Bleaching Therapy Research Articles

Low-Level Laser Therapy for Tooth Sensitivity after Tooth Bleaching: A Systematic Review

Tooth bleaching is a popular cosmetic procedure known for its effective whitening results. However, it may cause tooth sensitivity. Various desensitizing therapies, including laser treatments, are used to alleviate pain and improve patient comfort. This study aims to conduct a systematic review to evaluate the effectiveness of low-level laser therapy for treating tooth sensitivity following bleaching therapy. A comprehensive search was conducted across 13 electronic databases (PubMed, Scopus, ScienceDirect, Google Scholar, Web of Science, Ovid, BMJ evidence-based medicine, proQuest, Greylit.org, Ethos, Livivo, Clinical trials gov, and Meta register of controlled trials) to identify relevant studies according to specific eligibility criteria, following the PRISMA guidelines. Two independent reviewers screened and selected the studies, performed data extraction, and assessed the risk of bias using the revised Cochrane risk-of-bias tool for randomized clinical trials (RCTs). The initial search yielded 2875 articles, which were subsequently screened to remove duplicates. After evaluating 1532 articles based on title and 136 by abstract, 21 studies remained for full-text assessment. Ultimately, only six RCTs met all of the eligibility criteria. The application of low-level laser therapy appears to reduce tooth sensitivity following tooth bleaching. Despite the positive reported effects, further research is necessary to determine the optimal use of low-level laser therapy for effective pain relief.

Catalysis-based approaches with biopolymers and violet LED to improve in-office dental bleaching.

This in vitro experimental investigation aimed to evaluate the impact of the combined application of a nanofiber scaffold (NS), a polymeric catalyst primer (PCP) containing 10mg/mL of heme peroxidase enzyme, and violet LED (LEDv) on the esthetic efficacy (EE), trans-amelodentinal cytotoxicity (TC), and procedural duration of conventional in-office bleaching therapy. To achieve this, 96 standardized enamel/dentin discs were individually placed in artificial pulp chambers. A 35% hydrogen peroxide (H2O2) bleaching gel was administered for 45, 30, or 15min to the enamel, either previously coated with NS + PCP or left uncoated, followed by irradiation with LEDv for 15min or no irradiation. The established groups were as follows: G1, negative control (no treatment); G2, 35% H2O2/45min; G3, NS + PCP + LEDv; G4, NS + PCP + 35%H2O2/45min + LEDv; G5, NS + PCP + 35%H2O2/30min + LEDv; and G6, NS + PCP + 35%H2O2/15min + LEDv. Extracts (culture medium + gel components diffused through the discs) were collected and applied to odontoblast-like MDPC-23 cells. EE (ΔE00 and ΔWI) and TC were assessed using ANOVA/Tukey analysis (p < 0.05). The EE analysis revealed no statistical differences between G6 and G2 (p > 0.05). Cells in G6 exhibited higher viability and lower oxidative stress compared to other bleached groups (p < 0.05). In conclusion, employing NS + PCP + LEDv to catalyze a 35%H2O2 bleaching gel applied for 15min to the enamel resulted in successful esthetic improvements and reduced the cytotoxicity commonly linked with traditional in-office bleaching procedures.

Effect of medium or high concentrations of in-office dental bleaching gel on the human pulp response in the mandibular incisors.

The present study evaluated the pulp response of human mandibular incisors subjected to in-office dental bleaching using gels with medium or high concentrations of hydrogen peroxide (HP). The following groups were compared: 35% HP (HP35; n = 5) or 20% HP (HP20; n = 4). In the control group (CONT; n = 2), no dental bleaching was performed. The color change (CC) was registered at baseline and after 2 days using the Vita Classical shade guide. Tooth sensitivity (TS) was also recorded for 2 days post-bleaching. The teeth were extracted 2 days after the clinical procedure and subjected to histological analysis. The CC and overall scores for histological evaluation were evaluated by the Kruskal-Wallis and Mann-Whitney tests. The percentage of patients with TS was evaluated by the Fisher exact test (α = 0.05). The CC and TS of the HP35 group were significantly higher than those of the CONT group (p < 0.05) and the HP20 group showed an intermediate response, without significant differences from either the HP35 or CONT group (p > 0.05). In both experimental groups, the coronal pulp tissue exhibited partial necrosis associated with tertiary dentin deposition. Overall, the subjacent pulp tissue exhibited a mild inflammatory response. In-office bleaching therapies using bleaching gels with 20% or 35% HP caused similar pulp damage to the mandibular incisors, characterized by partial necrosis, tertiary dentin deposition, and mild inflammation.

