Co-doped titanium dioxide nanoparticles decrease the cytotoxicity of experimental hydrogen peroxide gels for in-office tooth bleaching.

OBJECTIVE: To evaluate the efficacy and cytotoxicity of experimental 6% and 35% hydrogen peroxide gels (HP6 or HP35) incorporated with titanium dioxide nanoparticles (NP) co-doped with nitrogen and fluorine and irradiated with a violet LED light (LT). METHODS: Bovine enamel-dentin disks adapted to artificial pulp chambers were randomly assigned to bleaching (n = 8/group): NC (negative control), NP, HP6, HP6 + LT, HP6 + NP, HP6 + NP + LT, HP35, HP35 + LT, HP35 + NP, HP35 + NP + LT, and commercial HP35 (COM). Color (ΔE00) and whiteness index (ΔWID) changes were measured before and 14 days after bleaching. The extracts (culture medium + diffused gel components) collected after the first session were applied to odontoblast-like MDPC-23 cells, which were assessed concerning their viability, oxidative stress, and morphology. The amount of HP diffused through the disks was determined. Data were analyzed by generalized linear models or Kruskal Wallis Tests (α = 5%).  RESULTS: HP6 + NP + LT exhibited ΔE00 and ΔWID higher than HP6 (p < 0.05) and similar to all HP35 groups. HP6 + NP + LT showed the lowest HP diffusion, and the highest cell viability (%) among bleached groups, preserving cell morphology and number of living cells similar to NC and NP. HP6 + LT, HP6 + NP, and HP6 + NP + LT exhibited the lowest cell oxidative stress among bleached groups (p < 0.05). HP35, HP35 + LT, and HP35 (COM) displayed the lowest cell viability. CONCLUSION: HP6 achieved significantly higher color and whiteness index changes when incorporated with nanoparticles and light-irradiated and caused lower cytotoxicity than HP35 gels. The nanoparticles significantly increased cell viability and reduced the hydrogen peroxide diffusion and oxidative stress, regardless of HP concentration. CLINICAL SIGNIFICANCE: Incorporation of co-doped titanium dioxide nanoparticles combined with violet irradiation within the HP6 gel could promote a higher perceivable and acceptable efficacy than HP6 alone, potentially reaching the optimal esthetic outcomes rendered by HP35. This approach also holds the promise of reducing cytotoxic damages and, consequently, tooth sensitivity.

Climate adaptive loci revealed by seascape genomics correlate with phenotypic variation in heat tolerance of the coral Acropora millepora.

One of the main challenges in coral reef conservation and restoration is the identification of coral populations resilient under global warming. Seascape genomics is a powerful tool to uncover genetic markers potentially involved in heat tolerance among large populations without prior information on phenotypes. Here, we aimed to provide first insights on the role of candidate heat associated loci identified using seascape genomics in driving the phenotypic response of Acropora millepora from New Caledonia to thermal stress. We subjected 7 colonies to a long-term ex-situ heat stress assay (4 °C above the maximum monthly mean) and investigated their physiological response along with their Symbiodiniaceae communities and genotypes. Despite sharing similar thermal histories and associated symbionts, these conspecific individuals differed greatly in their tolerance to heat stress. More importantly, the clustering of individuals based on their genotype at heat-associated loci matched the phenotypic variation in heat tolerance. Colonies that sustained on average lower mortality, higher Symbiodiniaceae/chlorophyll concentrations and photosynthetic efficiency under prolonged heat stress were also the closest based on their genotypes, although the low sample size prevented testing loci predictive accuracy. Together these preliminary results support the relevance of coupling seascape genomics and long-term heat stress experiments in the future, to evaluate the effect size of candidate heat associated loci and pave the way for genomic predictive models of corals heat tolerance.

Gene expression plasticity governing symbiosis during natural coral bleaching.

