ISO/DTS 4640

• Abstract:

  This document gives guidance on substrate selection, storage and handling as well as essential characteristics of tensile bond strength test methods for quality testing of the adhesive bond between restorative dental materials and tooth structure, i.e. enamel and dentine. Some specific test methods for tensile bond strength measurements are given in Annex A. This document does not include requirements for components of adhesive materials and their performance.

• Status: Not Published
• ICS: 11.060.10 - Dental materials
• Technical Committee: ISO/TC 106/SC 1 - Filling and restorative materials
• Drafting Committee: ISO/TC 106/SC 1/WG 11 - Adhesion test methods
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 27-Aug-2026
• Completion Date: 27-Aug-2026

• Revises: ISO/TS 4640:2023 - Dentistry — Test methods for tensile bond strength to tooth structure
• Effective Date: 07-Jan-2025

Overview

ISO/DTS 4640: Dentistry - Test methods for tensile bond strength to tooth structure is an ISO technical specification that provides essential guidance on laboratory test methods for assessing the tensile bond strength between restorative dental materials and tooth structure, including enamel and dentine. The document covers critical aspects such as substrate (tooth) selection, storage and handling protocols, preparation and application procedures, and the main variables influencing bond strength testing. These standardized approaches are fundamental for comparable, repeatable quality testing in dental materials research and development.

Key Topics

• Substrate Selection and Preparation

  • Specifies the use of human permanent premolars/molars or bovine mandibular incisors as substrates.
  • Emphasizes the use of caries-free, unrestored human teeth where possible, excluding root-filled teeth.
  • Highlights the significance of donor factors such as age and health history, while noting the challenges in variable control.

• Tooth Storage and Handling

  • Details protocols for immediate washing, tissue removal, and storage in either distilled water or specific chloramine-T trihydrate solutions.
  • Stresses conditions to minimize dentinal protein degradation and prevent chemical absorption that may alter material performance.
  • Advises on regular replacement of storage media and temperature-controlled environments to maintain sample integrity.

• Surface Preparation

  • Requires creation of a reproducible, flat, and hydrated surface using abrasive paper (e.g., P600 grit in line with ISO 6344-3).
  • Includes inspection criteria to exclude teeth with cracks, perforations, or surface irregularities that may impact adhesion.

• Tensile Bond Strength Test Methods

  • Describes apparatus alignment, methods for limiting bonding area, and procedural requirements for consistent test results.
  • Provides guidance on preconditioning tooth surfaces and applying adhesives per manufacturer instructions.
  • Outlines both bulk and thin-film application scenarios, and the use of transparent material holders for light-curing adhesives.

• Measurement and Analysis

  • Raw data is converted from force (N) to stress (MPa) based on the defined bonding area.
  • Stresses the importance of reporting, including detailed sample preparation and outcome analysis.

Applications

ISO/DTS 4640 is vital in many areas of dental material science and practice:

• Quality Assurance & Research: Provides recognized, repeatable methods for laboratories and manufacturers to evaluate the adhesive performance of restorative dental materials before market release.
• Product Development: Assists dental materials researchers and developers in benchmarking new products and adhesives under consistent, controlled laboratory conditions.
• Regulatory Compliance: Enables dental product manufacturers to meet international requirements and facilitate global market access by complying with recognized ISO test methods.
• Academic & Clinical Research: Offers a foundation for comparative studies of bond strengths, allowing research findings to be reliably communicated across the dental field.
• Material Performance Comparison: Supports informed selection of dental adhesives and restorative materials suited to clinical needs by providing standardized test outcomes.

Related Standards

Organizations working with ISO/DTS 4640 may also reference the following standards for complementary guidance:

• ISO 29022: Dentistry - Adhesion - Notched-edge shear bond strength test, offering methods for shear rather than tensile bond testing.
• ISO 1942: Dentistry - Vocabulary, for harmonized terminology in dental standardization.
• ISO 3696: Water for analytical laboratory use - Specification and test methods, relevant to the water quality used in sample storage.
• ISO 6344-3: Coated abrasives - Determination and designation of grain size distribution - Part 3: Microgrit sizes P240 to P5000, specifying abrasives for surface preparation.

Summary

ISO/DTS 4640 is a key reference for the standardized evaluation of adhesive dental materials, focusing on tensile bond strength to tooth structure. By adhering to the test methods, labs, manufacturers, and researchers can generate reliable and comparable data, ultimately supporting advances in dental restorative technology and patient outcomes.