Effect of bleaching gel volume on color change and postoperative sensitivity: a randomized clinical study.

Although bleaching therapy is considered a dose-dependent treatment, the effect of the volume of product used is yet to be studied. This study thus aimed to evaluate the influence of bleaching gel volume on chromatic alteration and postoperative sensitivity. Thirty patients were selected and allocated into three groups; the lower canines were analyzed according to the volume of gel used: GI-0.025mL, GII-0.05mL, and GIII-0.10mL. Chromatic alteration analysis was performed using a portable digital spectrophotometer by calculating the ΔE, ΔE00, ΔL*, Δa*, and Δb* values and the whiteness index (WID). Spontaneous sensitivity was assessed using a questionnaire, and sensitivity was stimulated by thermo-sensory analysis. Analyses were conducted in five stages: baseline, after 1st, 2nd, and 3rd bleaching sessions, and 14days after the end. Data were analyzed using the two-way ANOVA test with repeated measures and Tukey's post hoc test (p < 0.05). It was observed that ΔE, ΔE00, and ΔL* were similar between groups at the end of the bleaching therapy; and the values of Δa*, Δb*, and WID were higher in the GIII group. For sensitivity, it was found that the GI was the one with the lowest values; o GII intermediate values; while the GIII group presents the highest values of spontaneous and stimulated sensitivity. Gel volume influenced the response to bleaching and significantly influenced the spontaneous sensitivity and cold stimulus. The amount of bleaching gel used during therapy is key to both the response to color change and postoperative sensitivity.

Assessment of a novel bleaching agent formula containing 35% hydrogen peroxide and titanium tetrafluoride: an in vitro study.

This study developed experimental gels containing titanium tetrafluoride (TiF4) combined with commercial 35% hydrogen peroxide (HP), and evaluated bleaching efficacy and pH of the gels, and mineral content and morphology of enamel submitted to these treatments. In phase-1, different stock gels mixed with TiF4 were combined with HP. In phase-2, the selected gels were tested on enamel/dentin specimens (n=8): HP; HP and Natrosol+TiF4 (HPnT); HP and Natrosol+Chemygel+TiF4 (HPncT); HP and Aristoflex+TiF4 (HPaT). Bleaching was performed in four sessions (3x15min-application/session). Color (CIEL*a*b*) and whiteness index (WID) were measured after each session, whereas whiteness index differences (ΔWID), color alteration (CIELab-ΔE, CIEDE2000-ΔE00), enamel morphology and pH, at end of bleaching therapy. The change in Knoop microhardness (ΔKHN) was compared before and after bleaching. Data were analyzed by two-way repeated measures ANOVA and Bonferroni (CIEL*, a*, b*), one-way ANOVA and Tukey (ΔWID, ΔE, ΔE00), and LSD (ΔKHN) tests (α=5%). SEM and pH measurements were submitted to descriptive analysis. No differences were observed in lightness (L*) or WID among the groups (p > 0.05), but HP exhibited lower b* values (p<0.05), higher ΔWID than HPnT, and the highest ΔE among the groups (p < 0.05). No differences in ΔE00 were observed between HP and HPncT (p > 0.05), and HPncT showed higher ΔKHN than HP (p < 0.05). HP presented pH values closer to neutral (6.9), whereas experimental agents showed acidic pH values (2.3-3.9). No morphological changes were observed in HP or HPncT groups. HPncT was able to bleach the enamel and maintain enamel microhardness and surface integrity, even at low pH.

Influence of Tooth Pigmentation on H2O2 Diffusion and Its Cytotoxicity After In-office Tooth Bleaching.

