Peroxide Gel Research Articles

Bleaching efficacy, decomposition rate and pH of experimental bleaching gels incorporating bioactive materials

Aim: To evaluate the bleaching efficacy, decomposition rate, and pH of experimental gels containing 35% hydrogen peroxide (HP) and different concentrations of 45S5-bioglass (BG) or Biosilicate® (BS). Methods: Bovine enamel/dentin blocks (n=10) were allocated into the groups HP_BG or HP_BS (2.5, 5, 7.5 and 10 wt%) and HP (35% HP – positive control). The blocks were submitted to three sessions of 40 min and 7-day intervals. During the interval, the blocks were kept in artificial saliva at 37ºC. Color change (ΔE00) and whiteness index change (ΔWID) were determined after staining with black tea (T1) and 24 h after the 3rd bleaching session (T2). HP decomposition rate (%) and pH were evaluated for 40 min. Two-way ANOVA and Tukey analyzed ΔE00 and ΔWID data, while the Kruskal-Wallis test determined the decomposition rate and pH of the gels. Results: There were no differences in ΔE00 and ΔWID among the experimental bleaching gels containing BG or BS and 35% HP (p > 0.05), but BG and BS gels displayed lower HP concentration than 35% HP, regardless of the bioactive material concentration (p < 0.05). The experimental BG and BS gels exhibited alkaline pH (ranging from 9.28 to 9.82), which was higher than that of 35% HP (p < 0.05). But regardless of the gel, all kept the pH values stable for 40 min. Conclusion: The experimental gels containing BG and BS did not hamper the 35% HP bleaching efficacy. Moreover, BG or BS gels decreased the hydrogen peroxide concentration and exhibited alkaline pH values.

Penetration of Intracoronal Bleaching Agents Across a Calcium Silicate-Based Coronal Barrier in Pulpless Immature Permanent Teeth: An In Vitro Study.

Tooth bleaching procedures on nonvital teeth have been performed for crown discoloration caused by regenerative endodontic therapy (RET). However, leakage of bleaching agents across the root canal can be detrimental. This study aimed to assess and compare the penetration levels of hydrogen peroxide (HP) from different bleaching agents across calcium silicate-based coronal barriers in immature permanent teeth. Fifty extracted single-rooted human teeth were randomly divided into four groups (n = 10): Group I (HH)-35% hydrogen peroxide (HP); Group II (SS)-a mixture of sodium perborate (SP) powder and saline; Group III (SH)-a mixture of SP powder and 30% HP liquid; Group IV (CP)-10% carbamide peroxide gel. The control group (Group V, CC) was treated with distilled water. The bleaching agent was replaced on the 4th day, and penetration analysis was performed on the 7th day using ferro thiocyanate (FTC) method and a UV-spectrophotometer at a wavelength of 480 nm. Compared with the control group, the SH group (SP mixed with HP) showed a significant difference, indicating substantial HP penetration across the root canal space (p value < 0.0001). Intergroup comparisons also revealed a significant difference between the SS and SH groups (p value < 0.0001), suggesting that the SS group had less penetration. Compared with other bleaching agents, SP mixed with saline/water resulted in the lowest HP penetration in the pulp canals of the RET-simulated tooth models. This study is the first to investigate HP penetration from different bleaching agents in teeth that have undergone RET, identifying the safest bleaching agent for use in these cases. This study also provides a foundation for further research to develop precise guidelines for nonvital tooth bleaching protocols in RET-treated teeth.

Tooth sensitivity in different arches post in-office dental bleaching: A multicenter randomized controlled trial

