Effect of Two In-office Whitening Agents on the Enamel Surface In Vivo: A Morphological and Non-contact Profilometric Study

Abstract

This study evaluated the morphological effects produced in vivo by two in-office bleaching agents on enamel surface roughness using a noncontact profilometric analysis of epoxy replicas. The null hypothesis tested was that there would be no difference in the micromorphology of the enamel surface during or after bleaching with two different bleaching agents. Eighteen subjects were selected and randomly assigned to two treatment groups (n=9). The tooth whitening materials tested were 38% hydrogen peroxide (HP) (Opalescence Xtra Boost) and 35% car- Clinical RelevanceThis in vivo study supports the hypothesis that the use of in-office bleaching agents is a safe and reliable procedure, inducing no structural damage to the enamel surface, even after prolonged and repeated applications. The bleaching agents were applied in accordance with manufacturer protocols. The treatments were repeated four times at one-week intervals. High precision impressions of the upper right incisor were taken at baseline as the control (CTRL) and after each bleaching treatment (T 0 : first application, T 1 : second application at one week, T 2 : third application at two weeks and T 3 : fourth application at three weeks). Epoxy resin replicas were poured from impressions, and the surface roughness was analyzed by means of a non-contact profilometer (Talysurf CLI 1000). Epoxy replicas were then observed using SEM. All data were statistically analyzed using ANOVA and differences were determined with a t-test. No significant differences in surface roughness were found on enamel replicas using either 38% hydrogen peroxide or 35% carbamide peroxide in vivo. This in vivo study supports the null hypothesis that two in-office bleaching agents, with either a high concentration of hydrogen or carbamide peroxide, do not alter enamel surface roughness, even after multiple applications.

Effectiveness of nano-calcium phosphate paste on sensitivity during and after bleaching: a randomized clinical trial

“…21,22 It appears that these small changes in the enamel produced by bleaching did not seem to be a problem as they were resolved by the remineralizing action of saliva. 23 This explains why previous application of fluoride before bleaching was not capable of reducing the bleaching-induced tooth sensitivity.…”

Correlation between pH and surface structural changes on human enamel submitted to different tooth whitening agents

“…A high concentration of hydrogen peroxide (G 4 ; pH = 7.01) caused a generalized dissolution of nonprismatic enamel, [5,14,16,17] however, without exposing enamel prisms [ Figures 10-12]. The quick dissolution and slow recrystallization of non-prismatic enamel resulted in a surface showing some erosions.…”

Fracture resistance of bleached teeth restored with different procedures

“…Some studies have evaluated the effects of peroxide-containing products on the physical and chemical properties of tooth. However, researches in this area have been controversial [6][7][8][9][10] . Pobbe et al 18 evaluated the fracture resistance of endodontically treated teeth submitted to dental bleaching.…”

“…The use of these traditional bleaching materials, especially hydrogen peroxide, has been associated with complications such as cervical root reabsorption, increased dentine permeability, changes in the biomechanical properties of tooth related to alteration in the chemical structure of tooth occurred by demineralization and quantitative mineral loss 6,7 . However, some studies reported that there was no evident change in mechanical and morphology after bleaching treatment 3,[8][9][10] . In addition, the endodontically treated teeth have high risk of biomechanical failure caused by elasticity of dentin decreased, lost of tooth structure from previous caries, pre-existing restorations, coronary access for endododontic treatment, suggesting the need for additional restorative considerations [11][12][13] .…”