What is the recommended storage medium for an avulsed permanent tooth when immediate reimplantation isn't possible?

Hank's Balanced Salt Solution (HBSS) is considered the gold-standard storage medium per current IADT (International Association of Dental Traumatology) guidelines, best preserving periodontal ligament cell viability. When HBSS isn't available, milk is the next best widely accessible alternative — water should be avoided, as its hypotonicity causes PDL cell lysis.