Effects of microabrasion association to at-home bleaching on hydrogen peroxide penetration and color change

Impact of microabrasion and a remineralizing agent before in-office bleaching on hydrogen peroxide permeability, color alteration, and enamel morphology

OBJECTIVE

This in vitro study evaluated hydrogen peroxide (HP) penetration into the pulp chamber, bleaching efficacy, and surface enamel morphology of human teeth subjected to enamel microabrasion (MA) combined with in-office bleaching (IOB), with or without the application of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) remineralizing agent.

METHODS

Forty sound premolars were randomly divided into four groups: no treatment (NT), IOB only (IOB), MA followed by IOB (MA+IOB), and MA followed by CPP-ACP and then IOB (MA+CPP-ACP+IOB). HP concentration in the pulp chamber was measured using UV-Vis spectrophotometry, while bleaching efficacy was assessed with a digital spectrophotometer. Surface morphology was analyzed using scanning electron microscopy (SEM), and data were statistically analyzed.

RESULTS

The NT group exhibited lower HP penetration compared to experimental groups, while MA+IOB showed higher HP levels than IOB and MA+CPP-ACP+IOB. All experimental groups demonstrated significant color changes, except NT. The MA+IOB group displayed more grooves on enamel surfaces than the MA+CPP-ACP+IOB group, which had remineralizing agent deposits.

CONCLUSION

Combining MA and IOB increases HP penetration into the pulp chamber, but using CPP-ACP after MA can mitigate this effect without compromising bleaching efficacy.

CLINICAL SIGNIFICANCE

Employing a CPP-ACP remineralizing agent post-microabrasion can help reduce HP levels in the pulp chamber while maintaining effective whitening.

Hydrogen Peroxide in the Pulp Chamber and Color Change in Maxillary Anterior Teeth After In-Office Bleaching

While the literature has noted variations in hydrogen peroxide (HP) permeability, and consequently, tooth sensitivity among different types of anterior teeth, there is a scarcity of research on this specific topic. This study evaluated HP permeability and color change (CC) in different groups of human maxillary anterior teeth (canines, lateral incisors, and central incisors) after in-office bleaching with HP at 35%. Thirty teeth maxillary anterior (n=10) were bleached with HP at 35% gel in one session of three 15-minutes applications. Buccal thickness (mm) was measured from images obtained using cone beam computed tomography. The concentration of HP (µg/mL) that reached the pulp chamber was assessed using UV-Vis spectrophotometry. CC (WID, ∆Eab, and ∆E00) was evaluated before and after bleaching with a digital spectrophotometer. One-way ANOVA and Tukey's test were applied to statistically evaluate the data for buccal thickness, HP permeability, and CC (α=0.05). Comparison between thickness and HP permeability was performed using Pearson's correlation. Thicker teeth, such as canines, had lower HP amounts inside the pulp chamber compared to central and lateral incisors. Despite the significant effect of buccal thickness on HP permeability (p<0.05), no correlation was found between the two factors. CC was similar across tooth types (p>0.05). The difference in buccal thickness among the superior anterior teeth does not interfere with CC. However, a thinner buccal wall thickness is associated with greater HP permeability detected in the pulp after in-office bleaching.

Evaluating color change and hydrogen peroxide penetration in human and bovine teeth through in-office bleaching procedures

OBJECTIVE

Assess color alteration and hydrogen peroxide (HP) penetration in human and bovine teeth using various in-office bleaching protocols with different application times.

MATERIALS AND METHODS

Thirty healthy human premolars and 30 healthy bovine incisors were divided into five groups and subjected to different bleaching protocols: 2 × 15 min, 1 × 30 min, 2 × 20 min, or 1 × 40 min, with a control group for each tooth type. All teeth were treated with 35% HP gel. Color alteration was measured using digital spectrophotometry before and 1 week after bleaching. HP concentration within the pulp was determined via UV-Vis spectrophotometry. Statistical analysis included one-way ANOVA, Tukey's, and Dunnett's tests (α = 0.05).

RESULTS

All groups exhibited significant color alteration, with no statistically differences among them (p > 0.05). However, significant differences were observed when compared with their respective control groups (p < 0.05). HP penetration into the pulp was evident in all bleached teeth compared to the control groups (p < 0.05), with the 2 × 20 group showing the highest HP levels within the pulp cavity, irrespective of tooth type (p < 0.05).

CONCLUSION

A simplified 1 × 30-min protocol can be recommended as it effectively maintains color alteration and HP penetration, irrespective of whether human or bovine teeth.

CLINICAL SIGNIFICANCE

This study suggests that an in-office dental bleaching protocol using a 1 × 30-min session is recommended, as it ensures both effective color change and no increase in the amount of HP penetration.

