What topical fluoride agent should NOT be applied to a patient with bulimia nervosa due to dental erosion?

Acidulated phosphate fluoride (APF) has a pH of approximately 3.5, making it contraindicated in patients with dental erosion (such as those with bulimia, GERD, or intrinsic acid exposure). The low pH of APF can further demineralize and etch the already compromised enamel surface. Neutral sodium fluoride (NaF) products (pH ~7) or fluoride varnish are the preferred alternatives because they do not contribute to acid erosion. For patients with bulimia, management also includes neutralizing the mouth with a sodium bicarbonate rinse after purging, waiting at least 30-60 minutes before toothbrushing, and using remineralizing agents (MI Paste, fluoride varnish).