Pigments in tooth structures affect the diffusion of H2O2 through enamel and dentin. The bleaching methodology can be impacted. Objective: The aim of this study was to evaluate the influence of the presence of pigments in tooth structures on the trans-enamel and trans-dentin diffusion of hydrogen peroxide (H2O2) and its cytotoxicity after carrying out an in-office bleaching therapy.Methods and Materials: A bleaching gel with 35% H2O2 was applied for 45 minutes (three times for 15 minutes) on enamel and dentin discs (n=6), either previously submitted to the intrinsic pigmentation protocol with a concentrated solution of black tea, or not, defining the following groups: G1, unbleached untreated discs (control 1); G2, unbleached pigmented discs (control 2); G3, bleached untreated discs; G4, bleached pigmented discs. The discs were adapted to artificial pulp chambers, which were placed in wells of 24-well plates containing 1 mL culture medium (Dulbecco's modified Eagle's medium [DMEM]). After applying the bleaching gel on enamel, the extracts (DMEM + components of bleaching gel that diffused through the discs) were collected and then applied on the cultured MDPC-23 odontoblast-like cells. Cell viability (methyl tetrazolium assay and Live & Dead, Calcein AM, and ethidium homodimer-1 [EthD-1] probes), the amount of H2O2 that diffused through enamel and dentin (leuco-crystal violet product), and the H2O2-mediated oxidative cell stress (SOx) and components of degradation were assessed (analysis of variance/Tukey; α=0.05).Results: There was no significant difference between the groups G1 and G2 for all the parameters tested (p>0.05). Reduction in the trans-enamel and trans-dentin diffusion of H2O2 occurred for G4 in comparison with G3. Significantly lower cell viability associated with greater oxidative stress was observed for G3 (p<0.05). Therefore, in-office tooth bleaching therapy performed in pigmented samples caused lower cytotoxic effects compared with untreated samples submitted to the same esthetic procedure (p<0.05).Conclusion: According to the methodology used in this investigation, the authors concluded that the presence of pigments in hard tooth structures decreases the trans-enamel and trans-dentin diffusion of H2O2 and the toxicity to pulp cells of an in-office bleaching gel with 35% H2O2.

INFLUENCE OF DIFFERENT BLEACHING SYSTEMS ON THE BOND STRENGTH OF LAMINATE VENEER TO ENAMEL

Purpose: The objective of this in-vitro study was to examine the microtensile bond strength of a porcelain laminate veneer (PLV) to tooth surface bleached with photoactivation by blue light-emitting diode (LED) or diode laser. Methods: Eigthteen extracted human central incisors were randomly divided into three groups. Two sticks were obtained from each tooth (n=12). Before surface treatments; teeth were prepared to provide space for PLVs. The first group teeth were bleached with Whiteness HP which is contain 35% hydrogen peroxide (HP) and then photoactivated with a LED for 20 seconds. The second group were bleached with Laserwhite 20 which is contain 46% HP and photoactivated with a diode laser for 30 seconds. The third group received no surface treatment and served as the control group. IPS Esthetic ceramic veneers were luted with Variolink II veneer cement . The teeth were sectioned to obtain porcelain-resin-enamel/dentin sticks and submitted to a MTB testing device. The maximum load at fracture was recorded. Data were analyzed using one-way ANOVA followed by the Tukey HSD post-hoc test at a preset α of 0.05. Results: One-way ANOVA revealed that there was significant difference between LED unit group and control group (p&lt;.05) but no statistical differences were observed with diode laser group (p&gt;.05) The LED unit group presented significantly lower bond strength value (6.49±2.3 MPa) than diode laser (8.49 ±3.1 MPa) and control groups (9.53±2.7 MPa). Conclusion: The results suggested that bleaching therapy with activation by LED or diode laser reduced the bond strength of IPS Esthetic ceramic veneers to tooth surfaces.&#x0D; Keywords: Teeth Bleaching; Photoactivation; Semiconductor lasers; Diode laser; Microtensile.

