SIST EN ISO 12836:2012

SLOVENSKI STANDARD
SIST EN ISO 12836:2012
01-december-2012
=RER]GUDYVWYR'LJLWDOQHQDSUDYH]DXSRUDERVLVWHPRY&$'&$0]DSRVUHGQH
]REQHUHVWDYUDFLMHREQRYR3UHVNXVQHPHWRGH]DXJRWDYOMDQMHWRþQRVWL,62

Dentistry - Digitizing devices for CAD/CAM systems for indirect dental restorations - Test
methods for assessing accuracy (ISO 12836:2012)
Zahnheilkunde - Digitalisierungsgeräte für CAD/CAM-Systeme für indirekte dentale
Restaurationen - Prüfverfahren zur Beurteilung der Genauigkeit (ISO 12836:2012)
Médecine bucco-dentaire - Dispositifs de numérisation des systèmes CAD/CAM pour
restorations dentaires indirectes - Méthodes d'essai pour l'exactitude d'évaluation (ISO
12836:2012)
Ta slovenski standard je istoveten z: EN ISO 12836:2012
ICS:
11.060.01 Zobozdravstvo na splošno Dentistry in general
35.240.80 Uporabniške rešitve IT v IT applications in health care
zdravstveni tehniki technology
SIST EN ISO 12836:2012 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST EN ISO 12836:2012

---------------------- Page: 2 ----------------------

SIST EN ISO 12836:2012


EUROPEAN STANDARD
EN ISO 12836

NORME EUROPÉENNE

EUROPÄISCHE NORM
September 2012
ICS 11.060.01
English Version
Dentistry - Digitizing devices for CAD/CAM systems for indirect
dental restorations - Test methods for assessing accuracy (ISO
12836:2012)
Médecine bucco-dentaire - Dispositifs de numérisation des Zahnheilkunde - Digitalisierungsgeräte für CAD/CAM-
systèmes de CFAO pour restaurations dentaires - Systeme für indirekte dentale Restaurationen -
Méthodes d'essai pour l'évaluation de l'exactitude (ISO Prüfverfahren zur Beurteilung der Genauigkeit (ISO
12836:2012) 12836:2012)
This European Standard was approved by CEN on 14 September 2012.

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
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 12836:2012: E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------

SIST EN ISO 12836:2012
EN ISO 12836:2012 (E)
Contents Page
Foreword .3

2

---------------------- Page: 4 ----------------------

SIST EN ISO 12836:2012
EN ISO 12836:2012 (E)
Foreword
This document (EN ISO 12836:2012) has been prepared by Technical Committee ISO/TC 106 "Dentistry" in
collaboration with Technical Committee 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 2013, and conflicting national standards shall be withdrawn at
the latest by March 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.
According to the CEN/CENELEC Internal Regulations, the national standards organisations 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 12836:2012 has been approved by CEN as a EN ISO 12836:2012 without any modification.

3

---------------------- Page: 5 ----------------------

SIST EN ISO 12836:2012

---------------------- Page: 6 ----------------------

SIST EN ISO 12836:2012
INTERNATIONAL ISO
STANDARD 12836
First edition
2012-10-01
Dentistry — Digitizing devices for
CAD/CAM systems for indirect dental
restorations — Test methods for
assessing accuracy
Médecine bucco-dentaire — Dispositifs de numérisation des systèmes
de CFAO pour restaurations dentaires — Méthodes d’essai pour
l’évaluation de l’exactitude
Reference number
ISO 12836:2012(E)
©
ISO 2012

---------------------- Page: 7 ----------------------

SIST EN ISO 12836:2012
ISO 12836:2012(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2012
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 2012 – All rights reserved

---------------------- Page: 8 ----------------------

SIST EN ISO 12836:2012
ISO 12836:2012(E)
Contents Page
Foreword .iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements . 4
4.1 General . 4
4.2 Accuracy . 4
5 Test methods . 4
5.1 General . 4
5.2 Test conditions . 4
5.3 Accuracy . 5
6 Test report . 5
Annex A (normative) Inlay-shaped specimen . 6
Annex B (normative) Crown- and bridge-shaped specimens .10
Annex C (normative) Sphere .14
Bibliography .17
© ISO 2012 – All rights reserved iii

