In 1955 Shanahart described a technique he called «swallowing or free closure». This technique was based upon the fact that swallowing saliva was the determining factor to obtain vertical dimension and centric relation.
En 1955, Shanahan describió la técnica «swallowingor free closure» , la cual estaba basada en que el tragar saliva era el factor determinante para obtener la dimensión vertical y relación céntrica.