Overview
EN ISO 23298:2023 (ISO 23298:2023) specifies standardized test methods to evaluate the machining accuracy of computer-aided milling machines used in dental CAD/CAM systems for fabricating restorations such as inlays, crowns and bridges. Published by CEN and adopted from ISO, this standard defines how to measure and report milling accuracy so manufacturers, test laboratories and users can assess the performance of dental milling equipment consistently.
Key topics and technical requirements
- Two normative test methods
- Metal die method (Clause 5.1) - evaluates marginal adaptability of a milled restoration by fitting it to a master metal die; includes target restorations, apparatus, measurement of metal dies, CAD data preparation, machining and accuracy evaluation.
- Software method (Clause 5.2) - compares scanned 3D data of milled specimens with reference CAD data; covers test object, equipment, machining, measurement, data alignment and error calculation.
- Scope and selection - either or both methods may be applied; manufacturers should state which method(s) were used and provide corresponding results in instructions for use or technical documentation.
- Material-specific testing - machines must be tested on each blank/stock material type the manufacturer recommends, since material affects machining accuracy.
- Measurement and reporting - Clause 6 and informative Annexes (A–C) describe required test-report content, flow charts and measurement/data-preparation guidance.
- Normative references - integrates terminology and processes from ISO 1942 and ISO 18739 to ensure consistent definitions for dentistry and CAD/CAM process chains.
Practical applications and users
- Who benefits
- Dental milling machine manufacturers - to validate and declare machining accuracy for technical literature and user manuals.
- Third‑party testing laboratories and conformity assessors - to perform repeatable, comparable performance tests.
- Dental laboratories and large clinics - to compare machine performance when selecting equipment for restorative workflows.
- Regulators and procurement teams - to interpret manufacturer accuracy claims and compare devices objectively.
- Use cases
- Verifying marginal fit capability for crowns/bridges prior to market release.
- Benchmarking machine models across different materials (discs, blocks).
- Supporting quality control and R&D when optimizing milling strategies and toolpaths.
Related standards
EN ISO 23298:2023 provides a practical, standardized framework for measuring and reporting milling accuracy in dental CAD/CAM workflows, improving comparability of results and supporting informed device selection and quality assurance.
