Nightguard vital bleaching and its effect on enamel surface morphology

Background : The effect that nightguard vital bleaching (NGVB) has on enamel surface morphology is a subject of debate. Previous studies that have evaluated the effect of NGVB on the enamel surface report minimal changes to changes that appear to worsen post-treatment. The purpose of this in vivo NGVB study was to evaluate by scanning electron microscopy (SEM) the effects that 10% carbamide peroxide has on enamel morphology after 2 weeks of treatment and at 6 months post-treatment.
Materials and Methods: Ten patients participated in the study. Each participant wore a guard filled with an active whitening solution for 8 to 10 hours per day for 14 treatment days. An impression of the study teeth (maxillary incisors) was taken at baseline, after 14 days of treatment, and at 6 months post-treatment, and an epoxy cast made. The epoxy casts were prepared for viewing under the SEM and photographs were taken at 200 times and 2000 times magnification. Six examiners evaluated changes in enamel surface morphology by comparing the SEM photographs taken at baseline, on treatment day 14, and at 6 months post-treatment. Still masked, the examiners also compared each patient's baseline: treatment day 14 and baseline: 6 months post-treatment photographs with photographs of a known standard.
Results : This in vivo study demonstrated that a 14-day regimen of NGVB using a 10% carbamide peroxide solution had minimal effect on the surface morphology of enamel and that the effects did not worsen over time.