Which tray whitens better? new study tests soft vs rigid for brighter smiles

This study looks at whether using a soft or rigid tray for at-home tooth whitening with 16% carbamide peroxide makes a difference in how satisfied people are, how white their teeth get, and how much tooth sensitivity or gum irritation they experience. About 100 adults with healthy, unstained front teeth will use the gel for 2 hours daily over 3 weeks. Researchers will check results up to a year later.