Tooth bleaching with low‐temperature plasma lowers surface roughness and Streptococcus mutans adhesion

Aim To evaluate the structural–morphological changes in enamel surface roughness and Streptococcus mutans adhesion after tooth bleaching using plasma in combination with a low concentration of 15% carbamide peroxide (CP). Methodology Sixty pairs of premolars were randomly assigned to the treatment groups ( n  =   30; buccal surface, groups 1A/2A) or controls ( n  =   30; palatal surface, Groups 1B/2B). Group 1A received a low concentration of 15% CP and low‐temperature plasma. Premolars in group 1B were placed in phosphate‐buffered saline and served as controls. The buccal surface of Groups 2A was subjected to 15% CP alone, whilst the palatal surface was subsequently immersed in PBS (group 2B). After bleaching, all teeth were soaked for 1 h in artificial saliva at 37 °C. Subsequently, teeth were placed in brain–heart infusion with S. mutans at 37 °C for 24 h. The assessment of the structural–morphological changes was carried out using a biofilm assay, scanning electron microscopy and atomic force microscopy. Statistical analysis of the data was performed with the SPSS (SPSS Inc., Version 18.0, Chicago, IL, USA). The Student's t ‐test was used to determine whether there was a significant difference in the structural–morphological effects with and without plasma. Results Significantly less S. mutans adhesion was observed in group 1A compared with the other groups ( P  <   0.05). Moreover, the surface roughness was significantly greater in group 2A compared with the other groups ( P  <   0.05). Conclusions The application of plasma did not result in any structural–morphological and topographic changes in the enamel. The combined bleaching method using plasma and a low concentration of 15% CP was less destructive, particularly with respect to tooth surface changes.