Dental bridge vs. Dental implant

I am a 43 yr old woman, with good gums but terrible teeth. I presently have an upper bridge, consisting of 3 teeth, towards the back of my mouth. I now have a tooth, from an old root canal that has to extracted. This is a lower molar on the same side where I have my upper bridge. My choice is another bridge or an implant. The teeth on both sides of the molar that has to be removed are teeth with fillings, so they aren't in the best of shape. My concern is having both an upper and lower bridge on the same side of the mouth. Unfortunately, finances are a concern.

[Jerome Tsang, DDS]

So your question is whether to do an implant or a bridge?

If given a choice and finances were not an option, I would go with the implant.  

An implant has more advantages over a bridge which include not having you prepare the other two adjacent teeth for crowns.  It is also easier to maintain hygienically because you can floss between your teeth easier.  It also stimulates the jaw bone so there won't be a thinning of the jaw although cosmetically it won't matter as much in the back.  

Bridges are faster to do and they usually cost quite a bit less.  That's about the only two major advantages of a bridge.  

Of course the last option is a denture so a bridge has the advantage of being in your mouth constantly so it won't pop out or require you to clean it at night and keep it in a container overnight but I'm assuming we're specifically discussing replacing one tooth.