EN ISO 6872:2008

SLOVENSKI STANDARD
01-november-2008
1DGRPHãþD
SIST EN ISO 6872:2000
=RER]GUDYVWYR.HUDPLþQLPDWHULDOL,62
Dentistry - Ceramic materials (ISO 6872:2008)
Zahnheilkunde - Keramikwerkstoffe (ISO 6872:2008)
Art dentaire - Produits céramiques (ISO 6872:2008)
Ta slovenski standard je istoveten z: EN ISO 6872:2008
ICS:
11.060.10 =RERWHKQLþQLPDWHULDOL Dental materials
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 6872
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2008
ICS 11.060.10 Supersedes EN ISO 6872:1998
English Version
Dentistry - Ceramic materials (ISO 6872:2008)
Art dentaire - Produits céramiques (ISO 6872:2008) Zahnheilkunde - Keramische Werkstoffe (ISO 6872:2008)
This European Standard was approved by CEN on 24 August 2008.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 6872:2008: E
worldwide for CEN national Members.

Contents Page
Foreword.3

Foreword
This document (EN ISO 6872:2008) has been prepared by Technical Committee ISO/TC 106 "Dentistry" in
collaboration with Technical Committee CEN/TC 55 “Dentistry” the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by March 2009, and conflicting national standards shall be withdrawn at
the latest by March 2009.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 6872:1998.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 6872:2008 has been approved by CEN as a EN ISO 6872:2008 without any modification.

INTERNATIONAL ISO
STANDARD 6872
Third edition
2008-09-01
Dentistry — Ceramic materials
Art dentaire — Produits céramiques

Reference number
ISO 6872:2008(E)
©
ISO 2008
ISO 6872:2008(E)
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ii © ISO 2008 – All rights reserved

ISO 6872:2008(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
3.1 Material . 1
3.2 Processing. 3
3.3 Properties . 3
4 Types, classes and their identification. 4
5 Requirements . 5
5.1 Uniformity . 5
5.2 Freedom from extraneous materials. 5
5.3 Mixing and condensation properties, type I ceramics. 5
5.4 Physical and chemical properties. 5
5.5 Biocompatibility. 5
6 Sampling. 6
6.1 Type I ceramics . 6
6.2 Type II ceramics. 6
7 Test methods. 6
7.1 Preparation of test specimens . 6
7.2 Radioactivity of dental ceramic. 7
7.3 Flexural strength. 7
7.4 Linear thermal expansion coefficient . 13
7.5 Glass transition temperature. 13
7.6 Chemical solubility . 14
8 Information and instructions . 15
8.1 Information . 15
8.2 Instructions for use . 16
9 Packaging, marking and labelling. 16
9.1 Packaging . 16
9.2 Marking and labelling . 16
Annex A (informative) Fracture toughness. 17
Annex B (informative) Weibull statistics. 22
Bibliography . 24

ISO 6872:2008(E)
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 6872 was prepared by Technical Committee ISO/TC 106, Dentistry, Subcommittee SC 2, Prosthodontic
materials.
This third edition cancels and replaces the second edition (ISO 6872:1995) and Amendment 1:1997 which
have been technically revised.
iv © ISO 2008 – All rights reserved

ISO 6872:2008(E)
Introduction
Specific qualitative and quantitative requirements for freedom from biological hazard are not included in this
International Standard, but it is recommended that, in assessing possible biological or toxicological hazards,
reference be made to ISO 10993-1 and ISO 7405.

INTERNATIONAL STANDARD ISO 6872:2008(E)

