practice Guidelines for Magnetic Attachments Applications - Analysis and Selection of the Clinical
Questions (CQ) -. J J Mag Dent 20: 5-10, 2011.
5) Atkins D, et al. GRADE Working Group. Grading quality of evidence and strength ofrecommendations. BMJ；328：1490，2004..
6) Aihara M, Mihara K, GRADE Working Group, et al. GRADE System for Clinical Practice
Guidelines (in Japanese). Toppan Media Co.
7) Nagao K, Goto T, Ishida Y, Ichikawa T: What is the Delphi method? (in Japanese). Journal ofMagnetic Dentistry, Vol. 21, No. 1, 32-36, 2012.
8) M. Hideshima, T. Ichikawa, H. Koshino, K. Hoshiai, J. Tanaka, S. Ozawa, Y. Suzuki, Y.
Umekawa, T. Ishigami, K. Nagao, M. Sone, M. Kono, J. Wada, J. Wadachi Y. Suzuki, Y. Umekawa,
T. Ishigami, K. Nagao, M. Sone, M. Kono, J. Wada, J. Wadachi: Formulating clinical practiceguidelines for magnetic attachment applications: The process and results of a survey using theDelphi J J Mag Dent 22: 47-53, 2013.
9) Hideshima M: If you have a problem with magnetic attachments: Based on the clinical practiceguidelines. (in Japanese). Journal of Magnetic Dentistry, Vol. 22, No. 1, 19-23, 2013.
10) Hideshima M.: Medical Committee [Practice guideline project] Application of magnetic
attachments to implants vs. natural teeth, background of guideline development and practiceguideline for application of magnetic attachments to free end dentures.(in Japanese). Journal ofMagnetic Dentistry, Vol. 23, No. 1, 45-49, 2014.
11) Nakayama T. Practice guidelines using EBM: A guide to preparation and utilization (inJapanse), Kanehara Shuppan 2004.
12) Fukui, T., Yoshida, M., and Yamaguchi, N. A Guide to the Preparation of Minds Clinical Practice
Guidelines 2007(in Japanse). Igaku Shoin, 2007.
13) The Japanese Society for Prosthetic Dentistry (ed.): Guidelines for Prosthetic Dental Practice;
Guidelines for Prosthetic Dental Practice of Missing Teeth 2008 (in Japanse). 1-117, Tokyo, 2009.
120.

34

V. Clinical Questions and Evaluation/Recommendation Profiles
The following is a list of 12 CQs, their evaluation profiles, and recommended profiles. For details,
please refer to the website of the Japanese Dental Association and the Clinical Guideline Libraryof the Japanese Association for Dental Science.
＊MA: Magnetic Attachment＊Other devices described in each CQ refer to various attachments other than clasps and MAs.
CQ1: In case of implant-supported overlay dentures, are magnetic attachments (MAs) more
effective than other types of retainers?
【Recommended profile】
Although MAs are slightly inferior to bar and O-ring attachments in terms of retentive force andmasticatory function, they are effective in terms of comfort and maintenance of periodontal health.
Long-term follow-up reports indicate that MAs are as effective as other attachments as abutment
teeth for implant overdentures, and may be recommended in appropriate cases after fully
explaining the current available evidence to the patient.

Quality of
Evidence

Outcome

Evaluation(validity, etc.)

1.Retentive force

M

N

2.Masticatory function

M

N

3.Pronunciation

M

U

4.Aesthetics (appearance)

LU

5.Comfort (fit)M

P (for female)

6.Repairability (Repair)

L

U

M

U

L

P

7.Durability (prolongation ofabutment teeth, etc.)

8.Periodontal condition

Delphi method
evaluation

9.Overload
10. Harm (tooth damage,pain)
11.CostRecommendation

Judgment as a wholeP

35

CQ2: In case of implant-supported overlay dentures, is the application of MAs to implant
abutments superior to applying them to natural teeth?
(Composite defect of mandibular bilateral free end and middle, and abutment teeth should bebicuspids or premolars adjacent to the defect.)【Recommended profile】(In a composite defect of mandibular bilateral free ends and middle, application of MA may be recommended
in terms of retentive force, masticatory function, etc. (weak level of recommendation).

Quality of
Evidence

Outcome

Evaluation(validity, etc.)