ObjectiveTo compare the risk and intensity of tooth sensitivity (TS) and gingival irritation (GI), as well as bleaching efficacy (BE) in the maxillary and mandibular arches after in-office dental bleaching. Materials and Methods90 participants were randomly into two groups according to the arch (maxillary or mandibular) in which the patient will first receive a 35 % hydrogen peroxide gel (2 sessions; 1 × 30 min; 1 week apart). TS and GI were recorded immediately after, up to 1 h, 24 h and 48 h after bleaching, using the 0–10 Visual Analogue Scale (VAS). BE was assessed before bleaching and 30 days after the end of the treatment (shade guide units [ΔSGU], CIELab [ΔEab], CIEDE2000 [ΔE00], and Whiteness Index for Dentistry [WID]). TS and GI were compared using McNemar's and paired t-test. BE were compared with Wilcoxon Signed Rank Test (ΔSGU) and paired t-test (ΔEab, ΔE00, and WID) (α = 0.05). ResultsThe risk and the intensity of TS was statistically higher for the mandibular arch (p < 0.003). The risk and intensity of GI did not differ between arches (p > 0.38). Both arches demonstrated significant BE (ΔSGU, ΔEab, ΔE00 and WID), without differences between them (p > 0.08). ConclusionsIn-office dental bleaching induces higher risk and the intensity of TS in the mandibular arch when compared to maxillary arch, without significant differences in gingival irritation, or bleaching efficacy. Clinical RelevanceMost patients experience tooth sensitivity regardless of the dental arch involved. However, when performing in-office dental bleaching, clinicians should consider that the mandibular arch is more likely to experience greater sensitivity compared to the maxillary arch.

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

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). 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 14days 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 orKruskal 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. 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. 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.

54413 Efficacy of a dermocosmetic cream compared to benzoyl peroxide gel on acne vulgaris treatment

54413 Efficacy of a dermocosmetic cream compared to benzoyl peroxide gel on acne vulgaris treatment

Enhanced tooth bleaching with a hydrogen peroxide/titanium dioxide gel

BackgroundThis study aimed to explore the effects of the titanium dioxide (TiO2) concentration and particle size in hydrogen peroxide (HP) on tooth bleaching effectiveness and enamel surface properties.MethodsTiO2 at different concentrations and particle sizes was incorporated into 40% HP gel to form an HP/TiO2 gel. The specimens were randomly divided into 8 groups: C1P20: HP + 1% TiO2 (20 nm); C3P20: HP + 3% TiO2 (20 nm); C5P20: HP + 5% TiO2 (20 nm); C1P100: HP + 1% TiO2 (100 nm); C3P100: HP + 3% TiO2 (100 nm); C5P100: HP + 5% TiO2 (100 nm); C0: HP with LED; and C0-woL: HP without LED. Bleaching was conducted over 2 sessions, each lasting 40 min with a 7-day interval. The color differences (ΔE00), whiteness index for dentistry (WID), surface microhardness, roughness, microstructure, and composition were assessed.ResultsThe concentration and particle size of TiO2 significantly affected ΔE00 and ΔWID values, with the C1P100 group showing the greatest ΔE00 values and C1P100, C3P100, and C5P100 groups showing the greatest ΔWID values (p < 0.05). No significant changes were observed in surface microhardness, roughness, microstructure or composition (p > 0.05).ConclusionsIncorporating 1% TiO2 with a particle size of 100 nm into HP constitutes an effective bleaching strategy to achieve desirable outcomes.

Clinical comparison of whitening efficacy and tooth sensitivity of different concentrations of hydrogen peroxide photoactivated with violet or blue LEDs.

This study evaluated the photoactivation of hydrogen peroxide gels at different concentrations using blue or violet LED in terms of whitening efficacy and tooth sensitivity. Forty patients were randomly divided into 4 groups: HP6V(violet LED and 6% hydrogen peroxide), HP6B(blue LED and 6% hydrogen peroxide), HP35V(violet LED and 35% hydrogen peroxide), and HP35B (blue LED and 35% hydrogen peroxide). The L*, a* and b* values were measured before, 1 week and 3 months after treatment, and the ΔE and ΔWID values were calculated. Tooth sensitivity was measured using a visual analogue scale (VAS) before, immediately after, and 24h after bleaching. The ΔE, ΔWID and bleaching sensitivity values were subjected to the ANOVA test and Bonferroni post-test. HP35V and HP35B showed higher whitening efficacy than HP6VL, while HP6V did not show statistical differences compared to the other groups. Regarding bleaching-related sensitivity, the HP6V and HP6B groups presented the lowest values when compared to HP35V and HP35B. HP6V showed whitening efficacy comparable to HP35V and HP35B but with reduced tooth sensitivity. TRIAL REGISTRATION NUMBER: NCT06165458; registration date: 12/09/2023.

The decomposition rate and bleaching efficacy of in-office bleaching gels with different pHs: a randomized controlled trial.