Dentistry — Ceramic materials
1 Scope
This International Standard specifies the requirements and the corresponding test methods for dental ceramic
materials for fixed all-ceramic and metal-ceramic restorations and prostheses.
2 Normative references
The following referenced documents are indispensable for the application 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
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1942 and the following apply.
3.1 Material
3.1.1
addition ceramic
dental ceramic material that is fired at a reduced temperature and is normally applied to restore contact points
on a dental restoration or prosthesis
3.1.2
dental ceramic
inorganic, non-metallic material that is specifically formulated for use, when processed according to
manufacturer's instructions, to form the whole or part of a dental restoration or prosthesis
3.1.3
dental porcelain
predominantly glassy dental ceramic material used mainly for aesthetics in a dental restoration or prosthesis
3.1.4
dentine ceramic
dental ceramic material used to form the overall shape and basic colour of a dental restoration or prosthesis,
simulating the natural tooth dentine
3.1.5
enamel ceramic
dental ceramic material used to overlay either partially or wholly the dentine ceramic and also to form the
more translucent incisal third of a dental restoration or prosthesis, simulating the natural tooth enamel
ISO 6872:2008(E)
3.1.6
flame-sprayed dental ceramic
dental ceramic core or substructure layer formed via the technique of flame spraying
3.1.7
glass-ceramic (dental)
dental ceramic material formed by the action of heat treatment on a glass, in order to cause initiation and
growth of a wholly or predominantly crystalline microstructure
3.1.8
glass-infiltrated dental ceramic
dental ceramic core or substructure layer, which is porous and is subsequently densified by the infiltration of
specialized glass at elevated temperature
3.1.9
glaze ceramic
dental ceramic material that is overlayed and fired at a reduced temperature compared to dentine or enamel
ceramic, to produce a thin coherent sealed surface, the level of gloss being determined by the firing conditions
3.1.10
liner
dental ceramic material used on all-ceramic substructure forming a layer that provides a background colour
upon which dentine or opaceous dentine ceramic can be applied to achieve overall aesthetics
3.1.11
modelling fluid
liquid with which a dental ceramic powder is mixed, in order to shape or model it into its required form prior to
firing
3.1.12
opaceous dentine ceramic
dental ceramic material having a higher opacity than a dentine ceramic material, but which can still be used to
contribute to the overall shape and basic colour of a dental restoration or prosthesis, simulating the natural
tooth dentine
3.1.13
opaque dental ceramic
dental ceramic material that, when applied to a metallic substructure in accordance with manufacturer’s
instructions, acts to bond to the metal surface forming a layer that provides a background colour and interface
upon which other dental ceramic materials can be applied to achieve overall aesthetics
3.1.14
shoulder ceramic
dental ceramic material used to form shape and colour at the marginal area of the dental restoration or
prosthesis, simulating natural tooth dentine in this area
3.1.15
stain ceramic
dental ceramic powder or paste that is normally intensely coloured and that is formulated to be used either
internally or externally, during the build up of a dental restoration or prosthesis, to simulate details within or on
the surface as are respectively found in natural teeth
3.1.16
substructure (core) dental ceramic
predominantly polycrystalline dental ceramic material that forms a supporting substructure upon which one or
more layers of dental ceramic or dental polymer material are applied, either partially or totally, to form a dental
restoration or prosthesis
2 © ISO 2008 – All rights reserved

ISO 6872:2008(E)
3.2 Processing
3.2.1
air firing dental ceramic
firing of dental ceramics under ambient atmospheric pressure
3.2.2
CAD/CAM dental ceramic
computer aided design/computer aided manufacture (CAD/CAM) procedures to manufacture a dental
restoration or prosthesis normally including the following stages:
1) a digital scanning procedure of the model or wax-up to produce a 3D data set
2) software manipulation of the 3D data set to design the prosthesis
3) a computer directed machine tool that performs the manufacturing process
3.2.3
condensation of dental ceramic
powder process whereby a slurry of dental ceramic powder is vibrated to compact the powder prior to
sintering
3.2.4
injectable, castable or pressable dental ceramic
dental ceramic material, normally in the form of a pellet or ingot (often pre-sintered), designed for use in a
specialized furnace, which enables the pellet or ingot to be injected/cast/pressed into a mould, prepared via
the lost wax technique
3.2.5
sintering of a dental ceramic
process whereby heat and potentially other process parameters (e.g. pressure and atmosphere) are applied
to a ceramic powder or powder compact, in order to densify the ceramic into its required form
NOTE “Firing” and “sintering” are used interchangeably in this document (“firing” connotating the application of heat
to drive sintering).
3.2.6
vacuum firing dental ceramic
firing of dental ceramics at reduced pressure (i.e. under vacuum) to yield the required density and associated
aesthetics, especially the degree of translucency
NOTE Dental ceramics for vacuum firing have a specific particle size distribution to reduce the entrapment of porosity.
3.3 Properties
3.3.1
class of dental ceramic
classification of a dental ceramic material according to its intended function
3.3.2
fracture toughness
conventional fracture mechanics parameter indicating the resistance of a material to crack extension
(propagation)
3.3.3
glass transition temperature
approximate mid-point of the temperature range over which a glass transforms between elastic and
viscoelastic behaviour, characterized by the onset of a rapid change in its coefficient of thermal expansion
ISO 6872:2008(E)
3.3.4
glaze (medium)
surface appearance obtained when the gloss is clinically and aesthetically acceptable
4 Types, classes and their identification
For the purposes of this International Standard, dental ceramics are designated into two types:
⎯ Type I: ceramic products that are provided as powders, pastes or aerosols;
⎯ Type II: all other forms of ceramic products.
Ceramics are divided into six classes according to their intended clinical use according to descriptions in
Table 1. If colour is added to a ceramic powder for identification purposes, the colour coding given in Table 2
is recommended.
Table 1 — Classification of ceramics for fixed prostheses by intended clinical use
Mechanical and chemical properties
Flexural strength Chemical solubility
Class Recommended clinical indications
minimum (mean) maximum
−2
MPa
µg·cm
a) Aesthetic ceramic for coverage of a metal
or a ceramic substructure.
1 50 100
b) Aesthetic-ceramic: single-unit anterior
prostheses, veneers, inlays, or onlays.
a) Aesthetic-ceramic: adhesively cemented,
single-unit, anterior or posterior 100 a) 100
prostheses.
b) Adhesively cemented, substructure
ceramic for single-unit anterior or 100 b) 2 000
posterior prostheses.
Aesthetic-ceramic: non-adhesively cemented,
3 300 100
single-unit, anterior or posterior prostheses.
a) Substructure ceramic for non-adhesively
cemented, single-unit, anterior or
posterior prostheses.
4 300 2 000
b) Substructure ceramic for three-unit
prostheses not involving molar
restoration.
Substructure ceramic for three-unit prostheses
5 500 2 000
involving molar restoration.
Substructure ceramic for prostheses involving
6 800 100
four or more units.
4 © ISO 2008 – All rights reserved