ブリーチング法を利用したエナメル質表層下脱灰病巣の再石灰化戦略 : 第1報 30%過酸化水素水による唾液成分タンパク質の化学的変化

ブリーチング法を利用したエナメル質表層下脱灰病巣の再石灰化戦略 : 第1報 30%過酸化水素水による唾液成分タンパク質の化学的変化

Does the Use of a "Walking Bleaching" Technique Increase Bone Resorption Markers?

This randomized clinical trial evaluated the effect of 35% hydrogen peroxide in comparison with 37% carbamide peroxide in a nonvital bleaching technique of "walking bleaching" (four sessions of treatment) on periodontal markers: nuclear factor kappa B-ligand (RANK-L-process of root resorption marker) and interleukin 1β (IL-1β-inflammatory response marker). Fifty volunteers presenting with discoloration of nonvital teeth and endodontic treatment in good condition participated. Fifty teeth were randomly divided into two study groups according to bleaching gel: HP = 35% hydrogen peroxide (n=25) and 37% carbamide peroxide (n=25). Nonvital bleaching was performed with a walking bleaching technique consisting of four sessions of bleach application. Gingival crevicular fluid samples were taken in order to quantify the RANK-L and IL-1β levels by enzyme-linked immunosorbent assay. Samples were obtained from six periodontal sites for each bleached tooth: three vestibular and three palatine (mesial, middle, and distal) at seven time periods: baseline, after each of the four sessions of nonvital bleaching, at one week, and at one month after nonvital bleaching. Tooth color variations were analyzed in each session by VITA Bleachedguide 3D-MASTER (ΔSGU). Significant increments in the RANK-L and IL-1β levels were detected in each evaluated time compared with baseline ( p<0.05); however, no differences were detected between hydrogen peroxide and carbamide peroxide on increments of the biomarkers studied. The change of color was effective for both nonvital bleaching therapies ( p<0.05). Nonvital bleaching induced a significant increment in the RANK-L and IL-1β levels in periodontal tissues around bleached, nonvital teeth.

Port wine stains and Pulsed Dye Laser: study of prognostic factors in 74 Moroccan patients

Le laser à colorant pulsé (LCP) est actuellement le traitement de référence des Angiomes Plans (AP). Cependant, les critères cliniques prédictifs d'une bonne ou d'une mauvaise réponse ne sont pas encore clairement établis dans notre contexte. Notre but était de déterminer les facteurs de mauvaise /bonne réponse des AP traités par le LCP dans la population marocaine. Une étude rétrospective des patients suivis pour AP a été réalisée au service de dermatologie du CHU Ibn Rochd de Casablanca entre Janvier 2008 et Décembre 2013. Nous avons collecté les paramètres cliniques suivants : âge, sexe, localisation, antécédents, paramètres utilisés, nombre de séances, phototype et la satisfaction des médecins soignants basée sur le blanchiment des lésions. La bonne réponse a été définie par le palissement de 50% des lésions au bout de la 6ème séance. Les patients ont été contactés par téléphone afin d'évaluer leur degré de satisfaction. Ces résultats ont été corrélés aux paramètres cliniques sus cités. Un seuil de signification de 0.05 a été utilisé. Soixante-quatorze patients ont été éligibles. Le sexe féminin représentait 69% et l'âge médian était de 18 ans. La localisation au visage était prédominante (94%). L'étude comparative des groupes bons / mauvais répondeurs a montré que l'âge moyen du groupe bon répondeur était inférieur au groupe mauvais répondeur avec une différence significative (p = 0.047). Le nombre de séances du groupe bon répondeur était plus élevé (p = 0.044). Les paramètres étaient variables d'un patient à un autre. Aucune différence n'a été notée concernant le type de peau entre les deux groupes. La localisation la mieux blanchie était la zone V2. Cette étude a montré que les AP pris en charge à un âge jeune en plusieurs séances avaient une réponse thérapeutique supérieure dans notre contexte. Ceci implique l'intérêt du diagnostic précoce et une prise en charge rapide à des intervalles courts afin d'améliorer les résultats et de minimiser les effets indésirables.

