SIST EN ISO 28399:2026

• Abstract:

  This document specifies the requirements and test methods for external tooth bleaching products. These products are intended for use in the oral cavity, either by professional application (in-office tooth bleaching products) or consumer application (professional or non-professional home use of tooth bleaching products) or both. It also specifies requirements for their packaging, labelling and manufacturer’s instructions for use.; This document is not applicable to tooth bleaching products:; specified in ISO 11609;; intended to change colour perception of natural teeth by mechanical methods (e.g. stain removal) or using restorative approaches, such as veneers or crowns;; auxiliary or supplementary materials (e.g. tray materials) and instruments or devices (e.g. lights) that are used in conjunction with the bleaching products.; This document does not specify biological safety aspects of tooth bleaching products.; NOTE The maximum concentration of a bleaching agent for professional or non-professional use is subject to each country’s regulatory body.

• Status: Not Published
• Public Enquiry End Date: 30-Oct-2025
• ICS: 11.060.01 - Dentistry in general
• ICS: 71.100.70 - Cosmetics. Toiletries
• ICS: 97.170 - Body care equipment
• Technical Committee: VAZ - Healthcare
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 02-Nov-2026
• Due Date: 07-Jan-2027
• Ref Project: EN ISO 28399:2026 - Dentistry - External tooth bleaching products (ISO 28399:2026)

• Replaces: SIST EN ISO 28399:2021 - Dentistry - External tooth bleaching products (ISO 28399:2021)
• Effective Date: 01-Dec-2026

SIST EN ISO 28399:2026 is the Slovenian standard for dentistry that sets requirements and test methods for external tooth bleaching products. It covers products for professional in-office use, consumer home use, or both, and it also covers packaging, marking and manufacturer instructions for use. The document is aimed at manufacturers, test laboratories, dental professionals and buyers who need a common way to assess product concentration, surface effects and product information.

What does SIST EN ISO 28399:2026 specify?

SIST EN ISO 28399:2026 specifies how external tooth bleaching products are classified, tested and presented for use. It applies to products used in the oral cavity to change the colour of natural teeth towards a lighter or whiter shade.

The scope excludes products specified in ISO 11609, products that change tooth colour by mechanical stain removal or restorative approaches such as veneers or crowns, and auxiliary materials or devices used with bleaching products. The standard also leaves biological safety aspects outside its scope. A note adds that the maximum concentration of a bleaching agent for professional or non-professional use is set by each country's regulatory body.

The document is organized into seven clauses and three informative annexes.

Annex	What it covers
Annex A	Test procedure for measuring hydrogen peroxide concentration
Annex B	Light microscopy method for measuring enamel and dentine erosion
Annex C	Laboratory method for assessing tooth bleaching efficacy

What are the key requirements of SIST EN ISO 28399:2026?

SIST EN ISO 28399:2026 focuses on three product-performance checks and on how the tests are carried out. In practice, these are the points that matter most for product development, quality control and conformity checking.

1. Classification is by intended user

Clause 4 classifies external tooth bleaching products as either for professional application or for consumer application. Professional application means use only by dental professionals. Consumer application covers products intended for home use, including professional home use and non-professional home use.

This matters because the claimed user type determines how the product is labelled, how it is described in instructions, and how it is placed on the market.

2. Active-ingredient concentration must stay within limits

Clause 5.1 requires the concentration of active ingredients for bleaching, expressed as equivalent to hydrogen peroxide, to remain within +10 % and -30 % of the original unopened-product concentration stated by the manufacturer, when the product is used before expiry and according to the instructions for use. Annex A gives the titration procedure for measuring hydrogen peroxide concentration, and the clause allows any validated equivalent method with similar sensitivity and accuracy.

This means manufacturers need a reliable way to verify that the delivered product still matches its declared strength.

3. Surface hardness loss is limited

Clause 5.2 limits the reduction in surface hardness after bleaching to not more than 10 %, using Knoop hardness number (KHN) or Vickers hardness number (VHN) measurements under the test method in 6.3.

This matters because the standard treats excessive softening as a material performance problem that can be measured on enamel after treatment.