FINAL DRAFT
Technical
Specification
ISO/TC 106/SC 1
Dentistry — Test methods for
Secretariat: AFNOR
tensile bond strength to tooth
Voting begins on:
structure
2026-08-27
Médecine bucco-dentaire — Méthodes d’essai pour l’adhérence
Voting terminates on:
par traction à la structure dentaire
2026-10-22
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 SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
Technical
Specification
ISO/TC 106/SC 1
Dentistry — Test methods for
Secretariat: AFNOR
tensile bond strength to tooth
Voting begins on:
structure
Médecine bucco-dentaire — Méthodes d’essai pour l’adhérence
Voting terminates on:
par traction à la structure dentaire
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 SUPPOR TING DOCUMENTATION.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Sampling . 2
5 Test methods . 2
5.1 General .2
5.2 Tooth substrate and storage .2
5.2.1 Substrate .2
5.2.2 Time after extraction .2
5.2.3 Condition of teeth .3
5.2.4 Preparation and storage of teeth .3
5.3 Tooth surface preparation .3
5.3.1 Requirement for the surface of tooth to be adhered .3
5.3.2 Requirement for the procedure of preparation of tooth surface .4
5.3.3 Surface preparation of tooth plane for adhesion .4
5.4 Application of adhesive .4
5.4.1 General .4
5.4.2 Adhesive and/or adherend material in bulk .5
5.4.3 Adhesive material as thin film and adherend material as preformed rod .6
5.5 Storage of test specimens .6
5.5.1 General .6
5.5.2 Recommended procedures and conditions of durability test .6
5.6 Apparatus .7
5.6.1 General .7
5.6.2 Alignment .7
5.6.3 Connecting device .7
5.7 Tensile loading .7
5.8 Test .7
5.9 Recording, treatment and analysis of results .8
5.9.1 Recording and treatment of results .8
5.9.2 Analysis of results .8
5.10 Test report .8
Annex A (informative) Test methods for measurement of tensile bond strength .10
Bibliography .18

iii
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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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.
This second edition cancels and replaces the first edition (ISO/TS 4640:2023), which has been technically
revised.
The main changes are as follows:
— concentration range of chloramine-T trihydrate for prepared tooth storage has been expanded;
— the specification of number of specimens tested has been added;
— the specification for abrasive paper grain material has been deleted;
— Figure A.1 have been replaced.
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
Introduction
Adhesion in restorative dentistry is an important topic. This document intends to describe various laboratory
procedures of tensile bond strength tests whereby the effect or quality of a bond between a dental material
and tooth structure can be substantiated.
Adhesive materials are used in many types of restorative and preventive treatments. Even if the stress on
the bond in most circumstances can be defined as either tensile, shear or a combination of these, there are
no specific laboratory tests which can be valid for all the various clinical applications of adhesive materials.
The relative performance of materials that are claimed to bond to tooth structure is usually evaluated by
laboratory assessment of bond strengths. While bond strengths are unable to predict clinical behaviour or
performance, they are useful for comparing adhesive materials.
[1]
ISO 29022 prescribes the notched-edge shear bond strength test.
Annex A lists several published laboratory methods for tensile bond strength measurement.
Tensile bond strength testing is also common in general materials science. See Reference [2] for a list of
many test methods.
v
FINAL DRAFT Technical Specification ISO/DTS 4640:2026(en)
Dentistry — Test methods for tensile bond strength to tooth
structure
1 Scope
This document specifies substrate selection, storage and handling as well as essential characteristics of
tensile bond strength test methods for quality testing of the adhesive bond between restorative dental
materials and tooth structure, i.e. enamel and dentine. Specific test methods for tensile bond strength
measurements are given in Annex A.
This document does not include requirements for components of adhesive materials and their performance.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 1942, Dentistry — Vocabulary
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 6344-3, Coated abrasives — Determination and designation of grain size distribution — Part 3: Microgrit
sizes P240 to P5000
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1942 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
adhere
be in a state of adhesion (3.3)
3.2
adherend
body that is held or intended to be held to another body by an adhesive (3.4)
3.3
adhesion
state in which two surfaces are held together by either chemical or physical or both forces with the aid of an
adhesive (3.4)
3.4
adhesive
substance capable of holding materials together

