Most of these studies address two major issues: the geometry of the tooth root fillet
(Hebbal et al., 2009) and the rim thickness (Nan & Zang, 2008).
If a root fillet
on a gear, for instance, had only partial coverage, the flat or undimpled areas now would carry higher tensile stresses and premature gear failure is possible.
This stress concentration at the root is further amplified by the second fact--the absence of root fillets