Enamel Color Change Research Articles

Effect of an orthodontic resin modified with silver-nanoparticles on enamel color change

BackgroundTo evaluate the effect of an orthodontic resin modified with various concentrations of silver-nanoparticles (AgNPs) on enamel color. Material and MethodsTwenty lower premolars were collected and divided into four groups (n = 5) according to the concentration of AgNPs (0.05%, 0.1%, 0.5%, and 1% wt/wt). Additionally, a group bonded with a conventional resin was used as control (n=5). Previous to the bracket bonding, enamel color was measuring with a spectrophotometer. Specimens were stored for 6 months in deionized water. Brackets were debonded and color changes of enamel were calculated with the CIEDE 2000 formula (∆E00). One-way ANOVA and Tukey test were used to assess the color change (α = .05). ResultsThe control group showed the lowest ∆E00 values, and no significant difference was observed when compared to the group with 0.05% of AgNPs (P > .05). The highest color change was observed in the group with 1% of AgNPs (∆E00 = 8.04±1.48), however no significant difference was observed between groups with 0.1% and 0.5% AgNPs. ConclusionsThe incorporation of AgNPs into orthodontic resin result in tooth color alteration. Lower concentrations of AgNPs should be considered to minimize negative changes in enamel color. Key words:White spot lesions, antibacterial, orthodontics, adhesive, Silver-nanoparticles.

Efficacy of products for bleaching and whitening under orthodontic brackets.

Many patients wearing orthodontic appliances request alterations in the shade of their teeth during orthodontic treatment. This study aimed to evaluate the efficacy of different products for bleaching and whitening under orthodontic brackets. Seventy bovine incisors were randomly divided into five groups (n = 14): C) non-whitening toothpaste (control); WTsi) hydrated silica whitening toothpaste; WThp) 2% hydrogen peroxide whitening toothpaste; OB) in-office bleaching; and HB) at-home bleaching. Two buccal surface areas were evaluated using the Easyshade spectrophotometer: under the metal bracket (experimental) and around the bracket (control). The paired t-test, ANOVA, and Tukey tests were applied for statistical analysis. Intragroup comparisons showed that in groups C, WThp and HB, there were statistically significant differences in the enamel color changes (ΔEab) between under and around the bracket areas (C - under bracket = 7.97 ± 2.35, around bracket = 2.86 ± 0.81, p< 0.01; WThp - under bracket = 4.69 ± 2.98, around bracket = 2.05 ± 1.41, p< 0.01; HB - under bracket = 7.41 ± 2.89, around bracket: 9.86 ± 3.32, p= 0.02). Groups WTsi, OB and HB presented similar perception of tooth whiteness (ΔWID) between the tested areas. Intergroup comparisons demonstrated that under the bracket area, the color change (ΔEab) was similar for all groups, except WThp (C = 7.97 ± 2.35; WTsi = 8.54 ± 3.63; WThp = 4.69 ± 2.98; OB = 9.31 ± 4.32; HB = 7.41 ± 2.89; p< 0.01). The dental color changes were effective for the products tested in groups WTsi, OB and HB in the presence of metallic orthodontic brackets.

Effect of Arginine and nano-hydroxyapatite application on the hypersensitivity and color change of bleached enamel: A randomized controlled clinical trial.

BackgroundTo evaluate the effect of 2.5% Arginine and nano-hydroxyapatite (nHA) application on the post-bleaching hypersensitivity (HS) and color change in a randomized controlled trial. Material and MethodsSixty-four participants were randomly allocated to four groups (n=16) according to the investigated desensitizing agents (UltraEZ gel, experimental 2.5% Arginine, 2.5% nHA pastes and control (no treatment) groups). An in-office chemical bleaching agent (40% hydrogen peroxide) was used for vital bleaching of the anterior teeth. The desensitizing agents were applied to the assigned groups and left for 30 min then rinsed off the teeth. HS was evaluated using Visual Analogue Scale (VAS) from 0-10, immediate (after bleaching), first seven days, then every week for 3-w. Color change was evaluated using VITAPAN classical A1-D4 at baseline (before bleaching), immediate (after bleaching), and after 1,2, 3-w. ResultsHS results showed statistically insignificant difference between the tested groups at day-1 and -2. All groups showed no HS (0) at/and after day-3. There was a statistically significant color change between immediate, 1-w and 2-w and baseline results for investigated materials. No statistically significant difference was recorded between the baseline and 3-w for the investigated materials. Both Arginine and nHA groups showed a higher color change compared to UltraEZ group. ConclusionsArginine and nHA present a potential treatment modality for the post-bleaching HS without jeopardizing the bleaching efficiency. Key words:Arginine, nano-hydroxyapatite, bleached enamel, hypersensitivity, color change, clinical trial.

