What is the best course of action for an avulsed (knocked-out) tooth?

The best course of action for an avulsed tooth is to re-implant it promptly if possible because teeth have a good chance of being saved if they are put back into their socket within a short time frame, ideally within 30 minutes to 1 hour after the injury. Keeping the tooth moist is crucial for preserving the periodontal ligament cells that help in reattachment. If the tooth cannot be re-implanted immediately, it should be stored in a suitable solution such as saline or the patient's own saliva, rather than in salt or dry conditions, which can damage the tooth.

The options that suggest leaving the tooth out to heal or ignoring it completely do not take into account the possibility of successful re-implantation, which is vital for maintaining the tooth's function and aesthetics. Furthermore, storing the tooth in salt is not a safe or recommended method, as it can lead to further damage. Therefore, re-implanting the tooth promptly remains the most effective action to take.