there is a mirror which has a telescoping handle and
swivellng ball joint allowing it to adjust to different
angles. it is made for mechanics or carpenters (?) and
might be available at a hardware store..I think i got
mine when i was in a guitar buildiong class..the viewing
surface is probably 2 X 3 inches. the dental mirror is
probably smaller than 1 X 2 inch. there are a couple of
them on e-bay--1 1/4 inch round..see this link
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3185716289&category=3191
called telescoping inspection mirror
for plumbers, mechanics, and electricians...
or go to e-bay and look for inspection mirror
there are 3 avaialbe from one person and another
in UK has some for sale too.