The increasing global frequency and severity of coral bleaching events, driven by the loss of endosymbiotic algae, pose a significant threat to these vital ecosystems. However, gene expression plasticity offers a potential mechanism for rapid and effective acclimatization to environmental changes. We employed dual transcriptomics to examine the gene expression profile of Seriatopora hystrix, an ecologically important scleractinian coral, across healthy, mildly bleached, and severely bleached colonies collected from the waters of Likupang, North Sulawesi, Indonesia. Our analysis revealed that coral bleaching is associated with gene plasticity in calcium signaling and focal adhesion within coral hosts, as well as with endoplasmic reticulum stress in symbionts. Notably, we identified specific genes associated with innate immunity that were predominantly overexpressed in mildly bleached coral hosts. This overexpression implies that high expression plasticity of these key genes might contribute to bleaching resistance and the preservation of the host-symbiont relationship. Our findings offer a detailed insight into the dynamics of bleaching resistance in S. hystrix, shedding light on the variability of bleaching risks in Indonesian reefs and underscoring the coral's ability to utilize gene expression plasticity for immediate survival and potential long-term adaptation to climate changes.

Effect of peroxide-free and peroxide-based in-office bleaching on the surface and mechanical properties of CAD/CAM esthetic restorative materials.

The study aimed to investigate the influence of H2O2-based and H2O2-free in-office bleaching on the surface and mechanical attributes of CAD/CAM composite blocks. CAD/CAM composite blocks from five different composite materials (CC1, CC2, CC3, CC4, and CC5) were randomly divided into two groups according to bleaching application (H2O2-based and H2O2-free). The surface topography, morphology, nanohardness, elastic modulus, flexural strength, and fracture toughness were measured. A paired and unpaired sample t-tests gauged the effect of pre- and post-bleaching on the substrates. The estimated mean differences (before-after bleaching) suggested an increase in surface roughness for two materials CC2 and CC4, and a significant decrease in nanohardness for material CC4 and in elastic modulus for materials CC2 and CC4 with H2O2-based bleaching, whereas H2O2-free bleaching resulted in changes compatible with no change in these properties. Flexural strength and fracture toughness showed no evidence of changes, irrespective of the bleaching gel used. Scanning electron microscopic analysis revealed erosive effects and micropore formation due to H2O2-based bleaching. H2O2-based bleaching deteriorates the surface of CAD/CAM composite materials while H2O2-free bleaching gel had an insignificant effect on both surface and bulk properties. The clinician should carefully evaluate the potential effects of H2O2-based bleaching on the surface properties of CAD/CAM composites.

Extrusion pre-treatment of cowpea (Vigna unguiculata (L.) Walp.) lignocellulosic sidestream to produce cellulose fibres.

BACKGROUND: Various agricultural sidestreams have been demonstrated as feedstock to produce cellulose. To the best of our knowledge, there is no research work on the potential of agricultural sidestream from cowpea (Vigna unguiculata (L.) Walp.), a neglected and underutilised crop to produce cellulose fibres. Conventional methods to produce cellulose consume large amounts of chemicals (NaOH) and produce a high amount of effluent waste. Herein, we investigated extrusion pre-treatment without and with an alkali followed by bleaching as an alternative method to conventional alkaline pre-treatment followed by bleaching to produce cellulose fibres from cowpea sidestream. RESULTS: Cellulose extracted by extrusion without and with mild alkali followed by bleaching consumed about 20 times less NaOH compared to the conventional method and produced less effluent waste. Extrusion with mild alkali followed by bleaching resulted in higher cellulose yield, purity, and crystallinity compared to extrusion without an alkali followed by bleaching. However, the conventional method resulted in higher cellulose yield, purity and crystallinity compared to extrusion pre-treatment followed by bleaching. Scanning electron microscopy revealed that micro-sized cellulose fibres with an average diameter of 10-15 µm were extracted using both methods. Notably, cellulose fibres extracted using extrusion pre-treatment were shorter than those extracted using the conventional method. CONCLUSION: Extrusion pre-treatment is a promising continuous alternative to alkaline pre-treatment to produce micro-sized cellulose fibres from low-value, underutilised cowpea lignocellulosic sidestream, for potential use as a filler in composite plastics. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effect of immune-boosting beverage, energy beverage, hydrogen peroxide superior, polishing methods and fine-grained dental prophylaxis paste on color of CAD-CAM restorative materials.