A global overview of enamel microabrasion for white spot lesions: a bibliometric review

This study aimed to identify and analyze articles on enamel microabrasion for the treatment of white spot lesions. A search was conducted on the Web of Science. The following parameters were recorded and analyzed: number of citations, year, journal, impact factor, study design, theme, country and continent, institution, authors, and keywords. Data was analyzed using VOSviewer software. The initial search resulted in 1,126 documents, of which 94 articles were included. The highest number of citations an article received was 65. The oldest article was published in 1975, and the most recent in 2023. The most frequent study design was case report (n = 42). Regarding the themes, it was observed that the main objective of the studies was to evaluate the clinical performance of enamel microabrasion (n = 75), primarily using Opalustre (Ultradent Products Inc., South Jordan, UT, USA) (n = 37) for treating white stains caused by dental fluorosis (n = 41). Most articles originated from Latin America (n = 31), mainly from Brazil (n = 26). The most frequent author was Sundfeld RH (n = 10). This study reveals research trends in the field of enamel microabrasion. The publications were mainly case reports/series using Opalustre for the removal of fluorosis stains.

At-home bleaching with carbamide peroxide with concentrations below 10%: bleaching efficacy and permeability in the pulp chamber

OBJECTIVES

To evaluate the bleaching efficacy and permeability of hydrogen peroxide (HP) in the pulp chamber of human teeth bleached with lower concentrations of carbamide peroxide gel (4%, 5% and 7% CP).

MATERIALS AND METHODS

Bleaching gels with lower concentrations were formulated and a commercial standard gel, 10% CP, was used as a reference. Fifty-six human premolars were randomly divided into four groups. Applications of the bleaching gel were made for 3 h for 21 days. The bleaching efficacy was evaluated by digital spectrophotometry on 1, 7, 14 and 21 days, with analysis in the ∆Eab, ∆E00 and WID color spaces. The concentration of HP in the pulp chamber was measured in the same periods by UV-Vis spectrophotometry (µg/mL). Two-way repeated analysis of variance (ANOVA) examined bleaching efficacy and HP permeability, followed by Tukey's post-hoc test (α = 0.05).

RESULTS

All groups showed significant color changes, with no statistical differences after the second and third week of bleaching (p > 0.05). The 'time' factor was statistically different (p < 0.05), increasing the bleaching efficacy throughout the treatment. The 4% CP group had lower HP levels in the pulp chamber (p < 0.05).

CONCLUSIONS

The results seem promising, revealing that low concentration gels are as effective as 10% CP with the benefit of reducing the amount of HP in the pulp chamber.

CLINICAL RELEVANCE

Low concentration 4% PC and 5% PC maintains bleaching efficacy, reduces the penetration of HP peroxide into the pulp chamber, and may reduce tooth sensitivity.

Evaluation of at-home bleaching protocol with application on different surfaces: bleaching efficacy and hydrogen peroxide permeability

Objectives

This study aimed to evaluate the bleaching efficacy and hydrogen peroxide permeability in the pulp chamber by the at-home bleaching gel in protocols applied on different dental surfaces.

Materials and Methods

Forty premolars were randomly into 4 groups: control group no bleaching, only application on the buccal surface (OB), only application on the lingual surface (OL) and application in buccal and lingual surfaces, simultaneously (BL). At-home bleaching gel (White Class 7.5%) was used for the procedure. The bleaching efficacy was evaluated with a digital spectrophotometer (color change in CIELAB [ΔE ab] and CIEDE 2000 [ΔE 00] systems and Whitening Index for Dentistry [ΔWID]). The hydrogen peroxide permeability in the pulp chamber (µg/mL) was assessed using UV-Vis spectrophotometry and data were analyzed for a 1-way analysis of variance and Tukey's test (α = 0.05).

Results

All groups submitted to bleaching procedure showed bleaching efficacy when measured with ΔE ab and ΔE 00 (p > 0.05). Therefore, when analyzed by ΔWID, a higher bleaching efficacy were observed for the application on the groups OB and BL (p = 0.00003). Similar hydrogen peroxide permeability was found in the pulp chambers of the teeth undergoing different protocols (p > 0.05).

Conclusions

The application of bleaching gel exclusively on the OB is sufficient to achieve bleaching efficacy, when compared to BL. Although the OL protocol demonstrated lower bleaching efficacy based on the ΔWID values, it may still be of interest and relevant in certain clinical scenarios based on individual needs, requiring clinical trials to better understand its specificities.

Bleaching Gels Used After 1 Week of Mixing: Efficacy, Hydrogen Peroxide Penetration, and Physical-chemical Properties

OBJECTIVES

This in vitro study aimed to evaluate the bleaching efficacy (BE), hydrogen peroxide penetration into the pulp chamber (HPP), and physical-chemical properties (concentration, pH, and viscosity) of in-office bleaching gels immediately and after 1 week of mixing.

