Hi, my question is what could be the best treatment plan for me. I live in Canada and hope the teeth numbering system is the same worldwide.

I have a bridge on my 3 left upper front teeth (#21, 22 and 23) made 14 years ago but it is still in good shape. It has the #22 missing and #21 is a crown with steel pole. The left one #23 is a natural tooth.

Now I have my upper right hand #11 extracted recently. The adjacent 12 and 13 are natural and in good shape. I have optional treatment plan to fill this gap.
a)Do an implant on #11 only. I intend to avoid such surgery. It is an expensive treatment that is not covered by any insurance at all.
b)Do a #12, 13 and 11 cantilever bridge. I feel guilty of damaging the healthy natural teeth #12 and 13. So far I booked treatment for this option.
c)Take out the old bridge on #21/22/23 and make a new one that is longer to accommodate #11. Then #11 will be a cantilever. The question is if this cantilever bridge is strong enough for many years? What I worry about is that my #21 has a root and a pole inside for almost 20 years already. Of course I have to be more careful while biting if I choose to do this option.

I am kind of thinking to take treatment to Option c) now. It will be a bit more expensive than Option b), but it leaves teeth #12 and 13 untouched. At the same time the old bridge will be replaced by a new one. Is 14 years long enough for replacement? I still feel it is in good shape any how. Could removing the old bridge damage the teeth underneath?