Changes in physical properties of universal composites and CAD/CAM materials after bleaching and antioxidant applications: Scanning electron microscope and atomic force microscope evaluation.

To evaluate the effects of vital bleaching agents and the subsequent application of ascorbic acid (AA) to universal composites and resin-based CAD/CAM blocks on the physical properties of materials. In the study; G-enial A'chord (GCA), Filtek Ultimate (FU), Clearfil Majesty (CM) composites, and LAVA Ultimate (LU), Cerasmart (GCC) CAD/CAM blocks were used. The materials were divided into two subgroups based on the applied bleaching type (n = 30/group): office bleaching (OB) and home bleaching (HB). After bleaching, AA was applied to the samples. Surface roughness, microhardness, and color change values of all samples were measured at three stages: initial (I), post-bleaching (B), and post-bleaching+AA application (BA). Statistical analysis was performed using 3-way Mixed ANOVA with Bonferroni correction (p < .05). The BA of the HB group of CM; the B of the HB group of LU; the B roughness values of both the OB and HB groups of GCC were significantly lower than I. The microhardness values of all the materials examined decreased significantly after both bleaching (p < .05). With regard to the AA application, it significantly decreased Ra values in the HB group of CM. In addition, it significantly increased the microhardness values in the HB groups of CM and GCC. Also, the ΔE001 and ΔE002 values for the FU and GCC HB groups were significantly higher than in the OB groups (p < .05). Bleaching and AA application affected the physical properties of the materials. The physical properties of the materials either remained unchanged or improved with the application of AA after bleaching. RESEARCH HIGHLIGHTS: This article presents in vitro results of a new approach that has not been studied before. Ascorbic acid, used to increase the bond strength between the material-tooth after bleaching, was used to eliminate the adverse effects of bleaching on the physical properties of aesthetic restorative materials. Additionally, the effects of all procedures on the materials were examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). As a result of the study, it was concluded that the application of ascorbic acid after bleaching improved the physical properties of some of the materials.

Intracoronal tooth bleaching - A review and treatment guidelines.

Intracoronal bleaching is a minimally invasive procedure that was introduced into dentistry in the 19th century. The role of that procedure in enhancing the colour of teeth subjected to internal discolouration while being conservative made it extremely popular amongst dental professionals. Different materials and techniques have been utilized over the years attempting to obtain predictable long-term results while minimizing any associated risks. Contemporarily, bleaching agents are mainly based on peroxide-releasing compounds in different formulations and delivery systems. Different theories have been formulated on the bleaching mechanism of such agents, but the exact mechanism is yet to be proven. The effect of hydrogen peroxide-based bleaching agents on the organic structure of enamel and dentine has been extensively investigated to address the effects of bonding of resin-based restorative materials to hard tooth structure. Multiple case reports raised a concern about the contribution of intracoronal bleaching in developing invasive root resorption. Modification of intracoronal bleaching techniques was thus necessary to address such concerns. This review will provide a summary of the important aspects of intracoronal bleaching, focusing on how it applies to the contemporary clinical setting. © 2023 Australian Dental Association.

Dental aesthetic perception of patients submitted to activated charcoal-based bleaching agents: A randomized clinical trial.

OBJECTIVE: To evaluate the effects of activated charcoal-based products used in two presentation forms (powder or toothpaste), compared to 10 % carbamide peroxide and conventional toothpaste on aesthetic perception and psychosocial impact before and after treatment. METHODS: Fifty-six participants were divided into 4 experimental groups (n = 14). Activated charcoal-based powder (PW); Activated charcoal-based dentifrice (AC); Conventional fluoride toothpaste (CD) and 10 % carbamide peroxide (CP). All products were used for 14 days. Psychosocial impact on dental esthetics (PIDAQ), oral health impact profile (OHIP- Esthetics) and orofacial esthetics scale (OES) questionnaires were applied before and after treatment. Descriptive and exploratory data analyses were performed and analyzed using linear mixed models for repeated measures over time considering significance level of α = 0.05. RESULTS: For PIDAQ, the CP group showed significant decrease in psychological impact, aesthetic perception domains and overall score, while in the PW group, there was only a significant decrease in the psychological impact domain. Decrease in OHIP was observed for the functional limitation domain scores for treatments with CP and PW, in the psychological discomfort domain, decrease was observed for all groups, while for the OES questionnaire, significant increase in the color domain was observed for the CP group. CONCLUSION: Activated charcoal-based products showed lower scores in all questionnaires when compared with carbamide peroxide; thus, charcoal-based products promoted lower impact on quality of life and aesthetic perception. CLINICAL RELEVANCE: In this randomized clinical trial, charcoal-based OTC products had inferior quality of life and aesthetic perception results compared to conventional carbamide peroxide bleaching.

