EN ISO 20795-1:2008

SLOVENSKI STANDARD
01-november-2008
Zobozdravstvo - Osnovni polimeri - 1. del: Osnovni polimeri za proteze (ISO 20795-
1:2008)
Dentistry - Base polymers - Part 1: Denture base polymers (ISO 20795-1:2008)
Zahnheilkunde - Kunststoffe - Teil 1: Prothesenkunststoffe (ISO 20795-1:2008)
Art dentaire - Polymères de base - Partie 1: Polymères pour base de prothèses dentaires
(ISO 20795-1:2008)
Ta slovenski standard je istoveten z: EN ISO 20795-1:2008
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 20795-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2008
ICS 11.060.10
English Version
Dentistry - Base polymers - Part 1: Denture base polymers (ISO
20795-1:2008)
Art dentaire - Polymères de base - Partie 1: Polymères Zahnheilkunde - Kunststoffe - Teil 1: Prothesenkunststoffe
pour base de prothèses dentaires (ISO 20795-1:2008) (ISO 20795-1:2008)
This European Standard was approved by CEN on 18 July 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 20795-1:2008: E
worldwide for CEN national Members.

Contents Page
Foreword.3

Foreword
This document (EN ISO 20795-1:2008) 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 February 2009, and conflicting national standards shall be withdrawn
at the latest by February 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.
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 20795-1:2008 has been approved by CEN as a EN ISO 20795-1:2008 without any
modification.
INTERNATIONAL ISO
STANDARD 20795-1
First edition
2008-08-01
Dentistry — Base polymers —
Part 1:
Denture base polymers
Art dentaire — Polymères de base —
Partie 1: Polymères pour base de prothèses dentaires

Reference number
ISO 20795-1:2008(E)
©
ISO 2008
ISO 20795-1:2008(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO 2008
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2008 – All rights reserved

ISO 20795-1:2008(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Classification. 3
5 Requirements . 4
5.1 Unpolymerized material . 4
5.2 Polymerized material. 4
6 Sampling. 6
7 Preparation of test specimens . 7
7.1 Laboratory environment . 7
7.2 Procedures . 7
7.3 Special equipment . 7
8 Test methods. 7
8.1 Inspection for compliance determination . 7
8.2 Packing plasticity. 8
8.3 Colour . 10
8.4 Colour stability. 10
8.5 Polishability, translucency, freedom from porosity, ultimate flexural strength and flexural
modulus . 12
8.6 Fracture toughness with a modified bending test . 17
8.7 Bonding to synthetic polymer teeth . 22
8.8 Residual methyl methacrylate monomer. 23
8.9 Water sorption and solubility . 28
9 Requirements for labelling, marking, packaging and instructions supplied by the
manufacturer . 30
9.1 Packaging . 30
9.2 Marking of outer packages and containers . 30
9.3 Manufacturer’s instructions . 31
Annex A (normative) HPLC method for determination of MMA content . 33
Bibliography . 36

ISO 20795-1:2008(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 20795-1 was prepared by Technical Committee ISO/TC 106, Dentistry, Subcommittee SC 2,
Prosthodontic materials.
This first edition cancels and replaces ISO 1567:1999 and Amendment 1:2003.
Significant differences between this first edition of ISO 20795-1 and the third edition of ISO 1567 and
Amendment 1 lie with requirements and tests for materials with improved impact resistance.
ISO 20795 consists of the following parts, under the general title Dentistry — Base polymers:
⎯ Part 1: Denture base polymers
⎯ Part 2: Orthodontic base polymers
iv © ISO 2008 – All rights reserved

ISO 20795-1:2008(E)
Introduction
Specific qualitative and quantitative requirements for freedom from biological hazard are not included in this
part of ISO 20795, 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 20795-1:2008(E)