Can ozone or violet light improve the color change or physicochemical properties of hydrogen peroxide-bleached tooth?

This study investigated the bleaching effectiveness and the physicochemical effects on enamel of violet light and ozone, associate or not to hydrogen peroxide, compared to 35%-hydrogen peroxide. Enamel-dentin blocks from human molars were randomly allocated to receive one of the following bleaching protocols (n=15): (HP) 35%-hydrogen peroxide, (VL) violet light, (OZ) ozone, the association between hydrogen peroxide with ozone (OZ+HP) or violet light (VL+HP). All protocols were performed in two sessions with a 48h interval. Color (spectrophotometer) and mineral composition (Raman spectroscopy) were measured before and after the bleaching. Color changes were calculated by ΔEab, ΔE00, and whitening index (WI). The surface roughness was measured with an atomic force microscope. Data were analyzed by One-way or Two-way repeated measure ANOVA followed by the Tukey's test (α = 0.05). The lowest color change values (either measured by WI, ΔEab, or ΔE00) were observed for VL and OZ used with no HP. Violet light associate with HP was unable to improve the color changes observed for the peroxide alone, in combination with OZ and HP, the highest color changes were verified. Regardless of bleaching protocol, the bleached enamel presented higher contents of PO4 and CO3 -2 than those observed at baseline. All bleaching protocols resulted in similar enamel surface roughness. Both the VL and the OZ caused reduced effects on the enamel color change when used alone. The ozone therapy improved the bleaching effect in the group that received the association of HP.

Effect of Spondias mombin L. extract on the wettability, roughness, color and morphology of bovine enamel

Although Spondias mombin L. extract has an excellent antimicrobial effect against oral microorganisms, it should be clarified how it affects enamel surface properties. Aim: To evaluate the color change, wettability/contact angle, surface roughness and morphology of bovine enamel submitted to the Spondias mombin L. extract. Methods: Thirty bovine teeth were distributed into the following groups: 0.12% chlorhexidine digluconate, 1:32 Spondias mombin L. extract and distilled water. Color change (CC) was evaluated after immerging specimens into the solutions for 14 days. Surface roughness (Ra) was measured using a roughness meter; wettability/contact angles (CA) were determined by the sessile drop method, and scanning electron microscopy images were obtained to characterize the morphology (SMA). The pH of the solutions was evaluated using a pHmeter. The Ra, CA, and CC data were parametric (Kolmogorov-Smirnov; p&gt;0.05). Two-way ANOVA (for Ra and CA) and one-way ANOVA (for CC) with Tukey’s posthoc tests at a significance level of 5% were used. SMA was analyzed descriptively. Results: The Spondias mombin L. extract revealed an acidic pH, and when in contact with the bovine teeth, it increased the wettability, but it did not cause statistically significant differences in the Ra. Spondias mombin L. extract caused the highest color change. The SEM images showed differences in the specimens’ surface submitted to the extract compared to the other groups. Conclusion: Spondias mombin L. extract provided negative effects on bovine enamel’s surface, including a high color change and a more wettable substrate.

Can the efficacy of in-office tooth bleaching change in the presence of orthodontic brackets? An in vitro study

Objective: To assess the color change of bovine enamel after tooth bleaching while using orthodontic brackets. Methodology: This in vitro study selected 48 bovine incisors without visible fractures or cracks (cut in blocks of 8x12x3 mm). They were distributed in four groups: no staining and with brackets (NSWB), no staining and no brackets (NSNB), with staining and brackets (WSWB), and with staining and no brackets (WSNB) (n=12). The color was initially assessed with a spectrophotometer for NS (no staining). The teeth in WS (with staining) groups were immersed in an instant coffee solution for 15 days and the initial color was also assessed. After prophylaxis and adhesive treatment, the brackets were bonded to the teeth. The teeth were bleached with 35% hydrogen peroxide and the color was analyzed 30 days after bleaching. A two-way Analysis of Variance was applied as well as a subsequent multiple comparison analysis (p&gt;0.05). Results: According to the data obtained, the factor of the presence of brackets (p=0.569) had no significant influence. This differed from the factor of tooth staining (p&lt;0.001). Moreover, there was no interaction between them (p=0.863). Conclusion: The presence of brackets in non-stained teeth did not affect bleaching effectiveness. The ΔE of stained teeth was always lower than non-stained teeth, especially for the NB (no brackets) group.