---------------------- Page: 9 ----------------------

SIST EN ISO 12836:2012
ISO 12836:2012(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 12836 was prepared by Technical Committee ISO/TC 106, Dentistry, Subcommittee SC 9, Dental
CAD/CAM systems.
iv © ISO 2012 – All rights reserved

---------------------- Page: 10 ----------------------

SIST EN ISO 12836:2012
ISO 12836:2012(E)
Introduction
The application of dental CAD/CAM systems is increasing throughout the world.
This International Standard specifies three test methods for assessing the accuracy of dental digitizing devices
used for CAD/CAM systems.
This International Standard is based on the premise that only the matched point cloud and the resulting
Standard Tesselation Language surface (STL surface) thereof be regarded as the product of scanning the
physical object.
This International Standard includes the measurement of the image that is digitized from dental scanners (intra-
oral scanners, lab-based optical scanners and lab-based mechanical contact scanners). Digitized images are
not only used for the fabrication of restorative products but also applied to teaching and research in dentistry,
in such areas as occlusion, tooth and gingival contour change measurements, and so forth.
It was felt that, besides the sphere, more physical objects are required, for example a surface with an inlay-
shaped cavity with a sharp edge to simulate the edge of an inlay preparation. When no means (for example
software algorithm) are available to calculate a standard deviation of discrepancies between the points of
the point cloud or STL surface and the physical object’s surface as a measure for accuracy, some software
is required to match the CAD STL formatfile of the physical object with the point cloud or STL surface and
visualize discrepancies, resulting in a qualitative assessment.
The following three specimens (two dental and one technical), which are specified in Annexes A, B and C, can
be used for assessing digitizing devices:
a) inlay-shaped specimen in order to simulate inlay-shaped cavities;
b) multi-unit specimen, consisting of two full coverage dies with a centre-to-centre distance of 30 mm, being
designed to simulate digitizing a 4-unit-bridge;
c) a sphere, the measurement of which is limited to the hemisphere lying above the horizontal plane.
ISO 5725-1 uses two terms, “trueness” and “precision”, to describe the accuracy of a measurement method.
“Trueness” refers to the closeness of agreement between the arithmetic mean of a large number of test results
and the true or accepted value. “Precision” refers to the closeness of agreement between test results. The
general term “accuracy” is used to refer to both trueness and precision.
© ISO 2012 – All rights reserved v

---------------------- Page: 11 ----------------------

SIST EN ISO 12836:2012

---------------------- Page: 12 ----------------------

SIST EN ISO 12836:2012
INTERNATIONAL STANDARD ISO 12836:2012(E)
Dentistry — Digitizing devices for CAD/CAM systems for indirect
dental restorations — Test methods for assessing accuracy
1 Scope
This International Standard specifies test methods for the assessment of the accuracy of digitizing devices for
computer-aided design/computer-aided manufacturing (CAD/CAM) systems for indirect dental restorations.
These test methods are not applicable to digitization by radiographic methods (X-ray) and by magnetic
resonance imaging methods (MRI).
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable
for its application. For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
ISO 554, Standard atmospheres for conditioning and/or testing — Specifications
ISO 1942, Dentistry — Vocabulary
ISO 3290-2, Rolling bearings — Balls — Part 2: Ceramic balls
ISO 5725-1, Accuracy (trueness and precision) of measurement methods and results — Part 1: General
principles and definitions
ISO/IEC Guide 99, International vocabulary of metrology — Basic and general concepts and associated terms (VIM)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1942, ISO 5725-1 and ISO Guide 99
and the following apply.
3.1
accuracy
〈measurement〉 closeness of agreement between a result of a measurement and a true value of the measurand
NOTE 1 to entry: Accuracy is a qualitative concept. Its quantitative counterpart is trueness.
[SOURCE: ISO 5725-1:1994, definition 3.6, modified]
3.2
calibration
set of operations that establish, under specified conditions, the relationship between values of quantities
indicated by a measuring instrument or measuring system, or values represented by a material measure or a
reference material and the corresponding values realized by standards
3.3
digitizing device
dental surface data acquisition device
device for computer-aided design and manufacturing of custom-made indirect dental restorations used to
record the topographical characteristics of teeth and surrounding tissues, implant connecting components,
dental impressions, dental moulds or stone models by analogue or digital methods
NOTE 1 to entry: These systems consist of a scanning device, hardware and software.
© ISO 2012 – All rights reserved 1