4. Erosion must stay below a reference level

Clause 5.3 requires the erosion caused by the product to be lower than the erosion produced by the standard reference solution. Annex B provides the light microscopy method for that comparison, and equivalent methods are allowed.

This gives manufacturers and laboratories a comparative way to check whether a bleaching product causes too much surface loss.

5. Test specimens must be prepared in a controlled way

Clause 6.1 specifies how enamel and dentine specimens are prepared from extracted human or bovine teeth. The specimens are taken from a consistent location, stored in a neutralized disinfecting solution that does not alter physical properties, ground and polished with controlled abrasives and water, and kept hydrated.

This is important because specimen preparation affects the repeatability of the test results.

6. Application during testing must follow the instructions for use

Clause 6.2 requires the test product to be dispensed, processed and applied according to the manufacturer's instructions for use. The test method must simulate the clinical procedure in quantity, frequency and duration, and specimens are stored at 37 °C in artificial saliva between intervals and for 24 h after the last application before testing.

This means the laboratory method is intended to reflect how the product is actually used.

7. Packaging, marking and instructions are controlled

Clause 7 requires sealed packaging that protects the contents and does not harm product quality. Table 1 sets out the information that must appear on the outermost package, container and/or instructions for use, including product identification, manufacturer identification, storage conditions, lot number, expiry date, active ingredients, instructions, warnings and consultation advice. For single-use containers, the minimum labelling on secondary packaging is also defined.

This matters for traceability, safe use and clear product identification after sale.

What terms does SIST EN ISO 28399:2026 define?

The document defines a small set of core terms in Clause 3.

• Bleaching - In natural teeth, this means removing intrinsic or acquired discoloration, or moving the tooth colour toward a lighter or whiter shade using chemicals, sometimes together with auxiliary means.
• Professional home use - A product use prescribed by a professional and carried out at home under repeated supervision by the dentist.
• Erosion - The progressive loss of calcified tooth tissue caused by chemical processes that do not involve bacterial action.
• Hydrogen peroxide (H2O2) - The reference chemical used in the concentration test for bleaching active ingredients and the basis for reporting equivalent concentration.
• Knoop hardness number (KHN) - A hardness measure used in the surface microhardness test to check whether bleaching weakens enamel.
• Vickers hardness number (VHN) - An alternative hardness measure used for the same surface microhardness assessment.
• Colour difference (ΔE*ab) - The calculated change in tooth colour from L*, a* and b* values in Annex C when electronic instruments are used.

Who uses SIST EN ISO 28399:2026?

SIST EN ISO 28399:2026 is used by manufacturers of external tooth bleaching products, especially when they need to design a product, write instructions, and verify product claims before placing it on the market. Testing laboratories use it for concentration checks, hardness measurements, erosion assessment and laboratory efficacy studies.

Dental professionals use it when they prescribe or apply professional or professional-home-use products and when they review manufacturer information. Quality and regulatory teams use it to compare products, document test methods and check whether labelling and packaging are complete.

What changed in SIST EN ISO 28399:2026 from the previous edition?

SIST EN ISO 28399:2026 cancels and replaces ISO 28399:2021. The foreword states that this fourth edition has been editorially revised, and that the changes compared with the previous edition are editorial changes to improve clarity throughout the document.

Which standards are used with SIST EN ISO 28399:2026?

• ISO 1942 - supplies the general dental vocabulary used in Clause 3.
• ISO 1042 - provides the Class A volumetric flasks used in Annex B.
• ISO 3696 - specifies water quality for laboratory use and is used in specimen preparation and annex methods.
• ISO 6344-1 - defines abrasive grain size analysis for the sandpaper used in specimen preparation.
• ISO 8601-1 - sets the date format for the expiry date in marking and instructions.
• ISO 11664-2 - provides the standard illuminant used for colour-corrected lighting in Annex C.
• ISO/CIE 11664-1 - is used for calibrated visual shade assessment in Annex C.
• ANSI/ADA Specification No 41 - supports the artificial saliva conditions used after bleaching in 6.2.
• ISO 10993-1 and ISO 7405 - are named in the introduction as references for biological or toxicological hazard assessment.
• ISO 22727 - is named in Clause 7 as an option when additional public information symbols are needed.
• ISO 11609 - is named in the scope as the separate standard covering products outside this document.

