SIST EN ISO 20795-1:2013

SLOVENSKI STANDARD
01-junij-2013
1DGRPHãþD
SIST EN ISO 20795-1:2008
SIST EN ISO 20795-1:2008/AC:2009
Zobozdravstvo - Osnovni polimeri - 1. del: Osnovni polimeri za proteze (ISO 20795-
1:2013)
Dentistry - Base polymers - Part 1: Denture base polymers (ISO 20795-1:2013)
Zahnheilkunde - Kunststoffe - Teil 1: Prothesenkunststoffe (ISO 20795-1:2013)
Médecine bucco-dentaire - Polymères de base - Partie 1: Polymères pour base de
prothèses dentaires (ISO 20795-1:2013)
Ta slovenski standard je istoveten z: EN ISO 20795-1:2013
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
March 2013
ICS 11.060.10 Supersedes EN ISO 20795-1:2008
English Version
Dentistry - Base polymers - Part 1: Denture base polymers (ISO
20795-1:2013)
Médecine bucco-dentaire - Polymères de base - Partie 1: Zahnheilkunde - Kunststoffe - Teil 1: Prothesenkunststoffe
Polymères pour base de prothèses dentaires (ISO 20795- (ISO 20795-1:2013)
1:2013)
This European Standard was approved by CEN on 26 February 2013.

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-CENELEC 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-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20795-1:2013: E
worldwide for CEN national Members.

Contents Page
Foreword . 3
Foreword
This document (EN ISO 20795-1:2013) 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 September 2013, and conflicting national standards shall be
withdrawn at the latest by September 2013.
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 20795-1:2008.
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, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 20795-1:2013 has been approved by CEN as EN ISO 20795-1:2013 without any modification.

INTERNATIONAL ISO
STANDARD 20795-1
Second edition
2013-03-01
Dentistry — Base polymers —
Part 1:
Denture base polymers
Médecine bucco-dentaire — Polymères de base —
Partie 1: Polymères pour base de prothèses dentaires
Reference number
ISO 20795-1:2013(E)
©
ISO 2013
ISO 20795-1:2013(E)
© ISO 2013
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
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Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
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Published in Switzerland
ii © ISO 2013 – All rights reserved

ISO 20795-1:2013(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Classification . 3
5 Requirements . 3
5.1 Unpolymerized material . 3
5.2 Polymerized material . 4
6 Sampling . 6
7 Preparation of test specimens . 6
7.1 Laboratory environment . 6
7.2 Procedures . 7
7.3 Special equipment . 7
8 Test methods . 7
8.1 Inspection for compliance determination . 7
8.2 Packing plasticity . 7
8.3 Colour . 9
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 .21
8.8 Residual methyl methacrylate monomer .22
8.9 Water sorption and solubility .27
9 Requirements for labelling, marking, packaging, and instructions supplied by
the manufacturer .29
9.1 Packaging .29
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 .32
Bibliography .35
ISO 20795-1:2013(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 second edition cancels and replaces the first edition (ISO 20795-1:2008), of which it constitutes a
minor revision. It also incorporates the Technical Corrigendum ISO 20795-1:2008/Cor 1:2009.
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 2013 – All rights reserved

ISO 20795-1:2013(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 20795-1:2013(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 is applicable 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, Geometrical Product Specifications (GPS) — Dimensional measuring equipment — Design and
metrological characteristics of mechanical dial gauges
ISO 1942, Dentistry — Vocabulary
ISO 3696:1987, Water for analytical laboratory use — Specification and test methods
ISO 7491:2000, Dental materials — Determination of colour stability
ISO 20795-1:2013(E)
ISO 8601, Data elements and interchange formats — Information interchange — Representation of
dates and times
ISO 22112:2005, Dentistry — Artificial 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
3.10
packing
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
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ISO 20795-1:2013(E)
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
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
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).
ISO 20795-1:2013(E)
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 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.
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.
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ISO 20795-1:2013(E)
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
1/2
factor 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)].
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.
ISO 20795-1:2013(E)
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
Residual methyl
Flexural properties methacrylate Sorption Solubility
monomer
Ultimate
Flexural
flexural
Requirements
modulus
strength
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 — Additional requirements for materials with improved impact resistance described in
5.2.10 and 5.2.11
Fracture toughness
Maximum stress intensity
Total fracture work
factor
Requirements
K W
max f
1/2 2
MPa m J/m
min. min.
Materials with improved impact
1,9 900
resistance
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.
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.
6 © ISO 2013 – All rights reserved

ISO 20795-1:2013(E)
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 part of ISO 20795.
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).
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.
ISO 20795-1:2013(E)
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.
8.2.4 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.
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ISO 20795-1:2013(E)
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:
′
Dd=−d
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.
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.
ISO 20795-1:2013(E)
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.
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)
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ISO 20795-1:2013(E)
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.
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.
ISO 20795-1:2013(E)
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).
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.
12 © ISO 2013 – All rights reserved

ISO 20795-1:2013(E)
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
−1
329 m/min and 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.
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 on the surface of the
specimen plate nearest to the light bulb. 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.
ISO 20795-1:2013(E)
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.
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 (P1000), and 15 µm (P1200).
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
14 © ISO 2013 – All rights reserved

ISO 20795-1:2013(E)
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.
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
is the maximum load, in newtons, exerted on the specimen;
F
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.
ISO 20795-1:2013(E)
8.5.3.5.2.2 Flexural modulus
Calculate the flexural modulus, E, in megapascals using the following equation:
Fl
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/deflection curve;
NOTE For greater accuracy, the straight line may be extended.
d
is the deflection, in millimetres, at load F ;
are as defined in 8.5.3.5.2.1.
l , b , and h
8.5.3.5.2.3 Pass/fail determination of ultimate flexural strength
If at least four out of fi
...