Dentistry — Base polymers —
Part 1:
Denture base polymers
1 Scope
1.1 This part of ISO 20795 classifies denture base polymers and copolymers and specifies their
requirements. It also specifies the test methods to be used in determining compliance with these requirements.
It further specifies requirements with respect to packaging and marking the products and to the instructions to
be supplied for use of these materials. Furthermore it applies to denture base polymers for which the
manufacturer claims that the material has improved impact resistance. It also specifies the respective
requirement and the test method to be used.
1.2 Although this part of ISO 20795 does not require manufacturers to declare details of the composition,
attention is drawn to the fact that some national or international authorities require such details to be provided.
1.3 This part of ISO 20795 applies to denture base polymers such as those listed below:
a) poly(acrylic acid esters);
b) poly(substituted acrylic acid esters);
c) poly(vinyl esters);
d) polystyrene;
e) rubber modified poly(methacrylic acid esters);
f) polycarbonates;
g) polysulfones;
h) poly(dimethacrylic acid esters);
i) polyacetals (polyoxymethylene);
j) copolymers or mixtures of the polymers listed in a) to i).
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 463:2006, Geometrical Product Specifications (GPS) — Dimensional measuring equipment — Design
and metrological characteristics of mechanical dial gauges
ISO 20795-1:2008(E)
ISO 1942, Dentistry — Vocabulary
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 7491:2000, Dental materials — Determination of colour stability
ISO 8601, Data elements and interchange formats — Information interchange — Representation of dates and
times
ISO 22112:2005, Dentistry — Artifical teeth for dental prostheses
3 Terms and definitions
For the purposes of this document the terms and definitions given in ISO 1942 and the following apply.
3.1
autopolymerizable materials
products having polymerization initiated by chemical means and not requiring application of temperatures
above 65 °C to complete the polymerization
3.2
capsulated material
material consisting of two or more components supplied in a container that keeps them separated until the
time they are mixed together and dispensed for use directly from the container
3.3
denture
artificial substitute for missing natural teeth and adjacent tissues, to also include any additions needed for
optimum function
3.4
denture base
that part of a denture which rests on soft tissue foundations and to which artificial teeth are added
3.5
heat-polymerizable materials
products requiring application of temperatures above 65 °C to complete polymerization
3.6
immediate container
container that is in direct contact with the denture base materials
3.7
liquid
monomeric liquid to be mixed with polymeric particles to form a mouldable dough or fluid resin mixture used
for forming denture bases
3.8
powder
polymeric particles to be mixed with monomeric liquid to form a mouldable dough or fluid resin mixture used
for forming denture bases
3.9
outer packaging
labelled container or wrapping within which other containers are packed
2 © ISO 2008 – All rights reserved

ISO 20795-1:2008(E)
3.10
packing
〈of a denture〉 act of filling a denture base mould with a material (using a compression, pour or injection
technique) to form a denture base
3.11
initial packing time
time after mixing, or other preparation, when a denture base material mixture first reaches packing
consistency
3.12
final packing time
last time, after achievement of the initial packing time, at which a denture base material mixture retains
packing consistency
3.13
processing
procedure of preparing a solid denture base polymer plate and/or specimen by polymerization or injection
moulding
3.14
thermoplastic, adj
characteristic of a hard polymeric material that allows it to be softened by application of heat to make it
mouldable, and then return to the hardened state upon cooling
3.15
translucency
capacity of a body of material to allow the passage of light, yet diffusing the light so as not to render objects
lying beyond the body clearly visible
4 Classification
Denture base polymers covered by this part of ISO 20795 are categorized into the following types and
classes:
⎯ Type 1: Heat-polymerizable materials
⎯ Class 1: Powder and liquid
⎯ Class 2: Plastic cake
⎯ Type 2: Autopolymerizable Materials
⎯ Class 1: Powder and liquid
⎯ Class 2: Powder and liquid for pour-type resins
⎯ Type 3: Thermoplastic blank or powder
⎯ Type 4: Light-activated materials
⎯ Type 5: Microwave cured materials
ISO 20795-1:2008(E)
5 Requirements
5.1 Unpolymerized material
5.1.1 Liquid component
5.1.1.1 General
The liquid shall consist essentially of monomeric material compatible with the powder.
5.1.1.2 Homogeneity
The liquid shall be free of deposit or sediment that can be observed by visual inspection (see 8.1.1).
5.1.2 Solid components
The solid or semi-solid components shall be free of extraneous material that can be observed by visual
inspection (see 8.1.1).
5.1.3 Packing plasticity
When Type 1 Class 1 and Type 2 Class 1 materials are tested in accordance with 8.2, at the initial packing
time recommended by the manufacturer, they shall be capable of being intruded into at least two holes in the
die (8.2.2.1) to a depth of not less than 0,5 mm (see 8.2.4.2). Type 1 Class 1, Type 1 Class 2, and Type 5
materials shall meet the requirements when tested at the final packing time (see 8.2.4.3).
5.2 Polymerized material
5.2.1 Biocompatibility
Specific qualitative requirements for freedom from biological hazard are not included in this part of ISO 20795,
but it is recommended that, in assessing possible biological or toxicological hazards, reference be made to
ISO 10993-1 and ISO 7405.
5.2.2 Surface characteristics
5.2.2.1 When processed in the manner recommended by the manufacturer and in contact with materials
recommended by the manufacturer, denture base specimens prepared in accordance with 8.4.3, 8.8.2.2 and
8.9.3 shall have a smooth, hard and glossy surface (see 8.1.1).
5.2.2.2 The specimens for colour stability, the specimens for residual methyl methacrylate monomer and
the specimens for sorption and solubility testing shall retain their form without visible distortion after
processing (see 8.1.1).
5.2.2.3 When polished in accordance with 8.5.1.4, the specimen plates shall present a smooth surface
with a high gloss (see 8.1.1).
5.2.3 Shape capability
When prepared in accordance with the manufacturer’s instructions, all types of denture base polymers shall
produce a test specimen plate (8.5.1.4) with defined edges after deflasking (see 8.5.1.4).
5.2.4 Colour
The colour of a specimen strip shall be as stated by the manufacturer when tested in accordance with 8.3 and
inspected in accordance with 8.1.1.
4 © ISO 2008 – All rights reserved

