I want to replace molars 31 and 30, is a dental bridge an option?

When teeth are missing you can replace them with implants, a partial or a fixed bridge. There are several indications for when a stress breaker is used.  The female portion is usually on the anterior abutment and the male end on the posterior portion. 

 

Stress breakers can be used when the anterior abutment has an inlay (very conservative tx) vs a full crown to prevent dislodgement, To correct for angulation with minimal tooth reduction or to allow more normal movement.  They are also used if there is concern about future problems with one abutment to allow for easier fixes in the future.  

 

 

I think my colleagues have answered your questions thoroughly.   Long term, you will likely be much happier with implants then a bridge.  Of course, every individual is unique with their own individual set of circumstances  - timing, appetite for a number of dental appointments, budget, and other preferences.    Bridges can generally be completed more quickly than implants, however they do have disadvantages (as mentioned below.)   If you don't mind a few extra appointments and waiting a few months (your dentist will provide you with something temporary to tidy you over while you wait), implants would be the way to go.   

If the cost of implants is prohibitive, you can discuss alternatives with your dentist - implant supported bridge or even a single implant on #30 to give you first molar occlusion may be appropriate to your circumstance and age. 

That is too long for a posterior bridge. Occlusal stresses are progressively high there. An implant(s) are a more reliable treatment option.