BACKGROUND: The effect of an immune-boosting beverage (SAM) containing Sambucus Nigra, an energy beverage (ENE), an in-office bleaching (BLE) agent with 25% hydrogen peroxide superior, glazing (GLA) or polishing (POL) methods, and professional dental prophylaxis (PDP) on the color of CAD-CAM restorative materials is unknown. METHODS: In total 210 specimens were prepared, consisting of CAD-CAM feldspathic (FC), zirconia-reinforced lithium disilicate ceramic (ZLS) and hybrid ceramic (HC). The ceramic specimens were divided according to the polishing methods of glazing (GLA) and mechanical polishing (POL). All materials were divided into two groups: with and without BLE. A 25% hydrogen peroxide superior (HPS) gel was used for BLE. After the baseline (BAS) measurement, the specimens were immersed in 3 different beverages (distilled water (DIS), SAM, ENE). After 28 days, a fine-grained (RDA 7) prophylaxis paste was applied. Statistical analysis of ∆E00 color difference values was performed by 3-way ANOVA and Bonferroni test (α = 0.05). RESULTS: The effect of all other actions except material-BLE-beverage on color for BAS-Day 28 was statistically different (p < 0.05). The effect of material, material-BLE, beverage on color for Day 28-PDP was statistically different (p < 0.05). After 28 days, the lowest color change was found in FC-GLA and HC immersed in DIS (p = 0.0001) and the highest in FC-POL immersed in ENE (p = 0.0002). PDP was efficient in color recovery in HC immersed to DIS, ENE and SAM (p = 0.0010). For FC, HC and ZLS, BLE caused a higher color change (p < 0.0001). Regardless of the material, the highest color change for BLE-beverage was found in BLE-treated specimens immersed in ENE (p = 0.0496) and the lowest color change was found in non-BLE-treated specimens immersed in SAM (p = 0.0074). CONCLUSIONS: In materials pre-exposed to 25% HPS, the effect of PDP on color recovery was lower than in unexposed materials. After 28 days, mechanical polishing produced higher color change in FC than glazing, however, in ZLS effects of glazing and mechanical polishing on color were similar. For material/polishing method, HC was the most effective. ENE caused higher color change than DIS and SAM. PDP was more effective than ENE in restoring color to DIS- and SAM-immersed specimens.

Study of the effect of bleaching agents on the crystalline index of cellulose-based materials derived from corn husk by CP/MAS 13C NMR and FT-IR spectroscopies.

This work proposes an evaluation of the Crystalline Index (CrI) in function of the bleaching process employed during cellulose extraction from corn husk, for further characterization using CP/MAS 13C NMR, XRD, and FT-IR. In that sense, CrI values were calculated by FT-IR and the bands associated with the crystalline and amorphous regions were observed at 1424 cm-1 and 896 cm-1, respectively. Similarly, the signals due to ordered (89.1 ppm) and disordered (84.2 ppm) cellulose chains were detected by solid-state 13C NMR, while the Segal equation was only used for comparison purposes. Additionally, PCA studies showed consistent results attributed to the crystalline region in cellulose domains analyzed by both, FT-IR and solid-state 13C NMR. The results revealed the coexistence of cellulose I/cellulose II and its effect on CrI, as well as the incomplete mercerization process, in some cases non-cellulosic residues can cause an overestimation of CrI. Additionally, the thermal stability and the glass transition temperature were determined by TGA/DTA and DSC analyses. Finally, a partially fibrillated-network morphology with a diameter of 20.47 ± 2.77 µm was observed in cellulose bleached with peracetic acid, whereas organosolv method provides flexible and clean microfibrils with diameter sizes between 10 and 9 µm.

Effects of microabrasion and bleaching on color and shear bond strength of simulated stained-remineralized caries lesions.

Purpose: This study investigated the effects of bleaching and microabrasion on the color and shear bond strength (SBS) of stained-remineralized caries-like lesions (s-RCLs). Methods: Human enamel specimens were demineralized, stained (coffee/tea), then remineralized (2% NaF and artificial saliva [AS]) to create s-RCLs. Specimens were randomly divided into five groups (n = 18): G1, demineralized/AS; G2, s-RCLs/AS; G3, s-RCLs/at-home bleaching (15% carbamide peroxide [CP)], 6 h/d×7)/AS; G4, s-RCLs/microabrasion (6.6% hydrochloric acid, [1min/3cycles]/AS; and G5, s-RCLs/microabrasion and at-home bleaching/AS. Color was spectrophotometrically measured at baseline, after demineralization, after staining, and after treatment. After two weeks, the SBS was tested using a universal testing machine. Outcomes were analyzed using ANOVA models followed by Tukey's test (α = 0.05). Results: The mean colors (ΔE) for demineralization and staining were significant (ΔE ≤ 5.9 and ≤14.4, respectively). G3 (ΔE 23.9) and G5 (ΔE 25.2) were significantly improved compared to G4 (ΔE 12.3). The SBS in G5 had the highest significant value (25.2 MPa), followed by G4 and G3 (21.5-20.6 MPa), which were significantly higher than G2 (16.8 MPa). G2, in turn, was more significant than G1 (10.9 MPa). Conclusion: At-home bleaching (15% CP) for seven days eliminated and improved organic stains on RCLs. Faster results were achieved when combined with microabrasion. All surface treatments resulted in high SBS.