ISO 20795-1:2008(E)
The manufacturer shall provide a shade guide on request.
Coloured denture base polymers shall be translucent (see 5.2.6 and 8.5.2) and pigment and fibres shall be
evenly distributed.
Clear (transparent) denture base polymers shall be clear and colourless.
5.2.5 Colour stability
When tested in accordance with 8.4 and inspected in accordance with 8.1.1, test specimens shall not show
more than a slight change in colour.
5.2.6 Translucency
When tested in accordance with 8.5.2.3 the shadow of the illuminated opaque disc shall be visible from the
opposite side of the test specimen plate.
5.2.7 Freedom from porosity
When prepared in accordance with 8.5.3.3, a specimen’s strips shall not show voids that can be observed by
visual inspection (see 8.1.1).
5.2.8 Ultimate flexural strength
When determined in accordance with 8.5.3.5, the ultimate flexural strength shall be not less than 65 MPa for
Type 1, Type 3, Type 4 and Type 5 polymers and not less than 60 MPa for Type 2 polymers (see Table 1).
5.2.9 Flexural modulus
When determined in accordance with 8.5.3.5, the flexural modulus of the processed polymer shall be at least
2 000 MPa for Type 1, Type 3, Type 4 and Type 5 polymers and at least 1 500 MPa for Type 2 polymers
(see Table 1).
5.2.10 Maximum stress intensity factor for materials with improved impact resistance
Where a manufacturer claims a material with improved impact resistance, the maximum stress intensity factor
1/2
shall be at least 1,9 MPa m when tested in accordance with 8.6 (see Table 2).
5.2.11 Total fracture work
Where a manufacturer claims a material with improved impact resistance, the total fracture work shall be at
least 900 J/m when tested in accordance with 8.6 (see Table 2).
5.2.12 Bonding to synthetic polymer teeth
Denture base polymers intended for use with synthetic polymer teeth shall meet one of the following
requirements.
a) The polymer shall, when tested in accordance with 8.7, be capable of bonding to polymer teeth complying
with the bonding requirements of ISO 22112.
b) If there are problems of achieving bonding, the manufacturer’s instructions shall contain information about
special treatments necessary to achieve bonding [see 9.3 k)].
ISO 20795-1:2008(E)
5.2.13 Residual methyl methacrylate monomer
When prepared and tested in accordance with 8.8 the following shall apply (see Table 1).
The upper limit (maximum) for residual methyl methacrylate is 2,2 % mass fraction for denture base polymers
of Type 1, Type 3, Type 4 and Type 5.
The upper limit (maximum) for residual methyl methacrylate is 4,5 % mass fraction for denture base polymers
of Type 2.
If lower percentages of residual methyl methacrylate monomer are claimed by the manufacturer [see 9.3 m)],
the content shall not be more than 0,2 % mass fraction higher than that stated by the manufacturer.
5.2.14 Sorption
When the processed polymer is tested in accordance with 8.9, the increase in mass per volume (water
sorption) shall not exceed 32 µg/mm (see Table 1).
5.2.15 Solubility
When the processed polymer is tested in accordance with 8.9, the loss in mass (soluble matter) per volume
shall not exceed 1,6 µg/mm for Type 1, Type 3, Type 4 and Type 5 polymers, and shall not exceed
8,0 µg/mm for Type 2 polymers (see Table 1).
Table 1 — Summary of requirements described in 5.2.8, 5.2.9, 5.2.13, 5.2.14 and 5.2.15
Flexural properties
Ultimate flexural Flexural Residual methyl methacrylate
Sorption Solubility
strength modulus monomer
Requirements
σ E w w
sp sl
3 3
MPa MPa Percent mass fraction µg/mm µg/mm
min. min. max. max. max.
Types 1, 3, 4, 5 65 2 000 2,2 32 1,6
Type 2 60 1 500 4,5 32 8,0
Table 2 — Additonal requirements for materials with improved
impact resistance described in 5.2.10 and 5.2.11
Fracture toughness
Maximum stress intensity factor Total fracture work
K W
Requirements
max f
1/2 2
MPa m J/m
min. min.
Materials with improved impact resistance 1,9 900
6 Sampling
The test sample shall consist of a retail package or packages, containing sufficient material to carry out the
specified tests, plus an allowance for any necessary repetition of the tests. If more than one package is
required, all material shall be of the same batch.
6 © ISO 2008 – All rights reserved