To evaluate the decomposition rate of active hydrogen peroxide (HP) and bleaching efficacy during in-office bleaching using high-concentration HP gels with different pHs. A randomized, parallel, double-blind controlled trial was conducted with 40 volunteers randomized into four groups (pH 5.4; pH 7.0; pH 7.7, and pH 8.0). During the first session in-office bleaching, approximately 0.01g of the gel was collected and titrated with potassium permanganate to obtain the concentration of active HP and pH values were measured using an electrode. Bleaching efficacy was assessed using a spectrophotometer [∆Eab, ∆E00, and WID], Vita Classical and Vita Bleachedguide scales [∆SGU]. The decomposition rate of HP concentration and pH values change were calculated using ANOVA one-way. The bleaching efficacy was assessed using two-way repeated measures ANOVA. Tukey's test was applied as a post-hoc test (p < 0.05). All gels experienced decreasing HP concentration over time. pH 5.4 gel showed greatest reduction after 50min (p < 0.001). pH 8.0 and 7.7 gels remained stable; pH 5.4 remained acidic, while pH 7.0 turned acidic (p < 0.001). No significant difference in bleaching degree was observed among gels. They all showed a similar and clinically important color change after two clinical sessions, remained stable 1-month post-treatment (p > 0.05). All bleaching gels kept at least 70% of their HP content after 50min, suggesting that there is a surplus of HP. They provided similar whitening efficacy 1-month after bleaching. It is possible that lower HP concentrations may be equally effective in achieving desired results while reducing the potential for side effects. RBR-35q7s3v.

Whitening toothpastes with hydrogen peroxide concentrations vs. at-home bleaching.

To evaluate the effect of whitening toothpastes with different hydrogen peroxide (HP) concentrations on HP permeability, color change, and physicochemical properties, compared to at-home bleaching treatment. Forty-nine premolars were randomized into seven groups (n = 7): untreated (control); at-home bleaching with 10% carbamide peroxide gel (AH; 10% CP) with 14 and 28 applications of 180min each (AH [14 × 180min] and AH [28 × 180min]); three whitening toothpastes (3% HP; 4% HP and 5% HP) and 10% CP brushed 28 times for 90s each (TB [28 × 90s]). HP permeability was measured using a UV-VIS spectrophotometer and color change by a digital spectrophotometer (ΔEab, ΔE00, and ΔWID). Initial concentration, pH, and viscosity were measured through titration, digital pH meter, and rheometer, respectively. Statistical analysis included one-way ANOVA, Tukey's test, and Dunnett's test (α = 0.05). 4% HP group showed acidic pH, the lowest viscosity and the highest HP concentration into the pulp chamber (p < 0.05). The 10% CP groups had lower HP in the pulp chamber and greater color change than other groups (p < 0.05), except the 5% HP group in ΔEab and ΔE00. For ΔWID, the 10% CP AH groups showed greater whitening than other groups (p < 0.05). Whitening toothpaste with up to 5% HP resulted in higher HP permeability and less color change compared to 10% CP. Higher HP commercial concentrations in toothpaste increased whitening effect; however, acidic pH toothpastes exhibited greater HP permeability. Whitening toothpastes with high hydrogen peroxide concentrations were less effective than at-home bleaching, resulting in less color change and greater permeability of hydrogen peroxide, potentially increasing the risk of tooth sensitivity.

Inorganic Phosphate Effect in a Hydrogen Peroxide-based Bleaching Agent: Physicochemical, Mechanical, and Morphological Properties of Dental Enamel.

This in vitro study aimed to assess the impact of incorporating calcium glycerophosphate (CaGP) and sodium fluoride (NaF) in addition to 35% hydrogen peroxide concerning the enamel mechanical and morphological properties. Specimens of bovine enamel were chosen based on their initial surface hardness (SHi) and subsequently divided into five gel groups (n=12): 1) 35% Hydrogen Peroxide (HP) Gel; 2) HP + 0.1% NaF Gel (HP/NaF); 3) HP + 0.25% CaGP Gel (HP/CaGP); 4) HP + 0.1% NaF + 0.25% CaGP Gel (HP/NaF/CaGP) and 5) HP Blue 35% Gel (HP Blue). The bleaching gels were applied thrice, for 40 min, at intervals of 7 days each. After 21 days, the final surface hardness (SHf), integrated hardness (IH), Polydispersity Index (PdI) and Zeta Potential (Zp), surface roughness (Ra, after and before), and surface/structural analysis by Scanning Electron Microscopy (SEM) were determined. The data were submitted to ANOVA (one-way and two-way) followed by the Student-Newman-Keuls test (α=0.05). The addition of NaF to HP reduced demineralization by 11.5% in relation to HP (p<0.05). The NaF/CaGP association reduction is 22.8 and 20% higher in comparison to HP/NaF/CaGP and HP Blue, respectively. The IH when the PH/NaF/CaGP bleaching gel was applied, was 14% higher compared to HP and HP Blue groups. It can be concluded that the association of NaF and CaGP with the 35% hydrogen peroxide gel (HP/NaF/CaGP) significantly changed tooth enamel demineralization in terms of surface, depth, roughness, and enamel morphology.

