The effect of two bleaching products on microhardness and surface texture of different dental aesthetic restorative materials

In this study, the effect of two different bleaching agents on the microhardness and the surface texture of six different aesthetic restorative materials were evaluated. <br>Four different composite resins (a hybrid, a flow, a micro-hybrid and a nano-hybrid), an ormocer, and a ceramic, were used and two bleaching agents were tested: hydrogen peroxide 38% and carbamide peroxide 15%. <br>For the first part of the study, where the microhardness was evaluated, 28 samples were prepared from every material (14 polished and 14 unpolished), except the ceramic (only 14 polished samples). All samples categories were divided in groups, 7 samples each, for every bleaching agent. The bleaching procedure followed. <br> On the top-surface of every sample, 5 Knoop microhardness measurements were made on every tested time period. For hydrogen peroxide 38%, the tested time periods were: before bleaching, after 15, 30 and 45 min bleaching, 24 hours later and 1 month later. For carbamide peroxide 15% the tested time periods were: before bleaching, after 8 and 56 hours bleaching, 24 hours later and 1 month later. For the second part of the study, where the surface texture was tested, 3 samples of every category and for every time period described above, were prepared respectively. <br>The statistical analysis showed that the effect of bleaching on microhardness of composite resins and ceramic was not statistically significant (hybrid: p=0,8670>0,05, flow: p=0,9479>0,05, micro-hybrid: p=0,3542>0,05, nano-hybrid: p=0,7665>0,05, ceramic:0,8255>0,05). In contrast, the effect of bleaching on microhardness of ormocer was statistically significant (p=0,0435<0,05). <br>The SEM evaluations showed slight changes on the surface of the samples. The polished samples were more stable compared to the unpolished ones. The hydrogen peroxide 38% caused more surface changes compared to carbamide peroxide 15%. <br>In conclusion, bleaching seems to cause slight but not significant changes on the restorative materials. There is no reason to avoid bleaching when composite materials are present in the oral cavity.

Author dc:creator

• Polydorou, Olga

Contributors dc:contributor

• Hellwig, Elmar

• bleaching
• composite
• ormocer
• microhardness
• SEM

Repository record source_url

https://freidok.uni-freiburg.de/data/1433

OAI identifier oai:identifier

oai:freidok.uni-freiburg.de:1433