Your idea for ivory chip repair using dental techniques is a good one,
though it has already been done.  Richard Wagner has a product called
AcryliKey.  It's not cheap, but a little goes a long way.  It's nice
for chip repairs on nice keyboards where you don't want to replace the
whole ivory.  His e-mail address is "Rjwag@pacifier.com".

Philip Jamison
West Chester, Pennsylvania