Investigating the Use of 0.3% Adapalene/2.5% Benzoyl Peroxide Gel for the Management of Moderate-to-Severe Acne in Indian Patients: A Phase 4 Study Assessing Safety and Efficacy.

Background Acne vulgaris is a chronic inflammatory disease of the pilosebaceous unit associated with an increase in sebum secretion. Topical treatment with adapalene and benzoyl peroxide (BPO) is considered effective when used either as monotherapy or in fixed-dose combinations. However, the combination gel of 0.3% adapalene with 2.5% benzoyl peroxide (A0.3%+BPO2.5%) has not been evaluated in Indian patients with acne. This study aimed to evaluate the safety and efficacy of A0.3%+BPO2.5% gel in Indian patients with moderate-to-severe acne vulgaris. Methodology This was a 12-week prospective, multicenter, open-label, phase IV study conducted at six centers in India. Safety was assessed based on local tolerability (stinging or burning, erythema, dryness, and scaling) and any reported adverse events. Efficacy was evaluated based on reductions in the number of inflammatory and noninflammatory lesions, the Investigator's Global Assessment (IGA) scale, and the Global Assessment of Improvement (GAI) score. The patient-reported outcome was measured using the Subject Satisfaction Questionnaire. Results Of the 135 patients, 132 completed the study between December 24, 2021, and July 18, 2022 (93.9% had moderate acne; 6.1% had severe acne at baseline). The A0.3%+BPO2.5% gel was well tolerated. The reductions in the severity scores of erythema, scaling, and dryness from baseline to week 12 were 38.9%, 47.4%, and 76.5%, respectively. A targeted reduction of ≥50% in the number of inflammatory and noninflammatory lesions was achieved in 115 (87.1%) and 109 (82.6%) patients, respectively. Based on the investigator's responses to the IGA questionnaire at week 12, 28% and 40.9% of patients had clear and almost clear skin, respectively. Using the GAI scale, investigators reported that at 12 weeks from baseline, most patients presented with improvements in symptoms, such as erythema, scaling, and dryness, and none reported any worsening. Treatment satisfaction was rated as 91% by the patients. Conclusions The A0.3%+BPO2.5% gel effectively reduced the inflammatory and noninflammatory lesions and was found to be safe and well tolerated in Indians with moderate‑to‑severe acne vulgaris.

A Comparative Analysis to Evaluate the Outcome and Effectiveness of Increasing the Therapeutic Agents for the Treatment of Acne Vulgaris

Abstract Background: Acne vulgaris is a long-term inflammatory condition impacting the pilosebaceous units. The guidelines largely rely on expert opinions in light of certain facets of acne treatment. Before initiating our study, we conducted a prescription analysis involving 100 patients diagnosed with acne vulgaris. We noted that in the majority of these cases, the established guidelines were not adhered to. Therefore, we decided to conduct this study at our institute to see if there is any additional benefit of adding multiple drugs to the treatment regimen and to find out if there is a way to rationalize the same. Materials and Methods: For the study, 120 patients with acne vulgaris, graded 2 and 3 according to the Investigator’s Global Assessment (IGA) Scale, were enrolled and divided into four groups. Patients were followed up for 8 weeks with visits at 4, 6, and 8 weeks. Group A was given clindamycin gel, Group B was given clindamycin gel + benzoyl peroxide gel (BPO) (2.5%), Group C was given clindamycin gel + BPO gel (2.5%) + oral doxycycline 100 mg, and Group D was given clindamycin gel + BPO gel (2.5%) + oral isotretinoin 20 mg. Results: This study showed that combination therapy with isotretinoin showed maximum reduction in IGA as well as in the total number of inflammatory lesions. Group C had similar efficacy to combination therapy with Group D as the results were not significantly different. Conclusions: The guidelines recommend adhering to protocols, specifically reserving isotretinoin for cases of very severe and treatment-resistant acne.

