Whether or not to Apply Occlusal Pressure in Fixation of Magnet Assemblyto Denture? - Evaluation using Delphi Technique K. Nagao1, T. Goto1, Y. Ishida1, T. Ichikawa1, M. Hideshima2, H. Koshino2，K. Hoshiai2 and Y. Umekawa2
1Departmentof Oral & Maxillofacial Prosthodontics, Institute of Health

Biosciences, The University of Tokushima Graduate School
2DentalCare Council, the Japanese Society of Magnetic Applications inDentistry

Introduction
It is important to distribute the occlusal force to mucosa and abutment
efficiently in magnet-retained overdentures.

The difference of tissuedisplacement between the tooth and mucosa is the most common
precipitating factor of the overstressing to the abutment tooth.

However

there are few articles related to this subject; how to fix the magnet assembly
to denture base in magnet-retained overdentures.

Thus, it is difficult tobuild consensus if we have only insufficient and/or poor clinical evidences.
Consensus method with questionnaire for experts has been occasionallyused to build the consensus.
the consensus method.

The Delphi technique is a typical method ofThe questionnaire survey is conducted for experts

and the grade of the consent to questions is investigated. This questionnaire
survey is repeatedly conducted until the consensus is built.

Objective
The purpose of this study was to build the consensus: whether or not apply
occlusal pressure in the fixation of magnet assembly to denture base using
Delphi technique with the reference to the expert’s opinions.

This

presentation describes the outline of the Delphi technique effective to draw
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up the clinical practice guideline on magnetic attachment with insufficientevidence.

Materials and Methods
 Process of questionnaires using Delphi technique
Process of questionnaires survey was as follows:
1. Selection of experts and making the questionnaire.
Dental Care Council, the Japanese Society of Magnetic Applications in
Dentistry picked 71 prosthodontists who were familiar with magnetic
attachments as the experts.
2. Giving out the questionnaire to the experts, collecting and tallying up theanswer sheets.
3. Giving out the questionnaire with the outcomes of previous answers andcollecting the answer sheets again (Table 1).

2 Decision of consent level
Consent level was decided by convergence level and median (Table 2).
Convergence level was provided as follows: “high” of 3 or less distributions,“medium” of 4 to 6 distributions and “low” of 7 or more distributions exclude
2 or less frequency. Consent level was defined as PP: strong positiveagreement, P: light positive agreement, N: light negative agreement, NN:
strong negative agreement and U: unidentifiedResults
The answers were obtained from 38 experts; 25 specialists on dental
implant and 13 on prosthodontics.
Figure 1 shows the frequency distribution concerning the questions:“Effective in permanence of abutment teeth and/or denture” and “Effective inhealth of periodontal tissue”.

When the magnet assembly is fixed to3

denture by no occlusal pressure, consent level toward these two questions
was N of light negative agreement.

Table 3 shows the consent level of each questions and the recommendationlevel.

Convergence levels toward “Effective in phonetic function”, “Effectivein comfortableness”, “Task body of patient/dentist and loss of time” and“Harmful to abutment teeth and patient” were “high” with medians of0.

In other words, phonetic function, comfortableness, suffering to patients
and/or dentists and harm were not affected by occlusal pressure when themagnet assembly was fixed to the denture.

Recommendation level toward

this CQ: “How is it harmful when the magnet assembly is fixed to denture by
no occlusal pressure?” was N of light negative agreement synthetically.

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Discussion
When the magnet assembly is fixed to denture by no occlusal pressure, it isharmful to the health of periodontal tissue in abutment teeth, however noclinical evidences about the quantity of occlusal pressure were shown.
Furthermore, it is important for the prognosis of abutment teeth how muchpressure from impression material to the tissue under denture base was,when the denture was fabricated.

It is necessary to build the clinicalevidences and consensus of these subjects.

Conclusions
The evaluation using Delphi technique suggested that it was harmful to5the health of periodontal tissue of abutment teeth when the magnet
assembly was fixed to denture by no occlusal pressure. Moreover, themoderate occlusal pressure to the tissue under denture is recommended
when the magnet assembly is fixed to denture.

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