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.