جستجوی مقالات مرتبط با کلیدواژه "tooth bleaching" در نشریات گروه "پزشکی"

Tooth bleaching sensitivity (TBS) after bleaching procedures is a common problem. This study was undertaken to determine the effect of preoperative systemic capsaicin on tooth sensitivity (TS) after in‑office bleaching procedures.

Thirty participants received the treatment in this clinical trial. The subjects were randomly assigned to two groups (n = 15). Placebo and 0.25% capsaicin were administered three times daily for 24 h,with the first dose being administrated 1 h before the bleaching procedure. The subjects underwent two bleaching sessions at a 2‑week interval by applying 40% hydrogen peroxide gel on six upper anterior teeth. A visual analog scale (VAS) was used to evaluate TS. Data were analyzed with SPSS 24. Statistical analyses were carried out with the Wilcoxon test and paired t‑test. Statistical significance was set at P ≤ 0.05.

In the capsaicin group, there was a significant increase in TBS between the immediate and 1‑h postoperative intervals and a significant decrease between 1‑ and 24‑h postoperative intervals (P = 0.01 and P = 0.000,respectively).In the placebo group,there was a significant decrease between immediate and 24‑h and between 1‑ and 24‑h postoperative intervals (P = 0.007, P = 0.02). Milder TS was detected in the placebo group 24 h after bleaching (P < 0.05).

Under the limitations of this study, preoperative use of systemic capsaicin did not significantly affect TS after the in‑office bleaching procedure.

 When bleaching agents contact dental structures, they act on restorative materials and adhesive interfaces. This study investigated the effect of “at-home” and “in-office” bleaching on the microleakage of composite resin restorations performed with different universal adhesives in self-etch and etch-and-rinse modes.

 Class V cavities were prepared in 132 premolars. The samples were divided into four groups (n=33). All Bond Universal adhesive was used in the first and second groups, and G-Premio Bond adhesive was used in the third and fourth groups. The total-etch mode was used in the first and third groups, and the self-etch mode was used in the second and fourth groups. The samples were divided into three subgroups (n=11). In the first subgroup, home bleaching was used, and in the second subgroup, office bleaching was used. In the third subgroup, bleaching was not performed. The specimens were examined under a stereomicroscope for microleakage. Ordinal regression analysis was applied (P<0.05).

 The adhesive type, application method, and margin type significantly affected microleakage (P<0.05). The amount of microleakage in All Bond Universal adhesive was significantly higher than in G-Premio Bond adhesive. The chance of microleakage in the self-etch mode was almost twice as high as in the etch-and-rinse mode. The bleaching method did not significantly affect microleakage (P>0.05).

 Based on the results of the microleakage test, bleaching after composite resin restorations did not significantly affect the microleakage of Class V restorations.

Objectives :

In endodontics, mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM cement) are commonly used bioceramic materials. Regenerative endodontics often involves the use of double or triple antibiotic pastes (DAP or TAP), which are effective but may cause discoloration. This study aims to examine the effectiveness of internal bleaching in addressing discoloration caused by 4 different materials.

Methods:

 This in vitro study was conducted on 40 single-rooted anterior and premolar human teeth that did not have caries, restorations, obvious discoloration, or fractures and were extracted due to periodontal disease or orthodontic treatment. The teeth were randomly assigned to 4 groups (n=10). After root canal instrumentation, the baseline color of the specimens was measured using a spectrophotometer. After applying the aforementioned materials in the canals, access cavities were sealed with glass ionomer (GI), and the color of the specimens was measured again after 1 month to calculate color change (∆E). Internal bleaching was performed with 35% hydrogen peroxide 3 times within 3 weeks, and values were calculated at each time point. Data were analyzed using paired t-tests and 1-way analysis of variance (ANOVA).