A Survey among Palestinian Dentists Regarding Preferences Over Vital and Non-Vital Teeth Bleaching:A Cross-Sectional Study

Background: With bleaching treatments becoming very popular, assessment was conducted among Palestinian dentists to check their preferences. Objective: To evaluate the preferences of general dentists regarding vital and non-vital tooth bleaching therapies and to investigate whether the time of clinical practice influences these options. MaterialM At home therapies were the least preferred (19.3%). Hydrogen peroxide more than 22% was the preferred treatment of choice for vital bleaching therapy (57.9%), whereas the combination of sodium perborate with water or hydrogen peroxide (46.5%) was the preferred treatment of choice for non-vital bleaching. There was a significant association between the time since graduation and the preference for in-office bleaching (P = 0.01) and no significant association between the time since graduation and the material used. Conclusion: In-office bleaching was preferred over at-home therapies; HP >22% and sodium perborate with water or HP were chosen as first treatment options to manage discolored vital and non-vital teeth, respectively. The time in clinical practice had an effect only on the choice of vital bleaching technique.

Antioxidant therapy enhances pulpal healing in bleached teeth.

ObjectivesThe purpose of this study was to evaluate the histopathological effects of an antioxidant therapy on the pulp tissue of rat teeth exposed to a bleaching gel with 35% hydrogen peroxide.Materials and MethodsForty rats were subjected to oral ingestion by gavage of distilled water (DW) or ascorbic acid (AA) 90 min before the bleaching therapy. For the bleaching treatment, the agent was applied twice for 5 min each to buccal surfaces of the first right mandibular molars. Then, the animals were sacrificed at 6 hr, 24 hr, 3 day, or 7 day post-bleaching, and the teeth were processed for microscopic evaluation of the pulp tissue.ResultsAt 6 hr, the pulp tissue showed moderate inflammatory reactions in all teeth of both groups. In the DW and AA groups, 100% and 80% of teeth exhibited pulp tissue with significant necrosis and intense tissue disorganization, respectively. At 24 hr, the AA-treated group demonstrated a greater regenerative capability than the DW group, with less intense inflammatory reaction and new odontoblast layer formation in 60% of the teeth. For up to the 7 day period, the areas of pulpal necrosis were replaced by viable connective tissue, and the dentin was underlined by differentiated odontoblast-like cells in most teeth of both groups.ConclusionsA slight reduction in initial pulpal damage during post-bleaching was promoted by AA therapy. However, the pulp tissue of AA-treated animals featured faster regenerative potential over time.

Pre- and postoperative dexamethasone does not reduce bleaching-induced tooth sensitivity: A randomized, triple-masked clinical trial

BackgroundTooth sensitivity (TS) is the most common side effect of dental bleaching therapies. Dexamethasone has been used with tooth bleaching to reduce TS. The efficacy of dexamethasone for this purpose has not been well studied. MethodsThe authors conducted a triple-masked, randomized, clinical trial with a parallel design involving 63 healthy participants who received either a placebo or dexamethasone. The placebo or dexamethasone (8 milligrams) was administered 1 hour before the in-office bleaching (35% hydrogen peroxide) and extra doses of 4 mg were administered every 6 hours for a total of 48 hours. TS was recorded on 2 scales: visual analog scale (0-10) and numeric rating scale (0-4) in different periods. The color evaluations were performed before and 1 month after dental bleaching with visual shade guides VITA Classical (VITA Zahnfabrik) and VITA Bleachedguide 3D-MASTER (VITA Zahnfabrik), and for a shade guide evaluation, the authors used a digital spectrophotometer, VITA Easyshade (VITA Zahnfabrik). The absolute risk of TS was evaluated by a Fisher exact test. Data of TS intensity using the NRS scale for the 2 groups were compared with Mann-Whitney and Friedman tests, whereas data from the visual analog scale were evaluated by 2-way repeated measures analysis of variance. The color changes between groups were compared using a t test (α = .05). ResultsIn both groups, the authors detected a high risk of TS, which was approximately 90%. No significant difference was observed in terms of TS intensity. A whitening of approximately 3 shade guide units of the VITA Classical was detected in both groups, which were statistically similar. ConclusionsThe use of dexamethasone before bleaching did not reduce the risk and intensity of bleaching-induced TS. Practical ImplicationsThe use of the steroidal anti-inflammatory agent dexamethasone was not capable of preventing TS arising from in-office dental bleaching.