Effect of carbamide peroxide treatment on the ion release of different dental restorative materials.

BACKGROUND: To predict the long-term performance of restorative materials in the oral environment, it is important to evaluate their resistance to chemical and mechanical degradation and to know the toxic potential of the type and amount of ions eluted from the filling material. In this study, home bleaching was applied to dental materials with different contents and it was aimed to determine the type and amount of ions released from these materials. METHODS: In this study, amalgam, posterior composite resin, anterior composite resin, bulk fill composite resin, indirect composite resin, hybrid ceramic and all-ceramic were used as restorative materials. 10 specimens of each material were prepared according to the manufacturer's instructions. Each material group was divided into two subgroups as the bleached group and the control group. After bleaching, all specimens were stored in 1 ml of 75% ethanol/water solution. Solutions were renewed after 1, 14 and 28 days. The type and amount of ions released from the materials were determined using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Data were analyzed using the Friedman, Wilcoxon Signed Ranks, and Mann-Whitney U tests (α = 0.05). RESULTS: It was determined that the amount of ions release from the restorative materials decreased over time (p < 0.05). According to the results of the Mann-Whitney U test, there was no difference between the bleaching and control groups in most of the restorative materials (p > 0.05). CONCLUSION: Within the limits of this study, home bleaching system does not have a significant effect on ion release from restorative materials.

Thermal tolerance traits of individual corals are widely distributed across the Great Barrier Reef.

Adaptation of reef-building corals to global warming depends upon standing heritable variation in tolerance traits upon which selection can act. Yet limited knowledge exists on heat-tolerance variation among conspecific individuals separated by metres to hundreds of kilometres. Here, we performed standardized acute heat-stress assays to quantify the thermal tolerance traits of 709 colonies of Acropora spathulata from 13 reefs spanning 1060 km (9.5° latitude) of the Great Barrier Reef. Thermal thresholds for photochemical efficiency and chlorophyll retention varied considerably among individual colonies both among reefs (approximately 6°C) and within reefs (approximately 3°C). Although tolerance rankings of colonies varied between traits, the most heat-tolerant corals (i.e. top 25% of each trait) were found at virtually all reefs, indicating widespread phenotypic variation. Reef-scale environmental predictors explained 12-62% of trait variation. Corals exposed to high thermal averages and recent thermal stress exhibited the greatest photochemical performance, probably reflecting local adaptation and stress pre-acclimatization, and the lowest chlorophyll retention suggesting stress pre-sensitization. Importantly, heat tolerance relative to local summer temperatures was the greatest on higher latitude reefs suggestive of higher adaptive potential. These results can be used to identify naturally tolerant coral populations and individuals for conservation and restoration applications.

Can discolored dental composites be bleached in depth?

Objectives: Previous in vitro studies determined the whitening effects of bleaching products on stained resin composite surfaces. This in vitro study aimed to verify the effectiveness of a whitening system on composite resin previously subjected to pigmentation, specifically examining the depth of whitening effectiveness within the material structure. Materials and Methods: A commercially available nano-filled composite resin was used. Specimens were stained using a coffee-based solution and a 10% carbamide peroxide-based gel was employed as the whitening agent. The pigment's penetration and the effect of the bleaching gel were evaluated by measuring color (CieLab values) from the outer edge to the inner part of the specimens. Color measurements were taken at 14 points, starting from 0.1 mm from the external perimeter up to 3.0 mm. Results: Analysis of variance tests showed a statistically significant difference between the Control Group (CG), Pigmentation Group, and Whitening Group. The whitening agent was effective up to 1.5 mm in depth, with Whiteness index (W) values not statistically different from those of CG up to 0.5 mm in depth. Conclusions: Whitening agents on nano-filled resin composite previously pigmented appear effective in restoring the W to values similar to the original, particularly in the superficial layers of the sample.