The effect of in-office bleaching agents on the Vickers hardness and surface topography of polished and unpolished CAD/CAM composite materials.

In-office bleaching, using hydrogen peroxide, is effective to remove dental enamel stains. However, bleaching agents can deteriorate surface properties of CAD-CAM materials. This in vitro study aimed to investigate the effect of in-office bleaching agents on Vickers hardness and surface topography of polished and unpolished dental CAD-CAM composite materials (Grandio blocs, Lava Ultimate, BRILLIANT Crios, Cerasmart), and a polymer-infiltrated ceramic network block (Vita Enamic). The specimens were randomly divided into two groups: unpolished or polished. The micro-hardness and surface topography of each group were measured before bleaching, after a 60 min bleaching period, and 24-h and one-month post-bleaching. In-office bleaching significantly influenced the Vickers hardness of both the polished and unpolished CAD/CAM composite blocks, with Vita Enamic exhibiting the least hardness stability among all groups. Furthermore, in-office bleaching significantly influenced the surface roughness of unpolished CAD/CAM composite blocks. There was a significant difference in hardness reduction between the polished and unpolished specimens for most of the investigated materials at different time points. The bleaching did not influence the surface roughness of the investigated polished group, except for Vita Enamic and Lava Ultimate. However, it did influence the surface roughness of the investigated materials in the unpolished group.

Anti-Melanogenic and Antioxidant Activity of Bifidobacterium longum Strain ZJ1 Extracts, Isolated from a Chinese Centenarian.

Melanin produced by melanocytes protects our skin against ultraviolet (UV) radiation-induced cell damage and oxidative stress. Melanin overproduction by hyperactivated melanocytes is the direct cause of skin hyperpigmentary disorders, such as freckles and melasma. Exploring natural whitening agents without the concern of toxicity has been highly desired. In this study, we focused on a Bifidobacterium longum strain, ZJ1, isolated from a Chinese centenarian, and we evaluated the anti-melanogenic activity of the distinctive extracts of ZJ1. Our results demonstrated that whole lysate (WL) and bacterial lysate (BL) of ZJ1 ferments efficiently reduce α-melanocyte-stimulating hormone (α-MSH)-induced melanin production in B16-F10 cells as well as the melanin content in zebrafish embryos. BL and WL downregulate melanogenesis-related gene expression and indirectly inhibit intracellular tyrosinase activity. Furthermore, they both showed antioxidant activity in a menadione-induced zebrafish embryo model. Our results suggest that ZJ1 fermentation lysates have application potential as therapeutic reagents for hyperpigmentary disorders and whitening agents for cosmetics.

Hybrid light applied with 37% carbamide peroxide bleaching agent with or without titanium dioxide potentializes color change effectiveness.

BACKGROUND: The effectiveness of dental color change was assessed by incorporating titanium dioxide (TiO2) into 37% carbamide peroxide bleaching agent associated with hybrid light. METHODOLOGY: Fifty bovine incisors were selected to receive the bleaching treatment, and separated into five groups (n = 10): 35% hydrogen peroxide (HP) (Whiteness HP, FGM/HP); 37% carbamide peroxide (CP) (Whiteness SuperEndo, FGM/CP); CP + hybrid light (HL) (CP HL); CP + 1% TiO2 (CP TiO2); CP TiO2 + hybrid light (CP TiO2 HL). The bleaching gels were applied to the dental surface for 30 min. Hybrid light (Whitening Plus, DMC/infrared laser diodes + blue LEDs +violet LEDs) was applied with 1 min of active light, alternating with 1 min of pause. A spectrophotometer (VITA Easyshade® Advance, Vita) was used to determine the color of the dental elements at baseline and time points after the 1st, 2nd and 3rd bleaching sessions. Color change effectiveness was evaluated using Vita Classical, CIEL*a*b*, WID and ΔEab, ΔE00 and ΔWID parameters. RESULTS: Generalized mixed linear models for repeated measures (α = 5%) showed significant decrease in Vita Classical scores and a* and b* values, as well as an increase in L* and ∆WID values for all the groups. Higher color change values for ΔEab were observed for CP HL and CP TiO2 HL, while those of ΔE00 and ΔWID were higher for CP TiO2 HL at the end of the bleaching treatment. CONCLUSION: Hybrid light applied with TiO2 incorporated into CP potentiated the effectiveness of the color change in the tooth structure.