Delphi method
evaluation

1.Retentive force

M

U

P

2.Masticatory function

M

U

PP

3.PronunciationU

4.Aesthetics

U(appearance)
5.Comfort (fit)MU

6.Repairability (Repair)
7.Durability (prolongationof abutment teeth, etc.)

U
U

M

U

U

8.Periodontal condition

U

9.OverloadU

10. Harm (tooth damage,
pain)

M

U

U

11.CostRecommendation

U

Judgment as a whole P

CQ3: When applying magnetic MAs to implant-supported overlay dentures, are maxillary
applications superior to than mandibular ones?
【Recommended profile】
There seems to be no clear difference in the prognosis of maxillary and mandibular implant
overdentures to which MA is applied. The effect of MA application to maxillary implant
overdentures is expected to be an improvement in phonatory function and comfort. The reason for36this is that the application of MA in the maxilla allows the release of the palatal portion of thedenture, which may reduce the patient's pronunciation-related problems and discomfort.

Delphi method evaluation（25 persons）
degree ofrecommendation
medianconvergence

Outcome
1.Retentive force

0

H

U

2.Masticatory function

0

H

U

3.Pronunciation

0

H

U

4.Aesthetics (appearance)

0

H

U

5.Comfort (fit)

0

H

U

6.Repairability (Repair)

0

H

U

0

H

U

8.Periodontal condition

0

H

U

9.Overload

0

H

U

10. Harm (tooth damage, pain)

0

H

U

11.Cost0

HU

7.Durability(prolongationofabutment teeth, etc.)

Judgment as a whole U

Recommendation

CQ4: When applying magnetic MAs to implant-supported overlay dentures, are multiple
abutments with MAs more effective than single abutments?
【Recommended profile】
The application of MAs to multiple implant-over-denture abutments seems to be effective in termsof retentive force.

Outcome
1.Retentive force

Quality of

Evaluation

Delphi method

Evidence(validity, etc.)

evaluation

H

P

P

37

2.Masticatory functionP

3.PronunciationU

4.Aesthetics (appearance)U

5.Comfort (fit)U

6.Repairability (Repair)U

7.Durability(prolongationofPP

abutment teeth, etc.)

8.Periodontal condition

U

9.OverloadU

10. Harm (tooth damage, pain)

H

U

U
NN

11.Cost

Judgment as a whole P

Recommendation【CQ５】In cases in which individuals have few mandibular teeth, is the application of MAs more
effective than the use of other types of retainers?

【Recommended profile】
MAs application to overdentures with a few remaining teeth may be recommended in terms of denture
maintenance, esthetics, comfort, and overload (weak level of recommendation).

OutcomeQuality of

Evaluation

Delphi method

Evidence(validity, etc.)

evaluation

1.Retentive force

M

P

2.Masticatory function

M

P

4.Aesthetics (appearance)

VL

U

5.Comfort (fit)

M

P

VL

U

3.Pronunciation

6.Repairability (Repair)
7.Durability (prolongation of38

abutment teeth, etc.)

8.Periodontal condition

VL

U

9.Overload

LU

10. Harm (tooth damage,pain)
11.Cost
Judgment as a whole P

Recommendation【CQ６】

In cases involving removable partial dentures with a free-end saddle, is the application of MAs
more effective than the use of other types of retainers?
(In case of Bilateral free end defects with bicuspids or canines as abutment teeth)【Recommended profile】
Application of MA s to free end dentures may be recommended in terms of denture maintenance, esthetics,
comfort, responsiveness, and durability (weak level of recommendation).

OutcomeQuality of

Evaluation

Delphi method

Evidence(validity, etc.)

evaluation

1.Retentive force

H

P

P

2.Masticatory function

H

U

U

3.PronunciationU

4.Aesthetics (appearance)

L

P

P

5.Comfort (fit)H

P or UP

6.Repairability (Repair)