Use of 3D printing technology for custom bolus fabrication in the management of palmar or plantar fibromatosis with radiotherapy: A retrospective case series.

PURPOSE: Palmar or plantar fibromatosis is a benign fibroproliferative disorder affecting the fascia of the hands or feet. Management involves surgery, typically reserved for cases where progression limits function. Retrospective series demonstrate that radiation therapy (RT) can stabilize the disease course in many patients and improve symptoms in some cases. RT techniques vary between the use of electrons and superficial or orthovoltage photons and often require lead cutouts or custom boluses. We present a new approach demonstrating the implementation and effectiveness of three-dimensional (3D)-printed bolus material in patients receiving RT for fibromatosis. MATERIALS AND METHODS: A total of 3 patients, one with plantar and two with palmar fibromatosis, were treated with radiation using 3D-printed boluses over the past year. Bolus's design was based on computed tomography (CT) imaging data. Palmar patients were treated with a single en-face electron field, with a two-part accessory as a bolus and an immobilization device encasing the hand. The plantar case required 6MV photons delivered with a Volumetric Modulated Arc Therapy (VMAT) technique to cover the deeper target volume adequately. Dose and fractionation were based on guidelines from the Royal College of Radiologists in the United Kingdom. CT was used to assess printed shape and density accuracy. RESULTS: The mean deviations in shape between the printed bolus pieces and their designs were all less than 0.4 mm. The differences in mean Hounsefield units (HU) between the printed boluses and their expected values were between 7 and 44 HU. No significant issues were encountered when applying the bolus to patients. The thermoluminescent dosimeters (TLD) used demonstrated dose accuracy to within TLD precision (5 %). CONCLUSIONS: 3D printing bolus technology represents a novel approach to treating fibromatosis with radiation. It offers superior dosimetry through the reduction of air gaps and by permitting custom bolus thickness. Also, it simplifies clinical set-up by acting as an immobilization device and a visual aid for daily field placement.

Evaluation of Enamel Surface Properties Submitted to Bleaching With 35% Hydrogen Peroxide Associated With Titanium Tetrafluoride (TiF4).

OBJECTIVE: This study evaluated the color change, surface roughness, mineral content and morphology of enamel bleached with 35% hydrogen peroxide (HP) combined with an experimental gel containing 1% titanium tetrafluoride (TiF4). MATERIALS AND METHODS: Bovine enamel blocks were treated with (n = 12): (TiF) experimental gel containing 1% TiF4, (HP) 35% HP, (HPT) 35% HP + 1% TiF4 and (CT) control. Bleaching with HP was performed in 3 sessions (3 × 15 min/applications). pH, colorimetric parameters, surface roughness, mineral content and enamel morphology were determined. The pH was evaluated for 45 min. The color parameters were determined before bleaching (T0), and 14 days elapsed from the last bleaching session (T4). Surface roughness was analyzed at T0 and immediately after last bleaching session (T3). Enamel mineral content and morphology were verified at T4. Data were statistically analyzed by one-way, two-way ANOVA and Kruskal-Wallis (α = 0.05). RESULTS: TiF increased surface roughness, and no differences between HP and HPT in terms of color and CO 3 2 - $$ {\mathrm{CO}}_3^{2-} $$ - PO 4 3 - $$ {\mathrm{PO}}_4^{3-} $$ mineral content. Ti was detected only on TiF, and slight surface morphology changes were observed in bleached enamel. CONCLUSIONS: The combination of TiF4 and 35% HP did not interfere with the enamel bleaching effect, controlled surface roughness, and kept mineral content but promoted a minor surface morphology alteration. CLINICAL SIGNIFICANCE: Due to the adverse effects of bleaching, titanium tetrafluoride (TiF4) has gained attention for its therapeutic properties, including the ability to reverse mineral loss and neutralize remineralization of mineral structures. Therefore, TiF4's remineralizing capacity may be a good alternative for incorporation into hydrogen peroxide bleaching agents.

Phytochemicals in vital tooth bleaching: Spectrophotometric evaluation of efficacy with papaya, pineapple, or kiwi extracts and 30% hydrogen peroxide.