Comparison of treatment time versus patient satisfaction in at-home and in-office tooth bleaching therapy

Statement of the problemThere are different approaches and treatment times to achieve tooth whitening. PurposeThe purpose of this study was to evaluate the efficacy of different agents and the treatment time required to achieve participant satisfaction with at-home and in-office tooth whitening. Material and methodsThirty participants were selected based on the shade of the anterior teeth (between A2 and A3.5; Vita Classic Shade Guide). Each participant received both in-office and at-home bleaching agents in a split-mouth design at both arches. In-office bleaching was performed in the maxillary quadrants, applying 35% hydrogen peroxide (HP35%) (right) and 35% HP with calcium (HP35%Ca) (left) for 40 minutes/week. Home bleaching was performed in mandibular quadrants using carbamide peroxide 10% (CP10%) (right) and CP22% (left) for 2 hours/day. Bleaching treatments were performed until participant satisfaction was achieved (maximum 6 sessions [S] in the dental office or 6 weeks [W] in the home). The shade was measured with a spectrophotometer before treatment, then at 2 and 4 weeks, and at the last week for at-home bleaching; and 1 week after the second, fourth, and last sessions for in-office bleaching. Student t and Tukey-Kramer tests were used (α=.05). ResultsAll bleaching agents were effective for vital tooth whitening. No significant differences were observed for color changes between CP10% and CP22% or between HP35% and HP35%Ca for all periods. Treatment times required to achieve patient satisfaction for the in-office bleaching technique were 4S (12 participants), 5S (10 participants), and 6S (8 participants); and 4W (6 participants), 5W (8 participants), and 6W (16 participants) for the at-home bleaching technique. ConclusionsTreatment time to participant satisfaction ranged from 4 to 6 weeks regardless of the bleaching agent used in at-home and in-office therapy.

Indirect cytocompatibility of a low-concentration hydrogen peroxide bleaching gel to odontoblast-like cells.

To assess the initial cytotoxicity and the late phenotype marker expression of odontoblast-like cells (MDPC-23) subjected to less aggressive in-office bleaching therapies. A 17.5% hydrogen peroxide (H2O2) gel was applied for 45, 15 or 5 min to enamel/dentine discs adapted to trans-wells positioned over cultured MDPC-23 cells. No treatment was performed on the negative control. Immediately after bleaching, the cell viability, gene expression of inflammatory mediators and quantification of H2O2 diffusion were evaluated. The ALP activity, DSPP and DMP-1 gene expression and mineralized nodule deposition (MND) were assessed at 7, 14 or 21 days post-bleaching and analysed statistically with Mann-Whitney U-tests (α = 5%). H2O2 diffusion, proportional to treatment time, was observed in all bleached groups. Reductions of approximately 31%, 21% and 13% in cell viability were observed for the 45-, 15- and 5-min groups, respectively. This reduction was significant (P < 0.05) for the 45- and 15-min groups, which also presented significant (P < 0.05) over-expression of inflammatory mediators. The 45-min group was associated with significant (P < 0.05) reductions in DMP-1/DSPP expression at all periods, relative to control. The ALP activity and MND were reduced only in initial periods. The 15-min group had less intense reduction of all markers, with no difference to control at 21 days. The 17.5% H2O2 applied to tooth specimens for 5 min caused no alteration in the odontoblast-like cells. When this gel was applied for 45 or 15 min, a slight cytotoxicity, associated with alterations in phenotypic markers, was observed. However, cells were able to recover their functions up to 21 days post-bleaching.

Microhardness of demineralized enamel following home bleaching and laser-assisted in office bleaching.

