If you damage the small tips around the perimeter of the crank
sprocket, your vehicle will not run right on reassembly. You will
need to replace the crank sprocket to complete your repair.
The tips around the perimeter of the crank sprocket tell the
computer exactly what position each of the pistons are in as the
engine rotates. It does this by "counting" the tips as they pass
the crank sensor. The long spot where a few tips are normally
missing tells the computer that this is the #1 piston being all the
way up. With that information, it can tell where all the other
pistons are as it rotates. If any of the tips were to be removed, it
would confuse the computer as the long spot would appear to be
in more than one place, or coming around too fast.
The crankshaft sprockets are just cheap pot-metal and break
really easy (I've broken one or two in my time as well). The good
news is that means they are cheap... list price is $26 new from
Toyota. You will most likely need to special order it, as it is not
normally stocked at dealerships. As far as I know there is no
aftermarket part available for this piece.