Diet soda is highly acidic and eats at enamel. Since I started working from home, My water intake has gone way down and I’ve developed a Coke Zero addiction…consequently, after having no cavities for the entirety of 40 years on earth - my last dentist appointment revealed 7 cavities!
The variables are age, a new dentist and diet soda…it’s likely a combination, but the dentist claimed it was likely the diet soda.