Ok, that is helpful and much as I suspected. It sounds like your vet is doing a good job. It doesn't sound like it has to do with any loss of kidney function as can happen sometimes after an anesthesia if there was not good fluid support. There are a few thoughts I have as far as why Kes may not be wanting to eat or drink well and I will list below.
1) Mouth pain - this doesn't sound likely as she was on the pain meds and it sounds like the extraction sites have healed up. Also if the roots were already gone, there would not have been a lot of oral surgery to remove them.
2) Adverse reaction to the antibiotics - making her nauseous. The Clavamox may have set it off but if you are still seeing soft stool, her GI tract may still be affected. Perhaps a round of probiotics may help to replace the good bacteria.
3) Adverse reaction to the metacam. This is a non-steroidal anti-inflammatory (NSAID), which is commonly used for pain, but can have GI side effects. In some cats, after prolonged use, GI irritation or even ulceration can occur. Even though her regime was only for 5 days, she may have been sensitive. Antacid meds like Pepcid AC (famotidine) - 1/2 of a 10 mg tab once daily may help. Your vet would be able to prescribe even stronger GI meds if needed.
4) This final one is the most worrisome, but I have seen it on more than one occasion. It is possible that there was underlying GI disease before the dental and the two teeth that were extracted were incidental and had no bearing on her decrease in appetite prior to the procedure. If this is the case, a further GI workup would be needed to rule out things like pancreatitis, inflammatory bowel disease (IBD) or even GI lymphoma. These are not uncommon disorders in cats and often when they first present, they signs are subtle and often can be thought to be due to something less serious, like dental disease. Unfortunately, IBD or lymphoma can be present and there can be no other abnormalities noted on bloodwork, xray or even ultrasound. The only way to confirm the diagnosis is with a biopsy of the intestine. This can be done via endoscope, but is better performed with an exploratory surgery. The problem with this is that many cat owners are not willing to pursue the diagnosis by these means. It is for that reason that many cats are "suspected" to have IBD or GI cancer as the cause of their weight loss and anorexia once all of the other easy to find things have been ruled out.
I hope her reluctance to eat is one of the more easily treated possibilities and not the last one, but just to be aware, I wanted to describe it to you. I would continue with supportive care as mentioned and perhaps add an appetite stimulant like mirtazipine. Give her a little more time and see if she starts to come around and if not, you can discuss a further workup with your vet.
I hope this is helpful. If you would like any additional information or have additional questions please don't hesitate to ask!
Please remember to rate my answer, but only if you are satisfied with my service. If you feel my service is not worthy of 3 stars or above and if you feel the need to click either "Helped a little" or "I expected more", please stop and reply to me via the CONTINUE CONVERSATION button with the issue you have. Let me know how I can improve my service and I will be happy to try to provide you with what you are seeking. I am only credited for my work when you are happy with the service you receive.