Effect of different types of acid-etching agents and adhesives on enamel discoloration during orthodontic treatment.

Background. Acid etching and bonding is a routine process in orthodontic treatment. The present study aimed to evaluate enamel discoloration after using different types of acid etching and adhesive agents. Methods. A total of 105 extracted human premolars were divided into six groups regarding the type of acid etching agent: solution and gel of 37% phosphoric acid, and type of self-cured adhesive agent: Unite (3M, fluoride-free), Resilience (Ortho Technology), and Rely-a-Bond (Reliance, fluoride-releasing adhesive), with each group containing 15 specimens. All the selected teeth were subjected to a staining process, and color parameters were determined using a spectrophotometer. Results. The type of phosphoric acid (solution or gel) had no significant effect on the color change of enamel (P >0.05). Resilience significantly changed the enamel color compared to the Unite and Rely-a-Bond (P <0.001). There was no significant difference in color change between the Unite and Rely-a-Bond adhesives (P =0.67). The difference in color change between all the three time intervals (T0-T1, T1-T2, and T0-T2) was significant (P <0.001). Conclusion. In this study, the type of phosphoric acid (solution or gel) did not result in any significant difference in enamel color. Also, considering the lack of the effect of the orthodontic adhesive type in terms of fluoride release or no fluoride release, it can be concluded that this is most affected by the commercial brand of adhesives.

Influence of brushing with natural dentifrices on color change: In vitro study.

BackgroundTo evaluate in vitro the influence of daily brushing with the use of natural toothpastes on the color change of enamel in bovine teeth. Material and MethodsFour dentifrices were used, one conventional Colgate Total 12 - Clean Mint (G1), and three natural, Contented Toothpaste with Organic and Natural Ingredients (G2); Dental Toothpaste (G3) and Aliv-Gaia Toothpaste (G4). Eighty bovine teeth were distributed in four experimental groups with 20 teeth each (n = 20). The buccal enamel surface of the teeth was subjected to brushing, with the related dentifrices of each group, for 2.13 seconds three times a day, with an electric brush Oral B 5000 Professional Care. Before and after brushing, color measurement tests with a spectrophotometer were performed. The color variation was calculated using the formula ΔE = [(ΔL *) 2+ (Δa *) 2+ (Δb *)2] 1/2. The results obtained were tabulated and submitted to the Kruskal Wallis non-parametric test. ResultsThe color change (ΔE) observed was 7.551 and p-value equal to 0.056, determining that there was no statistically significant difference between the groups. However, qualitative tests showed the clearing of all experimental groups, G3 with the greatest change, followed by G2, G1 and G4. ConclusionsThe evaluated dentifrices were not able to promote color change. Key words:Dental enamel, plant extracts, saliva, artificial, dentifrices.

Role of enamel and dentin on color changes after internal bleaching associated or not with external bleaching.

Objective To evaluate the effect of the association between external and internal tooth bleaching on color changes in dentin and enamel, individually or recombined, previously stained with triple antibiotic paste (TAP).Methodology Forty enamel-dentin specimens from bovine incisors were separated into ten blocks according to similarity in their whiteness index (WID). Three specimens within each block were stained by dentin exposure to TAP, and the remaining specimen was used as control to estimate color changes. Specimens were sectioned to separate tissues, and dentin and enamel colors were measured individually and after being recombined. Alterations in color (CIEDE2000 - ΔE00) and translucency parameter (TP) resulting from staining were estimated by color difference between stained and control specimens. The contribution of each tissue to the color change (CTCC) was also calculated. Non-sectioned stained specimens were bleached by applying sodium perborate on dentin, associated or not with 35% hydrogen peroxide on enamel. Color changes caused by bleaching procedures were estimated and data were analyzed using the paired t-test or Two-way repeated measures ANOVA.Results TAP caused more pronounced changes in dentin, but enamel color was also affected. Both protocols presented a similar ΔE00, and dentin showed the greater color change. After exposure to TAP, we observed a reduction in WID; WID values were the same for bleached and control specimens regardless of protocol. We found no significant effect of substrate and bleaching technique on TP. Enamel played a more critical role in color changes caused by either staining or bleaching procedures.Conclusion Enamel color played a greater role on tooth color changes than dentin. External and internal bleaching association did not improve bleaching effect on specimens stained with TAP.

