Some practitioners have relied on mechanical retention
such as grooves or undercuts to retain the composite
resin to ceramic or metal. Owing to microleakage and
humid intra-oral conditions, this type of repair was
considered as an interim procedure. It was reported that
the use of fine and coarse diamond burs increases crack
initiation and propagation through the ceramic which
could result in failure (Wood et al., 1992). These trials did
not give long lasting, predictable results in ceramic repair