3.5
bond strength
force per unit area required to break a bonded assembly with failure occurring in or near the adhesive (3.4)
or adherend (3.2) interface
3.6
substrate
material upon the surface of which an adhesive (3.4) is spread for any purpose, such as bonding or coating
4 Sampling
The amount of test material shall be sufficient for all planned tests. The samples shall be from the same
batch.
5 Test methods
5.1 General
Adhesive materials are used for many different purposes in the oral cavity. This document describes tensile
bond strength tests. When bond strength is measured, the raw data are in unit of force (N). This shall be
converted into a stress unit, i.e. force per unit area (MPa). Hence, it is important to control the area and
roughness of the surface when applying the adhesive material.
The following two critical variables or factors shall be incorporated when designing test equipment and
preparing specimens for tensile testing of bond strength:
a) alignment of the tensile forces acting on the specimen;
b) limitation of the bonding area.
5.2 Tooth substrate and storage
5.2.1 Substrate
5.2.1.1 Types of the substrate
Use either human permanent premolars/molars or bovine mandibular incisors for the measurement of bond
strength. The donor bovine shall not be more than five years old.
5.2.1.2 Characteristics of the substrate
When measuring bond strength to human dentine, it is recommended to use the buccal superficial dentine
that is as close to the enamel as possible in order to reduce variations. Third permanent molars from 16- to
40-year-old individuals should be used.
5.2.2 Time after extraction
There is increasing evidence that changes in dentine occur after extraction that can influence bond strength
measurements. The effect can vary with different types of bonding materials. Ideally, bond strengths should
be measured immediately post-extraction.
NOTE Teeth within six months after extraction can be used. Teeth extracted more than six months prior to use
undergo degenerative changes in dentinal proteins.

5.2.3 Condition of teeth
5.2.3.1 History on clinical treatment (of human teeth)
Human teeth used for bond strength measurement shall be caries-free and preferably unrestored. However,
small and superficial restorations not in the adhesion test area are permitted. Root-filled teeth shall not be
used.
5.2.3.2 Site of the dentition and life-history of the donating patient (of human teeth)
There is some evidence to suggest that different teeth in the dentition can give different results with bonding
to dentine and enamel. It is impossible to have complete control of variables (e.g. age of the donating patient,
ethnicity, dietary history and state of health) or to standardize the composition and structure of the teeth.
5.2.4 Preparation and storage of teeth
5.2.4.1 Preparation of extracted teeth
Immediately after extraction, human teeth shall be thoroughly washed in running water. All blood and
adherent tissue shall be removed using sharp hand instruments. Bovine teeth shall be cleaned as soon as
possible after extraction. The soft tissue in the pulp chamber shall be removed in a similar fashion.
5.2.4.2 Storage of prepared teeth
Prepared teeth shall be placed in distilled water of grade 3 in accordance with ISO 3696 or in a 0,5 % to
1) ®
1,0 % chloramine-T trihydrate (CAS Registry Number 7080-50-4) bacteriostatic/bacteriocidal solution
for a maximum of one week and thereafter stored in distilled water grade 3 in a refrigerator, i.e. nominal
4 °C. To minimize deterioration, the storage medium shall be replaced at least once every two months.
No other chemical agents shall be used, as they can be absorbed by tooth substance and alter its behaviour.
For prevention of viral infections, 2,0 % to 4,0 % chloramine-T trihydrate can be used.
NOTE 1 Chloramine-T trihydrate is a strong oxidant and can oxidise polymerisation initiators, particularly reducing
agents in chemical polymerisation initiator systems. The oxidation reaction affects the chemical polymerisation by
[3]
redox reaction between the oxidising agent and reducing agent and can reduce bond strength .
NOTE 2 Information on hazardous properties of chloramine-T trihydrate can be referenced in the safety data sheet
provided by the supplier.
5.3 Tooth surface preparation
5.3.1 Requirement for the surface of tooth to be adhered
A reproducible flat surface is required. Tooth surfaces shall be kept wet at all times during preparation.
NOTE Exposure of the surface of prepared tooth to the air for several minutes can cause irreversible changes in
bonding character. Dentine is especially sensitive to dehydration. ®
1) Chemical Abstracts Service (CAS) Registry Number is a trademark of the American Chemical Society (ACS). This
information is given for the convenience of users of this document and does not constitute an endorsement by ISO of the
product named. Equivalent products may be used if they can be shown to lead to the same results.