Dental bleaching with violet LED: Effects on dentin color change, resin-dentin bond strength, hybrid layer nanohardness and dentinal collagen biostability.

The purpose of this study was to investigate the effect of a novel dental bleaching technique with Violet LED on enamel color change, bond strength and hybrid layer nanomechanical properties in resin-dentin restoration, and dentin biostability. A total of 125 bovine incisors were distributed into a control group, violet LED group (LED), and 35 % peroxide hydrogen bleaching gel (BLG) groups (n = 15). Three 45-minute sessions were performed for both bleaching procedures every week. Enamel color change (ΔE, ΔL, and Δb) was determined after every bleaching session. After color analysis, dentin was exposed for the resin-dentin bond strength analysis using microtensile test and evaluation of the nanomechanical properties at the hybrid layer (nanohardness). While half of the specimens were tested immediately, the remaining were evaluated after 10,000 thermal cycles (TC). Thirty additional teeth were used to investigate dentin ultimate tensile strength (UTS) after the bleaching treatments. UTS was evaluated before and after an enzymatic challenge. Two-way repeated measures ANOVA and Tukey's post-test were used for the statistical analysis (α = 0.05). Enamel bleaching effect was observed in the LED and BLG groups with significant alterations in the ΔE, ΔL, and Δb in the BLG group. No difference was observed in the resin-dentin bond strength among the groups (p > 0.05), however, TC negatively affected the bond strength values for all the groups. Nanomechanical properties ​​remained unchanged when comparing immediate and after TC results (p > 0.05). Bleaching with BLG reduced significantly the dentin UTS, while all groups showed major decrease in UTS after the enzymatic challenge. Although violet LED was able to promote a bleaching effect, less color changes was observed when compared to BLG. None of the bleaching techniques effected the resin-bond strength or the nanomechanics of the hybrid layer. Violet LED did negatively effect dentin biostability as observed for BLG and it may promote less changes to the organic content of dentin.

Effect of Actilux - Activated Whitening Toothpaste and Marine Salts on Color Change and Microhardness of Bovine Enamel

Purpose: To evaluate the effect of Actilux-activated whitening toothpaste and Marine salts powder on color change and microhardness of bovine enamel. Methods: Thirty intact bovine incisors were used in this study to produce enamel specimens. The specimens were randomly distributed into three groups (n= 10) according to the tested whitening agents as follows: Group I: BW; BlanX LED White Shock (Actilux-activated), Group II: MS; Marine salts whitening powder and Group III: CR; Crest regular fluoridated toothpaste. The specimens were stained using black tea solution for 5 days. Each specimen was brushed twice daily for 8 then 15 days. The color was assessed according to CIE (Lab) color system using a VITA Easyshade spectrophotometer. The microhardness was assessed using Digital Display Vickers Microhardness Tester at baseline, after staining, after 8 days, and 15 days brushing. Data were tabulated and statistically analyzed. Results: After 8 days brushing, BW showed the highest mean (ΔE) while MS and CR both showed lower mean (ΔE). BW and MS showed the highest mean (ΔE) after 15 days brushing with no statistically significant difference between them. After 15 days; BW showed the highest mean microhardness followed by MS while CR showed the lowest mean microhardness. Conclusion: Both Actilux-activated toothpaste combined with LED device and Marine salts powder were effective in tooth whitening as well as increasing enamel microhardness. The whitening efficacy and microhardness is time dependent.

Color heterogeneity and individual color changes in dentin and enamel bleached in the presence of a metallic orthodontic bracket.

This in-vitro study evaluated the color changes in enamel and dentin bleached in the presence of an orthodontic bracket, as well as the heterogeneity of the color and contribution of each tissue to the color change (CTCC). Enamel-dentin specimens from extracted bovine teeth were bleached before or after bracket removal or maintained without any treatment (control). The colors of the dentin and enamel were measured individually and after recombining these substrates. The changes in the color (ΔE00 ) and whitening index (ΔWID) were estimated by the color difference between the bleached specimens and those of the control. The CTCC was also calculated by recombining the tissues from different treatments. Images of specimens obtained from a stereomicroscope were used to analyze the color homogeneity within each tissue. The highest values of ΔE00 and ΔWID were observed in the specimens bleached in the absence of a bracket. Bleaching in the presence of a bracket resulted in enamel with a center that was whiter than the periphery. Dentin and enamel presented similar CTCC values. Tooth bleaching performed in the presence of a metallic bracket resulted in a reduced bleaching effect and increased color heterogeneity within both tissues. Tooth bleaching before the orthodontic bracket removal reduces the bleaching effect in both dentin and enamel. Moreover, a heterogeneous color of enamel surface can be observed after tooth bleaching in the presence of a nickel-free metallic orthodontic bracket.

