ISO 9693:2019 download.Dentistry – Compatibility testing for metal-ceramic and ceramic-ceramic systems.
Introduction
Dental veneering ceramics and metal alloys or substructure ceramics are suitable materials for the fabrication of dental restorations. Compatibility between the veneering ceramic and the substructure material under mechanical and thermal loading is essential if they are to function in a prosthetic construction.
ISO 9693 specifies requirements and test methods for assessing the risk of failure associated with masticatory forces and the oral environment.
ISO 9693 specifies requirements and test methods to assess the thermomechanical compatibility between a veneering ceramic and a metallic or ceramic substructure material used for dental restorations.
ISO 9693 applies only to the materials used in combination. Conformity cannot be claimed for single material.
For requirements for ceramic materials, see Iso 6872. For requirements for metallic materials se€
ISO 22674.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their conteni constitutes requirements of ISO 9693. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 1942, Dentistry — Vocabulary
ISO 6872:2015, Dentistry — Ceramic materials
ISO 22674:2016, Dentistry — Metallic materials for fixed and removable restorations and appliances
4 Requirements
4.1 Biocompatibility
Specific qualftatlvc and quantitative test methods for demonstrating freedom from unacceptable biological risks arc not Included in this document, but It Is recommended that. [or the assessment of such biological risks. reference be made to ISO 10993-1 and ISO 7405.
4.2 Physical properties
4.2.1 General
The indh’idual component materials shall fulfil the requirements of ISO 6872 for ceramics or ISO 22674
for metallic materials. The materials shall also be In accordance with the requirements of 4.22 to 42A
where applicable.
In particular, the elastic modulus cii the substrate material shall be determined in order to interpret the measurements in the dc-bonding test.
4.2.2 Thermal expansion
The coefficients of thermal expansion of the substructure ceramic and the veneering ceramic shall be determined according to ISO 6H72,
The coefficients of thermal expansion of the metallic substructure material shall be determined according to ISO 22674.
The same measurement protocol shall be used for both the veneering and substructure materials (e.g. same lowest temperature).
Test in accordance with 6.1.
NOTE The measured values for coelllclents of linear thermal expansion are compared with the manufacturer’s values as a means ci quality control, but the values cannot provide an assurance that the ceramtc or metallic substructure and ceramic veneer are compatible.
4.2.3 De.hondingJcrack-initiation test
4.2.3.1 Metallic substructure material
The debondlng/crack.initIatIon strength of the metallic substructure material and at least one, nominated selected dental veneering ceramic shall be greater than 25 MPa.
Test in accordance with 6.4.
4.2.3.2 Ceramic substructure material
For ceramic-ceramic combinations this test shall be used for zlrconia-veneerlng ceramic only.
The de-bonding/crack-initiation strength of the ceramic substrate material and at least one nominated dental veneering ceramic present shall be greater than 20 MPa.
Test in accordance with 4.
NOTE According to 6.4, the dc-bonding test only applies to materials with an elastic tensile modulus less than or equal to 250 GPa. This excludes some stiff ceramic materials such as ahimlna.
6.5.2 Preparation of test specimen
Prepare, according to the instructions For use, either at least one veneered prosthesis of three units
(bridgework, with the geometry of tooth positions 11 to 13 or 14 to 16) or, If multiple units are not
Indicated, at least five anterior crowns (geometry of tooth posItion 11 or 21). Apply the veneer to the
substructure material with at least two firings.
NOTE The namerlcal tooth designations arc in accordance with ISO 395O
6.5.3 Therm ocyding test with fixed temperature interval
6.5.3.1 Apparatus
6.5.3.1.1 ContaIner with cold water maintained at (10± 10) °C.
6.5.3.1.2 Container with water maintained at Its boiling point.
6.5.3.1.3 Wire basket suitable br transferring the test specimen(s) rapidly between the containers, and preventing them from coming in direct contact with the walls or bottom while ensuring that the test piece or pieces remain submerged.
