We review recent advances concerning the nature of fluctuation effects occu
rring at continuous filling transitions pertinent to fluid adsorption in we
dge geometries. Unlike continuous (critical) wetting transitions for planar
interfaces which are an extremely rare experimental phenomena, continuous
filling transitions should be easily observable in the laboratory since the
y can occur even if the underlying wetting transition is first-order. We ar
gue that interfacial fluctuation effects at filling transitions are extreme
ly strong and lead to a remarkable universal divergence of the interfacial
roughness xi perpendicular to similar to (T-F - T) (-1/4) on approaching th
e transition temperature TF, valid for all types of intermolecular forces.
The results of renormalisation group and transfer matrix calculations of a
novel interfacial model yielding a complete classification of the critical
exponents for all dimensions and ranges of forces are given. (C) 2001 Elsev
ier Science B.V. All rights reserved.