Overview
ISO 5139:2023 - "Dentistry - Polymer-based composite machinable blanks" defines the characteristics and test methods for polymer-based composite blanks used in milling to fabricate permanent dental restorations (for example, single crowns and inlays). The standard focuses on requirements that affect the milling process and clinical performance, and it specifies what manufacturers must declare on packaging and in instructions for use. Note: large multi-unit discs and temporary restorative materials are excluded.
Key topics and technical requirements
- Scope and definitions: Covers polymer-based composite machinable blanks (solid polymer-based composites used with subtractive CAD/CAM milling).
- Dimensional tolerances: Measure five product blanks - each blank’s dimension shall not be more than 0.25 mm smaller nor 1.00 mm larger than the size declared by the manufacturer (measured per Clause 6.2).
- Machining damage & strength testing:
- Machining damage is assessed using a three‑point flexural strength comparison between control specimens (cut and ground/polished) and milled specimens (Clause 6.3).
- Test specimen geometry: width w = 4.0 ± 0.2 mm, thickness b = 1.2 ± 0.2 mm, test span l = 12.0 ± 0.5 mm.
- Test conditions: specimens stored in water at 37 ± 1 °C for 7 days; universal testing machine crosshead speed 1.0 ± 0.5 mm/min.
- Machinability: Recommended to use the merlon fracture test from ISO 18675:2022 to evaluate machinability.
- Bonding to holding jig: Bonding properties between blank and holding jig should be evaluated; Annex C provides an example test method.
- Sampling and environmental conditions: Sampling from a single batch, tests performed at 23 ± 2 °C and relative humidity ≥30%.
- Packaging, labelling and instructions for use: Specifies mandatory information to be declared on outer packs and on the blank, plus required directions for use related to milling, handling and clinical application.
Practical applications
- Ensures consistent, reliable performance of CAD/CAM‑milled permanent restorations manufactured from polymer composite blanks.
- Helps manufacturers demonstrate product quality, machinability and risk of machining damage.
- Supports dental labs and clinicians by providing verified guidance on handling, milling parameters and expected dimensional accuracy.
Who should use ISO 5139:2023
- Dental material manufacturers and R&D teams
- CAD/CAM system and milling machine vendors
- Dental laboratory quality managers and technicians
- Test laboratories performing material validation and conformity testing
- Regulatory and compliance professionals in dental device supply chains
Related standards
Keywords: ISO 5139:2023, polymer-based composite machinable blanks, dentistry, CAD/CAM, milling, machinability, machining damage, three-point flexural strength, dental restorative appliances.