Unusual extensibility of the tongue is a characteristic feature of:

EHLERS -DANLOS syndrome is a connective tissue disorder characterized by hyper elasticity of skin, hyper extensibility of joints (Rubber man) and fragility of skin and oral mucosa) Hyper mobility of TMJ, resulting in "repeated dislocations" of Jaw; lack of normal scalloping of the dentinoenameL junction, passage of many dentinal tubules into the enamel, with a tendency to form multiple pulp stones are oral manifestations of EHLERS -DANLOS syndrome