https://www.journalofprosthodonticresearch.com/article/S1883-1958(15)00099-7/pdf

Applications of polyetheretherketone (PEEK) in oral implantology and prosthodontics

Nonvital Tooth Bleaching: A Review of the Literature and Clinical Procedures

Effect of bleaching on restorative materials and restorations—a systematic review

Photopolymerization upon LEDs: new photoinitiating systems and strategies

Purpose: This review integrated the current literature on diffusion of whitening agents, their interactions with stain molecules, and changes to the surface, with the aim of establishing a better understanding of the mechanism underlying tooth whitening. Materials and Methods: An electronic PubMed database search, with combinations of the following terms was performed:Tooth Bleaching,Tooth Bleaching Agent, Hydrogen Peroxide, Pharmacokinetics,Tooth Permeability, Oxidation-Reduction,Tooth Demineralization, and Color. Results: Tooth whitening is a dynamic process that involves diffusion of the whitening material to interact with stain molecules and also involves micromorphologic alterations on the surface and changes within the tooth that affect its optical properties.The interaction seems not to be limited to stain molecules, but rather an affinity-based interaction process that also accompanies effects on sound enamel and dentin structures. Conclusions: This review underlines that supervision by dental health professionals as recommended by the American Dental Association (ADA) Council on Scientific Affairs is critical to achieving a successful and safe whitening outcome. CLINICAL SIGNIFICANCE The mechanism that underlies tooth whitening with the use of peroxide-based materials is a complex phenomenon encompassing diffusion, interaction, and surfaces changes within the tooth.Therefore, supervision by dental health professionals as recommended by the ADA Council on Scientific Affairs is imperative to achieve a successful and safe whitening outcome. (J Esthet Restor Dent ••:••-••, 2015)

Review of the Mechanism of Tooth Whitening

Recent studies have concluded that carbamide peroxide bleaching agents significantly affect the bond strength of composite to bleached enamel. This study evaluated the effects of bleaching regimen with different carbamide peroxide concentrations and post-treatment times on composite bond strength to enamel. Two hundred and four flat buccal and lingual enamel surfaces obtained from erupted sound third molars were randomly divided into 17 groups (n = 12). Sixteen experimental groups comprised the evaluation of four carbamide peroxide home bleaching agents (Opalescence 10%-20% and Whiteness 10%-16%) and four time intervals after bleaching (one day, one, two and three weeks). Specimens of control group were not submitted to bleaching and were stored in artificial saliva at 37 degrees C for 10 days. The specimens of experimental groups were exposed to one daily application of carbamide peroxide for six hours for 10 consecutive days. After each daily treatment and post-bleaching, the specimens were stored in artificial saliva solution. Bonds were formed with Scotchbond MP and Z-100 composite resin, and shear bond test was carried out 24 hours after adhesive-composite application. Two-way ANOVA showed that the bond strengths were significantly different (p < 0.05). For the first two weeks post-bleaching, the bond strengths of resin to enamel were low. After a lapse of three weeks, the bond strength returned to that of the untreated control group. Increased concentration did not prolong the time needed prior to bonding.

The effect of elapsed time following bleaching on enamel bond strength of resin composite.

The aim of this study was to evaluate the surface roughness, microhardness and morphology of human enamel exposed to six bleaching agents (at baseline and post-treatment). Human dental enamel samples were obtained from human third molars and randomly divided into seven groups (n = 11): control, Whiteness Perfect--10% carbamide peroxide (10% CP), Colgate Platinum--10% CP, Day White 2Z--7.5% hydrogen peroxide (7.5% HP), Whiteness Super--3% CP, Opalescence Quick--35% CP and Whiteness HP--35% HP. Bleaching agents were applied according to manufacturers' instructions. The control group remained not treated and stored in artificial saliva. Microhardness testing was performed with a Knoop indentor and surface roughness was analyzed with a profilometer. Morphologic observations were carried out with scanning electron microscopy (SEM). Results were statistically analyzed by two-way analysis of variance and Tukey's test (5%), and revealed a significant decrease in microhardness values and a significant increase in surface roughness post-bleaching. Changes in enamel morphology after bleaching were observed under SEM. It was concluded that bleaching agents can alter the microhardness, roughness and morphology of dental enamel surface.

/pdf/peroxide-bleaching-agent-effects-on-enamel-surface-1i0i3y6ht3.pdf

Peroxide bleaching agent effects on enamel surface microhardness, roughness and morphology

Concern has been expressed regarding the adverse effects of peroxide-containing tooth bleaching agents on enamel surface. This study examined enamel average surface roughness before (baseline) and after an in-office bleaching protocol and investigated the influence of high concentrations of carbamide peroxide gels on its surface staining and morphology. Flat enamel surfaces were submitted to 35 and 37% carbamide peroxide or to no bleaching treatment (n = 10) and evaluated with a profilometer. Eight specimens from each group were randomly selected and immersed in a 2% methylene blue solution. Afterwards, specimens were ground into powder and prepared for the spectrophotometric analysis. Two remained specimens of each group were examined using a scanning electron microscope. Data were subjected to analysis of variance and Tukey test (P > 0.05). Baseline roughness average was statistically similar for all groups, however, 35% carbamide peroxide produced the roughest enamel surfaces. Different concentrations of carbamide peroxide produced similar staining means and enamel surface morphological alterations.

High-concentrated carbamide peroxide bleaching agents effects on enamel surface.

Effect of carbamide peroxide bleaching agents on tensile strength of human enamel

Objective: Since little is known about the effects of carbamide peroxide (CP) containing fluoride (F) or calcium (Ca), this study evaluated the effects of experimental and commercially available bleaching agents, with or without F and Ca, on enamel. Method and Materials: Sound enamel slabs were randomly divided into six groups (n = 10): placebo gel (PLA); Whiteness (WHI-10% CP; FGM); Opalescence F (OPA-10% CP+F; Ultradent); Pola Night F (PN-10% CP+F; SDI); and experimental gels: 10% CP + F (CPF) and 10% CP + Ca (CPCa). The samples were submitted to 6-hour gel applications daily for 14 days and stored in remineralizing solution after treatment. Enamel microhardness measurements were performed at baseline and after bleaching. In addition, the analytical concentrations of F and Ca and the pH of the water used to rinse the bleached surface were analyzed by means of ion-selective electrode, atomic absorption spectroscopy, and pH meter, respectively. Results: Enamel surface microhardness significantly decreased after bleaching with nonenhanced 10% CP (WHI). The chemical analyses suggest F uptake promoted by high-concentrate F bleaching gels (CPF, OPA, and PN) and a F loss with nonenhanced 10% CP bleaching gels (PLA, WHI). CP agent enhanced with Ca (CPCa) also caused Ca enamel uptake. Conclusion: Enamel was susceptible to mineral changes during bleaching treatment, but mineral loss was minimized by the addition of F and Ca to bleaching agents.

Vanessa Cavalli

Papers

The effect of elapsed time following bleaching on enamel bond strength of resin composite.

Peroxide bleaching agent effects on enamel surface microhardness, roughness and morphology

High-concentrated carbamide peroxide bleaching agents effects on enamel surface.

Effect of carbamide peroxide bleaching agents on tensile strength of human enamel

Effects of bleaching agents containing fluoride and calcium on human enamel.