prEN ISO 21606

• Abstract:

  This document specifies the requirements and their test methods applicable to all elastomeric auxiliaries used for orthodontics both inside and outside the mouth, in conjunction with fixed and removable appliances.

• Status: Not Published
• Publication Date: 14-Nov-2027
• ICS: 11.060.10 - Dental materials
• Technical Committee: CEN/TC 55 - Dentistry
• Current Stage: 4060 - Closure of enquiry - Enquiry
• Start Date: 14-Aug-2026
• Completion Date: 14-Aug-2026
• Ref Project: oSIST prEN ISO 21606:2026 - Dentistry - Elastomeric auxiliaries for use in orthodontics (ISO/DIS 21606:2026)

• Revises: EN ISO 21606:2022 - Dentistry - Elastomeric auxiliaries for use in orthodontics (ISO 21606:2022)
• Effective Date: 12-Nov-2025

prEN ISO 21606 is a CEN standard for dentistry that specifies requirements and test methods for elastomeric auxiliaries used in orthodontics. It covers products used both inside and outside the mouth, in combination with fixed and removable appliances. In practice, it gives manufacturers, test labs and buyers a common way to specify size, force performance, marking and packaging.

What does prEN ISO 21606 specify?

prEN ISO 21606 specifies the requirements and test methods for all elastomeric auxiliaries used in orthodontics, whether they are used intra-orally or extra-orally. The document is organized into scope, normative references, terms and definitions, requirements, test methods, and marking, labelling and packaging.

The main clauses are:

• Clause 1 - Scope
• Clause 2 - Normative references
• Clause 3 - Terms and definitions
• Clause 4 - Requirements
• Clause 5 - Test methods
• Clause 6 - Marking, labelling and packaging

This structure matters because the document first defines what products are covered, then tells users how to measure them and what product information must be supplied.

What are the key requirements of prEN ISO 21606?

prEN ISO 21606 focuses on measurable product dimensions, force performance and product information. The key point for users is that compliance depends on testing the product against the manufacturer’s stated ranges.

Product dimensions and mechanical performance

Clause 4.2 requires the relevant dimensions to fall within the ranges stated by the manufacturer. Depending on product type, this includes inner diameter, outer diameter, link length and cross-section thickness. For a buyer or quality manager, this means the declared product size must match what is actually supplied.

Clause 4.3.1 and 4.3.2 require the initial extension force and the 24 h residual force to be within the stated ranges. These are the core performance checks for elastomeric auxiliaries because they show how the material behaves when stretched and after conditioning in water.

Clause 4.3.3 applies to elastomeric separators and requires ultimate extension to be within or above the stated range. This matters when comparing separator products because break extension is part of the functional specification.

Test conditions and sampling

Clause 5.1 treats all tests as type tests on 10 specimens selected at random from the same batch for retail sale. Each specimen is tested individually, and a break during testing counts as failure. In practice, this makes the test a batch-level check rather than a single-sample check.

Clause 5.2 sets the ambient conditions for force determinations at 23 °C plus or minus 2 °C and 50 % relative humidity plus or minus 10 %, unless a method states otherwise. That keeps results comparable between laboratories.

Clause 5.4 to 5.7 use a tensile testing machine with a crosshead rate of 100 mm/min plus or minus 10 mm/min. For the 24 h residual force, the specimen is first stretched, then held in ISO 3696 Grade 3 water at 37 °C plus or minus 2 °C for 24 h plus or minus 2 h, followed by conditioning at 23 °C plus or minus 2 °C before force measurement. This sequence matters because it simulates force loss after storage in a moist environment.

Marking, labelling and packaging

Clause 6.1 requires the intended use, material type, and the ranges of dimensions and mechanical properties from Clause 4 to be readily available. Clause 6.2 requires package information such as manufacturer or distributor details, product name, nominal dimensions or force, lot number, quantity, intended use, expiry date in ISO 8601-1 format, storage conditions, and warnings for hazardous elements where appropriate. For users, this supports traceability, shelf-life control and correct selection.

What terms does prEN ISO 21606 define?

• Elastomeric auxiliary - A device with elastomeric properties used to transmit force in orthodontics.
• Elastic - An intra-oral or extra-oral elastomeric ring used to apply forces to orthodontic devices.
• Elastomeric thread - An elastomeric strand, which may be hollow, with a constant cross-section used to apply force.
• Elastomeric chain - Interconnected elastomeric rings or a multi-perforated band used to apply forces to orthodontic devices.
• Elastomeric ligature - An elastomeric ring used to retain wires to orthodontic attachments.
• Elastomeric separator - An elastomeric product used to open interproximal spaces between teeth.
• Initial extension force - The force measured after extension to four times the test length and relaxation to three times the test length.
• 24 h residual force - The force remaining after 24 h conditioning, expressed as a percentage of the initial extension force.

Who uses prEN ISO 21606?

prEN ISO 21606 is used by manufacturers of orthodontic elastomeric auxiliaries, testing laboratories, and quality managers who need a common basis for product verification. It is also useful to clinicians and buyers who compare supplier data and want the declared dimensions and force values to be defined in the same way.

