Overview - EN ISO 18675:2022 (Dentistry - Machinable ceramic blanks)
EN ISO 18675:2022 defines standardized test methods and reporting requirements for machinable ceramic blanks used to fabricate dental fixed restorations. The standard covers commonly used blank types (notably partially sintered zirconia and various glass ceramics), addresses dimensional changes that occur during sintering or post‑machining crystallization, and sets out how to assess machining‑related damage and overall machinability. It also specifies the contents of the test report that manufacturers and testing laboratories should provide.
Keywords: EN ISO 18675:2022, Dentistry, machinable ceramic blanks, dental CAD/CAM, zirconia blanks, test methods
Key topics and technical requirements
- Homogeneity and shrinkage factor - Methods to determine blank density and shrinkage (important for partially sintered zirconia which commonly shrinks ~20–35% by volume when fully sintered). Classification and procedures for blanks with one or multiple shrinkage factors.
- Warpage assessment - Test methods for detecting warpage after sintering or processing, including procedures for large, medium and small zirconia blanks.
- Dimensional stability after crystallization - Procedures to measure dimensional change post‑machining crystallization for glass ceramics (sample preparation, heat treatment and pre/post characterization).
- Machining damage evaluation - Tests to detect surface and subsurface damage from milling that can reduce strength or affect minimum achievable thickness.
- Machinability (merlon fracture test) - A specific fracture‑based test geometry and method to quantify machinability performance.
- Test report content - Required information to be included in laboratory or manufacturer reports to ensure traceability and consistent interpretation.
Practical applications
- Quality control of ceramic blanks supplied for dental CAD/CAM workflows.
- Specification and acceptance testing by dental laboratories and clinical manufacturers.
- Input data for CAD/CAM milling systems (shrinkage factors) to ensure accurate restorations.
- R&D and material selection for dental materials scientists assessing new ceramic blanks.
- Regulatory and compliance documentation for product declarations and standards conformance.
Who uses this standard
- Dental materials manufacturers and blank suppliers
- Dental laboratories and CAD/CAM milling centers
- Test laboratories and conformity assessment bodies
- Dental device engineers and product developers
- Researchers in dental materials and prosthodontics
Related standards
- ISO 6872 (ceramic dental materials) - material property assessment
- ISO 10993‑1 and ISO 7405 - biological/toxicological evaluation referenced for hazard assessment
EN ISO 18675:2022 provides a practical, harmonized framework for testing and reporting the behaviour of machinable ceramic blanks so that CAD/CAM restorations meet dimensional, mechanical and clinical expectations.