Results:

 Clinically noticeable discoloration (∆E>3.7) occurred in the MTA Angelus (∆E=4.88) and TAP (∆E=17.3) groups. The ∆E of the TAP group was significantly higher than that of all other groups (P<0.05). The discoloration was borderline detectable in the CEM group (∆E=3.89) and clinically undetectable in the DAP group (∆E=2.02). Discoloration significantly improved after 3 rounds of bleaching in the TAP group (P<0.05), as well as after 2 rounds of bleaching in the MTA (P<0.05) and CEM (P<0.05) groups. In all groups, ∆E increased after each round of bleaching.

Conclusion :

The CEM cement may yield better results with lower discoloration compared to MTA and exhibit a more favorable response to internal bleaching. For canal disinfection using antibiotic paste, DAP is a good alternative to TAP.

Objectives :

The present experimental study aimed to assess the in vitro effect of sodium bicarbonate (SB) on tooth discolouration.

Methods:

 Forty-five extracted anterior teeth were decoronated 2 mm apical to the cementoenamel junction. The crowns were immersed in tea solution for 7.5 days. The teeth were divided into three groups (n = 15 per group) on a random basis. The groups were exposed to either SB paste 94%, hydrogen peroxide (HP) 40%, or carbamide peroxide (CP) 45%. Then, teeth were bleached according to the manufacturers' instructions. Next, all tooth samples were immersed again in tea solution for 10 min. The CIE L*a*b* colour parameters of the teeth were evaluated at baseline (T1), after primary staining (T2), after bleaching (T3), and after re-staining (T4) using a spectrophotometer. The enamel surface morphology of one sample from each group was evaluated pre- and post-bleaching using scanning electron microscopy (SEM). Within-group and between-group comparisons were made using repeated measures ANOVA and Tukey’s test.

Results:

 94% of cases had color change(∆E) more than 3.5 with no enamel surface wear after Applying SB. HP showed a maximum bleaching effect of ∆E = 8.77. After re-staining, the SB group showed minimal staining (∆E = 3.77) compared to the HP and CP groups.

Conclusion:

 The present findings show that SB can chemically resolve tooth discolouration and prevent re-staining. Considering its low abrasiveness, optimal safety, low cost, antimicrobial activity, and availability, it seems to be ideal for use at home.

This study assessed the efficacy of different combinations of oxalic acid, 35% hydrogen peroxide, and 5.25% sodium hypochlorite (NaOCl) for bleaching of tooth discolorations caused by hemoglobin.

In this in vitro study, 40 sound extracted human premolars were disinfected and decoronated. Their primary color parameters were measured (T1). The teeth were then centrifuged with human blood for 3 days, rinsed, polished, and their color parameters were measured again (T2). They were randomly divided into 4 groups (N=10) and treated as follows: Group A: in-office bleaching with Pola-Office Plus followed by 30 seconds of light-curing, group B: 0.24 M oxalic acid for 5 minutes followed by in-office bleaching, group C: 5.25% NaOCl for 5 minutes followed by in-office bleaching, and group D: 0.24 M oxalic acid (5 minutes) followed by 5.25% NaOCl (5 minutes) and subsequent application of in-office bleaching gel. The color parameters of the teeth were measured again (T3). Data were analyzed by one-way ANOVA and paired sample t-test (alpha=0.05).

T2-T3 ∆E in groups B and D was significantly higher than that in group A (P<0.05); the difference between groups B and D was not significant. The mean ∆E and ∆L in group C were not significantly different from those in group A (P>0.05). ∆L significantly and equally increased in groups B and D after bleaching.

Application of oxalic acid followed by in-office bleaching gel is more effective than the bleaching gel alone for correction of tooth discolorations caused by hemoglobin.

Teeth bleaching is an accepted and modern treatment in cosmetic dentistry. Bleaching agents may affect amalgam restorations and increase mercury release; therefore, patients are at increased risk of mercury exposure in the body. The aim of this study was to investigate the effect of polishing and universal bonding application on mercury release from aged amalgams exposed to bleaching.