L

P

P

M

P

U

8.Periodontal conditionL

U or NU

9.Overload

S，L

P or UU

10. Harm (tooth damage, pain)M

P or UU

7.Durability(prolongationofabutment teeth, etc.)3911.Cost

M
Recommendation

N

U

Judgment as a whole P

CQ7：In case of partially edentulous patients without occlusal contact, are MAs superior to othertype of retainers?
(In case of a horizontal crossbite with only one molar remaining on each side of the upper and lower jaws,
or a bicuspid or premolar adjacent to the defect as abutment.)【Recommended profile】
The application of MAs to cases of misaligned occlusion may be recommended in terms of themaintenance of the prosthetic device, masticatory function, esthetics, comfort, responsiveness,durability, and periodontal health in terms of prognostic outcomes. (Weak level recommendation)

OutcomeDelphi method evaluation（38 persons）
degree ofrecommendation
medianconvergence

1.Retentive force

3

M

P

2.Masticatory function

3

M

P

3.Pronunciation

0

M

Ｕ

4.Aesthetics (appearance)

4

M

P

5.Comfort (fit)

3

M

P

6.Repairability (Repair)

3

M

P

7.Durability (prolongation of abutment teeth, etc.)

3

M

P

8.Periodontal condition

2

M

P

9.Overload

0

M

Ｕ

10. Harm (tooth damage, pain)

0

M

Ｕ

11.Cost0

M

Ｕ

Recommendation

Judgment as a whole P40

CQ8：In cases of partially edentulous with undulating occlusal planes, is the application of MAs

more effective than the use of other types of retainers?
(In case of a composite defect of the maxillary free end and middle, with an erupted premolar or anterior
tooth as abutment.)【Recommended profile】
In cases with a disturbed occlusal plane, occlusal reconstruction with the application of MAs is more effective thanwith annular or bar clasps.

OutcomeDelphi method evaluation（38 persons）
degree ofrecommendation
medianconvergence

1.Retentive force

1

M

U

2.Masticatory function

1

M

U

3.Pronunciation

1

M

U

4.Aesthetics (appearance)

3

M

P

5.Comfort (fit)

2

M

P

6.Repairability (Repair)

2

M

P

7.Durability (prolongation of abutment teeth, etc.)

1

M

U

8.Periodontal condition

1

M

U

9.Overload

0

M

U

10. Harm (tooth damage, pain)

0

M

U

11.Cost-1

M

U

Recommendation

Judgment as a whole P

CQ9：When periodontal disease is affecting remaining abutments, is the application of MAs

superior to the use of other types of retainers?
（In case of the periodontal condition of the abutment tooth adjacent to the defect is P1 or P2
in a case of bilateral free end defects in the mandible.）【Recommended profile】
41

The application of MAs on abutment teeth with early periodontal disease is not well documented,
but it is highly regarded. The Delphi technique received generally good evaluations, except for cost,
and the overall recommendation was judged to be P.

OutcomeQuality of

Evaluation

Delphi method

Evidence(validity, etc.)

evaluation

PP

1.Retentive force
2.MasticatoryPfunctionP

3.Pronunciation
4.Aesthetics

PP(appearance)P

5.Comfort (fit)
6.Repairability

P(Repair)
7.Durability(prolongation ofabutment teeth, etc.)

8.Periodontal
condition

M

PP

PP

M

P

P
U

9.Overload
10. Harm (tooth
damage, pain)
11.Cost

M

P

U

M

PP

N

Recommendation

Judgment as a wholeP

CQ10：When applying MAs to multiple abutment teeth, are symmetrical arrangements more effective

than asymmetrical ones?

【Recommended profile】
Symmetrical placement of abutment teeth for overdentures is recommended over asymmetricalplacement.
42

Outcome

Quality of

Evaluation

Delphi method

Evidence(validity, etc.)

evaluation

1.Retentive force

PP

2.Masticatory function

PP

3.PronunciationU

4.Aesthetics (appearance)U

5.Comfort (fit)U

6.Repairability (Repair)U

7.Durability (prolongation ofabutment teeth, etc.)

L

U

U

8.Periodontal condition

U

9.OverloadU

10. Harm (tooth damage,

U

pain)
11.CostU
Judgment as a whole P

Recommendation

CQ11：When applying MAs to remaining abutment teeth, are flat type keepers more effective thandome-shaped keepers for stability of the denture?

【Recommended profile】
The flat type is recommended over the dome type depending on the number of abutments and loading points.

