ISO 6873:2013

Overview

ISO 6873:2013 - Dentistry - Gypsum products is the international standard that classifies dental gypsum materials and specifies the technical requirements and test methods for gypsum products used in dentistry. It applies to materials for making oral impressions, moulds, casts, dies, model bases and model mounting, including materials intended for CAD/CAM models. The standard also defines packaging, labelling and information that manufacturers must supply.

Key topics and technical requirements

• Classification (Clause 4): Five product types are defined:
  • Type 1: Dental plaster for impressions
  • Type 2: Dental plaster for mounting (Class 1) and models (Class 2)
  • Type 3: Dental stone for models
  • Type 4: Dental stone (high strength, low expansion) for dies/model bases/CAD-CAM dies
  • Type 5: Dental stone (high strength, high expansion) for dies where extra expansion is needed
• Setting time: Type 1 setting time range is 2.5–5.0 min; for all types the measured setting time must be within ±20% of the manufacturer’s claimed value.
• Fluidity (Type 1): Measured at 1.25 min after mixing; required fluidity is ≥ 70 mm.
• Linear setting expansion: Specified limits at defined times (Table 1), e.g. Type 4: 0.00–0.15% (2 h) and 0.00–0.18% (24 h). Other types have defined expansion ranges important for dimensional accuracy.
• Compressive strength: Minimum compressive strengths specified by type (see Table 1), e.g. Type 3 ≥ 20 MPa, Types 4 & 5 ≥ 35 MPa (measured at 1 h).
• Fracture and detail reproduction: Type 1 must break with a clean fracture and be reassemblable; all types have defined requirements for reproduction of grooves/detail (Clause 7.7).
• Testing and test conditions: Sampling from a single retail lot; tests at (23 ± 2) °C and (50 ± 10) % RH; use water complying with ISO 3696. Test methods are detailed in Clauses 7.1–7.7.
• Packaging and labelling (Clause 8): Requirements for labelling, expiry, batch/lot information and adequate instructions for use.

Practical applications and users

• Dental materials manufacturers use ISO 6873:2013 to design, test and declare gypsum products (plaster, dental stone) that meet international performance benchmarks.
• Dental laboratories and prosthodontists rely on standardized properties (setting time, expansion, strength, detail reproduction) to ensure dimensional accuracy for impressions, casts, dies and CAD/CAM models.
• Regulatory and quality teams use the standard to verify compliance during product approval and quality control testing.
• Purchasing and procurement professionals can compare products using standardized specifications and test results.

Related standards

• ISO 3696 - Water for analytical laboratory use (testing water quality)
• ISO 1942 - Dentistry vocabulary
• ISO 15223-1 - Medical device labeling symbols
• ISO 10993-1 / ISO 7405 - Recommended references for biological hazard assessment

Keywords: ISO 6873:2013, gypsum products, dental plaster, dental stone, setting time, linear setting expansion, compressive strength, dental gypsum testing, dentistry standards.