Cats are individuals and some will need their teeth cleaned more often than others. You also want a reputable vet, and not one who is looking to get as much money out of you as possible, as a certain national chain is known for. There is a prescription food that can help clean their teeth, and when
Leo was 5 he ate that food for a few years and it helped his teeth. But then I had to switch his food due to urinary tract health problems, and now he is 11, and he legitimately needed his teeth cleaned. I have never heard of a vet around here that did not put the cats under general anesthesia. But it is important since bacteria can get into their bloodstream if their teeth and gums are very bad, and that can be a problem.
Leo had blood work done and it was fine, so I went ahead with the cleaning. The vet called me about an hour and a half after I'd dropped him off, worried that he had a heart murmur. I said, "No, he is just terrified" since I'd been through that with another vet. Sure enough he was totally fine. He had to have one tooth extracted. They told me to take it easy with him that night, to give him water first and if he was okay to give him a little wet food. I took him home, he zoomed out of the carrier the instant I opened the door, and zoomed around the house, then ran over to me and made it clear he was starving. Here, Leo, I said, have some water. Leo: I don't want no stinkin' water, I want FOOD! So I mixed a little food into some water. Well,he thought there was too much water and not enough food. Splash, splash! Okay, so then I started over, and he ate all the food, then ate Callie's leftovers. Then we repeated that. Then I gave him a little dry food that I'd wetted down, and he ate all that. I thought we'd have a nice quiet evening, and he just ran around the house, and when he wasn't doing that, he sat in the kitchen, evidently hoping more food would fall from the sky.
The vet said his teeth were not all that bad, and that she'd been surprised he only had to have one pulled. And she said he would probably never need them cleaned again. So Leo came through it all fine. He is a big tough cat and the fasting is the hardest thing for him.
Callie is 14, on the other hand, and still does not need her teeth cleaned. She probably never will at the rate she is going.
Get it done if it's needed, and your cat will have a better quality of life.