A

Viaspan (University of Wisconsin solution) preserves periodontal-ligament cells better than any readily available alternative, maintaining >85 % cell viability even after 24 h, whereas HBSS or milk fall below 60 % over the same period [Osmanovic 2018, PMID 30193009; Buttke 2003, PMID 12656842]. Hence, for prolonged transport when immediate reimplantation is impossible, Viaspan is the optimal medium.