What does the SIST EN ISO 28399:2026 document contain?

SIST EN ISO 28399:2026 contains one main compliance-oriented table and three informative annexes with laboratory methods. Table 1 sets out marking and instructions-for-use content for different package levels. Annex A gives a thiosulfate titration procedure for hydrogen peroxide concentration, including a formula for calculating concentration and repeated measurements.

Annex B is a detailed erosion test with specimen preparation, positive and negative controls, microscopy, digital imaging and software-based measurement of cross-section loss. It also includes figures for specimen cutting, mounting and imaging. Annex C gives a bleaching-efficacy method using shade guides or electronic instruments, with procedures for specimen selection, visual assessment, instrument-based colour measurement and statistical analysis.

SLOVENSKI STANDARD
oSIST prEN ISO 28399:2025
01-oktober-2025
Zobozdravstvo - Proizvodi za zunanje beljenje zob (ISO/DIS 28399:2025)
Dentistry - External tooth bleaching products (ISO/DIS 28399:2025)
Zahnheilkunde - Äußere Zahnbleichmittel (ISO/DIS 28399:2025)
Médecine bucco-dentaire - Produits d'éclaircissement dentaire par voie externe (ISO/DIS
28399:2025)
Ta slovenski standard je istoveten z: prEN ISO 28399
ICS:
11.060.01 Zobozdravstvo na splošno Dentistry in general
71.100.70 Kozmetika. Toaletni Cosmetics. Toiletries
pripomočki
oSIST prEN ISO 28399:2025 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN ISO 28399:2025
oSIST prEN ISO 28399:2025
DRAFT
International
Standard
ISO/DIS 28399
ISO/TC 106/SC 7
Dentistry — External tooth
Secretariat: JISC
bleaching products
Voting begins on:
Médecine bucco-dentaire — Produits d'éclaircissement dentaire
2025-08-11
par voie externe
Voting terminates on:
ICS: 71.100.70; 97.170 2025-11-03
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,
TECHNOLOGICAL, COMMERCIAL AND
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 28399:2025(en)
oSIST prEN ISO 28399:2025
DRAFT
ISO/DIS 28399:2025(en)
International
Standard
ISO/DIS 28399
ISO/TC 106/SC 7
Dentistry — External tooth
Secretariat: JISC
bleaching products
Voting begins on:
Médecine bucco-dentaire — Produits d'éclaircissement dentaire
par voie externe
Voting terminates on:
ICS: 71.100.70; 97.170
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 2025
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 28399:2025(en)
ii
oSIST prEN ISO 28399:2025
ISO/DIS 28399:2025(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Classification . 2
4.1 General .2
4.2 Products for professional application .2
4.3 Products for consumer application .2
5 Requirements . 2
5.1 Concentration of active ingredients for bleaching .2
5.2 Surface microhardness .3
5.3 Surface erosion .3
6 Measurements and test methods . 3
6.1 Preparation of tooth specimens .3
6.2 Preparation and application of tooth bleaching product .3
6.3 Surface microhardness .3
7 Packaging, marking and information to be supplied by the manufacturer . 3
7.1 General .3
7.2 Packaging .3
7.3 Marking and instructions for use .3
Annex A (informative) Test procedure for the measurement of hydrogen peroxide
concentration . 5
Annex B (informative) Light microscopy method for measuring erosion of enamel and dentine
caused by external tooth bleaching products . 7
Annex C (informative) Test method for laboratory assessment of tooth bleaching efficacy . 19
Bibliography .22