Effects of Orthodontic Adhesives on Dental Enamel Color Alteration Using Chemically Cured and Light-Cured Composites.

Objectives:The purpose of this investigation was to evaluate the color alteration of dental enamel following the use of light-cured and chemically cured composites for bonding of metal brackets.Materials and Methods:Sixty extracted human premolars divided into five groups (n=12) were included in this study. Metal brackets were bonded using chemically cured (System 1+ and Unite) and light-cured (Transbond XT and Grengloo) composites. The control group remained untreated. After 72 hours of immersion in a staining solution and 24 hours of photoaging, the brackets were debonded, and adhesive remnants were cleaned using a 12-blade tungsten carbide bur and polished with Sof-Lex discs. The color was assessed at the baseline and after cleaning procedures in accordance with the CIE L*a*b (lightness, red/green, blue/yellow) color system. Statistical analyses were performed using paired sample t-test and one-way analysis of variance (ANOVA).Results:The L*, a*, and b* parameters showed a significant increase in all adhesive groups (P<0.001). The experimental groups showed significant color changes (P<0.05), and the mean ΔE ranged from 2.46 to 3.15 units. No significant difference was found between the ΔE of the adhesive groups (P>0.05).Conclusion:The enamel color change is influenced by bonding and debonding procedures. Chemically cured and light-cured composites have similar effects on dental enamel color alterations.

Effects of activated charcoal powder combined with toothpastes on enamel color change and surface properties.

To evaluate the effects of activated charcoal powder (COAL) combined with regular (RT) or whitening (WT) toothpastes on enamel color and surface in comparison to carbamide peroxide (CP). Dental blocks (n = 10/group) were randomly divided into COAL, COAL/RT, COAL/WT, CP, CP/RT, CP/WT, RT, WT, and CONT (without treatment). Simulated toothbrushing and whitening treatments were followed by colorimetric (ΔE00 , L*, a*, b*), surface roughness (Ra), and enamel topography assays. ΔE00 was submitted to two-way ANOVA and Tukey test. Color coordinates and Ra were tested with three-way repeated measures ANOVA (α = 5%). COAL exhibited greater ΔE00 than CONT (P = .048), but it did not enhance ΔE00 promoted by RT or WT (P > .05). COAL alone increased Ra (P < .001) and altered enamel topography. COAL did not increase Ra caused by RT and WT (P > .05). CP exhibited the highest ΔE00 (P < .05), but it raised Ra and changed enamel topography to a less extent than COAL. Even though charcoal powder did not increase enamel Ra when combined with toothpastes, the topography was negatively impacted by COAL. Also, COAL was unable to enhance the color change of RT and WT, or reach the effectiveness of CP. The use of activated charcoal-based product, claimed as a natural whitener, before brushing with toothpastes is not only ineffective to change the color of teeth, but also it might result in alterations on the enamel surface. Whitening with CP, instead, was effective during the same period of treatment, which still represents a more appropriate technique to whiten teeth.

Color stability, Roughness, and Microhardness of Enamel and Composites Submitted to Staining/Bleaching Cycles

