Overview
ISO 28319:2018 - Dentistry - Laser welding and filler materials - defines requirements and test methods for the use of laser welding and associated filler materials in dental laboratories for joining metallic restorations and appliances. The standard covers chemical composition declarations, mechanical and corrosion performance, specimen preparation, test methods (tensile and static immersion corrosion), and required information in instructions for use, marking and labelling.
Key topics and technical requirements
- Scope and terms: Applies to laser welding of similar or dissimilar metallic materials used in dental restorations; definitions align with ISO 1942 and ISO 22674.
- Chemical composition and labelling:
- Elements >1.0% (mass) must be declared to 0.1% precision; elements >0.1% but ≤1.0% must be identified.
- Permitted deviations from declared composition: noble/silver elements ±0.5%; base metals >20% ±2%; 1–20% ±1%.
- Hazardous element limits:
- Cadmium, beryllium, lead ≤ 0.02% (mass).
- If nickel > 0.1% (mass), the nickel content must be indicated on packaging/label.
- Biocompatibility guidance: Recommends reference to ISO 10993-1 and ISO 7405 when assessing biological hazards (specific biocompatibility limits are not included).
- Mechanical strength (tensile):
- Tensile strength of laser-welded joints is required, with pass/fail criteria tied to the 0.2% proof strength of the parent materials (350 MPa threshold is a key reference).
- Corrosion resistance:
- Static immersion test requirement: metal ion release limit of 200 μg·cm−2 over 7 days ±1 h.
- Appearance: no visible selective corrosion around welds after testing.
- Process, sampling and tests:
- Specifies specimen preparation, sampling from single lots, and measurement methods (visual inspection, chemical analysis, tensile testing, static immersion per ISO 10271).
- Annex A provides additional information on the laser welding process.
- Documentation: Instructions for use, marking and labelling requirements and test report content are specified (see Clauses 8–10).
Applications and users
ISO 28319:2018 is practical for:
- Dental laboratories and dental technicians performing laser welding of metallic restorations and appliances.
- Manufacturers of dental casting alloys and filler materials seeking conformity for product labelling and instructions for use.
- Test laboratories and quality managers conducting tensile and corrosion testing of welded dental components.
- Regulatory bodies and procurement specialists evaluating safety, chemical disclosure and performance of dental welding materials.
Keywords: ISO 28319:2018, laser welding, filler materials, dental laboratory, metallic restorations, tensile strength, corrosion resistance, biocompatibility, marking and labelling.
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