What are some options for cleaning my dogs teeth that dont involve anesthesia?

My 5 year old Pomeranian has a grade 3 heart murmur. We took him in for an echo-cardiogram and the veterinarian recommended that we DON'T put him under anesthesia, but his teeth are horrible! The vet told me to brush his teeth everyday but it doesn't help at all. His breath is very bad and we've tried everything - dental rinses, brushing, even this expensive gel that you put on his teeth and its supposed to remove plaque- it didnt. Are there any recommendations for cleaning his teeth that don't involve anesthesia? With his murmur I don't need his teeth to get any worse. Any advise would be highly appreciated! Thanks!