ObjectiveTo compare the effect of two bleaching systems (bleaching gel and whitening strips) on the color change, roughness, and microhardness of enamel and two resin composites. Material and methodsTwo cavities were prepared on bovine enamel specimens (n = 16) and restored with two composites: a nano-hybrid [Herculite Ultra (HU)] and a micro-hybrid composite [TPH Spectra (TS)]. Baseline color (CIE L*a*b*), roughness (μm), and microhardness (kgf/mm2) were measured using a spectrophotometer, optical profilometer, and Vickers microhardness (VHN) tester, respectively. The specimens were stained with coffee for 14 days, and randomized into two bleaching groups: gel and strips (n = 8), then submitted to a 10-day bleaching/staining test. Color, roughness, and microhardness were re-measured. The outcomes were analyzed using two-way ANOVA and Fisher’s-PLSD test (α = 0.05). ResultsGel significantly improved the color (ΔE 4.9–8.3) and increased the roughness (Ra 0.04–0.08 μm) of all substrates (p < 0.0001) compared to strips. Enamel color was significantly improved (ΔE 5.4–8.3) compared to that of HU (ΔE 2.6–4.9) and TS (ΔE 2.0–4.9) with either gels or strips. TS roughness (0.03–0.08 μm) was significantly higher than that of enamel (0.01–0.05 μm) and HU (0.02–0.04 μm). Enamel had significantly reduced microhardness compared to HU (p = 0.0144). ConclusionGels produced the greatest color improvement and roughness compared to strips. Enamel had significant color improvement but had the greatest decrease in microhardness. Clinical significanceThere was unacceptable color change between enamel and the composites after the combined cyclic effects of staining and bleaching.

Mechanical properties of toothpastes with diamond abrasives.

The aim of this study was to evaluate and compare surface roughness, gloss, and color change of dental enamel after being brushed with toothpastes containing diamond powder and traditional abrasives. Seventy enamel slabs were derived from 70 bovine incisors. The slabs were brushed with six different toothpastes and artificial saliva as a negative control. The specimens were then stained with black tea mixed with citric acid (3 days, pH = 4) and again brushed with the same toothpastes. Ra (contact profilometer), gloss (glossmeter), and color (CIE L* a* b* system) values were measured after each step. Emoform-F Diamond (contains diamond powder and traditional abrasives) offered significantly the best improvement of Ra and gloss values after the first brushing sequence and the best recovery of the brightness of enamel after staining and second brushing sequence (P < .05). AMC 2.5 (contains only diamond powder as abrasive) was not able to offer such improvement. Diamond powder as an additional abrasive in toothpastes could be able to offer a further improvement of Ra , gloss, and color values of enamel.

The ability of dual whitening anti-caries mouthrinses to remove extrinsic staining and enhance caries lesion remineralization – An in vitro study

ObjectivesThis laboratory study investigated the ability of dual whitening anti-caries mouthrinses to remove extrinsic staining from artificially stained caries lesions and to enhance their remineralization and fluoridation. Materials and MethodsEarly caries lesions were created in bovine enamel specimens. The lesions were artificially stained and pH cycled for 10 days with the daily cycling regimen consisting of twice daily 60s-treatments with one of 11 mouthrinses, a 4-h demineralization period and artificial saliva treatments in between. Mouthrinses were eight commercially available products, all containing 100ppm fluoride but utilizing hydrogen peroxide, pyro-, tri- or hexametaphosphate salts and/or sodium bicarbonate. The three control mouthrinses were 100ppm fluoride, 30 % hydrogen peroxide and deionized water. Enamel color changes (ΔE) were determined spectrophotometrically. Vickers surface microhardness (VHN) was used to determine lesion remineralization. Enamel fluoride content (EFC) was determined using the microbiopsy technique. Data were analyzed using ANOVA. ResultsΔE was significantly different among groups (p=0.0045). Thirty percent hydrogen peroxide was superior to all other mouthrinses, while there were no differences between commercial mouthrinses and deionized water. There were small, directional but non-significant differences between commercial mouthrinses with those containing hydrogen peroxide providing better whitening. There were no significant differences between mouthrinses in their ability to remineralize caries lesions (p=0.2898). EFC differed among groups (p<0.0001), with the two mouthrinses containing pyrophosphate salts having lower EFC than all but the deionized water group. ConclusionsArtificially stained caries lesions show reduced susceptibility to fluoride remineralization and whitening effects of commercial whitening and anti-caries mouthrinses. Clinical RelevanceArtificially stained caries lesions appear to require stronger than over-the-counter interventions to successfully whiten and remineralizing them.

Titanium dioxide nanotubes incorporated into bleaching agents: physicochemical characterization and enamel color change.