---------------------- Page: 13 ----------------------

SIST EN ISO 12836:2012
ISO 12836:2012(E)
NOTE 2 to entry: A surface digitization procedure starts with the generation of actually measured surface points (or
their conversion, for example, in STL format), which are the measured digitization data. In most digitizing systems, the
measured points are mathematically processed by operations such as:
— matching
— filtering
— weighing
— selective removal
— smoothing, etc.
This results in the processed digitization data (or surface data). These data depend very much on, for example, the
digitization protocol (for example the number of passes), the extraction method of a surface from the raw data points and
the matching of point clouds.
3.4
error
〈measurement〉 result of a measurement minus a true value of the measurand
NOTE 1 When it is necessary to distinguish “error” from “relative error”, the former is sometimes called “absolute trueness”.
NOTE 2 In many instances, the trueness is called “total error”.
3.5
indirect dental restoration
any kind of restoration manufactured extraorally which replaces intra-oral hard and/or soft tissues
EXAMPLE Crowns, bridges, inlays, implant superstructures, prostheses, provisional restorations.
NOTE 1 to entry: Epitheses that involve the oral cavity are included; devices for short-term use, for example surgical
guides, are excluded.
3.6
measurand
particular quantity subject to measurement
3.7
measurement procedure
set of operations which are specifically used in the performance of particular measurements according to a
given technique
NOTE 1 to entry: In a quality system, a measurement procedure is recorded as a working instructions document and
should be described in sufficient detail to enable an operator to carry out a measurement without additional information.
3.8
precision
closeness of agreement between independent results of measurement obtained under stipulated conditions
[SOURCE: ISO 5725-1:1994, definition 3.12, modified]
3.9
random error
result of a measurement minus the mean that would result from an infinite number of measurements of the
same measurand carried out under repeatable conditions
NOTE 1 to entry: Random error is equal to trueness minus systematic error.
NOTE 2 to entry: In practice, random error may be estimated from 20 or more repeated measurements of a measurand
under specified conditions.
2 © ISO 2012 – All rights reserved

---------------------- Page: 14 ----------------------

SIST EN ISO 12836:2012
ISO 12836:2012(E)
3.10
relative error
trueness divided by a true value of the measurand
3.11
repeatability
〈results of measurements〉 closeness of the agreement between the results of successive measurements of the
same measurand carried out under the same conditions of measurement
NOTE 1 to entry: Repeatability is a qualitative concept. Its quantitative counterpart is standard deviation of repeatability or
coefficient of variation of repeatability of the measurement results.
NOTE 2 to entry: Repeatability may depend on the value of the measurand.
3.12
repeatability conditions
conditions where independent results of measurements are obtained with the same measurement procedure
in the same laboratory by the same operator using the same equipment within short intervals of time without
new calibration
[SOURCE: ISO 5725-1:1994, definition 3.14, modified]
3.13
reproducibility
〈results of measurements〉 closeness of the agreement between the results of measurements of the same
measurand carried out under changed conditions of measurement
NOTE 1 to entry: The changed conditions may include the observer, measuring instrument, location and time.
NOTE 2 to entry: The set of specified conditions is termed “reproducibility conditions”.
NOTE 3 to entry: Reproducibility is a qualitative concept. Its quantitative counterpart is standard deviation of reproducibility
or coefficient of variation of reproducibility of the measurement results.
NOTE 4 to entry: Reproducibility may depend on the value of the measurand.
3.14
reproducibility conditions
conditions where results of measurements are obtained on the same measurand under different conditions in
different laboratories
NOTE 1 to entry: The different conditions should be specified.
[SOURCE: ISO 5725-1:1994, definition 3.18, modified]
3.15
systematic error
mean that would result from an infinite number of measurements of the same measurand carried out under
repeatable conditions minus a true value of the measurand
NOTE 1 to entry: Systematic error is equal to trueness minus random error.
NOTE 2 to entry: Systematic error may be constant or proportional to the value of the measurand.
NOTE 3 to entry: In practice, systematic error is estimated from 30 or more repeated measurements of a measurand under
specified conditions.
3.16
true value (of a quantity)
value consistent with the definition of a given particular quantity
NOTE 1 to entry: This is a value that would be obtained by a perfect measurement. True values are by nature indeterminate.
© ISO 2012 – All rights reserved 3