ISO 6872:2008(E)
Table 2 — Recommended colour coding for the identification of Type I dental ceramic powders
Material Colour coding
Dentine Pink
Enamel Blue
Fluorescent Yellow
Highly chromatic dentine Orange
Opalescent enamel Blue-green
Modifying enamel (e.g., translucent, clear) Purple
5 Requirements
5.1 Uniformity
The inorganic pigment(s) used to produce the colour of a fired dental ceramic and any organic colorants (for
colour coding) shall be uniformly dispersed throughout the dental ceramic material and, in powdered ceramic
products, no segregation of the pigment(s) shall take place when the powder is mixed as described in 7.1.4.
Check by visual inspection.
5.2 Freedom from extraneous materials
5.2.1 Dental ceramic materials shall be free from extraneous materials, when assessed by visual inspection.
−1
5.2.2 Dental ceramic materials shall not have an activity concentration of more than 1,0 Bq⋅g of
uranium . Test in accordance with 7.2.2.
5.2.3 Any colorants used to colour code the ceramic powder as listed in Table 2 are recommended to be
food quality organic materials.
5.3 Mixing and condensation properties, type I ceramics
When mixed as described in 7.1.4, with water or the modelling fluid recommended by the manufacturer, a
dental ceramic powder shall not form lumps or granules when assessed by visual inspection.
The paste so formed shall be suitable for making the indicated restorations and prostheses by condensation
of successive layers. When the paste is condensed as in 7.1.5, it shall not crack or crumble during drying, as
later assessed by visual inspection.
5.4 Physical and chemical properties
The physical and chemical properties of ceramic test specimens tested in accordance with the relevant
methods, detailed for Type I and Type II ceramics in Clause 7, shall comply with the requirements specified in
−6 −1
Table 1. The coefficient of thermal expansion of the ceramics shall not deviate by more than 0,5 × 10 K
from the value stated by the manufacturer [see 8.2.2 d)]. The glass transition temperature of the ceramics
shall not deviate by more than 20 °C from the value stated by the manufacturer [see 8.2.2 d)].
5.5 Biocompatibility
See the Introduction for guidance on biocompatibility.
ISO 6872:2008(E)
6 Sampling
6.1 Type I ceramics
Take a sufficient amount of ceramic to carry out the necessary tests. Where there is more than one shade in a
class of dental ceramic, combine equal quantities of each shade.
Sufficient quantities of essential modelling fluids shall be obtained, if their use is recommended by the
manufacturers. The quantities shall be those recommended by the manufacturer concerned.
6.2 Type II ceramics
All of a material procured for testing in accordance with this International Standard shall be of the same lot.
7 Test methods
7.1 Preparation of test specimens
7.1.1 General
For detailed instructions, see the individual test methods.
For Type I specimens (unless otherwise stated or inconsistent with the text) the apparatus detailed in 7.1.3
along with the conditions for mixing, condensation and firing (7.1.4 to 7.1.6) apply to all test methods.
7.1.2 Components of test specimens, Type I ceramics
The liquid used in the preparation of test specimens shall be water that complies with the requirements for
grade 3 water (see ISO 3696) or, when applicable, the modelling fluid recommended by the manufacturer of
the dental ceramic powder. The required amount of powder shall be taken from the appropriate pool of
powder obtained in accordance with 6.1.
7.1.3 Apparatus for mixing
All apparatus for mixing shall be clean and dry.
7.1.3.1 Glass slab or mixing palette.
7.1.3.2 Spatula, made from a material that is not readily abraded by the dental ceramic powder (glass is
recommended). Instruments used for the mixing procedure shall be made of materials that do not contaminate
the ceramic material.
7.1.3.3 Open multipart mould, from which the condensed specimen can be removed without distortion.
7.1.3.4 Vibration system (vibration table or mechanical brush), capable of vibrating at a frequency of
50 Hz to 60 Hz or in accordance with the manufacturer’s instructions.
7.1.4 Method of mixing
Combine the water or modelling liquid and the ceramic powder in the proportions recommended by the
manufacturer. Avoid vigorous mixing which will tend to incorporate air bubbles with the paste and, both during
and after mixing, examine for compliance with 5.1 and 5.2.1.
6 © ISO 2008 – All rights reserved

