I am very sorry for your loss. Sometimes unfortunately there are just no answers. I agree that it does make dealing with all the what if's the mind runs through hard to deal with. One of my close friends years ago had a healthy young adult cat pass away in his sleep one night. He had been to the vet for his annual check-up the day before and she was told her was very healthy. The best her vet could come up with was maybe Ripley had a heart attack in his sleep. I used to cat sit for this cat a lot and referred to him as my step-cat. I remember how difficult it was for both of us to process with no true answers. Please know you have nothing to blame yourself for here. You were doing the right thing for your baby and the results came out wrong but were beyond your control. Hugs to you during this difficult time.
Thank you all for your kind words. It's just hurts not having him around and this is my first cat that I've had to die suddenly in 30 years. It's a little harder to take....
I'm so sorry for the loss of your sweet friend. He was beautiful. You aren't responsible for what happened; you were just doing your best to take good care of your pet. Anyone who cares enough to go to the expense and trouble of having their cat's teeth cleaned is a truly responsible guardian.