Titanium dioxide nanotubes are nanostructures that can accelerate the oxidation reaction of bleaching procedures and promote a more effective whitening effect. Objective This study evaluated physicochemical properties of bleaching agents incorporated with titanium dioxide (TiO2) nanotubes, and the effects on tooth color change at different periods.Methodology 40 premolars were treated according to the following groups (n=10): CP - 10% carbamide peroxide (1 hour daily/21 days); CPN - CP incorporated into TiO2; HP - 40% hydrogen peroxide (three 40-minute sessions/7 days apart); HPN - HP incorporated into TiO2. Color shade was evaluated at five different periods (baseline, after 7, 14 and 21 days of bleaching, and 7 days after end of treatment) according to Vita Classical, CIELab and CIEDE2000 scales. Mean particle size (P), polydispersity (PO) and zeta potential (ZP) were evaluated using dynamic light scattering. Data on the different variables were analyzed by mixed model tests for measures repeated in time (ZP e L*), generalized linear models for measures repeated in time (P, PO, Vita Classical and b*), and Friedman and Mann-Whitney tests (a* and color change/ΔE and ΔE00).Results CP and CPN presented higher P, higher PO and lower ZP than HP and HPN (p≤0.05). All groups showed a significant decrease in Vita Classical color scores after 7 days of bleaching (p<0.05), and HPN presented a greater significant reduction than the other groups. L* increased in TiO2 presence, in all groups, without any differences (p>0.05) in bleaching time. A significant reduction occurred in the a* and b* values for all the groups, and HPN presented lower a* and b* values (p<0.05) than CPN. ΔE was clinically noticeable after 7 days, in all groups, and all groups resulted in a perceptible color change according to ΔE00.Conclusion TiO2 did not influence physicochemical properties of the bleaching agents. HPN presented more effective tooth bleaching than CPN.

Aesthetic perceptions and social judgments about different enamel opacities.

This study aimed to evaluate adolescents' aesthetic perceptions and their social judgments regarding different enamel opacities. Sample size was calculated and resulted in the inclusion of 100 adolescents (aged 10 to 15 years) from a public school in Jequié, Bahia, Brazil. Images of enamel opacities were manipulated to create aesthetic enamel defects, such as enamel color changes (unilateral and bilateral white opacity, unilateral and bilateral yellowish opacity, and unilateral and bilateral yellowish opacity with loss of structure). The images of the opacities were based on Fédération Dentaire Internationale's Developmental Defects of Enamel (DDE) Index. Aesthetic perception and social judgments were evaluated using a validated questionnaire with 12 questions (six positive and six negative points) on social aspects, considering the six manipulated images and the control. The photographic analyses were projected one-by-one by computer to adolescents individually in a classroom. Participants had one minute to observe each image and answer the questionnaire. The data were analyzed by descriptions, and the Friedman Wilcoxon test (p < 0.05). The results indicate that all opacities negatively impacted social judgment (p < 0.001). The enamel aesthetic defects most affecting an individual's perception were bilateral yellow opacity with or without loss of structure (p < 0.001). Regarding social judgment, all participants showed a negative perception of all the tested opacity types (p < 0.001). In conclusion, even opacities presenting only a color change caused aesthetic dissatisfaction to the individuals and changes in their social judgment toward others. Color changes in dental enamel have several aesthetic consequences.

Effect of novel charcoal-containing whitening toothpaste and mouthwash on color change and surface morphology of enamel.

Purpose:The aim of this in vitro study was to investigate the effectiveness of a novel charcoal-containing whitening toothpaste and a mouthwash on tooth color change and the alterations of enamel that may be induced after toothbrushing, corresponding to a 90-day period.Materials and Methods:Forty human canines were used, stained with coffee, and divided into four groups (n = 10) as follows: Group 1 (control) submitted to toothbrushing with deionized water, Group 2 with a regular toothpaste, Group 3 with a whitening toothpaste (1% charcoal), and Group 4 with the same whitening toothpaste in combination with a mouthwash (1% charcoal and 0.5% H2O2). After the treatments, ΔΕ of the teeth was evaluated using an ultraviolet/Vis spectrophotometer, whereas the changes in surface morphology were observed by means of a confocal microscope.Results:The whitening toothpaste increased significantly ΔΕ (40.5%) compared to the control group (P < 0.001). In addition, the tested whitening toothpaste also increased ΔΕ (17.7%) compared to the regular toothpaste (P = 0.023). The whitening toothpaste presented smoother surfaces after toothbrushing, but more heterogeneous with numerous large craters, whereas the whitening mouthwash did not influence surface morphology changes.Conclusions:Charcoal-containing toothpastes may enhance the whitening of the teeth, but they should be used carefully due to changes that may induce on enamel. The patients should consult a dental professional for proper use. A charcoal-containing mouthwash in combination with whitening toothpastes probably cannot offer additional whitening effect.