ISO 20795-1:2008(E)
7 Preparation of test specimens
7.1 Laboratory environment
Prepare and test specimens at (23 ± 2) °C and (50 ± 10) % relative humidity, unless otherwise specified in this
part of ISO 20795 or in the manufacturer's instructions.
7.2 Procedures
Prepare, manipulate and process materials for making the specimens using the equipment and procedures
recommended in the manufacturer's instructions (see 9.3), unless otherwise specified in this International
Standard.
From materials requiring a mixture of two or more ingredients, prepare separate mixes for each specimen or
specimen plate.
7.3 Special equipment
Any special equipment specified by the manufacturer for processing a material shall be made available by the
manufacturer.
8 Test methods
8.1 Inspection for compliance determination
8.1.1 Visual inspection
Observe the test samples by visual inspection to determine compliance with the requirements laid down in
5.1.1.2, 5.1.2, 5.2.2, 5.2.3, 5.2.4, 5.2.5, 5.2.6, 5.2.7 and Clause 9. [Inspect for colour (5.2.4) and colour
stability (5.2.5) in accordance with ISO 7491].
8.1.2 Expression of results
Report whether the liquid components pass or fail (see 5.1.1.2).
Report whether the solid components pass or fail (see 5.1.2).
Report whether the surfaces of the denture base specimens have a smooth, hard and glossy surface
(see 5.2.2.1), and whether the specimens pass or fail.
Report whether the form of specimens is retained without distortion and whether the specimens pass or fail
(see 5.2.2.2).
Report whether the specimen plates have a smooth surface with a high gloss after polishing, and whether the
specimen plate passes or fails (see 5.2.2.3).
Report whether the specimen plate has defined edges, and whether the specimen plate passes or fails
(see 5.2.3).
Report whether the material passes or fails the requirements for labelling, marking, packaging and instructions
(see Clause 9).
ISO 20795-1:2008(E)
8.2 Packing plasticity
8.2.1 Materials
8.2.1.1 Polyethylene or polyester film, 0,035 mm to 0,050 mm thick and approximately 50 mm × 50 mm.
8.2.1.2 Glass plate, (60 ± 5) mm × (60 ± 5) mm × (5 ± 1) mm.
8.2.2 Apparatus
8.2.2.1 Perforated brass die, having the dimensions shown in Figure 1, with perforations having a
diameter of (0,75 ± 0,05) mm.
Dimensions in millimetres
Dimensional tolerances not specified shall be ± 1 mm.
Figure 1 — Perforated brass die for packing plasticity test
8.2.2.2 Weight, capable of exerting a force of (50 ± 1) N.
8.2.2.3 Dial gauge, complying with ISO 463, or linear gauge accurate to 0,01 mm, equipped with a probe
capable of entering holes in the brass die for measuring depth of penetration of the material into the die.
8.2.3 Test conditions
Maintain the perforated brass die (8.2.2.1) and glass plate (8.2.1.2) at conditions specified in 7.1, except
where otherwise specified by the manufacturer.
8 © ISO 2008 – All rights reserved

