Overview
ISO 20795-2:2013 - "Dentistry - Base polymers - Part 2: Orthodontic base polymers" defines requirements and test methods for orthodontic base polymers and copolymers used in the construction of both active and passive removable orthodontic appliances. The standard covers material types, specimen preparation, mechanical and chemical property limits, packaging, marking and manufacturer instructions, and specific test procedures (including an HPLC method for residual methyl methacrylate).
Key Topics and Requirements
- Scope and classification
- Applies to materials used for orthodontic bases (removable appliances).
- Classifies materials into three types: Type 1 (autopolymerizable), Type 2 (light-activated), Type 3 (thermoplastic).
- Mechanical performance
- Ultimate flexural strength: not less than 50 MPa.
- Flexural modulus: at least 1 500 MPa.
- Fracture properties: minimum total fracture work and stress intensity factor specified (see Table 1 of the standard).
- Chemical safety and composition
- Residual methyl methacrylate (MMA): maximum mass fraction 5 % when tested per the standard.
- Plasticizers: extractable phthalate plasticizers must be identified and quantified; content must not exceed the manufacturer’s stated value by more than 10 %.
- Durability and stability
- Water sorption and solubility: limits specified for processed polymer (water sorption ≤ 32 µg/mm, solubility ≤ 5 µg/mm in the standard’s expression).
- Surface and aesthetic requirements
- Processed specimens must present a smooth, hard, glossy surface, retain form without distortion, and meet declared colour/transparency.
- Test methods & specimen preparation
- Procedures for sampling, specimen plates, environmental conditions (typically 23 ± 2 °C and 50 ± 10 % RH) and inspection are specified.
- Annex A includes an HPLC method for determining MMA content.
- Packaging, labelling and instructions
- Requirements for immediate and outer packaging, marking and mandatory manufacturer’s instructions.
Applications and Users
ISO 20795-2:2013 is used by:
- Manufacturers of orthodontic base materials for product development, quality control and labelling compliance.
- Dental laboratories and technicians who process removable orthodontic appliances.
- Independent test laboratories performing compliance and safety testing (mechanical, chemical).
- Regulatory bodies and procurement teams evaluating material specifications and safety claims.
- Clinicians and dental product purchasers seeking materials with documented performance limits.
Related Standards
Keywords: ISO 20795-2:2013, orthodontic base polymers, dental materials, residual methyl methacrylate, flexural strength, water sorption, fracture toughness, HPLC, packaging and labelling.