---------------------- Page: 15 ----------------------

SIST EN ISO 12836:2012
ISO 12836:2012(E)
NOTE 2 to entry: The indefinite article “a”, rather than the definite article “the” is used in conjunction with “true value”
because there may be many values consistent with the definition of a given particular quantity.
3.17
trueness
closeness of agreement between the mean obtained from repeated measurements and a true value or a
conventional true value
NOTE 1 to entry: Trueness is a qualitative concept. Its quantitative counterpart is systematic error.
[SOURCE: ISO 5725-1:1994, definition 3.7, modified]
4 Requirements
4.1 General
The manufacturer of the digitizing device shall provide product-specific information including instructions for use.
The digitization device shall be driven by software recommended by the supplier or manufacturer for digitization
and rendering of the scanned physical object surface.
4.2 Accuracy
The manufacturer of the digitizing device shall provide product-specific information on the accuracy (trueness
and precision) of the digitizing device (e.g. a description of the tested object) in the instructions for use.
In order to determine the quality of a digitizing device in terms of accuracy, repeatability and reproducibility,
known physical objects shall be analysed for structures that are important for the purpose of generating indirect
dental restorations. The manufacturer of the digitizing device shall report on the tests carried out, for example
in the instructions for use.
From the assessment performed with the test specimens specified in Annexes A, B or C, the manufacturer
shall derive comprehensive documentation.
The test procedure used shall be reported.
EXAMPLE “Tested in accordance with ISO 12836:2012, Annex A, Inlay-shaped specimen.”
5 Test methods
5.1 General
Use at least two of the test methods described in Annexes A, B and C.
5.2 Test conditions
Testing shall be done under the following test conditions:
a) the change of temperature during the test shall remain within ± 1 °C;
b) the ambient room temperature shall be (23 ± 2) °C in accordance with ISO 554;
c) the quality of the data set in terms of any missing or corrupted data shall be evaluated by the operator; in
cases of missing or corrupted data, the test shall be repeated.
4 © ISO 2012 – All rights reserved

---------------------- Page: 16 ----------------------

SIST EN ISO 12836:2012
ISO 12836:2012(E)
5.3 Accuracy
5.3.1 Repeatability
Repeat the measurement 30 times without removing the test specimen from the digitizing device. Use the test
specimen and procedures specified in Annex A, B or C as recommended in the manufacturer’s instructions for
use. Calculate the mean and standard deviation of the 30 measurements. Record this value(s).
5.3.2 Reproducibility
Repeat the measurement 30 times, removing the test specimen from the digitizing device and replacing it into
the digitizing device. Use the test specimen and procedures specified in Annex A, B or C as recommended in
the manufacturer’s instructions for use. Calculate the mean and standard deviation of the 30 measurements.
Record this value(s).
5.3.3 Trueness
Calculate the difference between the mean of the 30 repeatability measurements and the true value.
6 Test report
Prepare a written test report. The test report shall contain at least the following information:
a) reference to this International Standard;
b) reference to the annexes of this International Standard used for testing;
c) identification of the test specimen (i.e. inlay-shaped specimen, crown-shaped specimen, bridge-shaped
specimen, sphere specimen);
d) specimen surface preparation;
e) test conditions, including the number of scanning views manually matched, if it is necessary according to
the measurement procedure as specified in the manufacturer’s instructions;
f) trueness;
g) mean and standard deviation for repeatability and reproducibility of measurement;
h) software and the version of the software used for assessment;
i) full identification and qualifications of the person who performed the test;
j) full documentation of the conditions used during reproducibility testing.
In addition, the following information shall be included for tests made in accordance with Annex C:
— number of measured points;
— histogram distribution of points;
— mean radius, R ;
mn
— minimum and maximum radius;
— radius deviation.
© ISO 2012 – All rights reserved 5