5.3.2 Requirement for the procedure of preparation of tooth surface
5.3.2.1 Blocking of pulp chamber (for bovine teeth)
The pulp chamber of bovine teeth shall be blocked, for example by wax, to prevent penetration of resin into
the dentine. Alternatively, use a high viscosity potting medium that does not penetrate the pulp chamber.
NOTE This can be verified by preparing a set of potted teet
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Dentistry — Test methods for tensile bond strength to tooth .
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This document is not an ISO International Standard. It is distributed for review and comment. It is subject to
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change without notice and may not be referred to as an International Standard.
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Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of
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ISO #####-#:####(X)
Médecine bucco-dentaire — Méthodes d’essai pour l’adhérence par traction à la structure dentaire
2 © ISO #### – All rights reserved

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ISO copyright office
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CP 401 • Ch. de Blandonnet 8
between Asian text and numbers
CH-1214 Vernier, Geneva
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iii
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Contents
Line spacing: single
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Foreword . vi
Introduction . vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Sampling . 2
5 Test methods . 2
5.1 General. 2
5.2 Tooth substrate and storage . 2
5.3 Tooth surface preparation . 3
5.4 Application of adhesive . 4
5.5 Storage of test specimens . 6
5.6 Apparatus . 7
5.7 Tensile loading. 7
5.8 Test . 7
5.9 Recording, treatment and analysis of results . 8
5.10 Test report . 8
Annex A (informative) Test methods for measurement of tensile bond strength . 10
Bibliography . 27

Foreword . v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Sampling . 2
5 Test methods . 2
5.1 General . 2
5.2 Tooth substrate and storage . 2
5.2.1 Substrate . 2
5.2.2 Time after extraction . 3
5.2.3 Condition of teeth . 3
5.2.4 Preparation and storage of teeth . 3
5.3 Tooth surface preparation . 3
5.3.1 Requirement for the surface of tooth to be adhered . 3
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5.3.2 Requirement for the procedure of preparation of tooth surface . 4
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5.3.3 Surface preparation of tooth plane for adhesion . 4
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5.4 Application of adhesive . 5
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5.4.1 General. 5
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iv © ISO #### 2026 – All rights reserved
iv
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5.4.2 Adhesive and/or adherend material in bulk . 5
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5.4.3 Adhesive material as thin film and adherend material as preformed rod . 6
Line spacing: single
5.5 Storage of test specimens . 6
5.5.1 General. 6
5.5.2 Recommended procedures and conditions of durability test . 7
5.6 Apparatus . 7
5.6.1 General. 7
5.6.2 Alignment . 7
5.6.3 Connecting device . 7
5.7 Tensile loading . 8
5.8 Test . 8
5.9 Recording, treatment and analysis of results . 8
5.9.1 Recording and treatment of results . 8
5.9.2 Analysis of results . 8
5.10 Report . 8
Annex A (informative) Test methods for measurement of tensile bond strength .10
A.1 General .10
A.2 Test methods .10
[6],[7]
A.2.1 Kemper and Killian’s test method .10
A.2.2 Bencor’s test method .13
A.2.3 Dumbbell test .15
A.2.4 Micro-tensile test .17
Bibliography .19