Context: Dental bleaching, a common cosmetic treatment, typically uses hydrogen peroxide (H2O2). Yet, the search for natural options has prompted an investigation into fruit extract efficacies such as papain, bromelain, and actinidin for tooth whitening. Aim: The aim of this study was to evaluate the efficacy of 30% hydrogen peroxide and fruit extracts (papaya, pineapple, and kiwi) on human enamel using a spectrophotometer at different time intervals. Study Design: Eighty maxillary anterior teeth were stained with tea solution and evaluated for baseline color. They were then divided into four groups: hydrogen peroxide alone and hydrogen peroxide combined with papaya, pineapple, or kiwi extracts. Each group was further divided based on bleaching duration: 10 or 20 min. Materials and Methods: The color value of the bleached teeth was measured using a reflectance spectrophotometer. In order to analyze the data, one-way ANOVA, post hoc Tukey, and paired t-tests were used. The significance level was established at α =0.05. Results: Combining hydrogen peroxide with pineapple extract showed the highest efficacy, followed by papaya and kiwi extracts. Hydrogen peroxide alone also demonstrated significant bleaching efficacy, albeit lower than the combinations with fruit extracts. Conclusion: Combining hydrogen peroxide with pineapple and papaya extracts notably improves dental bleaching efficacy, as shown by reduced color difference (ΔE) values. This underscores the potential of natural enzymes in tooth whitening.

Effectiveness of KTP lasers in tooth bleaching, by comparing tooth color change after bleaching with KTP, Nd:YAG, Er:YAG, and diode laser system: A systematic review.

This systematic review evaluated the role of Potassium-titanyl-phosphate (KTP) lasers in dental bleaching by comparing tooth color change and rise in intrapulpal temperature after bleaching with KTP, Neodymium-doped yttrium aluminum garnet (Nd:YAG), Er:YAG, and diode laser system. Following were the inclusion criteria: in vitro studies in English available in full text. Articles published between 2000 and 2021 were selected. The search for was conducted on PubMed, Cochrane library/CENTRAL, Wiley online library, ProQuest, Science Direct, and Hand searching/specialized registers. Keywords were used: "Lasers" [Mesh] and "Tooth bleaching" [Mesh] using Boolean operators. A total of four articles fulfilled the inclusion criteria. The quality assessment of studies included was undertaken independently as part of data extraction process. KTP lasers demonstrated more effectiveness in attaining color change in stained teeth and showed the lowest rise in intrapulpal temperature. Based on the data obtained in the present review, the choice of bleaching treatment is directly related to the type of discoloration, activation of the bleaching agent, and esthetic requirement. Although all bleaching procedures were effective in color change, the KTP laser showed better results when compared to other laser activation. The bleaching treatment protocol is directly related to the type of discoloration, activation of the bleaching agent, and esthetic requirement. It has been demonstrated that a faster change in color can be obtained when bleaching is performed in combination with a light source, i.e., power bleaching aiming for a more in-depth change of color.

Effect of Experimental Bleaching Gels With Enzymes on Composite and Enamel.

INTRODUCTION AND AIMS: Potential secondary or toxic effects of peroxide-based whitening gels have driven the search for alternative methods that use natural compounds with gentle action on tooth enamel that provide remineralizing benefits. METHODS: This study introduces four innovative experimental whitening gels (GC, G1, G3, G4) formulated with enzymes (Bromelaine and Papaine) and natural extracts, along with SiO2. The efficacy of these gels was tested on nanohybrid dental composite (EsCOM100, Spident Company) and dental enamel stained with coffee and natural juice (Tedi) over 10 days. The structural changes in samples before and after bleaching were examined using scanning electron microscopy and atomic force microscopy. Additionally, cytotoxicity tests were conducted on the gels using mesenchymal stem cells from human dental pulp (dMSC) and human keratinocytes (HaCaT). Antibacterial activity was assessed on five strains (Streptococcus mutans. Porphyromonas gingivalis; Enterococcus faecalis; Escherichia coli; Staphylococcus aureus). RESULTS: Coffee and natural juice stains significantly increase the roughness of composite and enamel surfaces by forming deposits. The enzymatic action of bromelain and papain effectively disorganizes and removes these clusters, significantly reducing surface roughness. CONCLUSION: Notably, the gel containing papain and nanostructured SiO2 proved to be the most effective in removing coffee stains from both composite surfaces and enamel. On the other hand, the gel with bromelain and nanostructured SiO2 was the most efficient in removing natural juice stains. The absence of SiO2 in the experimental gels slightly decreased the enzymes' effectiveness in stain removal. The antibacterial activity observed in the experimental gels is attributed solely to the enzymatic compounds.