In this in-vitro experimental study, 64 dental amalgam specimens with dimensions of 3×5×10 were prepared and divided into two experimental and control groups. Each group was further divided into 4 subgroups and received one of the following treatments: no intervention, surface bonding, polishing, or polishing and surface bonding. Subsequently, the samples were immersed in bleaching agent containing 7% hydrogen peroxide and the amount of mercury released after 96h was measured. The results were analyzed by two-way ANOVA and Tukey post hoc tests (α≤0.05).

The results showed that the type of solution (P<0.05) and surface treatment (P<0.001) significantly affected the level of mercury release. However, there was no significant interaction between surface treatment methods in the bleaching group and those in the phosphate buffer group (P=0.621).

Bleaching agents were found to enhance mercury release from dental amalgam. The application of polishing and universal bonding on amalgam surfaces exhibited significant effects on the reduction of the mercury release.

Aims|: 

Tooth color is an important factor in smile esthetics. The present study aimed to evaluate the efficacy of three different whitening mouth rinses on color recovery of teeth with surface staining.

Thirty-two bovine incisors were used in this invitro study. First, the teeth were stained by being immersed in a tea solution for 14 days and then randomly assigned to four groups based on the type of mouth rinse used (n=8): C: control (distilled water); ZSW: Zenon Smart White (containing pyrophosphate and triphosphate); PCW: Pasta del Capitano Whitening (containing Plasdone); SWN: Signal White Now (containing Blue Covarine). Colorimetry was carried out using a spectrophotometer at baseline, after staining, and 2, 4, 8, and 12 weeks after immersion in mouth rinses. The data were analyzed with CIELab parameters and ANOVA, repeated measures ANOVA, and Tukey tests (α=0.05).

The mouth rinses decreased tooth staining. The mouth rinses resulted in significant color changes compared to the controls (Ppcw=0.028 and Pzsw=0.002), except for the SWN mouth rinse. The color recovery of the teeth by ZSW mouth rinse, compared to the baseline, was in the clinically acceptable range (ΔE<3.3), and the difference from the control group was borderline (P=0.05).

A relative recovery of tooth colors was only achieved using the ZSW mouth rinse, which contains pyrophosphate and triphosphate compounds.

Patient demand for esthetic dental treatments is increasing, and among different techniques, tooth bleaching is a popular procedure for smile improvement. There is a controversy over the demineralizing effect of hydrogen peroxide (HP) containing bleaching agents on tooth enamel. The aim of this study was to evaluate the effect of HP and its combinations with hydroxyapatite (HA) and bioactive glass (BG) on enamel demineralization and tooth color changes.

Three groups of 20 teeth were used. Bleaching regimens included HP alone, HP + HA, and HP + BG. Bleaching was repeated at six periods of 15 min. Energy dispersive spectrometry was performed to evaluate calcium, phosphorus, sodium, magnesium, and fluoride content of superficial enamel before and after bleaching. Tooth color was evaluated by spectrophotometer before and after bleaching and ΔE values were calculated. Data were statistically analyzed using SPSS version 17.

Ca and P content was increased significantly in group HP + BG (P < 0.05). There was no significant difference in ΔE values between the three groups (P > 0.05).(p value = 0.34).

Addition of BG to HP can increase superficial enamel mineral content after bleaching and has no effect on tooth color changes in comparison to HP alone.

The literature on the effect of bleaching on stainability and color stability of any composites is scarce and controversial. In the case of some composites and/or bleaching agents or staining solutions, there is no previous study. Therefore, this rather large study was conducted for the first time to examine simultaneously the effects of bleaching and 3 staining solutions on 3 composite types.