Background There is little data regarding the effect of tooth whitening on microhardness of white spot lesions. This study was conducted to investigate the effect of home-bleaching and laser-assisted in-office bleaching on microhardness of demineralized enamel. Material and Methods Forty bovine incisors were selected and immersed in a demineralizing solution for 12 weeks to induce white spot lesions. Enamel blocks were prepared and randomly assigned to two groups of 20 each. The first group underwent home bleaching with 15% carbamide peroxide which was applied for 8 hours a day over a period of 15 days. In the second group, in-office bleaching was performed by 40% hydrogen peroxide and powered by irradiation from an 810 nm gallium-aluminum-arsenide (GaAlAs) diode laser (CW, 2W). This process was performed for 3 sessions every seven days, in 15 days. The specimens were stored in Fusayama Meyer artificial saliva during the experiment. Surface microhardness was assessed before and after the bleaching therapies in both groups. Results Microhardness decreased significantly following both home bleaching and laser-assisted in-office bleaching (p<0.05). There were no significant differences in hardness values among the two groups either before (p=0.131) or after (p=0.182) the bleaching procedures. Conclusions Tooth whitening through home bleaching or laser-assisted in-office bleaching can result in a significant reduction in microhardness of white spot lesions. Therefore, it is suggested to take protective measures on bleached demineralized enamel. Key words:White spot lesion, bleaching, laser, microhardness, demineralized enamel, home bleaching, in-office bleaching.

Preferences on Vital and Nonvital Tooth Bleaching: A Survey Among Dentists from a City of Southern Brazil

This study evaluated the preferences of general dentists regarding vital and nonvital tooth bleaching therapies and investigated whether the time of clinical practice and post-graduate training influence these options. A cross-sectional study was conducted using a questionnaire with closed questions applied to dentists (n=276) of a mid-sized city of the southern Brazil (Pelotas, RS). Information was collected regarding sociodemographic variables, level of specialization and time since graduation. In addition, options regarding bleaching therapies including the first choice of material, technique and clinical practice for vital and nonvital tooth bleaching therapies were included. Data were submitted to descriptive analysis and the associations were evaluated using chi-square and Fisher exact tests (α=0.05). The response rate was 68% (n=187). At-home bleaching therapy was broadly preferred (78.1%) over in-office (21.9%) bleaching. For at-home bleaching, most dentists answered to use 10% carbamide peroxide (CP) (40.2%) and >30% hydrogen peroxide (HP) (31.7%) for nonvital therapies. The majority of dentists with post-graduation training preferred at-home bleaching techniques (p=0.003). At-home bleaching therapy was also more indicated by younger dentists. No association was found between the choice for nonvital bleaching therapies and time since graduation (p=0.532) or continuous education (p=0.083). In conclusion, at-home bleaching was preferred over in-office therapies; 10% CP and >30% HP were chosen as first option agents to treat discolored vital and nonvital teeth, respectively. The time in clinical practice and the level of specialization affected dentists' choices only for vital tooth bleaching treatment.

Effect of Nd:YAG Laser Bleaching and Antioxidizing Agents on the Shear Bond Strength of Brackets

The aims of this study were to evaluate the effect of hydrogen peroxide bleaching agents, both nonactivated and activated by a neodymium:yttrium-aluminum-garnet (Nd:YAG) laser, and of antioxidant treatment on the shear bond strength (SBS) of orthodontic brackets. Nd:YAG laser activation is expected to accelerate the bleaching therapy without decrease shear bond strength. Ninety extracted maxillary central incisors were divided into two experimental groups and a control group. Group I was the control group, Group II was bleached with 35% hydrogen peroxide and had no photoactivation, and Group III was bleached with 35% hydrogen peroxide with activation by a Nd:YAG laser (4.0 W, 60 Hz frequency, 1 mm distance, 20 sec). Each group was divided into two subgroups: Subgroup A was immersed in artificial saliva for 2 weeks, and then bonded using the total etch system, whereas subgroup B was treated with an antioxidant agent (10% sodium ascorbate) and then bonded using the same system. The samples were stored in water for 24 h at 37°C, and thermocycled. The SBS in megapascals (MPa) was determined by a shear test with 1 mm/min crosshead speed, and failure types were classified with modified adhesive remnant index scores. The data were analyzed with two way analyses of variance, Tukey, and χ(2) tests at the α = 0.05 level. In both Groups II and III, the SBSs of brackets bonded after bleaching (Group II 15.16, Group III 17.50 MPa) were significantly lower than those of brackets in the bonded unbleached group (Group I 22.13 MPa); however, sodium ascorbate treatment significantly increased the SBSs of brackets in the bleached groups (Group II 21.52, Group III 22.43 MPa), but had an insignificant effect on the SBS of the control group (Group I 23.66MPa). Hydrogen peroxide bleaching agents reduce the SBSs both with and without Nd:YAG laser activation; however, treatment of the bleached enamel surface with 10% sodium ascorbate prior to bonding negates the effect.

