Effect of Titanium Dioxide as bleaching Photocatalyst on tooth structure

Objectives: Evaluation of the effect of two in-office bleaching agents and two remineralizing agents on tooth color and surface roughness using titanium oxide as photocatalyst. Methods: Two in-office bleaching systems were used: GC-TiON (GC, U.S.A), Zoom advanced power (Discus Dental, USA). Two reminralizing agents were used: MI-Past (GC, U.S.A), Relief (Discus Dental, USA). 120 teeth were polished with non-fluoridated polishing paste (GC-TiON Prophy Paste). Photomicrographs were obtained before treatment; color was measured for 60 teeth using digital image analysis and Surface roughness was measured using 3-D analysis test. Each selected 60 teeth were divided into two equal groups, 30 teeth each according to bleaching system used. Each group was subdivided into three l subgroups, ten teeth each; relative to remineralizing agent applied. Teeth treated were stored in artificial saliva for 24 hours. Statistical analysis using Student's t-test, ANOVA test, and Duncan's test were made. Results: Before bleaching, the mean grey scale value for GC and Zoom groups were 101.8, 106.3. After bleaching, mean grey scale value for GC and Zoom subgroups were 153.2, 143.9. After remineralization with MI-Paste, the mean grey scale value for GC and Zoom subgroups were 152.1 and 140.4. After remineralization with Relief, the mean grey scale value for GC and Zoom subgroups were 150.5, 139.2. Irrespective of remineralizing agents used mean grey scale values of GC and Zoom groups were not affected. The mean surface roughness for GC subgroups after bleaching, after remineralization with MI-Past, and after remineralization with Relief were 155.7, 108.2, and 116.1. The mean surface roughness for Zoom subgroups after bleaching, after remineralization with MI-Past, and after remineralization with Relief were 150.9, 112.5, and 124. Conclusions: 20% hydrogen peroxide bleaching system containing nitrogen-doped titanium dioxide did affect the outcome of tooth lightening under optical irradiation. Remineralizing agents did not affect the tooth color.