Effect of Bleaching on Fracture Toughness of Resin Composites

Abstract

SUMMARYThis study determined the effect of bleaching agents on the fracture toughness of composite materials. Four nanofilled resin composites were evaluated: Filtek Supreme Plus, Tetric EvoCeram, Premise and Esthet-X. Four concentrations of bleaching agents were tested:Opalescence PF 10%, 20%, 35% and 45%. Fifty specimens of each composite conforming to ASTM guidelines for the single edge notch barshaped specimen were fabricated in a metal mold. The specimens were stored in artificial saliva at 37˚C for a minimum of 24 hours prior to exposing them to the bleaching agents. Ten specimens of each material were used as controls. Forty specimens of each brand were evenly divided into four groups for bleaching agent application (n=10). The resin composites were bleached on both sides for 14 days. The specimens were then subjected to a three-point bending test with a crosshead speed of 0.2 mm per second. The fracture toughness (K Ic ) was calculated. The control group K Ic value of Esthet-X was significantly higher than that of the other composites in the controlled groups. Bleaching agents significantly improved the fracture toughness values of Filtek Supreme Plus. The application of bleaching agents did not significantly change the fracture toughness values of the other nanofilled resin composites tested.

Effects of different concentrations of carbamide peroxide and bleaching periods on the roughness of dental ceramics

“…6,8,9,13 Although an increase in roughness has been observed in composite resins or glass ionomers after bleaching treatment, [18][19][20][21][22][23][24]27 no alteration in ceramic surfaces was observed after bleaching in the current study, 23 so the impact of bleaching agents on surface roughness may be considered material-dependent, as also demonstrated by previous studies. 16,[20][21][22][23] In these studies, the chemical stability of ceramics against bleaching agents was observed after treatment with 15% carbamide peroxide for 56 h, 23 16% carbamide peroxide for 126 h, 17 10% or 15% carbamide peroxide 27 and 38% hydrogen peroxide for 30 minutes 23 or 45 minutes, respectively.…”

“…[6][7][8][9][10][11][12][13][14][16][17] Similarly, bleaching agents may cause structural changes on restorative materials that may compromise their physical properties and lead to premature failure. [18][19][20][21][22][23][24] Although conventional dental ceramics are considered the most inert among all dental restorative materials, their surfaces can exhibit surface deterioration in contact with acidulated fluoride gels or other solutions. 25 In addition, the contact and possible diffusion of free radicals of H + or H 3 O + produced by bleaching agents 17 may selectively leach alkali ions and cause dissolution in ceramic glass networks.…”

The Effect Of Home Bleaching Agents On The Surface Roughness And Fracture Toughness Of Composite Resin Materials

“…When comparing the fracture toughness value of resin composites after bleaching with 10%, group 1 was significantly stronger. Our results are similar to study by Cho, et al [16] where the fracture resistance of four nanoparticle composite resins (Filtek Supreme Plus, Tetric EvoCeram, Premise and Esthet-X) was tested after exposure to four different concentrations of bleaching gels (Opalescence PF at 10%, 20%, 35% and 45%). Those authors found that bleaching had a significant effect on increasing the values of fracture resistance for the resin Filtek Supreme Plus, but not for the other resins.…”

“…This result supported data from the past that the materials categorized in the same group as nano-particle resin composites do not always have similar physical and mechanical properties. Previous studies reported various three-point flexural strength data within the same brands of resin composite [16].…”

“…It is considered to be a reliable indicator of the ability of dental materials to resist failure under load [15]. Cho, et al [16] found that bleaching had a significant effect on increasing the values of fracture resistance for the resin Filtek Supreme Plus, but not for the other resins.…”