Effect of in-office bleaching agent on the surface roughness and microhardness of nanofilled and nanohybrid composite resins.

Background: To compare the surface roughness and microhardness of Ceram.x® SphereTEC™ one and Filtek Z350 XT after in-office bleaching with Pola office. Methods: Twenty samples each of (10 mm diameter and 2 mm height) Ceram.x® SphereTEC™ one and Filtek Z350 XT were prepared. The samples were subjected to three bleaching sessions with 35% hydrogen peroxide (Pola office) with a seven-day interval between each session. Surface roughness and microhardness of the prepared samples prior to and after the bleaching regimen were measured using a profilometer and Vickers hardness tester, respectively. Results: A significant reduction (p <0.001) in the surface hardness of Filtek Z350 XT from 27.67 ± 2.10 to 17.83 ± 1.36 Vickers hardness number (VHN) was observed after the bleaching whereas no significant reduction in surface hardness was observed with Ceram.x® SphereTEC™ one. The adjusted mean (estimated marginal mean) microhardness after bleaching for Ceram.x ® SphereTEC™ one (35.79 ± 1.45) was significantly higher than Filtek Z350 XT (19.54 ± 1.45) (p < 0.001). However, in-office bleaching of these materials did not significantly alter their surface roughness. Conclusions: In office-bleaching with 35% hydrogen peroxide can reduce the microhardness of nanofilled composite. However, the surface roughness was not influenced by the bleaching procedure in both nanohybrid and nanofilled composite resin materials.

Quantitative analysis of the degree of demineralization for bleached enamel by optical coherence tomography.

BACKGROUND: Tooth bleaching imparts whitening effects along with adverse effects such as increased tooth sensitivity and enamel surface changes. Herein, we employed optical coherence tomography (OCT), a nondestructive optical detection technique, for evaluation of tooth enamel after treatment with peroxide-based bleaching agents. METHODS: Fifteen enamel samples were bleached using 38% acidic hydrogen peroxide-based bleach, subjected to OCT scanning, and then cross-sectioned and imaged under polarized light microscopy (PLM) and transverse microradiography (TMR). OCT cross-sectional images were compared with PLM and TMR. The depth and severity of demineralization produced in the bleached enamel were measured by OCT, PLM, and TMR. Comparison between the three techniques was performed using Kruskal-Wallis H non-parametric test and Pearson correlation. RESULTS: In comparison with PLM and TMR, OCT clearly detected the changes in the enamel surface after hydrogen peroxide bleaching. Significant correlations (p<0.05) were observed in lesion depth between OCT and PLM (r=0.820), OCT and TMR (r=0.822), and TMR and PLM (r=0.861). There was no statistically significant difference in demineralization depth values measured by OCT, PLM, and TMR (p>0.05). CONCLUSION: OCT can allow real-time, non-invasive imaging of artificially bleached tooth models and automatically measure the early changes in the enamel lesion structure upon exposure to hydrogen peroxide-based bleaching agents.

Prognosis in home dental bleaching: a systematic review.

OBJECTIVES: The aim of this systematic review was to evaluate the prognosis of at-home dental bleaching using low concentration bleaching products. MATERIALS AND METHODS: This review was conducted was performed following the recommendations of the 2020 PRISMA statement and was registered in the International Prospective Register of Systematic Reviews (PROSPERO-CRD42022360530). The PICO question was "What is the prognosis of home teeth whitening treatment?". An advanced electronic search was made in three databases: PubMed, Web of Science, and Embase. RESULTS: The database search led to the retrieval of 225 articles. After elimination of duplicate references, the titles and abstracts of the articles were analyzed with respect to the eligibility criteria, and 24 studies were included for the development of the systematic review. CONCLUSIONS: Most authors state that the color remains stable between 1 and 2.5 years regardless of the type of bleaching agent or the forms of administration, and color stability in cases of severe discolorations presents a higher degree of recurrence. CLINICAL RELEVANCE: Given the growing demand for dental cosmetic treatments, the following systematic review may aid the clinician's continuing education and evidence-based practice by providing knowledge on the field of at-home dental bleaching agents and their long-term effects.