ISO 20795-1:2008(E)
8.2.4 Procedure
8.2.4.1 General
The materials are tested at the times following mixing as shown in Table 3. See 3.11 and 3.12 for packing
time definitions.
Table 3 — Testing procedure
Type 1 Type 1 Type 2 Type 2
Type 3 Type 5
Class 1 Class 2 Class 1 Class 2
Initial packing time — — — —
× ×
Final packing time × × — — — ×
8.2.4.2 Initial packing time for Type 1 Class 1 and Type 2 Class 1
Prepare a sample of the material having a mass of 16 g to 20 g. Immediately prior to the manufacturer's
recommended initial packing time [see 9.3 e)], immediately shape one-half of the sample into a cake
approximately 5 mm thick, place it on the upper surface of the brass die (8.2.2.1) and cover it with a plastic
film (8.2.1.1). At the recommended initial packing time, place the glass plate (8.2.1.2) and the weight (8.2.2.2)
on the plastic-covered resin cake. After 10 min ± 30 s, remove the weight. When the material is firm, introduce
the measuring instrument probe (8.2.2.3) into each hole from the other side of the brass die, to contact the
penetrating material to determine the unpenetrated depth in the hole.
Calculate the depth of penetration for each hole according to the following formula:
′
D=−dd
P
where
D is the depth of penetration, in millimetres;
P
d is the thickness of the brass die, in millimetres;
d' is the depth not penetrated, in millimetres.
8.2.4.3 Final packing time for Type 1 Class 1, Type 1 Class 2 and Type 5
Immediately before the final packing time [see 9.3 e)] recommended by the manufacturer, immediately shape
the second half of the sample into a cake and test this portion in accordance with 8.2.4.2.
8.2.5 Pass/fail determinations
If the first sample fails to comply with the requirement stated in 5.1.3 test two additional samples. If the second
and third samples comply with the requirement, the product passes.
8.2.6 Expression of results
Report the number of holes penetrated to a depth of not less than 0,5 mm by each sample and whether the
material passes or fails.
ISO 20795-1:2008(E)
8.3 Colour
8.3.1 General
Compare a specimen strip prepared in accordance with 8.5.3.3, and inspected in accordance with 8.1.1, with
the shade guide, for compliance with 5.2.4.
8.3.2 Expression of results
Report whether the material passes or fails in accordance with ISO 7491.
8.4 Colour stability
8.4.1 Materials
8.4.1.1 Sheet of polyester film, having a thickness of (50 ± 25) µm to cover the steel mould (8.4.2.1).
8.4.1.2 Aluminium foil.
8.4.2 Apparatus
8.4.2.1 Circular stainless steel mould and cover (for Type 1 and Type 2 Class 1 materials), having the
dimensions shown in Figure 2, mounted in gypsum in separate halves of a denture flask.
10 © ISO 2008 – All rights reserved