ISO 6872:2008(E)
7.1.5 Procedure for specimen fabrication
Overfill the mould (7.1.3.3) with dental ceramic paste, and vibrate. When excess liquid appears at the free
surface of the specimen, place a paper tissue (or similar absorbent material) on the surface of the specimen,
and remove the excess liquid continually by replacing the tissue as soon as it becomes saturated with liquid.
Continue vibration and absorption until no further liquid can be removed, and then level the free surface of the
condensed specimen by means of a suitable instrument (a bevelled glass microscope slide is ideal for this
purpose). After removing the specimen from the mould, place it on a firing tray, dry it and check for
compliance with 5.3.
NOTE Other forming methods, such as dry pressing, are acceptable for specimen fabrication.
7.1.6 Firing
Position the specimens in the furnace so that they will be uniformly fired, and on a substrate to which they will
not adhere and from which there will be no pick-up of material. Obtain guidance from the manufacturer for the
firing of test specimens. These specimens shall be fired according to manufacturer's instructions so that their
final density and thermal history is representative of that found for indicated restorations or prostheses.
7.2 Radioactivity of dental ceramic
7.2.1 Preparation of samples
7.2.1.1 Type I ceramics
A 50 g sample as-manufactured is suitable, collected as described in 6.1.
7.2.1.2 Type II ceramics
Mill powder using tungsten carbide milling media or other appropriate media (to avoid contamination by
radioactive species). Sieve and obtain 50 g of powder with a particle size less than 75 µm.
7.2.2 Counting procedure
Use a sample volume of 50 g bulk powder and determine the activity concentration of uranium by neutron
activation or gamma spectroscopy (with gamma spectroscopy, techniques shall be used to screen for
adulteration).
7.2.3 Assessment of results
Each sample tested shall comply with the requirement in 5.2.2.
7.3 Flexural strength
7.3.1 General
Three flexural test methods are acceptable:
a) three-point bending;
b) four-point bending;
c) biaxial flexure (piston-on-three-ball).
ISO 6872:2008(E)
7.3.2 Three-point and four-point bending tests
7.3.2.1 Apparatus
7.3.2.1.1 Universal mechanical testing machine, capable of a cross-head speed of (1 ± 0,5) mm/min and
able to measure applied loads of between 10 N and 1 000 N (± 0,1 N).
7.3.2.1.2 Flexural test fixtures
a) for three-point bending, consisting of support rollers 1,5 mm to 5 mm (± 0,2 mm) in diameter positioned
with their centres 12,0 mm to 40,0 mm (± 0,5 mm) apart, the load shall be applied at the midpoint
between the supports by means of a third roller 1,5 mm to 5 mm (± 0,2 mm) in diameter. Rollers shall be
made from hardened steel or other hard material having a hardness greater than 40 HRC (Rockwell C
scale) and have a smooth surface with a roughness less than 0,5 µm Ra.
b) for four-point bending, consisting of a ¼-point test configuration, the test piece is loaded by two inner
bearing rollers located ¼ of the total span, L, from the outer support bearing rollers (see Figure 1).
Support rollers 1,5 mm to 5 mm (± 0,2 mm) diameter shall be positioned with their centres 16,0 mm to
40,0 mm (± 0,5 mm) apart. Rollers shall be made from hardened steel or other hard material having a
hardness greater than 40 HRC and have a smooth surface with a roughness less than 0,5 µm Ra. The two
lo
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