EE404 A Cost-Effectiveness Analysis of a Triple-Agent Topical Fixed-Dose Combination of 1.2% Clindamycin Phosphate, 0.15% Adapalene, and 3.1% Benzoyl Peroxide Gel for the Treatment of Moderate-to-Severe Acne Vulgaris in the United States

EE404 A Cost-Effectiveness Analysis of a Triple-Agent Topical Fixed-Dose Combination of 1.2% Clindamycin Phosphate, 0.15% Adapalene, and 3.1% Benzoyl Peroxide Gel for the Treatment of Moderate-to-Severe Acne Vulgaris in the United States

Reduction of surface treatment time by combination of citric acid and ascorbic acid while restoring shear bond strength of metal brackets bonded to bleached enamel: a pilot study

BackgroundTo investigate the effect of a 50% ascorbic acid with 50% citric acid solution on the immediate shear bond strength (SBS) of metallic brackets after tooth bleaching. The enamel etching pattern and the required quantity of these combined acids as antioxidants following 35% hydrogen peroxide (HP) bleaching were also determined.MethodsThe stability of the solution at room temperature was assessed at various time intervals. Fifty teeth were randomly divided into five groups: non-bleached (G1), bleached then acid etched (G2), bleached followed by a 10-minute treatment with 10% sodium ascorbate and acid etched (G3), 5-minute treatment with 50% ascorbic acid (G4), and 5-minute treatment with a combination of 50% ascorbic acid and 50% citric acid (G5). Groups G2, G3, G4 and G5 were bleached by 35% HP gel for a total of 32 min. Acid etching in groups G1, G2, and G3 was performed using 37% phosphoric acid (Ormco®, Orange, CA, USA) for 15 s. In all groups, metal brackets were immediately bonded using Transbond™ XT primer and Transbond™ PLUS adhesive, with light curing for 40 s. The SBS was tested with a universal testing machine, and statistical analysis was conducted using one-way ANOVA followed by Tukey’s HSD test. The level of significance was set at p < 0.05 for all statistical tests.ResultsStability tests demonstrated that the combined acids remained effective for up to 21 days. Group G5 significantly increased the SBS of bleached teeth to the level of G1 (p < 0.05), while G3 did not achieve the same increase in SBS (p > 0.05). SEM analysis revealed enamel etching patterns similar to those of both control groups (G1 and G2). Kinetic studies at 6 min indicated that the antioxidation in G5 reacted 0.2 mmole lower than in G3 and G4.Conclusion5-minute application of the combined acids enhanced the SBS of bleached teeth comparable to unbleached teeth. The combined acids remain stable over two weeks, presenting a time-efficient, single-step solution for antioxidant application and enamel etching in orthodontic bracket bonding.

Effectiveness and safety of biosilicate-enhanced bleaching gels on enamel with early erosion lesion.

This study evaluated the efficacy and cytotoxicity of 35% hydrogen peroxide (HP) gel incorporated with 10% (w/w) biosilicate (BioS) on sound enamel and early-stage enamel erosion lesions. Discs of enamel/dentin were selected, subjected to erosive cycles (0.3% citric acid, pH 2.6), and treated with (n = 8): HP (35% HP, positive control); HP_BioS [carboxymethyl cellulose (CMC) + HP + BioS]; BioS (CMC + BioS); CMC (negative control). The discs were adapted to artificial pulp chambers with the enamel exposed for bleaching, and the dentin facing toward the culture medium (Dulbecco's modified Eagle's medium [DMEM]). Bleaching was performed in three 30-min sessions at 7-day intervals. After bleaching, the diffusion product (DMEM extract + diffused HP) was pipetted onto MDPC-23 odontoblastic cell line and inoculated. Color parameters (ΔL, Δa, Δb), color change (ΔE00), and changes in whiteness index (ΔWID) were determined before (T0) and after the last bleaching session (T3). Cell viability (MTT, %), H2O2 diffusion (μg/mL), oxidative cell stress (OxS), and cell fluorescence (live/dead assay, in confocal microscopy) were assessed (ANOVA/Tukey; α = 0.05). No difference in ΔL, Δa, Δb, ΔE00, and ΔWID were found between HP and HP_BioS (p > 0.05). The incorporation of BioS decreased the HP diffusion into the substrates and mitigated oxidative stress in early-stage eroded enamel (p < 0.05). HP_BioS presented significantly higher cell viability compared with HP under erosion conditions. Live/dead assay indicated that BioS_HP maintained viability with larger clusters of viable cells. Incorporating BioS into HP maintained bleaching effectiveness, favored cell viability, reduced the oxidative stress, and the cytotoxicity in teeth with early-stage erosion. BioS formulation showed promising results for reducing cytotoxicity in patients seeking tooth bleaching and presenting undetectable early-stage erosion.