ISO 20795-1:2008(E)
Dimensions in millimetres
a)  mould b)  cover
a
mould depth to form specimen
Dimensional tolerances not specified shall be ± 0,2 mm
Figure 2 — Stainless steel mould and cover for specimen preparation of colour stability sorption
and solubility (see 8.4 and 8.9)
8.4.2.2 Moulds and/or equipment (for Type 2 Class 2, Type 3, Type 4, Type 5 and capsulated
materials) recommended by the manufacturer to produce specimens with the dimensions specified in 8.4.3.
8.4.2.3 Hydraulic or hand press and clamp, where applicable.
8.4.2.4 Water bath, capable of maintaining constant temperatures, where applicable.
8.4.2.5 Micrometer screw gauge or dial calliper, accurate to 0,01 mm and fitted with parallel anvils.
8.4.2.6 Oven, capable of being maintained at (37 ± 1) °C.
ISO 20795-1:2008(E)
8.4.2.7 Radiation source and test chamber, see 3.1.1 and 3.1.3 of ISO 7491:2000.
8.4.3 Preparation of test specimens
8.4.3.1 Type 1 and Type 2 Class 1 materials
Make two specimens from separate mixes. Mix the resin and pack the mixture into the mould (8.4.2.1) with the
polyester film (8.4.1.1) against the steel cover of the mould. Process the mixture in accordance with the
manufacturer's instructions (see 9.3), but retain the polyester film during the processing cycle.
Check with a micrometer or dial calliper (8.4.2.5) to ensure that each specimen has a diameter of (50 ± 1) mm
and a thickness of (0,5 ± 0,1) mm and that the top and bottom surfaces are flat.
8.4.3.2 Type 2 Class 2, Type 3, Type 4, Type 5 and capsulated materials
Prepare the specimens as described by the manufacturer.
Check with a micrometer or dial calliper (8.4.2.5) to ensure that each specimen has a diameter of (50 ± 1) mm
and a thickness of (0,5 ± 0,1) mm and that the top and bottom surfaces are flat.
8.4.4 Procedure
Store the two specimens in the oven (8.4.2.6) for 24 h ± 30 min at (37 ± 1) °C. Then store one specimen in the
dark in a laboratory environment (see 7.1) until the colour comparison test is made.
Cover half of the second specimen with aluminium foil (8.4.1.2) and transfer it to the radiation source and test
chamber (8.4.2.7). Immerse the specimen in water at (37 ± 5) °C when exposed to the radiation for
24 h ± 30 min in accordance with ISO 7491. After exposure, remove the aluminium foil before colour
comparison of the specimens including the unexposed specimen.
Carry out the colour comparison in accordance with the requirements specified in 5.2.5 and in accordance
with the procedure for colour comparison laid down in ISO 7491.
For Type 4 materials, store the exposed specimen in a laboratory environment (see 7.1) for 6 d ± 2 h until the
colour comparison test is made.
8.4.5 Expression of results
Report whether the material passes or fails in accordance with ISO 7491 and 5.2.5.
8.5 Polishability, translucency, freedom from porosity, ultimate flexural strength and
flexural modulus
8.5.1 Polishability
8.5.1.1 Materials
8.5.1.1.1 Polishing compound.
8.5.1.1.2 Wet pumice, having a grain size of approximately 10 µm to 20 µm.
8.5.1.2 Apparatus
8.5.1.2.1 Model of the specimen plate, in metal or polymer (see Figure 3).
12 © ISO 2008 – All rights reserved

