Although there are different definitions of posterior bite collapse, o
nly the classical definition of Amsterdam provides a definite diagnosi
s and treatment plan. This situation entails a subtle loss of the occl
usal vertical dimension with resultant flaring of the maxillary inciso
rs. Other causes for flaring, such as derangements of form and functio
ns of lips and tongue, bruxism, habits, as well as the presence of adv
anced periodontal disease or malocclusions, should be ruled out before
the diagnosis of posterior bite collapse can be made. The complexity
of differential diagnosis is illustrated with three case reports.