Distributors use the labelling and packaging clause to check product traceability, expiry date format and storage information. In regulatory and procurement work, the standard helps specify what data must accompany the product and how performance is measured.

What changed in prEN ISO 21606 from the previous edition?

prEN ISO 21606 is the third edition and replaces ISO 21606:2022. The stated technical changes are:

• the test apparatus in 5.4.1.2 changed from two half-rods or rods to two shepherd’s hooks
• Figure 2 was updated to match the new test apparatus
• the procedure in 5.5.2 was changed so the shepherd’s hooks are held in place by a locking collar during transfer to the constant temperature bath

These changes affect how force-retention testing is set up and handled in the laboratory.

Which standards are used with prEN ISO 21606?

• ISO 1942 - provides the dental vocabulary used for terms and definitions.
• ISO 3696 - specifies the water used for the residual-force conditioning step, including Grade 3 water.
• ISO 8601-1 - defines the date format used for the expiry date on packaging.

What does the prEN ISO 21606 document contain?

prEN ISO 21606 includes Table 1, which summarizes which requirements apply to each type of elastomeric auxiliary. It also includes Figure 1 for test dimensions and Figures 2 and 3 for the tensile test set-ups used in the force and residual-force methods.

The test methods cover specimen selection, ambient conditions, dimensional measurement, initial extension force, 24 h residual force and ultimate extension. The document also gives the packaging and labelling information that should accompany the product in use, retail sale and storage.

SLOVENSKI STANDARD
01-julij-2026
Zobozdravstvo - Elastomerni pripomočki za uporabo v ortodontiji (ISO/DIS
21606:2026)
Dentistry - Elastomeric auxiliaries for use in orthodontics (ISO/DIS 21606:2026)
Zahnheilkunde - Elastomeres Zubehör für die Kieferorthopädie (ISO/DIS 21606:2026)
Médecine bucco-dentaire - Auxiliaires élastomériques utilisés en orthodontie (ISO/DIS
21606:2026)
Ta slovenski standard je istoveten z: prEN ISO 21606
ICS:
11.060.10 Zobotehnični materiali Dental materials
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 21606
ISO/TC 106/SC 1
Dentistry — Elastomeric auxiliaries
Secretariat: AFNOR
for use in orthodontics
Voting begins on:
Médecine bucco-dentaire — Auxiliaires élastomériques utilisés en
2026-05-22
orthodontie
Voting terminates on:
ICS: 11.060.10 2026-08-14
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
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BEING ACCEPTABLE FOR INDUSTRIAL,
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USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Reference number
ISO/DIS 21606:2026(en)
DRAFT
ISO/DIS 21606:2026(en)
International
Standard
ISO/DIS 21606
ISO/TC 106/SC 1
Dentistry — Elastomeric auxiliaries
Secretariat: AFNOR
for use in orthodontics
Voting begins on:
Médecine bucco-dentaire — Auxiliaires élastomériques utilisés en
orthodontie
Voting terminates on:
ICS: 11.060.10
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2026
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
BE CONSIDERED IN THE LIGHT OF THEIR
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
or ISO’s member body in the country of the requester.
NATIONAL REGULATIONS.
ISO copyright office
RECIPIENTS OF THIS DRAFT ARE INVITED
CP 401 • Ch. de Blandonnet 8
TO SUBMIT, WITH THEIR COMMENTS,
CH-1214 Vernier, Geneva
NOTIFICATION OF ANY RELEVANT PATENT
Phone: [phone]
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ISO/DIS 21606:2026(en)
ii
ISO/DIS 21606:2026(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements . 3
4.1 General .3
4.2 Dimensions .3
4.3 Mechanical properties .3
4.3.1 Initial extension force .3
4.3.2 24 h residual force.3
4.3.3 Ultimate extension .3
5 Test methods . 4
6 Marking, labelling and packaging . 7
6.1 General requirements .7
6.2 Packaging and labelling .7
Bibliography . 8

iii
ISO/DIS 21606:2026(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent
rights identified during the development of the document will be in the Introduction and/or on the ISO list of
patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 106, Dentistry, Subcommittee SC 1, Filling and
restorative materials, in collaboration with the European Committee for Standardization (CEN) Technical
Committee CEN/TC 55, Dentistry, in accordance with the Agreement on technical cooperation between ISO
and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 21606:2022), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— Change in test apparatus in 5.4.1.2 from two half-rods or rods to two shepherd’s hooks.
— Change in Figure 2 to reflect the change from two half-rods or rods to two shepherd’s hooks.
— Change in procedure of 5.5.2 to reflect that the shepherd’s hooks will be held in place by a locking
collar during transfer to the constant temperature bath rather than moving the extended elastomeric
auxiliaries without any relaxation to the support plate for storage in the constant temperature bath.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
ISO/DIS 21606:2026(en)
Introduction
This document has been developed as a result of the difficulty often encountered by clinicians in making
meaningful comparisons between elastomeric auxiliaries using the information currently available from
manufacturers and suppliers.
NOTE Auxiliaries include orthodontic elastics, orthodontic elastomeric chains, orthodontic thread, orthodontic
elastomeric ligatures and orthodontic elastomeric separators.
Specifi
...