ISO 20795-1:2008(E)
Dimensions in millimetres
Dimensional tolerances shall be ± 1 mm.
Figure 3 — Model of the specimen plate
8.5.1.2.2 Denture flask, capable of accommodating the test specimen plate so that the corners are not
less than 5 mm from the walls of the flask.
8.5.1.2.3 Equipment for processing the resin, including gypsum or hydrocolloid investment system [see
9.3 f)].
8.5.1.2.4 Standard metallographic grinding paper, with a grain size of approximately 30 µm (P500).
NOTE See ISO 6344-1.
8.5.1.2.5 Muslin wheel, with 16 to 36 ply having a diameter of 70 mm to 95 mm and at least 10 mm
between the periphery and the stitching or other reinforcement.
8.5.1.2.6 Unstitched muslin wheel, with 16 to 36 ply having a diameter of 70 mm to 95 mm.
8.5.1.3 Preparation of the mould
For Type 1 and Type 2 Class 1 polymers, invest the model of the specimen plate (8.5.1.2.1) in the denture
flask (8.5.1.2.2) in accordance with the manufacturer's instructions. Prepare the mould for Type 2 Class 2,
Type 3, Type 4, Type 5 and capsulated materials in accordance with the manufacturer's instructions.
8.5.1.4 Procedure
Form and process, according to the manufacturer’s instructions, two specimen plates each from a separate
mix. Use the material (8.5.1.1), the apparatus (8.5.1.2) and the mould (8.5.1.3). Grind and polish the surfaces
of the specimen plates for no longer than 1 min with pumice (8.5.1.1.2) and with a wet muslin wheel
(8.5.1.2.5) at a circumferential speed of (650 ± 350) m/min.
−1
NOTE A wheel with a diameter of 70 mm rotating at 1 500 min will have a circumferential speed of 329 m/min and
−1
a 100 mm wheel rotating at 3 500 min will have a circumferential speed of 1 100 m/min.
Thereafter polish with an unstitched muslin wheel (8.5.1.2.6) using a polishing compound (8.5.1.1.1).
After polishing and cleaning, examine the polished surfaces for compliance with 5.2.2.3.
ISO 20795-1:2008(E)
8.5.1.5 Pass/fail determination
If both specimen plates comply with 5.2.2.3, the material passes.
If both specimen plates fail to comply with 5.2.2.3, the material fails.
If only one of the specimen plates complies, prepare and evaluate three new plates. The material passes only
if all three new plates comply.
8.5.1.6 Expression of results
Report the number of specimen plates evaluated, the number complying and whether the material passes.
8.5.2 Translucency
8.5.2.1 Materials
8.5.2.1.1 Two specimen plates, prepared and tested according to 8.5.1.
8.5.2.2 Apparatus
8.5.2.2.1 Electrical light bulb, frosted 40 W.
NOTE Other frosted electrical light sources of equivalent radiant excitance can be used.
8.5.2.2.2 Opaque disc, diameter (10 ± 1) mm and thickness (2 ± 1) mm.
8.5.2.3 Procedure
Examine each of the two specimen plates separately. Position the polished specimen plate approximately
500 mm from the light bulb (8.5.2.2.1) with the opaque disc (8.5.2.2.2) centred in between. Darken the room.
View the specimen plate from the side opposite the disc location to determine whether the material complies
with 5.2.6.
8.5.2.4 Pass/fail determination
If both specimen plates comply with 5.2.6, the material passes.
If both specimen plates fail, the material fails.
If only one of the specimen plates passes, prepare and evaluate three new plates. The material passes only if
all three new plates comply.
8.5.2.5 Expression of results
Report the number of specimen plates evaluated, the number complying and whether the material passes.
8.5.3 Freedom from porosity, ultimate flexural strength and flexural modulus
8.5.3.1 Materials
8.5.3.1.1 Two specimen plates, prepared and tested in accordance with 8.5.1 and 8.5.2.
8.5.3.2 Apparatus
8.5.3.2.1 Motorised saw, or other cutting device for sectioning the specimen plates.
14 © ISO 2008 – All rights reserved