The Effect of Two Different Wavelengths of Diode Laser on the Shear Bond Strength of Composite to Dental Enamel after Bleaching Process: An In Vitro Study.

In recent years, tooth whitening has become one of the most popular ways of achieving the original tooth color. The effect of whitening gel can be improved through heat, light or laser. The bond strength between the enamel and the composite can be reduced through bleaching and laser radiation. The purpose of this study is to assess the shear bond strength of resin composite to enamel after a bleaching process using hydrogen peroxide, with and without a laser (970 nm and 445 nm lasers). This study used 51 extracted anterior teeth without caries that were divided into three groups. A 40% hydrogen peroxide gel was used on the enamel of all teeth. The control group received bleaching without a laser. Both the second and third treatment groups received bleaching with a laser, one with 970 nm and the other with 445 nm. After the bleaching process, all groups had etching, bonding and curing of the composite performed. Lastly, the shear bond strength between the enamel and the composite was measured and the failure modes were recorded. The data were compared using a one-way ANOVA test. The mean shear bond strength between the enamel and the composite in the 445 nm group three (445 nanometer) was significantly lower than the other groups (p < 0.05). There was no significant difference between the control and the 970 nm groups (p = 0.2). According to the laser wavelengths and parameters that were used in this study and the results of this study, office bleaching with a 445 nm laser weakened the shear bond strength between the enamel and the composite.

Effect of Bleaching on Resin-Infiltration-Masked Artificial White Spots In Vitro.

Resin infiltration is an effective method to mask vestibular white spots. If needed, external bleaching is usually recommended before infiltration, whilst in clinical practice, this sequence may not always be feasible. This in vitro study evaluated the effect of bleaching after resin infiltration regarding surface roughness and color using bovine incisors. Unlike for the untreated specimens (control, n = 25), artificial caries lesions were created within the test group (n = 25) using a demineralization solution at 37 °C for five days (pH = 4.95). The lesions were subsequently infiltrated using a resin infiltrant (Icon, DMG, Hamburg, Germany), followed by polishing. Afterwards, all specimens were bleached with a 10% carbamide peroxide gel (Opalescence, Ultradent, South Jordan, UT, USA) for 8 h/day over a ten-day period. Between bleaching treatments, specimens were stored in an opaque container with moistened paper tissues at 37 °C. Surface roughness was measured using a profilometer, and color in the L*a*b* space was assessed spectrophotometrically before and after bleaching. Bleaching increased the L*-values of both infiltrated (mean ± SD; ΔL* = 3.52 ± 1.98) and untreated (control) specimens (ΔL* = 3.53 ± 2.30) without any significant difference between the groups (p = 0.983). Bleaching also induced a significant increase in the mean surface roughness of both infiltrated (p < 0.001) and untreated (p = 0.0134) teeth. In terms of clinical relevance; it can be concluded that bleaching resin-infiltrated enamel is as effective as bleaching sound enamel.

Bleaching efficacy of in-office dental bleaching with different application protocols: a single-blind randomized controlled trial.