In-Office Dental Bleaching Using 37% Carbamide Peroxide Versus 35% Hydrogen Peroxide: A Randomized, Double-Blind Clinical Trial.

OBJECTIVE: Compare the tooth sensitivity (TS) and bleaching efficacy (BE) of in-office dental bleaching performed with 35% hydrogen peroxide (HP) or 37% carbamide peroxide (CP). MATERIALS AND METHODS: Sixty-six participants were randomly divided into two groups according to the bleaching gel applied to the right hemiarch: 35% HP, or 37% CP. TS was recorded immediately after, up to 1, 24, and 48 h after bleaching, using the VAS and NRS scales. BE was assessed before bleaching and 1 month after using color guide units (ΔSGUs) and a spectrophotometer (ΔEab, ΔE00, and ΔWID). TS was assessed using McNemar's and paired t-test (VAS) or Wilcoxon signed rank (NRS). The paired t-test was used to analyze BE (α = 0.05). RESULTS: TS risk and intensity were lower for the 37% CP (p = 0.003 and p < 0.005). Despite significant differences between the groups after 1 month (ΔSGU and ΔE00; p < 0.05), the color measurements of both groups exceeded the 50%:50% perceptibility/acceptability threshold. CONCLUSION: In-office dental bleaching using 37% CP resulted in reduced risk and TS intensity, without prejudice to the BE. CLINICAL RELEVANCE: The use of 37% CP for in-office dental bleaching could decrease TS risk and intensity without affecting BE. TRIAL REGISTRATION: ClinicalTrials.gov identifier: RBR-683qhf.

Clinical evaluation of different types of teeth in in-office whitening.

OBJECTIVE: This prospective case series aimed to clinically evaluate the bleaching effect, spontaneous tooth sensitivity and variation in the thermal sensation threshold of different groups of teeth undergoing in-office bleaching. METHOD AND MATERIALS: Ten patients received conventional bleaching treatment: 35% hydrogen peroxide with 3 bleaching sessions of 45 minutes, evaluating color change (ΔE and ΔE00), whitening index (WID), and tooth sensitivity (VAS). Thermal stimulus-generating devices were used to simulate sensitivity caused by low temperatures through Quantitative Sensory Tests (QST). Analyses were conducted individually on different teeth groups (n=20) (lower incisors LI, upper incisors UI, canines C, upper first premolars PM). RESULTS: Regarding color change, LI and UI did not statistically differ from each other but showed significant difference and greater bleaching potential compared to C and PM (P =.018). Regarding sensitivity, LI and UI presented the highest spontaneous sensitivity values (P =.032), while PM did not display painful symptoms, also observed in provoked sensitivity analysis (P =.025). CONCLUSIONS: The general analysis of the results indicates that the tooth type responds differently to the whitening treatment, both in relation to the aesthetic benefit and the occurrence of tooth sensitivity. It was observed that lower incisors reach the degree of chromatic saturation before canines and premolars, in addition to presenting greater bleaching sensitivity. Personalizing the treatment, based on prior knowledge of the degree of saturation, anatomical factors and the risk of sensitivity, can provide considerable advantages in the whitening technique.

Role of the novel aloe vera-based titanium dioxide bleaching gel on the strength and mineral content of the human tooth enamel with respect to age.

