What types of stains does this kit work on, and what should I not expect it to change?

The gel-and-light system is designed for extrinsic staining — the yellow or brown film that builds up on enamel from pigmented beverages (coffee, tea, red wine, cola), tobacco, or certain foods. It works by breaking down chromophores on the tooth surface. It will not lighten intrinsic discoloration caused by medication (e.g., tetracycline), fluorosis, trauma, or natural ageing of the dentin beneath the enamel. It also does not whiten crowns, veneers, fillings, bonding, or dentures; those materials do not respond to peroxide-based gels the way natural enamel does. If you have a mix of natural teeth and restorations in your smile line, whitening may create a shade mismatch. For best cosmetic results, use on clean teeth after a professional hygiene visit, and avoid staining foods and drinks for at least an hour after each session. The kit is intended for adults over 18 and is not a substitute for dental care.