Hi... good morning. As you say all 6teeth are badly carious .... first you must visit my clinic to know if all need to be extracted or how many can be saved....It's always better to save your natural teeth. There are many ways to improve strength of your carious (rotten) teeth.  If at all, you need extractions then first best , durable option is to go for dental implants and avoid cutting your adjuscent healthy natural teeth for crown and bridge.No cantilevers advisable.

What type of bridge should be given depends on the amount of damage to your teeth as well as the condition of the surrounding teeth. This can be assessed by your dentist only.. Generally cantilever bridges are not preferred because they are bridges supported only on one side...Also it would be more advisable to get the entire bridge done in one go itself ,this way you will get a better looking functional bridge ...

Teeth that are infected should be removed first as they may otherwise cause pain under your bridge. After that any teeth that can be restored should be treated and a bridge can be done using adjacent teeth for support. Cantilever bridges should be avoided if possible