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v
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Foreword
Line spacing: single
ISO (the International Organization for Standardization) is a worldwide federation of national standards
Formatted: Line spacing: single
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/directiveswww.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
Formatted: English (United Kingdom)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
Formatted: Font color: Auto, English (United Kingdom)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents.www.iso.org/patents. ISO shall not be held responsible for identifying any or all such
Formatted: Font color: Auto, English (United Kingdom)
patent rights.
Formatted: Font color: Auto
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.htmlwww.iso.org/iso/foreword.html.
Formatted: Font color: Auto
This document was prepared by Technical Committee ISO/TC 106, Dentistry, Subcommittee SC 1, Filling and
restorative materials.
This second edition cancels and replaces the first edition (ISO/TS 4640:2023), which has been technically
revised.
The main changes are as follows:
Formatted: Font: Cambria, Font color: Auto
— — concentration range of chloramine-T trihydrate for prepared tooth storage has been expanded;
Formatted: Font color: Auto
Formatted: List Continue 1, Indent: Left: 0 cm, First
— — the specification of number of specimens tested has been added;
line: 0 ch, Line spacing: single
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— — the specification for abrasive paper grain material has been deleted;
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— — photographs of figure A.1 hasFigure A.1 have been replaced.
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Any feedback or questions on this document should be directed to the user’s national standards body. A Formatted: Font color: Auto
complete listing of these bodies can be found at www.iso.org/members.htmlwww.iso.org/members.html.
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pt, Line spacing: single
vi © ISO #### 2026 – All rights reserved
vi
ISO/TSDTS 4640:20##(E:(en) Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold
Introduction
Formatted: HeaderCentered, Left, Space After: 0 pt,
Line spacing: single
Adhesion in restorative dentistry is an important topic. This document intends to describe various laboratory
procedures of tensile bond strength tests whereby the effect or quality of a bond between a dental material
and tooth structure can be substantiated.
Adhesive materials are used in many types of restorative and preventive treatments. Even if the stress on the
bond in most circumstances can be defined as either tensile, shear or a combination of these, there are no
specific laboratory tests which can be valid for all the various clinical applications of adhesive materials.
The relative performance of materials that are claimed to bond to tooth structure is usually evaluated by
laboratory assessment of bond strengths. While bond strengths are unable to predict clinical behaviour or
performance, they are useful for comparing adhesive materials.
[1] [1]
ISO 29022 prescribes the notched-edge shear bond strength test.
Annex AAnnex A lists several published laboratory methods for tensile bond strength measurement.
[2] [2]
Tensile bond strength testing is also common in general materials science. See Reference for a list of many
test methods.
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vii
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Dentistry — Test methods for tensile bond strength to tooth structure
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This document specifies substrate selection, storage and handling as well as essential characteristics of tensile
bond strength test methods for quality testing of the adhesive bond between restorative dental materials and
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tooth structure, i.e. enamel and dentine. Specific test methods for tensile bond strength measurements are
given in Annex AAnnex A.
This document does not include requirements for components of adhesive materials and their performance.
2 Normative references
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The following documents are referred to in the text in such a way that some or all of their content constitutes
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requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 1942, Dentistry — Vocabulary
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 6344-3, Coated abrasives — Determination and designation of grain size distribution — Part 3: Microgrit
sizes P240 to P5000
3 Terms and definitions
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For the purposes of this document, the terms and definitions given in ISO 1942 and the following apply.
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ISO and IEC maintain terminology databases for use in standardization at the following addresses:
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— ISO Online browsing platform: available at https://www.iso.org/obphttps://www.iso.org/obp Formatted: List Continue 1, No bullets or numbering,
Don't keep with next
— IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/
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3.1 3.1
bullets or numbering, Don't keep with next
adhere
be in a state of adhesion (3.3(3.3) Formatted: TermNum2
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3.2 3.2
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adherend
body that is held or intended to be held to another body by an adhesive (3.4(3.4)
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3.3 3.3
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adhesion
state in which two surfaces are held together by either chemical or physical, or both forces with the aid of an
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adhesive (3.4(3.4)
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3.4 3.4
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adhesive
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substance capable of holding materials together
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3.5 3.5
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bond strength
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force per unit area required to break a bonded assembly with failure occurring in or near the adhesive
(3.4)/(3.4) or adherend (3.2(3.2) interface
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3.6 3.6
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substrate
