This study evaluated tooth whitening and sensitivity that occurred during and after 14 days of overnight bleaching with 15% carbamide peroxide gel with potassium nitrate and fluoride (Opalescence 15% PF, OP) and 16% carbamide peroxide with amorphous calcium phosphate (Nite White 16%, NW). Thirty-two subjects bleached their teeth using custom trays. The subjects had a baseline evaluation and returned after 7, 14, 21, 35 and 90 days for subjective and objective color evaluations. The subjects also recorded daily tooth and gingival sensitivity. The treatments were compared for differences in mean L*, a*, b* and shade guide rank order at baseline and each appointment thereafter, using repeated measures analysis of variance (ANOVA). OP and NW showed significant tooth whitening. Subjects using OP were significantly lighter in b* and E* than those using NW, while exhibiting no difference in tooth or gingival sensitivity overall or during any evaluation.