This study compared two methods of cleaning stained pits and grooves (fissures) on the chewing surfaces of back teeth before measuring them with a laser fluorescence device (DIAGNOdent), which is used to help detect early tooth decay. In the same patients, one side of the mouth was treated with mechanical polishing using a prophylaxis paste, while the other side was treated with a 35% hydrogen peroxide gel. The study measured whether either cleaning method changed the device's readings, and if so, by how much. The results showed that the readings increased after both procedures, but the increase was larger after polishing than after hydrogen peroxide application. These findings may help clinicians better interpret DIAGNOdent readings after cleaning stained teeth.