This randomized controlled trial aimed to evaluate the equivalence in the color change, adverse effects, self-perception (AS) and the impact on oral condition (IO) of participants submitted to different application protocols of in-office dental bleaching. 165 participants were bleached with a 35% hydrogen peroxide gel (Total Blanc Office One-Step, DFL), according to the following protocols: (1) 2 applications of 20-min each (2 × 20min); (2) 1 × 40-min and; (3) 1 × 30-min. The color change was evaluated with the Vita Easyshade spectrophotometer, Vita Classical and Vita Bleachedguide scales. The intensity and risk of tooth sensitivity (TS) and gingival irritation (GI) were recorded using a 0-10 visual analogue scale (VAS). AS and IO was assessed before and after the bleaching procedure using the Orofacial Aesthetic Scale and Oral Health Impact Profile-14, respectively. Equivalent color change were observed (p < 0.001), with no significant difference between groups. The group 2 × 20min presented the highest risk of TS (76%, 95% CI 63 to 85), compared to the 1 × 30min (p < 0.04). The intensity of TS and GI and the risk of GI was similar between groups (p > 0.31). Irrespectively of the group (p = 0.32), significant improvements were observed for all items of AS and IO after bleaching (p < 0.02). The 1 × 30min protocol produced equivalent color change to the other bleaching protocols with reduced risk of TS and shorter application time. A more simplified application regimen of a single application of 30min yields effective bleaching and patient satisfaction while minimizing undesirable side effects and improving patient satisfaction.

ВЛИЯНИЕ ВНУТРИКОРОНКОВОГО ОТБЕЛИВАНИЯ НА МИКРОТВЕРДОСТЬ ДЕНТИНА: КЛИНИЧЕСКИЙ СЛУЧАЙ С ОБЗОРОМ ЛИТЕРАТУРЫ

Aim. Analysis of literature sources about the effect of intracoronal bleaching on the microhardness of dentin, as well as demonstration of a clinical case of successful correction of tooth discoloration caused by endodontic sealant using the method of intracoronal bleaching with a one-year follow-up period. Materials and methods. A search of literature sources was carried out in the PubMed, Google Scholar, CyberLeninka databases on September 24, 2023 using keywords. Articles in English and Russian were selected for analysis. Inclusion criteria: original articles, in vitro and in situ studies, studies on extracted human teeth, studies that assessed dentin microhardness. As a result of the search, 11 sources were found in the PubMed database, 171 in the scientific electronic library e-library, and 2 in the CyberLeninka database. After eliminating duplication and assessing the inclusion/non-inclusion criteria, 7 literary sources remained. The presented clinical case demonstrates the successful correction of discoloration caused by endodontic sealant using intracoronal bleaching with 35 % hydrogen peroxide gel. Results. When analyzing the literature, laboratory studies revealed various conditions that make it possible to reduce the negative effect of the bleaching agent on dentin tissue, namely activation with an ultraviolet lamp, addition of a dye, and treatment with fluoride varnish after bleaching. In the clinical case, the desired shade was achieved in three bleaching procedures, then the existing defective restoration was replaced with a new shade-matching one. During the year of observation, there was no return of color, the aesthetic result was assessed as stable, the patient expressed high satisfaction with the result obtained. Conclusion. The intracoronal bleaching procedure can have a negative effect of varying severity on dentin microhardness. Identifying approaches that reduce this impact is a promising direction for future research. The clinical case demonstrates that intracoronal bleaching provides acceptable esthetic results and high patient satisfaction.

Comparative Evaluation of Various Antioxidants on the Shear Bond Strength of Composite Resin to Bleached Enamel - An In Vitro Study.

To evaluate and compare the effect of various antioxidants on the shear bond strength of composite resin to bleached enamel. Labial enamel surfaces of 90 extracted human maxillary central incisors were randomly divided into five groups based on the antioxidant used as follows: Group I ( n = 20): Bleaching with 40% hydrogen peroxide gel for 10 min, without the use of an antioxidant; Group II ( n = 20): Bleaching followed by the use of 10% sodium ascorbate solution; Group III ( n = 20): Bleaching followed by the use of 5% grape seed extract solution; Group IV ( n =20): Bleaching followed by the use of 5% pine bark extract solution; and Group V ( n =20): Control group in which no bleaching was done. Groups I-IV were further subdivided into two subgroups of 10 teeth each, whether the antioxidant application and composite build-up was done immediately (subgroup A) or after 2 weeks of postbleaching (subgroup B). Shear bond strength of the specimens was tested under a universal testing machine. One-way analysis of variance followed by Mann-Tukey posthoc multiple comparison test was used to analyse the data. The level of significance was established at P < 0.05. Within the limitations of this study, it was observed that the use of antioxidants effectively reversed the compromised bond strength of bleached enamel. Among the antioxidants, 5% pine bark extract application after bleaching showed better bond strength.