ISO 20795-1:2008(E)
8.5.3.2.2 Milling machine, or other equipment for air- or water-cooled cutting so as not to generate
temperatures above 30 °C during shaping of the specimens. (A machine with a milling head and a sharp
carbide edge, is suitable.)
8.5.3.2.3 Standard metallographic grinding papers, having a grain size of approximately 30 µm (P500),
18 µm (P1 000) and 15 µm (P1 200).
NOTE See ISO 6344-1.
8.5.3.2.4 Micrometer screw gauge and/or dial calliper, accurate to 0,01 mm and fitted with parallel
anvils.
8.5.3.2.5 Container containing water, complying with grade 3 of ISO 3696:1987, for storing the specimen
strips at (37 ± 1) °C for pre-test conditioning.
8.5.3.2.6 Testing machine, calibrated to provide a constant displacement rate of (5 ± 1) mm/min and
equipped with instrumentation for measuring the deflection of the specimen to within 0,025 mm.
Take into account any load exerted by the deflection instrument when calibrating the machine.
8.5.3.2.7 Metal flexural test rig, consisting of a central loading plunger and two polished cylindrical
supports, 3,2 mm in diameter and at least 10,5 mm long.
The supports shall be parallel to within 0,1 mm and perpendicular to the longitudinal centreline. The distance
between centres of the supports shall be (50 ± 0,1) mm, and the loading plunger shall be midway between the
supports to within 0,1 mm. Include means in the design, to prevent misalignment of the specimen.
8.5.3.2.8 Water bath, for maintaining the specimens wet and at a temperature of (37 ± 1) °C, during testing.
8.5.3.3 Procedure
Prepare six specimen strips. Cut each plate lengthways into three equal strips, 64 mm long, (10,0 ± 0,2) mm
wide and (3,3 ± 0,2) mm in height. Machine the strips in a milling machine (8.5.3.2.2) on the edges and
equally from both moulded surfaces so that the dimensions remain slightly oversized. Take care to avoid
overheating the specimen. Wet-grind all faces and edges smooth and flat with the metallographic grinding
papers (8.5.3.2.3) to the required width and height. Make three measurements of the specimen height along
the long axis with an accuracy of ± 0,01 mm using a micrometer, and/or dial calliper (8.5.3.2.4). The deviation
between the three measurements along the long axis shall be no more than ± 0,02 mm. The specimen shall
be flat and have an even height.
8.5.3.4 Freedom from porosity
8.5.3.4.1 Pass/fail determination
Prepare six test specimen strips in accordance with 8.5.3.3 and examine for compliance with 5.2.7.
The material passes only if at least five out of six specimen strips comply with the requirements given in 5.2.7.
8.5.3.4.2 Expression of results
Report the number of specimen strips complying and whether the material passes.
ISO 20795-1:2008(E)
8.5.3.5 Ultimate flexural strength and flexural modulus
8.5.3.5.1 Procedure
Store five specimen strips [or six in the case of repetition of the test (see 8.5.3.5.2.3 and 8.5.3.5.2.4)],
prepared according to 8.5.3.3 and complying with 5.2.7, in water (8.5.3.2.5) at a temperature of (37 ± 1) °C for
(50 ± 2) h prior to flexural testing. Take a specimen strip from water storage and immediately lay the flat
surface symmetrically on the supports of the flexural test rig (8.5.3.2.7) immersed in the water bath (8.5.3.2.8).
Allow the specimen to come to equilibrium with the water bath temperature.
Increase the force on the loading plunger from zero, uniformly, using a constant displacement rate of
(5 ± 1) mm/min until the specimen breaks.
8.5.3.5.2 Calculation and expression of results
8.5.3.5.2.1 Ultimate flexural strength
Calculate the ultimate flexural strength, σ, in megapascals using the following equation:
3Fl
σ=
2bh
where
F is the maximum load, in newtons, exerted on the specimen;
l is the distance, in millimetres, between the supports, accurate to ± 0,01 mm;
b is the width, in millimetres, of the specimen measured immediately prior to water storage;
h is the height, in millimetres, of the specimen measured immediately prior to water storage.
8.5.3.5.2.2 Flexural modulus
Calculate the flexural modulus E, in megapascals, using the following equation:
F l
E=
4bh d
where
F is the load, in newtons, at a point in the straight line portion (with the maximum slope) of the
load/displacement curve;
NOTE For greater accuracy, the straight line may be extended.
d is the deflection, in millimetres, at load F ;
l ,b and h are as defined in 8.5.3.5.2.1.
8.5.3.5.2.3 Pass/fail determination of ultimate flexural strength
If at least four out of five specimens give results not less than 65 MPa for Type 1, Type 3, Type 4 and Type 5
polymers and not less than 60 MPa for Type 2 polymers, the material is deemed to have complied with the
requirements of 5.2.8.
16 © ISO 2008 – All rights reserved

ISO 20795-1:2008(E)
If at least three of the results are less than 65 MPa for Type 1, Type 3, Type 4 and Type 5 polymers and less
than 60 MPa for Type 2 polymers, the material is deemed to have failed.
If two of the results are less than 65 MPa for Type 1, Type 3, Type 4 and Type 5 polymers and 60 M
...