---------------------- Page: 17 ----------------------

SIST EN ISO 12836:2012
ISO 12836:2012(E)
Annex A
(normative)

Inlay-shaped specimen
A.1 General
This annex specifies the measurement of an inlay-shaped physical object which simulates an inlay cavity. This
test procedure uses a negative geometry.
A.2 Principle
An inlay-shaped physical object is first measured with a reference measurement system in order to produce a
reference data set (calibration of the measurement object).
Then, the digitizing device under investigation is used to capture the inlay-shaped physical object. The resulting
measurement data are compared to the reference data set.
A.3 Apparatus
A.3.1 Test specimen, in the form of an inlay-shaped physical object, as specified in Figure A.1. The
material of the physical object shall be a dimensionally stable material. It shall be resistant to handling wear. It
shall be compatible with spray, when indicated as necessary for the use of the digitizing device.
NOTE The selection of a material which fulfils the condition of being a dimensional stable material depends on the
digitizing device.
A.3.2 Reference measurement system, with an accuracy of ± 2 µm.
A.3.3 Travelling microscope, with at least 20 × magnification, accurate to 0,01 mm.
A.3.4 Digitizing device under investigation.
A.4 Preparation of test specimen
A.4.1 Geometry, dimensions and tolerances
Figure A.1 gives three primary views of the inlay-shaped physical object.
The precisely machined physical object shall be produced with a defined edge radius.
The specimen consists of the physical object itself and a computer aided design model. Either the physical
object itself is produced with a manufacturing accuracy of ± 2 µm or the physical object is measured with a
measuring device with an accuracy of ± 2 µm.
6 © ISO 2012 – All rights reserved

---------------------- Page: 18 ----------------------

SIST EN ISO 12836:2012
ISO 12836:2012(E)
The dimensions are:
a (7 ± 0,5) mm
b (5 ± 0,5) mm
c (16 ± 1) mm
e (5 ± 0,5) mm
α (16 ± 1)°
x 0,02 mm
y 0,02 mm
z 0,02 mm
Figure A.1 — Test specimen: Inlay-shaped physical object
The parallelism of the planes shall be ± 0,01 mm and the deviation between the angles shall be ± 0,01°.
NOTE The roughness should range between that of a prepared tooth using a medium coarse diamond (about 50
microns) and that of the surface finish of an unprepared tooth (about 5 microns) for intra-oral scanners and that of an epoxy
and stone die material for laboratory-based scanners.
The edges at the top and the bottom of the valleys are generally difficult to manufacture precisely. Therefore,
exclude the corresponding areas shown in Figure A.2 as hatched areas when computing the values of interest.
© ISO 2012 – All rights reserved 7

---------------------- Page: 19 ----------------------

SIST EN ISO 12836:2012
ISO 12836:2012(E)
Dimensions of the hatched areas:
h 2 mm
j 3,5 mm
k
0,5 mm
m
8 mm
Figure A.2 — Hatched areas to be considered
The following data are of specific interest:
a) the height b, which is the distance between the upper and lower planes;
b) the angle α.
A.4.2 Reference data set and calibration of measurement object
Measure the inlay-shaped physical object (A.3.1) with a reference measurement system (A.3.2) in order to
produce a reference data set (calibration of the measurement object).
A.5 Test procedure
Visually inspect the physical object (A.3.1) with a travelling microscope (A.3.3) using 20 × magnification for
surface damage. If necessary, remake the physical object.
Use the digitizing device under investigation (A.3.4) to capture the inlay-shaped physical object (A.3.1). Digitize
the physical object (A.3.1) according to the recommended procedure specified in the manufacturer’s instructions
for digitizing inlay cavities.
Evaluate the processed data (output data) set without any further manipulation of the data handling beyond the
manufacturer’s procedure description for the intended end user.
8 © ISO 2012 – All rights reserved

---------------------- Page: 20 ----------------------

SIST EN ISO 12836:2012
ISO 12836:2012(E)
1)
If necessary, convert the processed data into ASCII or STL format and compare using 3D-analysis software
with the CAD model resulting from precise measurement of the physical object.
The proprietary software algorithms for best fit alignment of the measured data set to the computer-aided
design model are to be applied before extracting the data wh
...