Effect of the application of a hydrogen peroxide home bleaching agent on the cytotoxicity of different CAD-CAM restorative materials.

BACKGROUND: The information regarding the cytotoxicity of ceramic and resin-matrix ceramic materials subjected to over-the-counter bleaching agents is limited in the literature. OBJECTIVES: The aim of the present study was to investigate the cytotoxic effects of lithium disilicate ceramic (LDC), resin nano-ceramic (RNC) and nano-hybrid composite (NHC) computer-aided design/ computer-aided manufacturing (CAD-CAM) block materials subjected to a home bleaching agent and artificial saliva. MATERIAL AND METHODS: A total of 432 specimens were prepared from 3 different CAD-CAM materials. Each material group was divided into 4 groups according to the storage medium (phosphate-buffered saline (PBS) or artificial saliva), and whether the specimens were subjected to a bleaching agent or not. For the bleached groups, hydrogen peroxide (10%) was applied to the specimens for 30 min/day for 15 days, and the specimens were immersed in PBS or saliva after bleaching. The viability of epithelial cells was detected using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay at the end of the 5th, 10th and 15th day of the study. The data was statistically analyzed. RESULTS: Regardless of the storage medium and the time period, all restorative materials decreased the viability of cells. The highest cytotoxicity levels were determined on the 15th day of the study. The application of a bleaching agent increased the cytotoxicity of the LDC specimens stored in artificial saliva. The RNC material stored in PBS demonstrated significantly higher cell viability than the LDC and NHC groups. The LDC and RNC specimens stored in artificial saliva did not show any significant difference in cytotoxicity. When the materials were subjected to bleaching, NHC demonstrated the highest cytotoxicity during all periods. No significant difference was found between the LDC and RNC specimens subjected to both artificial saliva and bleaching in terms of cytotoxicity. CONCLUSIONS: The type of restorative material, the immersion medium, the application of a bleaching agent, and the application period affected the cytotoxicity of the materials. Over-the-counter home bleaching agents may induce cellular cytotoxicity due to the existing restorations, and patients should be informed about this potential biological response.

Effects of Dental Bleaching Agents on the Surface Roughness of Dental Restoration Materials.

Background and Objectives: This study aimed to evaluate the surface roughness evolution of several finished and polished composites when bleaching materials are applied. The research was conducted on four microhybrid or nanofilled composites that are used in dental restorations. Materials and Methods: For each composite type, 5 samples were selected for control, 5 samples were subjected to the bleaching protocol "office bleach" with 40% hydrogen peroxide, and 5 other samples were subjected to the "home bleach" protocol with 16% carbamide peroxide, resulting in a total number of 60 samples. The surfaces of all the samples were tested for roughness, and the values of the most relevant parameter (Ra), were collected. Comparisons between composites and samples were performed using one-way ANOVA (in Statistical Package for Social Sciences). Results: After the bleaching protocol with 40% hydrogen peroxide gel, it was found that the roughness of the group increased considerably compared to the control group, so the highest roughness was found at GC Gradia direct anterior group, and the lowest value was registered for the 3M ESPE Valux Plus group. Following the bleaching protocol with 16% carbamide peroxide (home bleach), it was noted that the sample surfaces were not as affected. In this case, the lowest roughness was found at 3M ESPE Valux Plus group, and the highest roughness was registered for the GC G-aenial anterior group. Following the interpretation of the results, all four types of dental composites tested showed significant surface roughness differences between the groups subjected to bleaching protocols and those kept as control (p < 0.05). Conclusions: The surfaces of the samples were affected by the bleaching protocols by increasing the roughness compared to the control samples.

Effects of in-office bleaching agents on polished and unpolished nanofilled resin composite.

