Do bleaching dentifrices associated with a low-concentration hydrogen peroxide gel affect the surface properties and mineral content of enamel?

Background. Comparing the new and existing products is essential to identify the one that minimizes risks to the dental structures while effectively fulfilling its intended purpose. Objectives. The aim of the present study was to evaluate possible changes in the surface properties, mineral loss and color of bovine enamel subjected to bleaching dentifrices used in combination with a low-concentration hydrogen peroxide (HP) bleaching gel. Material and methods. Bovine tooth substrates disinfected with thymol were used to make 112 circular samples with a diameter of 4 mm. After the samples were embedded in transparent acrylic resin, they were polished with grit of decreasing granulation and divided into 8 groups (n = 14 per group), according to the bleaching treatment (Opalescence Go (OpGo) – 10% HP or immersion in buffered water (BW) – control) and the toothpastes used (OMW – Oral-B 3D Mineral White Clean; CLW – Colgate Luminous White Advanced; STW – Sensodyne True White; or CT – Colgate Total 12). The bleaching gel was used for 30 min daily for 10 days. The samples were brushed using an electric brush and a slurry (3:1 ratio) for 120 s twice a day, with an interval of 12 h, with the first brushing immediately after the bleaching treatment. Prior to the commencement of the treatment, the initial microhardness, surface roughness and color data was evaluated. Results. For microhardness, a reduction in values was observed for all groups, except for the control (CT + salt), whereas for roughness, there was an increase in the final values for all groups. A significant difference in the post-treatment values was observed only for the lightening treatment factor (p = 0.0079). Conclusions. There was a reduction in enamel microhardness for all groups, except for the group that used a non-bleaching dentifrice and was treated with BW.