OutcomeQuality of

Evaluation

Delphi method

Evidence(validity, etc.)

evaluation

1.Retentive force

43

2.Masticatory function
3.Pronunciation
4.Aesthetics (appearance)
5.Comfort (fit)
6.Repairability (Repair)
7.Durability (prolongation ofabutment teeth, etc.)

8.Periodontal condition
9.Overload

HP

10. Harm (tooth damage, pain)
11.CostRecommendation

Judgment as a whole P

CQ12：When applying MAs to removable partial dentures, is the applied pressure method superior
to minimum pressure ones?
(In cases with a small number of remaining maxillary teeth, the abutment should be one or
two premolars or bicuspids.)【Recommended profile】
Since the attachment of MAs (or magnetic structures) to dentures without pressure has aslightly negative effect on the life of the abutment and denture and on periodontal disease
and dental caries of the abutment teeth, it may be recommended that MAs be attachedunder pressurized conditions.

OutcomeDelphi method evaluation（38 persons）
degree ofrecommendation
medianconvergence

1.Retentive force

-2

L

Ｕ

2.Masticatory function

0

L

Ｕ

3.Pronunciation

0

H

Ｕ

44

4.Aesthetics (appearance)

0

M

Ｕ

5.Comfort (fit)

0

H

Ｕ

6.Repairability (Repair)

0

M

Ｕ

7.Durability (prolongation of abutment teeth, etc.)

-2

M

Ｎ

8.Periodontal condition

-2

M

Ｎ

9.Overload

0

H

Ｕ

10. Harm (tooth damage, pain)

0

H

Ｕ

11.Cost0

M

Ｕ

Recommendation

Judgment as a whole Ｎ

45

VI. Conclusion
We have reported an overview of the clinical evaluation, international standardization, andformulation of practice guidelines for magnetic dental attachments that the society has been working on.
Magnetic attachments were approved as a medical device by the Ministry of Health, Labour andWelfare in 1990, and have since been improved through industry-academia collaboration in order toimprove retentive force, miniaturization, durability, and biocompatibility. ISO 13017:2012/Amd.1 (asupplement to ISO 13017) was published in 2015, and the ISO task force is currently preparing tointegrate the two international standards at the time of the international standards review to be
conducted in 2017.
As for clinical evaluation, each institution has conducted a prognostic survey of patients withmagnetic attachments from each manufacturer, and the usefulness of the attachments was reported.
Furthermore, a common protocol was established by the clinical evaluation committee, and long-term
follow-up reports were made at multiple institutions. However, it was difficult to collect and analyze
data systematically for the multicenter long-term follow-up survey due to the large number of elderly
patients, uninsured treatment, and changes in investigators. Based on these circumstances, the Clinical
Evaluation Committee has modified the protocol since 2015, and is now conducting a new multicenter
survey while continuing the existing survey.
On the other hand, the Medical Committee began formulating guidelines for medical practice in 2009,
and conducted a wide-ranging questionnaire survey of its members. In addition, oral presentations andsymposiums were planned at the annual meeting, and the practice guideline was disseminated to themembers, achieving a certain level of success. However, many CQs were difficult to collect evidence
when developing the practice guideline, and it was necessary to supplement the CQs with aquestionnaire survey of clinical specialists using the Delphi method, etc. We realized that it was too
early to develop the practice guideline and there were many issues to be solved. However, the society willneed to conduct related research, revise, and add to the guidelines.
The society has reported detailed studies on problems with magnetic attachments, such as artifacts on
MRI images and reduced magnetic force in magnetic structures, and the Safety Standards Review
Committee has published a report in the society's journal and a leaflet for medical professionals and thegeneral public.
Dental magnetic attachments are clinically excellent in operability, durability, and corrosion
resistance, and have good long-term results, but they are currently not widely used in general clinical46

practice because they are not covered by insurance. The Society has taken a cautious approach to theintroduction of insurance coverage, since there have been two sides to the issue, but the time has cometo consider advanced medical treatment, selected medical treatments, insurance coverage, etc. We hopethat this report will be of some help in this regard.
We would like to express our deepest gratitude to the members of the Society and all those involved indental care, including the various committees, for their cooperation to date, and we sincerely hope for
their further support and guidance.
March, 2017

Acknowledgments
This Project was supported by Japanese Dental Science Federation as JDSF-DSP1-2016-214-1.

47