BACKGROUND: This study investigates the effects of in-office bleaching agents on the color change and surface roughness of nanofilled resin composite finished by various polishing procedures. METHODS: The authors made 108 specimens from nanofilled resin composite, and the finishing and polishing procedures were performed with either Sof-Lex (3M ESPE) or OneGloss (Shofu). The specimens were then immersed in tea or coffee solution for 1 week, after which in-office bleaching agents were applied (n = 9). After polishing and bleaching, the surface roughness was measured with a surface profilometer. The specimen color parameters were measured with the Commission Internationale de l'Eclairage L∗a∗b∗ system in 3 stages, namely after polishing, after staining, and at the end of the bleaching procedure. The total color changes (ΔEab∗) were calculated, and ΔEab∗ not exceeding 2.7 was considered a clinically acceptable threshold. RESULTS: The highest initial roughness value was observed on surfaces polished with OneGloss. In all groups, the surface roughness increased significantly after bleaching. For the Sof-Lex group specimens stained in both tea and coffee solutions, bleaching agent Opalescence Boost (Ultradent) reduced the color change value to 2.7 or less after bleaching. CONCLUSIONS: In-office bleaching agents increased surface roughness in all groups, especially on unpolished surfaces. However, surface roughness was at an acceptable threshold for the multistep polished group, Sof-Lex, after bleaching. Nanofilled resin composite staining can be partially reduced by in-office bleaching agents but not completely removed. PRACTICAL IMPLICATIONS: To reduce the increase in surface roughness of composite restorations due to bleaching, polishing should be applied before and after bleaching.

Whitening efficacy and tooth sensitivity in a combined in-office and at-home whitening protocol: A randomized controlled clinical trial.

OBJECTIVE: This controlled randomized clinical trial determined the whitening efficacy and the intensity and absolute risk of tooth sensitivity in dual whitening when prefilled at-home whitening trays were used between in-office whitening intervals. MATERIALS AND METHODS: An in-office whitening agent containing 35% hydrogen peroxide was used. A prefilled tray with a whitening agent containing 6% hydrogen peroxide was used for at-home whitening. Sixty-six subjects were randomly assigned to three groups. Group I: at-home whitening was performed 10 times between the in-office whitening treatments. Group II: at-home whitening was performed five times between the in-office whitening treatments. Group III: only in-office whitening was performed. The tooth color changes were evaluated using a spectrophotometer. A visual analog scale was used to express the pain intensity. RESULTS: All the groups showed increased ΔE*ab, ΔE00 , and ΔWID with increased whitening sessions. Group I at the 3rd whitening session showed significantly higher ΔE*ab, ΔE00 , and ΔWID than group III. Tooth sensitivity showed higher values up to 24 h after whitening. CONCLUSIONS: Although dual whitening with the prefilled tray and in-office whitening had higher whitening ability than in-office whitening alone, the intensity and absolute risk of tooth sensitivity was similar. CLINICAL RELEVANCE: The dual whitening might produce faster and stronger whitening effects than in-office whitening alone.

The effect of propolis on the bond strength of composite resin to enamel after intracoronal bleaching with different bleaching agents.

This study evaluated the effect of propolis as an antioxidant agent on bond strength to enamel after intracoronal bleaching. A total of 160 incisors were endodontically treated. Sixteen teeth were served as control, and the remaining teeth were randomly divided into three main groups according to the bleaching agent used; group 1: Sodium perborate (SP); group 2: Carbamide peroxide (CP); group 3: Hydrogen peroxide (HP). After bleaching, the samples were divided into three subgroups; subgroup A: no antioxidant agent application, subgroup B: sodium ascorbate (SA), subgroup C: propolis (PP). After the antioxidant agents application, the sample's surfaces were washed and dried. After adhesive application, composite resin cylinders were applied to enamel surfaces using tygon tubes and a shear bond strength test was performed. The use of PP significantly decreased the bond strength of composite resin to the enamel (p < 0.05). Using propolis as an antioxidant agent adversely affects the bond strength to enamel after intracoronal bleaching.

Impact of different intraorifice barriers on fracture resistance of non-vital bleached teeth.

Background and Aim: This study aimed to evaluate the effects of bleaching agents on the fracture resistance of endodontically treated teeth using different intraorifice barrier (IOB) materials. Materials and Methods: The endodontic treatment was performed for 160 mandibular premolars, and then, the teeth were divided into four groups according to the IOB: Ionoseal, Biodentine, ProRoot MTA, and TheraBase. Then, these teeth were subdivided into four subgroups (n = 10) based on the bleaching agents as distilled water (control), hydrogen peroxide 35% (HP), sodium perborate (SP), and carbamide peroxide 37% (CP). The access cavities were restored with composite resin after applying the bleaching agents for 7 days. The fracture resistance test was performed using a universal testing machine. Data were statistically analyzed, and the significance level was set at 5%. A scanning electron microscope was used to evaluate the effect of bleaching agents on the surfaces of IOBs. Results: The highest fracture resistance values were observed in Biodentine groups with significant differences compared to Ionoseal and ProRoot MTA (P <.05). The distilled water groups showed significantly the highest fracture resistance compared to SP and HP groups (P <.05). There was no significant difference between SP, HP, and CP groups (P >.05). It was demonstrated that the morphological surface of the intact IOBs (control) was different from the surface of IOBs treated with bleaching agents. Conclusion: The intracoronal bleaching procedures affected negatively the fracture resistance of the endodontically treated teeth.

