Explanation: In the WHO classification, avulsion refers to the complete displacement of a tooth from its socket, and it is classified under 873.61. This classification is crucial for understanding the severity of the injury and determining the appropriate treatment.

Activity of disinfectants is indeed reduced by organic debris or blood. This is because organic materials can act as a barrier, protecting microorganisms from the disinfectant and reducing its effectiveness. The presence of organic matter can bind to the disinfectant, inactivate it, or consume it, thereby reducing its ability to kill or inhibit the growth of microorganisms. For this reason, it is essential to thoroughly clean and debride the area before applying a disinfectant to ensure optimal efficacy.

The stabilization of an avulsed tooth typically requires a period of 1-2 weeks. During this time, the tooth is often replanted and stabilized to allow for healing and reattachment of the periodontal ligament.

Gutta-percha cones are generally not recommended for root canal filling in primary teeth because the root canals of primary teeth are more likely to contain vital tissue, and the material can potentially cause harm to these tissues. However, they are suitable for permanent teeth with wide root canals and even those with curved roots, provided that the root canals are properly cleaned and shaped to allow for optimal filling.

 Identifying Root Curvatures

• Perception by instrumentation refers to the tactile feedback that a dentist can obtain while using instruments during procedures, allowing them to identify curvatures in the root canal system.