METHODS AND MATERIALS

We randomly divided 49 premolars into seven groups: control (no bleaching) and the following in-office bleaching (Opalescence Boost 40%, Total Blanc One Step 35%, and Whiteness HP Blue 35%) applied at two storage times: immediately and after 1 week. We evaluated the BE using a digital spectrophotometer and the HPP through UV-Vis spectroscopy. We measured the initial concentration, pH, and viscosity using titration, a Digital pH meter and Rheometer, respectively. For statistical analysis, we used a twoway analysis of variance and Tukey and Dunnet tests (α=0.05).

RESULTS

We observed higher BE and HPP for Opalescence Boost and Total Blanc One Step after 1 week of mixing than for Whiteness HP Blue (p<0.001). We observed a significantly lower initial concentration for Whiteness HP Blue 1 week after mixing compared to immediately (p=0.00001). All bleaching gels showed a decrease in pH after 1 week of mixing (p=0.00003). However, Total Blanc One Step had a lower pH at both evaluation times (p<0.001). Only Opalescence Boost maintained viscosity 1 week after mixing.

CONCLUSIONS

Opalescence Boost was the only bleaching gel able to keep bleaching efficacy, with the same characteristics of permeability and physical- chemical properties after 1 week of mixing.

Bleaching effectiveness and cytotoxicity of new experimental formulation of niobium-based bleaching gel

OBJECTIVES

The development of new bleaching agents with minimum concentration of hydrogen peroxide (HP), without adverse effects, and with bleaching effectiveness, has great clinical relevance. The aim of this study was to evaluate the bleaching efficacy and cytotoxicity of a new niobium-based bleaching gel, compared to already available HP-based gels.

MATERIALS AND METHODS

For the bleaching efficacy analysis, 40 bovine incisors were randomly divided into 4 groups according to the established bleaching protocol: control, untreated; 35HP, 35% HP bleaching gel; 6HP, 6% HP bleaching gel; NbHP, niobium gel associated with 3% HP gel. The color variation was measured in a spectrophotometer and the values of ΔL, Δa, Δb, and ΔE obtained. For the cell viability assay by MTT, MC3T3 cells were exposed to bleaching gel extracts (1:500, 1:250, 1:125 dilutions; immediately and 24 h). Statistical tests were performed (P < 0.05).

RESULTS

The color alteration for all bleaching gels was significant compared to control (P < 0.05), but the NbHP gel showed a significant ΔE than other gels, with expressive color alteration at 14 days (P < 0.05). The 35HP showed high cytotoxicity regarding control and the most groups in all periods and extracts analyzed (P < 0.05), while the NbHP showed greater cell viability than control in the immediate period, dilution of the 1:500 and superior to 6HP in the most extracts at 24 h.

CONCLUSION

The new experimental niobium-based gel has bleaching efficacy similar to that of gels with a high concentration of HP, and it has high cytocompatibility.

CLINICAL RELEVANCE

The use of this new generation of niobium-based whitening gel associated with a low concentration of hydrogen peroxide represents the possibility of a tooth whitening with lower dentin sensitivity.

Pilot study on the applicability of boron-doped diamond electrodes for tooth whitening

Objectives

While various approaches are available for tooth whitening, the basic concept employs the use of peroxides in the form of gels, which are applied to tooth surfaces. Previous studies have shown that reactive oxygen species acting as potent disinfectants can be produced using boron‐doped diamond (BDD) electrodes for the electrolysis of water. With these electrodes being applicable, for example, for endodontic treatment, it was the goal of this pilot study to use such electrodes for tooth whitening.

Material and Methods

Two groups (n = 10) of intact clinical crowns were obtained by horizontally cutting off roots of extracted human teeth. The crowns were either bleached by applying a commercially available agent based on 40% hydrogen peroxide or were immersed in saline undergoing electrolysis with BDD electrodes. Whitening of specimens was judged on standardized photographs by examiners with three different levels of experience. Statistical analysis was based on Gwet's AC2 coefficient with quadratic weights, Shapiro–Wilk tests, and two‐way analysis of variance of aligned rank transformed data (level of significance set at α = .05).

Results

Levels of reliability ranging from fair to substantial were recorded for single persons while the level of reliability ranged between fair and moderate for groups of raters. The level of experience had no significant effect on the ratings (p = .2500). The bleaching method had a significant effect on ratings (p = .0005) with BDD electrodes showing less effect.

Conclusions

Bleaching by applying BDD electrodes was possible, but was not as effective as the use of commercially available in‐office whitening gel. A potential explanation may be seen in different concentrations of reactive oxygen species.