Is using aspartame bad for your teeth?

No . No aspartame is an artificial sugar substitute. Because of this it is actually better for your teeth as the bacteria that cause cavities use sugar as their food source. If they dont get that sugar than they do not have a food source and you are less likely to get cavities.
Not for your teeth. Aspartame is an artificial sweetener. The most recognizable sweeter containing aspartame is equal. All artificial sweeteners do not cause cavities but the liquid or food that you consume may contain other compounds that could be bad for your teeth, such as acid. Some research also indicates that if you consume large quantities of any artificial sweetener it may be hazardous to your health.