iii
oSIST prEN ISO 28399:2025
ISO/DIS 28399:2025(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 7, Oral care
products, 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 fourth edition cancels and replaces the third edition (ISO 28399:2021), which has been editorially
revised. The changes compared to the previous edition are as follows:
— Editorial changes to improve clarity throughout the document.
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
oSIST prEN ISO 28399:2025
ISO/DIS 28399:2025(en)
Introduction
External tooth bleaching products are used in dentistry for changing the colour of natural teeth towards a
lighter or whiter shade. They are applied in the oral cavity directly on the outer surfaces of teeth.
Specific qualitative and quantitative requirements for freedom from biological hazard are not included in
this document. Reference should be made to ISO 10993-1 and ISO 7405 when assessing possible biological or
toxicological hazards.
v
oSIST prEN ISO 28399:2025
oSIST prEN ISO 28399:2025
DRAFT International Standard ISO/DIS 28399:2025(en)
Dentistry — External tooth bleaching products
1 Scope
This document specifies the requirements and test methods for external tooth bleaching products. These
products are intended for use in the oral cavity, either by professional application (in-office tooth bleaching
products) or consumer application (professional or non-professional home use of tooth bleaching products),
or both. It also specifies requirements for their packaging, labelling and manufacturer’s instructions for use.
This document is not applicable to tooth bleaching products:
— specified in ISO 11609;
— intended to change colour perception of natural teeth by mechanical methods (e.g. stain removal) or
using restorative approaches, such as veneers or crowns;
— auxiliary or supplementary materials (e.g. tray materials) and instruments or devices (e.g. lights) that
are used in conjunction with the bleaching products.
This document does not specify biological safety aspects of tooth bleaching products.
NOTE Maximum concentration of a bleaching agent for professional or non-professional use is subject to each
country’s regulatory body.
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 1042, Laboratory glassware — One-mark volumetric flasks
ISO 1942, Dentistry — Vocabulary
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 6344-1, Coated abrasives — Grain size analysis — Part 1: Grain size distribution test
ISO 8601-1, Date and time — Representations for information interchange — Part 1: Basic rules
ISO 11664-2, Colorimetry — Part 2: CIE standard illuminants
ANSI/ADA Specification No 41: Recommended Standard Practices for Biological Evaluation of Dental Materials
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 terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/

oSIST prEN ISO 28399:2025
ISO/DIS 28399:2025(en)
3.1
bleaching
removal of intrinsic or acquired discolorations of natural teeth, or changing their colour
towards a lighter or whiter shade using chemicals, sometimes in combination with the application of
auxiliary means
Note 1 to entry: Changing the colour of natural teeth towards a lighter or whiter shade is not limited to changing a
discoloration.
Note 2 to entry: Auxiliary means for bleaching other than the application of external energy are also conceivable.
[SOURCE: ISO 1942:2009, 2.28, modified — Note 1 to entry and Note 2 to entry have been added.]
3.2
professional home use
use prescribed by a professional and for use at home under the repeated supervision of the dentist
3.3
erosion
progressive loss of calcified tissue by chemical processes that do not involve bacterial action
[SOURCE: ISO 1942:2009, 2.292, modified — the term has been modified, the admitted term has been deleted
and a domain has been added.]
4 Classification
4.1 General
External tooth bleaching products can be classified for either:
a) professional application; or
b) consumer application.
NOTE External tooth bleaching products can be used alone or in conjunction with auxiliary means of application.
4.2 Products for professional application
These products are tooth bleaching products that are intended by the manufacturer to be applied only by
dental professionals (in office tooth bleaching products).
4.3 Products for consumer application
These products are tooth bleaching products that are intended by the manufacturer to be applied by the
consumer (for professional home use or for non-professional home use).
NOTE Such external bleaching products can be prescribed by a dental professional or directly available to
consumers.
5 Requirements
5.1 Concentration of active ingredients for bleaching
The concentration of active ingredients for bleaching (equivalent to hydrogen peroxide) delivered by the
unexpired product according to manufacturer's instructions for use shall be within the range of +10 % and
−30 % of the original concentration stated by the manufacturer for the unopened product. Annex A or any
other validated method that supports the use of the thiosulfate approach to H2O2 titrations, or any other
validated method of similar sensitivity, accuracy and free of biases can be used.