This 3‑phase experimental in vitro study was performed on 18 groups of 5 specimens each: 90 composite discs with 10 mm diameter and 1 mm thickness were fabricated from 3 resin composites (microhybrid, nanohybrid, and nanofilled). Forty‑five discs underwent bleaching with 15% carbamide peroxide, and the remaining 45 were immersed in distilled water at room temperature. The color assessment was performed before and after this step, and ∆a, ∆b, and ∆L color parameters were calculated for each specimen. The specimens were then immersed in coffee, cola, and red grape juice for 2 weeks, and underwent colorimetry again. The simultaneous effects of bleaching and staining agents and composite types on ΔE (color changes) of composite specimens were analyzed using an independent‑samples t‑test, a Mann–Whitney U‑test, and two‑way and one‑way analysis of variances followed by a Tukey and a Dunnett’s T3 tests ( = 0.05).

Bleaching had no significant effect on color changes of microhybrid, nanohybrid, or nanofilled composites (P > 0.05). The stainability of composites did not increase after bleaching (P > 0.05). Regardless of the composite type and the presence of bleaching, coffee had the worst effect on color of composite specimens, while cola had the smallest staining effect (P < 0.05).

Stainability of microhybrid/nanohybrid/nanofilled composites did not increase after bleaching with 15% carbamide peroxide. Coffee should be consumed with care, as far as composite coloring is a concern, regardless of the type of composite in use or its bleaching history. Cola was the weakest stainer. Coffee always caused perceptible staining (ΔE >3.7), regardless of the composite in use or its bleaching history. Red grape juice caused such perceptible colorations in most cases. Cola did not cause any perceptible discoloration in most cases.

The aim of this study was to investigate the effect of bleaching agent, sodium ascorbate as an antioxidant, and delay time on the shear bond strength (SBS) of orthodontic brackets to enamel using Transbond XT and universal adhesive.

In this in vitro experimental study, 80 extracted maxillary premolars without any defect or decay were randomly divided into eight groups of 1: no bleaching +Transbond XT (NB/TX) bonding agent, 2: no bleaching + All‑Bond Universal (NB/AB), 3: bleaching +Transbond XT (B/TX), 4: bleaching +All‑Bond Universal (B/AB), 5: bleaching + sodium ascorbate + Transbond XT (B/SA/TX), 6: bleaching + sodium ascorbate + All‑Bond Universal (B/SA/AB), 7: bleaching +Transbond XT after a 3‑week delay (B/3W/TX), and 8: bleaching +All‑Bond Universal after a 3‑week delay (B/3W/AB). After thermocycling (1000 cycles, 5–55°C), the SBS was measured, and the adhesive remnant index scores were determined to assess the failure mode. Data were analyzed by one‑way analysis of variance, Tamhane’s post hoc test, Kruskal–Wallis, and Mann–Whitney U‑test at the significance level of P < 0.05.

The mean SBS range was 5.5–29.78 MPa. The highest SBS values were related to Group 2 (NB/AB) which were significantly higher than all groups (P < 0.05) and the lowest values were observed in Group 5 (B/SA/TX) which were significantly lower than all groups except Group 3 (B/TX) (P < 0.05).

Bleaching with 40% hydrogen peroxide significantly decreased the SBS of orthodontic brackets, and 10% sodium ascorbate could not reverse the adverse effect of bleaching on SBS. Delaying the bonding procedure by 3 weeks using Universal adhesive considerably decreased the adverse effect of bleaching on SBS and increased the SBS to a clinically acceptable level for orthodontic treatment.

This study aimed to assess the effect of laser irradiation and Tooth Mousse on tooth hypersensitivity (TH) after office bleaching (OB).

This clinical trial, parallel‑design split‑mouth nonrandomized was conducted on 30 patients requiring OB.After scaling and fabrication of a custom tray,35% hydrogen peroxide was applied on all teeth, and 940 nm diode laser (10W,Class IV,110–240V) was irradiated to the upper and lower right quadrants.Laser in off mode was used for the left quadrants.Bleaching agent was then reapplied.After completion of bleaching,a custom tray containing tooth Mousse was placed on the maxillary arch while the tray was used without the paste for the mandibular arch. A visual analog scale was used to assess the degree ofTH at 15 min and 24 h after OB. Data were compared using t‑test, paired t‑test, and analysis of variance. Significance level was set at α = 0.05.