Effects of 45S5 bioglass on surface properties of dental enamel subjected to 35% hydrogen peroxide

Tooth bleaching agents may weaken the tooth structure. Therefore, it is important to minimize any risks of tooth hard tissue damage caused by bleaching agents. The aim of this study was to evaluate the effects of applying 45S5 bioglass (BG) before, after, and during 35% hydrogen peroxide (HP) bleaching on whitening efficacy, physicochemical properties and microstructures of bovine enamel. Seventy-two bovine enamel blocks were prepared and randomly divided into six groups: distilled deionized water (DDW), BG, HP, BG before HP, BG after HP and BG during HP. Colorimetric and microhardness tests were performed before and after the treatment procedure. Representative specimens from each group were selected for morphology investigation after the final tests. A significant color change was observed in group HP, BG before HP, BG after HP and BG during HP. The microhardness loss was in the following order: group HP>BG before HP, BG after HP>BG during HP>DDW, BG. The most obvious morphological alteration of was observed on enamel surfaces in group HP, and a slight morphological alteration was also detected in group BG before HP and BG after HP. Our findings suggest that the combination use of BG and HP could not impede the tooth whitening efficacy. Using BG during HP brought better protective effect than pre/post-bleaching use of BG, as it could more effectively reduce the mineral loss as well as retain the surface integrity of enamel. BG may serve as a promising biomimetic adjunct for bleaching therapy to prevent/restore the enamel damage induced by bleaching agents.

Comparison of Enamel Microabrasion with a Combined Approach to the Esthetic Management of Fluorosed Teeth

To compare in vivo the efficacy of enamel microabrasion alone or in combination with vital tooth bleaching for the management of tooth discoloration caused by fluorosis. A total of 118 maxillary and mandibular fluorosed incisors and canines in 10 patients, scored from 1 to 7 according to the Tooth Surface Index of Fluorosis, were included in this study. All of the teeth were initially treated with enamel microabrasion (Opalustre, Ultradent Products Inc, South Jordan, UT, USA), and after 24 hours, an in-office bleaching technique (Opalescence Boost, Ultradent) was utilized (n=118). Standardized images of the teeth were taken using a digital camera prior to treatment and 24 hours after the enamel microabrasion and after the in-office bleaching therapy. The study groups were assigned according to evaluation time: a) after enamel microabrasion (Group 1) and b) after the combined approach (enamel microabrasion and in-office bleaching) (Group 2). Two calibrated and blinded examiners scored Group 1 and Group 2 images by comparing each with baseline images for "improvement in appearance," "changes in brown stains," and "changes in white opaque areas" using the visual analogue scales (VAS) that range from 1 to 7. "Patient satisfaction," "tooth sensitivity," and "gingival problems" were also recorded. The data were analyzed using two sample paired Wilcoxon signed-rank, Kruskal-Wallis, and Mann-Whitney U-tests (α=0.05). The combined therapy revealed significantly higher scores than the enamel microabrasion procedure in terms of all of the evaluated criteria (p<0.001). Enamel microabrasion provoked less tooth sensitivity but led to lower patient satisfaction scores than the combined therapy (p<0.001); however, in terms of gingival problems, no differences were found between both groups. The combined therapy, including enamel microabrasion and in-office bleaching, was more effective than enamel microabrasion alone in the esthetic management of fluorosed teeth.