Chemical contaminants from food contact materials and articles made from or containing wood and bamboo - a review.

Due to recently introduced 'so-called' bio- and plant-based friendly food contact materials and articles (FCM/FCA), some neglected safety issues need to be raised. In this review, potential chemical contaminants from FCM/FCA made from or containing wood and bamboo are presented. Sources, migration, and analytical issues in determining contaminants including intentionally and non-intentionally added substances (IAS and NIAS, respectively) are reviewed. Most of the contaminants are components from melamine-formaldehyde-resin (MFR), paints and coatings, preservatives, and bleaching agents. Tableware made of MFR containing bamboo fibres as a filler are not always suitable for use as tableware since harmful amounts of melamine and formaldehyde can migrate from the tableware into food and even accelerate the degradation of certain polymers with which they are mixed. In addition, in the EU bamboo in plastic FCM is not authorized under Regulation (EU) 10/2011. Paints and coatings used to provide surface coverage for bamboo and wooden articles also pose a risk of migration of heavy metals. Limits on preservatives in wood FCM are covered by legislation in many countries, nevertheless their contamination should not be ignored. Some wood species are considered 'toxic' or contain 'toxic' constituents that should not be used in contact with food, which are worth considering for legislation. IAS analyses in bamboo and wooden FCM is generally not a problem, but has proven to be more challenging for NIAS. Due to a complex mixture of substances contained in plant-based materials, there is a need to improve databases for non-target screening of such chemicals.

Effectiveness and abrasiveness of activated charcoal as a whitening agent: A systematic review of in vitro studies.

INTRODUCTION: Tooth whitening is currently one of the most requested treatments to change the color of teeth. There are different types of whitening in the dental office and at home. There are also many whitening agents on the market. Nowadays, the public has shown great interest in a new natural compound: activated charcoal. It has an abrasive effect and it is included in toothpastes to whiten teeth quickly and easily. OBJECTIVES: The main objective of the systematic review is to perform a qualitative synthesis of the available literature on the use of activated charcoal-based toothpaste for tooth whitening. MATERIAL AND METHODS: An electronic search was carried out in PubMed, Web of Science, and Scopus databases. The search included the terms (charcoal-based OR activated charcoal OR charcoal OR soot) AND (toothpaste OR dentifrices OR bleaching OR oral hygiene OR enamel OR teeth). Inclusion criteria were articles that were published in English, that included activated charcoal toothpastes, that assessed the efficacy of activated charcoal bleaching and/or the safety of using activated charcoal toothpastes, that were conducted on humans or extracted teeth regardless of their origin and the year of publication. RESULTS: Out of 208 articles, 11 met the inclusion criteria, the Risk of Bias of the selected studies was determined as medium-high. Regarding the whitening effect, there is a variety of results depending on the study: in some there are no significant differences between the proposed treatments and in others activated charcoal is not the most whitening agent. Regarding the abrasive effect, most studies agree that activated charcoal toothpaste has a higher abrasive potential. CONCLUSION: Toothpastes based on activated charcoal possess a lower whitening effect than other alternatives and can be considered as less safe due to its high abrasive potential.

Titanium dioxide nanotubes in a hydrogen peroxide-based bleaching agent: physicochemical properties and effectiveness of dental bleaching under the influence of a poliwave led light activation.

