Dental worries inc food issues and whether to switch vets

Hi I'm concerned and feeling guilty about my indoor 3 year old calico/rescued kitty, Pixel. Today I noticed her front teeth are MAJORLY worn down and it seems like she's missing some teeth and her poor gums are red in one place. I'm making her a vet appt asap (calling them on Tuesday). I have no idea how her teeth got so horrible without us noticing since we socialize and cuddle lots. She has been shedding quite excessively but has still been eating.
My concerns
1. We started feeding the cats a dental diet as recommended by the vet 1.5 years old when our other cat, Proxy (my husband's a geek) had some gum tenderness and reduced diet as a result. I'm worried that the huge hard kibbles are what have wreaked havoc on Pixel's teeth since she really chomps on her food.
2. If it could be cause by the food recommended by the vet should I switch vets???
3. What can I do for Pixel in addition to her upcoming check up? I'm concerned about her eating for the rest of her life since she is only 3 years old.
4. Are there any questions I should ask the vet? What treatments might they recommend? I''d like a chance to research them before the visit so I'm prepared.
I feel so guilty. I had an iguana before the girls and researched so much about care and nutrition. Then after she passed on and we got the cats I didn't research since I figured I grew up with cats and "knew" about caring for them. I thought I was doing right by them since I didn't declaw them, I keep their shots up to date and had them both spayed.

I would doubt the food caused the problem. It's likely she chewed on something, potentially got her teeth stuck in something that caused the problem. I would reccomend switching foods, only because you could find a better quality food for what you are paying now... you could alternately use the dental diet for treats to help encourage good tooth health. Also you said she's a rescue, she could have come with missing teeth and you never really noticed. I really would not beat yourself up about it, she's 3 so probably coming close to needing her teeth cleaned anyway.

I wouldn't switch vets, I would ask about the food being a cause and see what the vet says to that though.

I would ask about alternatives to brushing and feeding the dental diet, ask about some mouth washes/oral gel, also ask about a wax called Oravet that is a wax you can put on your cats mouth once a week to help keep their teeth cleaned.

Also the front teeth are used to grab their prey and rip/tear they really aren't super important to them in terms of needing them as they chew/crush with their back teeth. Even if she ends up needing teeth pulled there are some cats out their whose immune systems attack their teeth and all of their teeth get pulled and they do just fine. You kitty will be okay, it's good you checked out her mouth and are trying to get prepared for a vet visit about teeth. You're a good kitty parent!

Update - Pixel wouldn't let the vet look at her mouth so he scheduled her for a cleaning and said some teeth may need to come out. We followed up witha cleaning and she had 13!? teeth pulled. For the moment she's on 100% canned food but I might add in a higher quality dry cat food in a few weeks. She has painkillers and antibotics. Thanks for the reassuring words about guilt.

Poor thing! She probably wouldn't let the vet look at her mouth because she was so miserable from the problems. I've read that cats do fine with minimal teeth, and I'm sure she'll adjust. You did well to have it taken care of promptly.

Keep in mind that cats are like humans insofar as they can have problems with their teeth that are genetic to some extent. My younger sister has had problems with her teeth since she was a toddler, whereas my brother and I have always had good teeth. My mother thought it might have been because she became ill with some kind of virus when she was pregnant with my sister. You never know.

Comfort yourself that you're giving this rescued kitty a good life now.