oSIST prEN ISO 28399:2025
ISO/DIS 28399:2025(en)
5.2 Surface microhardness
The reduction in the Knoop hardness (KHN) or Vickers hardness (VHN) after bleaching shall not exceed
10 %, when tested in accordance with 6.3.
5.3 Surface erosion
Surface erosion of the teeth tested shall be less than the level which is caused by the standard reference
solution. The method described in Annex B or other equivalent methods can be used.
6 Measurements and test methods
6.1 Preparation of tooth specimens
Prepare enamel and dentine specimens taken from a consistent location on extracted human or bovine teeth,
that have been stored in a neutralized solution that disinfects but does not alter the physical properties.
Grind the specimen surface under a constant flow of water in accordance with ISO 3696 starting at P400 and
sequentially to a minimum of P1200 silicon carbide paper in accordance with ISO 6344-1. Then polish the
surface using a slurry or paste of 0,3 µm mean particle size aluminium oxide. Ensure a minimum of 1 mm
thickness of enamel or dentine tissue for the test specimen. Prevent dehydration of test specimens during
the preparation procedure.
6.2 Preparation and application of tooth bleaching product
The dispensing, processing and application of the tooth bleaching product used in tests (see Annex C) shall
follow the manufacturer's instructions for use. The method of bleach application shall simulate the clinical
procedure in quantity, frequency and duration of the application. Between bleaching intervals, and for 24 h
after the last bleach application prior to testing, specimens shall be stored at 37 °C in an artificial saliva
[6]
solution similar to that described in the ANSI/ADA Specification No. 41.
6.3 Surface microhardness
Evaluate enamel surface microhardness before and after bleaching treatment.
Determine KHN or VHN surface microhardness by applying a load of 0,49 N (equivalent to a 50 g load)
for 15 s. Evaluate a minimum of 10 specimens for each group, with three indentations for each specimen.
Prevent dehydration of test specimens during the specimen preparation procedure.
7 Packaging, marking and information to be supplied by the manufacturer
7.1 General
Additional information may be included at the discretion of the manufacturer or as required by ISO 22727.
7.2 Packaging
The components of the material shall be supplied in properly sealed containers which adequately protect
the contents and do not adversely affect the product quality.
7.3 Marking and instructions for use
For each package, the following applies.
a) Information shall be clearly marked on the outermost package or containers appropriate to the product,
as indicated in Table 1.
oSIST prEN ISO 28399:2025
ISO/DIS 28399:2025(en)
b) Instructions shall accompany each package of the product and shall include the information appropriate
to the product, as indicated in Table 1.
Table 1 — Requirements for marking and instructions for use
Manufacturer’s
Outermost
No. Information Container instructions for
package
use
1 Name of the product M M M
2 Identification or name of the manufacturer M M M
3 Address of the manufacturer or the agent responsible for sale M — M
4 Recommended conditions of storage M — M
5 Manufacturer's lot number M M —
Expiry date given in accordance with ISO 8601-1 or —
6 M M
ISO 8601-2
Classification of the external tooth bleaching products
7 M — M
(Clause 4)
Clinical application of the external tooth bleaching products
8 — — M
(Clause 4)
9 Number of containers M — —
10 Net mass of product in each container M M —
11 Chemical name of active ingredient(s) M — M
12 Concentration of active ingredient(s) M — M
13 Concentration equivalent to hydrogen peroxide M M M
14 Instructions for use — — M
15 Recommended auxiliary device(s), exposure times and any special
instructions for use of the equipment
— — M
(for the materials requiring an auxiliary device only)
16 Specific contra-indication(s) or warning(s), such as 'irritation',
— — M
'avoid contact with eyes', as necessary
17 Statement equivalent to 'It is recommended that you consult with — — M
your dental professional before using this product.'
18 Date of issue or latest revision, if applicable — — M
Key
M: mandatory information
—: non-mandatory information
For single use containers, instructions may be labelled on the secondary packaging. The minimum information
on single use containers required are: manufacturer name, trade name, lot number, and expiry date.