OBJECTIVES: The effects of different concentrations of titanium dioxide (TiO2) into 40% hydrogen peroxide (HP) were evaluated as regards the effectiveness of dental color change either associated with activation by polywave LED light or not. MATERIALS AND METHODS: TiO2 (0, 1, 5, or 10%) was incorporated into HP to be applied during in-office bleaching (3 sessions/40 min each). Polywave LED light (Valo Corded/Ultradent) was applied or not in activation cycles of 15 s (total time of 2 min). The color of 80 third molars separated into groups according to TiO2 concentration and light activation (n = 10) was evaluated at baseline and at time intervals after the 1st, 2nd, and 3rd bleaching sessions. RESULTS: WID value was significantly higher when using HP with 5% TiO2 in the 2nd session than the values in the other groups (p < 0.05). After the 2nd and 3rd sessions, the ΔEab value was significantly higher when activated with light (p < 0.05) for all agents containing TiO2 or not. Zeta potential and pH of the agents were not modified by incorporating TiO2 at the different concentrations. CONCLUSIONS: The 5% TiO2 in the bleaching agent could enhance tooth bleaching, even without light application. Association with polywave LED light potentiated the color change, irrespective of the presence of TiO2 in the bleaching gel. CLINICAL SIGNIFICANCE: HP with 5% TiO2 could lead to a greater tooth bleaching response in the 2nd clinical session, as well as the polywave light can enhance color change.

Preclinical studies on melanogenesis proteins using a resveratrol-nanoformula as a skin whitener.

A naturally occurring polyphenol called trans-resveratrol has received a lot of attention due to its possible health advantages for humans. The low solubility of trans-resveratrol and its isomerization upon UV exposure strongly limit its application as a skin-whitening agent. In the present study, to increase trans-resveratrol solubility, a new nanoformula was created by combining hydrophilic surfactants and oils. Trans-Resveratrol nanoformula has been prepared, characterized, and applied as a skin-whitening agent on the dorsal skin of Guinea pigs. The optimized trans-resveratrol nanoformula with a particle size of 63.49 nm displayed a single peak and a polydispersity index [0.36 ± 0.02]. In addition, the zeta potential of the optimized formula was -30.4 mV, confirming the high stability of this nanoformula. The melanin contents in the trans-resveratrol nanoformula-treated group were substantially lower than those of the control and the blank nanoformula-treated groups after staining of the dorsal skins [black areas] of guinea pigs with Fontana Mountain dye. The pigmentation index in the control, blank nanoformula, and optimized trans-resveratrol nanoformula were 329.4 ± 36.9, 335.8 ± 71.4, and 124.8 ± 19.6 respectively. Confirming this finding, immunohistochemistry analysis of skin tissues revealed that the expressions of melanogenesis-regulating proteins such as tyrosinase and microphthalmia-associated transcription factor were down-regulated. The safety of topical application of trans-resveratrol nanoformula was validated by no changes in free radical levels and oxidative stress markers proteins in the livers and kidneys of guinea pigs at the end of the experiment. Conclusions: A novel trans-resveratrol nanoformula as well as the mechanism whereby it promotes skin whitening effects were presented. Furthermore, the study illustrated that trans-resveratrol nanoformula is safe, non-toxic, and can be applied for skin whitening, although more research on human skin is needed.

Comparative assessment of the efficacy of low concentration bleaching agents using quantitative light induced fluorescence in removing stains: An In vitro study.

Background: Tooth discoloration has become a common esthetic problem in recent years. Removal of stains by bleaching is well-documented. Low concentration home bleaching products are available in market in different forms and concentrations. Aim: The aim of this study is to evaluate and compare the efficacy of low concentration commercially available home bleaching products (whitening strip, gel, and mouthwash) in removing stains and whitening the tooth using clinical and digital methods. Materials and Methods: Sixty permanent enamel samples mounted in an acrylic block were artificially stained and randomly divided into four groups. Negative control, 15 % Carbamide peroxide gel group, 2% Hydrogen 16 peroxide mouthwash group and 6% Hydrogen peroxide strip group respectively. The samples were bleached with respective agents according to the manufacturer's instructions. The efficacy on 7th and 14th day was evaluated clinically (SGU change), photographically (ΔE), and using quantitative light-induced fluorescence (ΔF). The data were analyzed using paired t-test and analysis of variance. Results: Postbleaching, 6% hydrogen peroxide strips and 15% carbamide peroxide gel showed maximum improvement (ΔΔF - 15.73 and 11.89, ΔE - 19.8 and 18.9, respectively) when compared to 2% hydrogen peroxide mouthwash and negative control group (ΔΔF - 9.68 and 6.59, ΔE - 15.04 and 9.44, respectively). The difference was statistically significant (P = 0.001). Conclusion: 6% hydrogen peroxide strips and 15% carbamide peroxide gel showed maximum improvement in stain removal and tooth whitening however, the strips showed better efficacy than the gel. Strips have the added advantage of lesser contact period, less salivary dilution, and no gingival contact. Therefore, strips can be a better alternative for gels and mouthwashes.