6.5.32 Procedure
a) Place test objects in the wire basket so that they are not contacting each other and are not under mechanical stress
1,) Place the basket in the boiling water for (30 ± 5) s. When executed for the First time this step is counted as the first thermal shock.
c Transfer the basket from the boiling water to the cold water within 3 s and keep it submerged for (30 ± 5) s. When executed for the first time this step is counted as the second thermal shock.
d) Repeat steps b) and c) at least eight times or until failure of the materials is apparent. Transfer the test specimens between containers within 3 s.
e) After the last quenching, remove objects and dry them. fl Examine specimens according Lu 65.13.
6.5.3.3 Examination
Examine each specimen for cracks by light microscopy at magnifications up to 10 s with trans• illumination.
II cracking is not observed immediately after the test, repeat the examination after 48 h to test for delayed cracking.
6.5.3.4 Test report
Prepare a test report in accordance with Ciausei
6.5.4 Thermncycling test with Increasing temperature Interval
6.5.4.1 Apparatus
6.5.4.1.1 Container with cold water maintained at (10 t 10) °C by an external temperature control element
6.5.4.1.2 Furnace (hot air) capable of maintaining temperatures between (80 ± 5) C and at least (165i5)°C.
6.5.4.13 Wire basket suitable for rapid transfer of the test specimens between the water container and the furnace and preventing them from coming in direct contact with the walls or bottom while ensuring that the specimens remain submerged in the water.
6.5.42 Procedure
a) Place test oblects in the wire basket so that they arc not contacting each other and are not under mechanical stress.
b) Place the basket in the furnace to heat the specimens to 80 C and maintain for at least 10 mm. This process is not counted as thermal shock.
c) Transfer the test oblects In the basket Into the cold water with transfer time of less than 3s. Maintain the test oblects In the container for (30± 5) s. This step is counted as a single thermal shock.
d) Remove the specimens from the cold water and dry them. Examine for cracks at room temperature by light microscopy at magnifications up to 10 x with trans-illumination. If no cracks are apparent. continue with step e). If any specimen exhibits cracking, report the result according to 6.5.4.3.
e) Increase the temperature of the furnace by (12,5 ± 2,5) °C and repeat steps b) to d),
Perform test until final failure of all specimens or until at least live thermal shocks (quenching) have been performed, whichever occurs first.
An initial furnace temperature higher than HO C maybe used.
NOTE The holding time In the furnace ollO mlii Is Intended to ensure that the specimen has a uniform temperature.
6.5.4.3 Test report
Prepare a test report in accordance with Clause!.
7 Test report
Prepare a test report and report the following:
a) identification of the materials tested, including product names and lot numbers;
b) linear coefficient of thermal expansion and glass transition temperature of the veneering ceramic according to 6.1 and 6.2;
c) linear coefficient of thermal expansion of the substructure material according to 6..L
d) the characteristic dc-bonding strength obtained according to 6.4:
1) dimensions and thickness ratios of test specimens;
2) the value of elastic modulus E5 used in the analysis of measurements;
3) the results of each measurement (In MPa);
e) details of the preparation of the test specimens for thermocycling. including diagrams or photographs with a scale Indicating the relative thicknesses of substructure and veneer;
f) results obtained from the thermocycling test with fixed temperature interval according to ft.&3 (as applicable) Including the following;
1) detailed test set-up covering number and preparation of test specimens (6.5.2). apparatus (&&i1) and procedure (6Si2)
2) the number of specimens that tailed during the test, including the number of the thermal shocks at which they railed:
3) the number of specimens found to have failed on examination Immediately after performing the test;
4) the number of specimens found to have failed on examinatIon 48 h after performing the test;
g) results obtained from the thermocycling test with increasing temperature interval according to 6.5.4 (as applicable) induding the following:
1) dimensions and thickness ratios for specimens used in this test;
2) detailed test set-up covering number and preparation of test specimens (6.52), apparatus (6.5.4.1) and procedure (6.5.42);
3) how many specimens have failed at which temperature difference (and after how many thermal shocks);
h) name of the responsible person and the testing laboratory;
I) date of test report and signature of responsible person; a reference to this document. i.e. ISO 9693:2019.