Effect of at-home bleaching and fluoride desensitizing agents on surface properties of as-set vs. sof-lex finished contemporary direct esthetic restoratives

The present investigation was designed to study the effect of mechanical and chemical treatments on the surface properties of currently available direct tooth colored restoratives. Two types of esthetic restorative materials were used, the first was a hybrid dental composite while the second was a poly-acid modified resin. A total of sixty cylindrical specimens measuring 3 mm. in thickness and 5 mm. in diameter were prepared; 30 specimens for each restorative material. The specimens of each material were divided into two main groups. In the first group, the last increment of either composite resin or compomer was cured against mylar strip without any finishing or polishing procedure (as-set finish). In the second group, the last increment of the restorative material was cured against Mylar strip, then finished using silicon oxide discs (Sof-lex). Barcol hardness readings, surface roughness measurements, and SEM examination of the surfaces were carried out before and after bleaching using a 10% carbamide peroxide gel for 48 hours, and after fluoride application for 20 minutes. The results showed that finishing procedure was a significant variable for the surface roughness of the investigated hybrid composite and poly-acid modified resins. Sof-Lex finished composite and compomer specimens showed an increased surface roughness compared to the as-set surfaces. Bleaching gel application did not have any significant effect on the surface hardness of composite specimens. However, there was a contradiction in its effect on the surface hardness of compomer. A significant improvement in hardness of the as-set compomer as opposed to a significant reduction in hardness of the Sof-Lex finished specimens was revealed. Bleaching gel application resulted in marked erosion of the tested composite and compomer. This was manifested by the increased surface roughness of composite surface and the appearance of voids in the SEM photomicrographs of bleached compomer specimens. The application of fluoride gel following bleaching did not result in any significant change in both the surface hardness of the investigated composite and compomer, and the surface roughness of composite. However, a significant improvement in surface roughness resulted following fluoride gel application to bleached compomer surfaces.King Saud Universit