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material upon the surface of which an adhesive (3.4(3.4) is spread for any purpose, such as bonding or coating
4 Sampling
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The amount of test material shall be sufficient for all planned tests and. The samples shall be from the same
batch.
5 Test methods
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5.1 General
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Adhesive materials are used for many different purposes in the oral cavity. This document describes tensile
bond strength tests. When bond strength is measured, the raw data are in unit of force (N). This shall be
converted into a stress unit, i.e. force per unit area (MPa). Hence, it is important to control the area and
roughness of the surface when applying the adhesive material.
The following two critical variables or factors shall be incorporated when designing test equipment and
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preparing specimens for tensile testing of bond strength:
a) alignment of the tensile forces acting on the specimen;
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b, c, … + Start at: 1 + Alignment: Left + Aligned at: 0
b) limitation of the bonding area.
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5.2 Tooth substrate and storage
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5.2.1 Substrate
5.2.1.1 Types of the substrate
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Use either human permanent premolars/molars or bovine mandibular incisors for the measurement of bond
strength. The donor bovine shall not be more than five years old.
5.2.1.2 Characteristics of the substrate
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When measuring bond strength to human dentine, it is recommended to use the buccal superficial dentine
that is as close to the enamel as possible in order to reduce variations. Third permanent molars from 16- to
40-year-old individuals should be used.
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5.2.2 Time after extraction
There is increasing evidence that changes in dentine occur after extraction that can influence bond strength
measurements. The effect can vary with different types of bonding materials. Ideally, bond strengths should
be measured immediately post-extraction.
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NOTE Teeth within six months after extraction can be used. Teeth extracted more than six months prior to use
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undergo degenerative changes in dentinal proteins.
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5.2.3 Condition of teeth
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5.2.3.1 History on clinical treatment (of human teeth)
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Human teeth used for bond strength measurement shall be caries-free and preferably unrestored. However,
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small and superficial restorations not in the adhesion test area are permitted. Root-filled teeth shall not be
used.
5.2.3.2 Site of the dentition and life-history of the donating patient (of human teeth)
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There is some evidence to suggest that different teeth in the dentition can give different results with bonding
to dentine and enamel. It is impossible to have complete control of variables (e.g. age of the donating patient,
ethnicity, dietary history and state of health) or to standardize the composition and structure of the teeth.
5.2.4 Preparation and storage of teeth
5.2.4.1 Preparation of extracted teeth
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Immediately after extraction, human teeth shall be thoroughly washed in running water. All blood and
adherent tissue shall be removed using sharp hand instruments. Bovine teeth shall be cleaned as soon as
possible after extraction. The soft tissue in the pulp chamber shall be removed in a similar fashion.
5.2.4.2 Storage of prepared teeth
Prepared teeth shall be placed in distilled water of grade 3 in accordance with ISO 3696 or in a 0,5 % to 1,0 %
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®11)
chloramine-T trihydrate (CAS Registry Number 7080-50-4) bacteriostatic/bacteriocidal solution for a
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maximum of one week and thereafter stored in distilled water grade 3 in a refrigerator, i.e. nominal 4 °C. To
Subscript
minimize deterioration, the storage medium shall be replaced at least once every two months.
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No other chemical agents shall be used, as they can be absorbed by tooth substance and alter its behaviour.
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For prevention of viral infections, 2.,0 % to 4.,0 % chloramine-T trihydrate can be used.
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Not at 1.75 cm
NOTE 1 Chloramine-T trihydrate is a strong oxidant and can oxidise polymerisation initiators, particularly reducing
agents in chemical polymerisation initiator systems. The oxidation reaction affects the chemical polymerisation by redox
[3] [3]
reaction between the oxidising agent and reducing agent and can reduce bond strength. .
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NOTE 2 Information on hazardous properties of chloramine-T trihydrate maycan be referenced in the SDS (Safety
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Data Sheet)safety data sheet provided by the supplier.
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5.3 Tooth surface preparation
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5.3.1 Requirement for the surface of tooth to be adhered
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A reproducible flat surface is required. Tooth surfaces shall be kept wet at all times during preparation.
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NOTE Exposure of the surface of prepared tooth to the air for several minutes can cause irreversible changes in
bonding character. Dentine is especially sensitive to dehydration.
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1) ®
Chemical Abstracts Service (CAS) Registry Number is a trademark of the American Chemical Society (ACS). This
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information is given for the convenience of users of this document and does not constitute an endorsement by ISO of the
product named. Equivalent products may be used if they can be shown to lead to the same results.
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1) ®
Chemical Abstracts Service (CAS) Registry Number is a trademark of the American Chemical Society (ACS). This
