FAQ

YY 0341.1-2020 Passive Surgical Implants–Bone and Spinal Implants Part 1: Special Requirements for Bone Implants (Appendix B: Relevant Material Standards Acceptable with Clinical Use Proof) Biological evaluation cannot be exempted but can be simplified or waived through equivalence comparison, demonstrating that the device under application has the same biocompatibility as marketed products. Materials conforming to YY 0341.1 Appendix B, although clinically acceptable, still require equivalence comparison to ensure the production process does not introduce new biological risks. This includes comparing the production process, such as processing, sterilization, and packaging, to ensure no new harmful substances are introduced. If the production process does not introduce new biological risks upon evaluation, biological testing can be waived. Dental Implant (System) Registration Technical Review Guidelines (2016 Revision) According to international conventions, dental implants (systems) made of titanium or titanium alloy materials that comply with GB/T 13810 Surgical Implants–Wrought Titanium and Titanium Alloy for Surgical Implant Applications or the US ASTM series standards, and whose surfaces have not undergone modification or only sandblasting, can apply for exemption from biocompatibility testing but must submit a biocompatibility evaluation report.

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GB/T 16886.12-2017 recommends using a 24-hour extraction period for cytotoxicity testing with serum-containing media, which provides essential nutrients for cell growth. However, these nutrients are susceptible to time and environmental temperature changes. Currently, ISO/TC194 WG5 is conducting round-robin tests for implant cytotoxicity with 72-hour extraction followed by 24, 48, and 72-hour cell contact periods. Improvements to cytotoxicity testing will be based on international comparison results.

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1. The evaluation focus for acute, subacute, subchronic, and chronic toxicity is distinguished based on the definitions of each test. Consider factors such as the product’s contact duration (within 24 hours vs. more than 14 days to 12 months of repeated or prolonged contact), toxicity observation periods (within 72 hours vs. after 14 days to 12 months of repeated or prolonged contact), and observation technical indicators. 2. Select subacute, subchronic, and chronic toxicity tests reasonably based on the clinical use duration of the device. 3. Subchronic toxicity can generally replace subacute toxicity to obtain long-term toxicity data, but actual product usage conditions should be considered to avoid over-testing.

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According to current standards, dual-route exposure is suitable for non-implantable devices (e.g., vascular stents) and external contact devices (contacting blood, liquid path devices).

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Based on the equivalent coefficient between test animals and humans, the dose should be appropriately increased since it is difficult to obtain IC50 for medical devices. Currently, a 50-100 times increase is used based on toxicological research data, considering practical feasibility during testing.

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The design plan should simultaneously consider observation periods, doses, and observation indicators for both tests.

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If the pH of the dressing itself is abnormal or the extraction liquid cannot be tested, results without treatment should also be provided.

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It is necessary to determine if an endotoxin limit is required. If the dressing interferes with the endotoxin test (e.g., contains β-glucans, divalent metal ions), the endotoxin limit should be determined based on the product’s contact method, usage risk, and pyrogen test results.

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Select representative components and implant them using a clinical simulation approach.

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The role of chemical characterization in biological evaluation: 1. Provide chemical information for comparing the device under application with marketed devices (determine equivalence). 2. Provide a chemical basis for comparing the device under application with relevant material standards (confirm compliance). 3. Serve as the chemical information basis for toxicological risk assessment (ensure feasibility of the assessment). More in-depth and complex chemical characterization and data evaluation may be needed in the following situations: 1. The materials used lack a long history of clinical use. 2. Unexpected results occur in biological tests. 3. The device’s materials change upon application to the human body (e.g., in situ polymerization or resorbable materials). 4. The medical device contains known toxic materials. 5. New chemical substances are used in the material components or production process. 6. The medical device is made of new materials.

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1. The new standard uses “E” to indicate endpoints that should be considered (previously, “X” was used to indicate tests that needed to be performed; it’s not a checklist of tests to be selected). 2. The first column collects physicochemical information. Specific physicochemical characterization should refer to GB/T 16886.18 and GB/T 16886.19, with applicable endpoints like subacute, subchronic, and chronic toxicity evaluated as needed. 3. Long-term tests, such as chronic toxicity and carcinogenicity, are only conducted if data suggest necessity, typically for new materials, considering other test evaluations and clinical use history of marketed device materials. 4. For certain specific devices, more endpoints may need to be considered. 5. The ongoing revision of ISO 10993-1 includes table splitting and adjustments, along with added explanations.

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