Effect of in-office tooth bleaching on the microhardness of six dental esthetic restorative materials

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.…”

“…As the detrimental effects of bleaching treatment are time-dependent, more mineral loss is expected on enamel and dentin surfaces in extended treatments. 1,6,24 Therefore, despite the lack of changes in ceramic surface roughness from the beginning throughout 126 h of bleaching treatment, it is possible that overexposure to bleaching agents for longer than 126 h might lead to some degradation in ceramics due to the interaction between free radicals released from the bleaching gels and the ceramic glass network, which leads to the loss of alkali metal ions from the glass surface. However, only further evaluation, comprising longer exposure to bleaching agents, would confirm such speculation.…”

“…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. 24 The 126-hour bleaching protocol was chosen to simulate 21-day nightguard bleaching treatment, as most patients achieve the best results within this period. 4,5 Although this period may be considered optimal, bleaching treatment may be extended to longer treatment periods in patients with severe dis- coloration.…”

“…[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.…”

Changes in surface roughness and color stability of two composites caused by different bleaching agents

“…However, other studies did not observe such changes in the surface or on the microhardness of composites. (2,9,10). Regarding color change, it has been shown that HP is more effective at lightening composite materials when compared with CP at the same concentration (11) and it is also known that a nanoscale composite is more affected than a microhybrid composite when exposed to dyes, but this change can be reversed by bleaching (12).…”