There has been an increased demand for dental bleaching globally irrespective of age and gender. Main drawbacks associated with conventional tooth bleaching agents have been compromised strength and mineral-content of tooth enamel which results in sensitivity, discomfort, roughness, and structure loss of human teeth. Currently, nanoparticles synthesized by green synthesis have gained popularity especially in medical and dental applications because of their versatile and beneficial nano-scaled features. Titanium dioxide nanoparticles (TiO2Nps) in this study were prepared from green ecofriendly source using the aloe vera plant extract and were then characterized via dynamic light scattering (DLS), scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), and energy dispersive X-ray (EDX), for size, shape, composition and true-phase. These TiO2 Nps were incorporated in commercial bleaching gel containing hydrogen peroxide to form a novel TiO2-bleaching gel which was used to bleach extracted anterior teeth belonging to four different age groups: 20-29 years, 30-39 years, 40-49 years and ≥50 years. These teeth were investigated for micro-hardness (Vickers microhardness tester) and mineral-content (EDX spectroscopy) including sodium, magnesium, phosphorus, calcium in an in-vitro environment both before and after bleaching. Results revealed that TiO2 Nps prepared by aloe vera plant were nanos-sized of about 37.91-49 nm, spherical shape, true anatase phase with pure titanium and oxygen in their composition. The values of Vickers micro-hardness and mineral-content (Na, Mg, P, Ca) of enamel specimens belonging to different age groups enhanced in a linear pattern before bleaching with the increase in age (p value < 0.05). There was negligible reduction observed in Vickers micro-hardness and mineral-content elements (Na, Mg, P, Ca) of all enamel specimens belonging to different ages after the bleaching (p value > 0.05). The novel TiO2-bleaching gel prepared was effective enough in preventing the declination in Vickers micro-hardness strength and mineral-content of all the enamel specimens belonging to different age groups even after the bleaching procedure which makes it a promising biomaterial.

Sensibilidade dentinária associada ao clareamento dental em dentes vitais - uma revisão de literatura / Tooth sensitivity related to vital teeth dental bleaching ­ a literature review

O clareamento dental pode ser realizado através da técnica caseira ou de consultório, utilizando agentes como o peróxido de carbamida (PC) e peróxido de hidrogênio (PH). Apesar de seguro, existem alguns efeitos adversos relacionados ao clareamento dental, como a sensibilidade dentinária (SD), que pode estar presente em diferentes graus dependendo da técnica utilizada. A aplicação de agentes dessensibilizantes antes, durante ou depois do clareamento dental vem sido estudada para evitar ou reduzir a sensibilidade associada ao clareamento. O estudo visa revisar a literatura em relação a aspectos e conceitos importantes do clareamento dental, discutindo seus possíveis efeitos adversos com foco na sensibilidade dentinária. Foi realizada uma pesquisa digital da base de dados Medline, via PubMed, utilizando palavras-chave relacionadas ao tema, priorizando artigos publicados há menos de 20 anos e escritos em inglês ou português. Artigos também foram buscados manualmente e foram utilizados livros de odontologias relacionados ao tema. De um total de 48 artigos, 28 foram escolhidos para a composição do trabalho, além de 2 livros de dentística que abordam o clareamento dental. Constata-se que a sensibilidade dentinária é um efeito adverso comum relacionado ao clareamento dental, que possui causa exata desconhecida, porém sabe-se que está relacionada à difusão do peróxido de hidrogênio pelos tecidos dentários. A sensibilidade dentinária é mais frequente na técnica de clareamento de consultório do que na técnica caseira, e pode ser agravada por fatores relacionados ao indivíduo e/ou ao dente. Alguns agentes como o nitrato de potássio, fosfopeptídeos de caseína-fosfato de cálcio amorfo (CPP-ACP), vidros bioativos e partículas de hidroxiapatita, se mostraram efetivos no controle da sensibilidade dentinária.

Dental bleaching can be performed in at-home or in-office techniques, using agents such as carbamide peroxide or hydrogen peroxide. Although it's safe, there are some side effects related to dental bleaching, such as tooth sensitivity, which may be present in different degrees, depending on the chosen technique. The application of desensitizing agents before, during or after dental bleaching is being studied to avoid or reduce the bleaching related sensitivity. The study aims to review the literature over important aspects and concepts of dental bleaching, discussing its possible side effects, focusing on tooth sensitivity. Methods: an online search was done on Medline's database, through PubMed, using keywords related to the theme, prioritizing articles published less than 20 years ago, written in English or Portuguese. Articles were also researched manually, and dentistry books related to the theme were used as well. Out of 48 articles, 28 were chosen to this study's composition, in addition to 2 books that approach dental bleaching. Tooth sensitivity is a common side effect related to dental bleaching, with an unknown cause, however, it is known that it's related to hydrogen peroxide's diffusion through dental tissues. Tooth sensitivity is more frequent within in-office technique than within at-home technique, and may be worsen by individual and/or dental related factors. Agents such as potassium nitrate, CPP-ACP, bioactive glasses and hydroxyapatite particles, showed up to be effective in dental sensitivity control.