The effect of strip, tray and office peroxide bleaching systems on enamel surfaces in vitro

Improvement of the appearance of teeth by whitening systems is one of the goals of modern esthetic dentistry. Vital tooth bleaching is administered in a variety of forms including trays, strips and paint-on gels. The concentrations and conditions of bleaching systems vary considerably between these treatment forms. Objectives This study compared surface changes associated with exposure of human premolar teeth to topical cycling treatments with three different bleaching systems: Opalescence X-Tra Boost (OPXB), Opalescence 20% PF (OP20PF) and Crest Whitestrips Supreme (CWSS), respectively. Methods Extracted human premolars were prepared in Durabase blocks and measured for tooth color, surface microhardness and roughness. Teeth were cycled in a regimen including a pre-test period, test bleaching treatment and 7 days post-bleach period. Bleaching was segmented to 0 h for untreated control group (UC); 42 h for CWSS, 42 h for OP20PF and 45 min with OPXB. Following treatment specimens were re-measured as before. Results Bleaching treatments produced significant tooth lightening (yellow reduction). Hardness of enamel specimens from control and bleaching groups were unchanged during cycling: ΔVickers hardness number (VHN): UC (18 ± 11S.D.) a; CWSS (7.0 ± 29nsd) a; OP20PF (19 ± 15S.D.) a; OPXB (25 ± 13S.D.) a (nsd = non-significant difference post-cycle-treat vs. initial Studentʹs t; ANOVA p < 0.05 a ≠ b between group comparison post-treat). With respect to surface roughness, two-dimensional analysis showed no changes with bleaching: ΔRa (roughness) 2D = UC (0.06 ± 0.06nsd) a; CWSS (0.02 ± 0.07nsd) a; OP20PF (−0.14 ± 0.08nsd) a; OPXB (0.00 ± 0.12nsd) a. Conclusion Office administered, prescribed and OTC/prescribed bleaching systems were demonstrated as similarly safe to enamel surfaces including maintenance of both hardness and roughness in vitro.