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information is given for the convenience of users of this document and does not constitute an endorsement by ISO of the
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5.3.2 Requirement for the procedure of preparation of tooth surface
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5.3.2.1 Blocking of pulp chamber (for bovine teeth)
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The pulp chamber of bovine teeth shall be blocked, for example by wax, to prevent penetration of resin into
the dentine. Alternatively, use a high viscosity potting medium that does not penetrate the pulp chamber.
NOTE This can be verified by preparing a set of potted teeth and examining the pulp chambers for the presence of
polymerised resin.
5.3.2.2 Retention form in test tooth
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Ensure that the tooth has form (undercuts, holes or retentive pins) that will secure retention in the mounting
medium.
5.3.2.3 Mounting the prepared tooth in a holder
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To control the planing and the angle of the surface during preparation, the test tooth shall be mounted and
immobilised in a rigid holder by means of dental die stone or low exothermal-curing viscous resin. The
temperature of the polymerising resin shall not exceed 42 °C.
NOTE The absorption of resin can adversely affect the tooth.
5.3.2.4 Storage of the mounted tooth
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Place the mounted tooth in water at (23 ± 2) °C as soon as possible.
5.3.3 Surface preparation of tooth plane for adhesion
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5.3.3.1 Procedure of planing
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a) A standard surface shall be prepared by planing the exposed surface of the tooth against abrasive paper
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finally with a grit size of P600 as defined in ISO 6344-3 fixed on a hard and flat plate under running water.
Numbering Style: a, b, c, … + Start at: 1 + Alignment:
Left + Aligned at: 0 cm + Indent at: 0 cm
NOTE The "P" prefix by the grit number means this coated abrasive conforms to the Federation of European
[4] [4]
Producers of Abrasives (FEPA) grading system, see Reference. .
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b) Grind until the surface is even and smooth.
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b, c, … + Start at: 2 + Alignment: Left + Aligned at: 0
5.3.3.2 Inspection and treatment
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a) When inspected visually, the surface shall be even and smooth.
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b, c, … + Start at: 1 + Alignment: Left + Aligned at: 0
b) Discard teeth that have perforations into the pulp chamber.
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c) Discard teeth that have craze lines and cracks. Inspection can be carried out under light microscopy and
external fibre optic lighting.
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d) Ensure that the surface is confined to enamel or dentine.
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5.4 Application of adhesive
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5.4.1 General
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5.4.1.1 Specimens
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Prepare at least 10 specimens. Multiple teeth are used for micro-tensile test.
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5.4.1.15.4.1.2 Ambient conditions
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All of the procedures shall be performed at (23 ± 2) °C and (50 ± 10) % relative humidity.
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5.4.1.25.4.1.3 Preconditioning of the prepared surface of the tooth
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The tooth surface prepared for application of adhesive material shall be preconditioned according to the
manufacturer’s instructions. If no instructions are given, rinse with running water for 10 s and remove visible
water on the surface with a filter paper or by a light/ or brief stream of oil-free compressed air immediately
before application of the adhesive material.
5.4.1.35.4.1.4 Application of the adhesive material
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Mix if necessary. Apply the adhesive material according to the instructions given by the manufacturer.
5.4.2 Adhesive and/or adherend material in bulk
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5.4.2.1 Importance of limitation of the bonding area
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Tensile bond strength (TBS) exhibits an inverse relationship with the bonding surface area;: as the bonding
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[5] [5]
area becomes smaller, the tensile strength value becomes significantly greater . . This makes limiting the
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bonding area an important consideration.
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5.4.2.2 Methods to limit the bonding area
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5.4.2.2.1 General
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The typical examples of the methods to limit the bonding area are to use a material holder or a double sided-
adhesive tape.
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5.4.2.2.2 Material holder to limit the bonding area
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For example, limitingLimiting the bonding area can be achieved by using a material holder with a sharp edge
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contacting the tooth surface. This holder is also able to stabilise the material(s) on the tooth surface for curing.
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This holder also allows restriction of the substrate treatment area and demarcation of the extent of the
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adhesive and permits accurate limiting of the bonded surface.
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5.4.2.2.3 Material holder for light-curing adhesive or adherend materials b, c, … + Start at: 1 + Alignment: Left + Aligned at: 0
cm + Indent at: 0 cm
a) The transparency of the material holder shall be such that, for light-curing adhesives or adherend
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materials, the material holder shall give sufficient access to the curing light to allow a sufficient amount
