What the science says
Professional whitening uses hydrogen peroxide or carbamide peroxide to break down stain molecules within the enamel. The active ingredient penetrates the enamel surface without dissolving or weakening it. Multiple peer-reviewed studies have confirmed that professional whitening at dentist-prescribed concentrations does not cause structural damage to enamel.
What can damage enamel is misuse of over-the-counter products — particularly acidic whitening strips, charcoal toothpastes (which are abrasive, not whitening), and unregulated products bought online that may contain concentrations of hydrogen peroxide above legal UK limits. This is why professional whitening under dental supervision is important.