EFFECTS OF DIFFERENT BLEACHING AGENTS ON MICROHARDNESS OF COMPOSITE RESINS

Abstract

The objective of the study was to evaluate the effect of bleaching agents on micro hardness of com­posite resins. 15 specimens were fabricated, 10 of 3M Filtek Z350 (nano-filled composite) & 105 of Dentsply Esthet-X (hybrid composite) with 10mm diameter & 2mm thickness. Each composite group of 15 specimens was divided further into 3 groups of 5 specimens each. All four groups were tested for baseline Vickers hardness reading. One of each composite group was treated with home bleach (Beaming White home bleaching kit) & the other was treated with in-office bleach (Beaming White office bleach system) while controls were not treated with any bleaching system. The bleaching proce­dure was carried out according to the manufacturer instructions for each system respectively. Final Vickers hardness value were recorded after the respective bleaching procedures were completed .

Between-materials one-way ANOVA was used for comparison of groups at 5% level of significance & post Hoc Grames-Howell test was utilized for multiple comparisons.

Both bleaching systems significantly reduced microhardness of both composite groups. Further­more, although both bleaching agents reduced microhardness but there was no significant difference between them.

Both home & office bleaching agents reduce microhardness of hybrid & nano-filled composite resins. Therefore, it may be necessary to replace composite restorations after bleaching procedure.