oSIST prEN ISO 28399:2025
ISO/DIS 28399:2025(en)
Annex A
(informative)
Test procedure for the measurement of hydrogen peroxide
concentration
A.1 Principle
The content of generated hydrogen peroxide (H O ) in tooth bleaching products is determined using a
2 2
modified thiosulfate titration method.
A.2 Test condition
Perform the test at (23 ± 2) °C.
[7]
A.3 Procedure (modified thiosulfate titration method, )
Use analytical grade sulfuric acid, potassium iodide, ammonium molybdate, sodium thiosulfate, chloroform,
anhydrous sodium carbonate, deionized water, in accordance with ISO 3696, grade 2., starch and hydrogen
peroxide. Conduct a titration calibration curve using a series of freshly prepared H O solutions at
2 2
concentrations that include the highest possible H O concentration in the test product.
2 2
A.3.1 Preparation of the test sample solution
A.3.1.1 Add approximately 1,0 g (weighing precision to 0,001 g) of test product or an amount appropriate
to the test, with rapid stirring, to 400 ml deionized water that contains 10 ml of sulfuric acid (25 %), 25 ml
potassium iodide (10 %), and 4 drops of ammonium molybdate solution (5 %).
Note The reason for 'rapid stirring' is that bleaching materials need to be completely dissolved in the solvent
(especially for powder-type materials).
A.3.2 Preparation of 0,1 mol/l sodium thiosulfate solution.
It is technically very difficult to prepare the standardized solution of 0,1 mol/l sodium thiosulfate for a
technician who is not knowledgeable about applied chemistry; therefore, technicians who prepare the
[7]
standard solution can refer to the literature
A.3.2.1 Dissolve approximately 25 g sodium thiosulfate into 1 l freshly boiled d-H O. It is recommended to
add approximately 0,15 ml (3 drops) of chloroform and 0,1 g anhydrous sodium carbonate to stabilize the
[7]
thiosulfate solution. Keep the solution away from light which will lead to decomposition of the solution.
[7]
A.3.2.2 Standardize the sodium thiosulfate solution following any of the methods in .
Note Standardized sodium thiosulfate solution is commercially available. [Sigma-Aldridge]
[7]
A.3.3 Preparation of the standardized starch solution is described in .
Note Standardized starch solution is commercially available [Sigma-Aldridge].

oSIST prEN ISO 28399:2025
ISO/DIS 28399:2025(en)
A.3.4 Hydrogen Peroxide titration assay.
A.3.4.1 Perform the titration of 400 ml of test sample solution (contains 1,0 g test product) using 0,1 mol/l
sodium thiosulfate. Near the end of the titration when the colour of the solution is still faint yellow 2 ml of
starch solution are added. End of titration is marked by the sudden loss of blue colour of the indicator. It is
recommended to use a conical flask or a conical beaker, and to start titrating immediately after the sample
[7]
preparation to avoid oxygen contamination of the test solution .
A.3.5 Determine the hydrogen peroxide concentration.
A.3.5.1 Prepare a calibration curve using a range of known hydrogen peroxide solutions. Interpolate the
H O content using the titration calibration curve.
2 2
A.3.5.2 When using standardized titrants (e.g. USP standard grade), construction of a calibration curve is
not necessary. Calculate the mass concentration of H O using Formula (A.1):
2 2
C = (1,701× V/m) × Y/0,1 × 100 (A.1)
where
C is the mass concentration of H O , expressed as a percentage;
2 2
V is the titre of 0,1 N sodium thiosulfate, expressed in millilitres;
m is the mass of the test product dispensed, expressed in milligrams;
Y is the accurate concentration of sodium thiosulfate, expressed in mol/litre.
Repeat the measurement five times (n = 5) and calculate the mean H O concentration.
2 2
NOTE Formation of iodine can be indicative of the presence of sodium hypochlorite, which is relevant when the
method is used for testing an unknown active ingredient.

oSIST prEN ISO 28399:2025
ISO/DIS 28399:2025(en)
Annex B
(informative)
Light microscopy method for measuring erosion of enamel and
dentine caused by external tooth bleaching products
B.1 Principle
The depth of erosion of enamel and dentine caused by external tooth bleaching products is determined using
a light microscope.
Test summary: sound enamel and dentine slabs of approximately 4 mm × 4 mm × 1,4 mm are cut from caries
and erosion free molars or incisors of human or bovine tooth. These slabs are mounted on a plastic rod
and the natural surface of the slab is removed by sanding to expose fresh enamel or dentine. The surface is
protected with fingernail polish leaving a 1,0 mm unprotected stripe down the centre of the fresh enamel
or dentine surfaces. The specimens are exposed to the potentially erosive so
...