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of the light (e.g. by being made partly or totally of a transparent material).
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b) The amount of light energy applied to the material shall be in accordance with the manufacturer’s
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instructions. Left + Aligned at: 0 cm + Indent at: 0 cm
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5.4.2.2.4 Procedure to use the material holder
b, c, … + Start at: 2 + Alignment: Left + Aligned at: 0
cm + Indent at: 0 cm
a) When using the same material holder several times, coat the inner part of the material holder with a
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mould-releasing agent. Avoid coating the edge of the holder.
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NOTE If the edge of the material holder is coated with the mould-releasing agent, the agent can contaminate
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the surfaces to be adhered and therefore will affect the adhesion.
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b) Apply a thin layer of the adhesive material onto the holder surface.
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c) Fill the material holder to slight excess with the adhesive or the adherend material and place it firmly in
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the correct position on the tooth.
d) Ensure that the material holder maintains contact with the tooth surface in the correct alignment during
fixation.
e) If the manufacturer recommends a particular restorative material for use with the adhesive under
investigation, then the same restorative material shall be used for all tests of that adhesive.
f) The fixation of the material holder shall be finished within the manufacturer’s stated working time of the
adhesive material.
5.4.3 Adhesive material as thin film and adherend material as preformed rod
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a) If it is decided to restrict the bonding area and use an adherend rod, fix to the planed tooth surface a thin
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tape of material that is non-reactive with the adhesive with a hole of the same dimensions as the contact b, c, … + Start at: 1 + Alignment: Left + Aligned at: 0
area of the rod, to the planed tooth surface. cm + Indent at: 0 cm
b) Apply a thin layer of the adhesive material on the tooth surface inside the hole in the tape and lower the
adherend rod to contact the adhesive material inside the hole.
c) Fix the rod in exact position and alignment and place a constant load on top for constant time.
The rod should have flat top and bottom surfaces, and they should be parallel to each other. To apply the
load evenly, the rod should be placed in a normal position to the tooth surface where the adhesive has
been applied.
d) The total procedure from application of the material to the fixation of the upper rod shall be performed
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within the manufacturer’s stated working time. b, c, … + Start at: 4 + Alignment: Left + Aligned at: 0
cm + Indent at: 0 cm
e) Remove the tape after curing without applying any adverse force on the bonded specimen.
5.5 Storage of test specimens
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5.5.1 General
5.5.1.1 Temperature
Test specimens shall be prepared at (23 ± 2) °C and stored in water at (37 ± 2) °C prior to testing.
NOTE Storage in water for 24 h is normally sufficient to discriminate between materials that can withstand wet
environments and those that do not.
5.5.1.2 Thermocycling
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Thermocycling between 5 °C and 55 °C may be used as an accelerated ageing test.
5.5.1.3 Simple storage in water
Longer periods of water storage are supposed to be necessary to assess durability of the bond.
[6],[7] [6]],[ [7]
NOTE Simple water storage has been found to mimic clinically observed degradation of restorations . . Formatted: Font: 10 pt
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5.5.2 Recommended procedures and conditions of durability test
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5.5.2.1 Treatment of adhesion test specimen in water
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a) Test type 1: shortShort-term test for 24 h in water at 37 °C.
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b) Test type 2: thermocyclingThermocycling test comprising 500 cycles in water between 5 °C and 55 °C,
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starting after (20 to 24) h storage in water at 37 °C.
b, c, … + Start at: 1 + Alignment: Left + Aligned at: 0
cm + Indent at: 0 cm
The exposure to each bath should be at least 20 s, and the transfer time between baths should be
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(5 to 10) s.
Numbering Style: a, b, c, … + Start at: 1 + Alignment:
Left + Aligned at: 0 cm + Indent at: 0 cm
c) Test type 3: longLong-term test after six months storage in water at 37 °C (medium changed every seven
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days to avoid contamination).
b, c, … + Start at: 3 + Alignment: Left + Aligned at: 0
cm + Indent at: 0 cm
5.5.2.2 Timing of the tensile test after the treatment in water
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The specimens shall be tested for bond strength immediately after removal from water.
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5.6 Apparatus
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5.6.1 General
Several types of apparatus are available for measuring the tensile bond strength of an adhesive system. The
critical requirements for selection of a suitable instrument for the small and sometimes fragile specimens are:
a) the ability to mount the tooth/material specimen in the apparatus and the universal testing machine
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without application of load (tensile, bending, shear or torsion) on the specimen; b, c, … + Start at: 1 + Alignment: Left + Aligned at: 0
cm + Indent at: 0 cm
b) a sufficiently rigid construction, in order to avoid elastic deformation (or displacement) of the apparatus
and the connection to the testing machine;
c) the ability to apply a slowly increasing and unidirectional tensile load, and the ability to align the specimen
to avoid an uneven stress distribution during loading.
5.6.2 Alignment
The test apparatus shall secure alignment between substrate and adhesive material, i.e. the tensile force shall
be applied at a 90 ° angle to the planed substrate surface.
5.6.3 Connecting device
The connection between the apparatus and the crosshead of the universal testing machine sh
...