Which option is NOT a biocompatibility quality?

• A. Not toxic or injurious to living tissue
• B. Not causing immunological rejection
• C. Eliciting an appropriate biological response
• D. Causes immunological rejection

Answer: (D)

Biocompatibility means a material can coexist with living tissue without causing harm or unnecessary immune activation. A truly biocompatible dental material should be non-toxic to cells and tissues, should not trigger an immune rejection, and should elicit an appropriate biological response that supports healing and stable integration with surrounding tissues. Describing a material as causing immunological rejection is not a biocompatibility quality because it signals a strong adverse immune reaction, leading to inflammation, tissue damage, and potential failure of the restoration. The other statements describe desirable, compatible behaviors: non-toxicity protects tissues, not provoking immune rejection avoids harmful host responses, and eliciting an appropriate biological response aligns with constructive healing rather than adverse reaction.