My elderly yorkie is 16 and has horrendous bad breath - has anyone got a helpful remedy?

She was a sad rescue & poorly bred so as well as other health probs ociated with this breed she has always had poor teeth & needed a few dentals over the years but she is too old to risk an anathsetic now. She remains on a good dried food that she can tolerate which keeps her regular & comfortable (& has done for years), she can have no tit bits due to colic & irritable bowel, even fresh fish & chicken can cause her problems. Despite all her health issues & very small size she is brave smart tolerant loyal loving friendly & sociable with everyone including strangers, all children, all dogs & she even mothers birds & small animals. She has been a complete joy & is very much loved but is definately not a pampered pooch & lets anyone do anything to her. Sadly the bad breath issue has become increasingly worse & she has taken to leaving her tongue hanging out a lot so whilst none of us care & cuddle her regardless of the knockout breath, the smell is detectable from several feet & its a bit embaring when she strolls up to strangers or visitors to say hello. Can anyone suggest anything that may help?