We are not aware of any scientific evidence that vitamin D causes tooth resorption. Vitamin D deficiency is the greater danger with modern feeding practices.
The dry matter analysis is available on the Wysong website in the learn section
if you want to view vitamin D levels in the diets. The complete analysis for Epigen 90 is not available yet, however, and it not included on the chart.
Please also see this link: Does Your Pet Need A % Of Something?
For the teeth, we would recommend Wysong DentaTreat
™, which utilizes the beneficial properties of cheeses, probiotics and minerals to aid in maintaining pet oral health. The alkaline nature of the cheese shield the acidity of plaque and raises pH to neutralize tooth -destroying acids. Salivary flow is also increased causing sugars to be diluted clearing them from the oral cavity. Lastly, proteins from the cheese obstruct demineralization of tooth enamel and assist in remineralization.
As for diet, the Epigen™ and Au Jus™ are good choices. You might also want to consider the TNT™
diets in rotation. In general we recommend increasing the meat protein content of their diets. This reduces the amount of starch thus reducing bacterial growth in the mouth. Aside from this benefit, an all or mostly-meat diet is what cats and dogs were designed for, so moving toward this type of diet would be ideal for them.
It is most likely you cat is experiencing periodontitis. In that case the above recommendations will also help but if there is infection associated that will not abate, extraction may be a wise choice. Otherwise the infection can seed the system systemically and cause heart and kidney disease.