Comparison of TH at 15 min and 24 h after OB showed a significantly lower TH score in the left upper quadrant (tooth Mousse alone) than right upper quadrant (both laser and Tooth Mousse) (P < 0.05).The TH score in the right upper quadrant was significantly lower than that in the right lower quadrant (laser only) (P < 0.05).The meanTH score in the left upper quadrant was insignificantly lower than that in the left lower quadrant (no intervention) (P > 0.05).

The use of 940 nm diode laser for OB increases the postoperativeTH.The application of Tooth Mousse can effectively decrease TH after OB with/without laser irradiation.

Dental sensitivity is one of the most prevalent clinical consequences among patients who receive in-office bleaching therapy. This study aimed to evaluate the effect of adding sodium hexametaphosphate (SHMP) to an in-office bleaching gel on tooth whitening and sensitivity after the treatment. 

The right and left maxillary lateral incisors of 34 patients were randomly divided into intervention and control groups. In the control side, a bleaching gel containing 37.5% hydrogen peroxide was used, whereas in the intervention side, a combination of the same bleaching gel with 1% SHMP was applied for 30 minutes. Tooth sensitivity to cold, tactile sensitivity, and spontaneous sensitivity was measured before the treatment, and immediately, 24 hours, one week, and one month after therapy. Color changes were measured objectively by a spectrophotometer using the total variation in color (ΔE), and subjectively by a Vita Classical Shade Guide (ΔSGU). 

Immediately after bleaching, cold and tactile sensitivity was higher in the control group compared with the intervention group, but there was no significant difference between groups in any of the sensitivity parameters at different measurement intervals (P>0.05). Spontaneous and tactile sensitivity decreased significantly in both groups over one month (P<0.05). There was no significant difference in ΔE and ΔSGU between the intervention and control groups (P>0.05). 

The addition of SHMP to the bleaching gel could not reduce sensitivity to cold, as well as tactile and spontaneous sensitivity; however, it showed no adverse effect on the bleaching effectiveness. 

Aesthetic expectations have increased the use of aesthetic materials in dentistry. Lithium disilicates are frequently used materials for these expectations. Bleaching is another method used to provide aesthetics. Bleaching processes on restorative materials are not fully known. This study investigated the effect of at-home and in-office bleaching methods on the color change, surface roughness, and topography of lithium disilicate glass-ceramic materials produced with two different techniques and subjected to different polishing procedures.

A total of 144 disc-shaped pressed and computer-aided design (CAD) lithium disilicate glass-ceramic specimens were randomly divided into four groups. Glazing and three different chair-side polishing procedures were performed. The specimens in each group were randomly divided into two groups and subjected to at-home and in-office bleaching processes (n=9). The home bleaching process was repeated with 16% carbamide peroxide agent for six hours for seven days, while the in-office bleaching process was applied with 40% hydrogen peroxide agent for two sessions of 20 minutes. After the bleaching processes, the final color and surface roughness experiments of the specimens were carried out, and the results were recorded. ANOVA and Tukey multiple comparison tests were used FOR the statistical analysis of the data (α=0.05).

The material*polish*bleaching, polish*bleaching, material*bleaching, and material*polishing interactions were not statistically significant regarding color and roughness changes of both specimens (P>0.05).

Both bleaching processes can be safely applied to lithium disilicate glass-ceramic materials.

This study aimed to investigate the impact of three different bleaching protocols on tooth discoloration caused by tea.

Forty extracted sound premolars were cleaned, disinfected, and their initial color parameters were measured (T1). The teeth were then immersed in boiled tea solution for 24 hours, and their color was measured again (T2). The samples were divided into four groups of 10 teeth each. Group A was treated with an in-office bleaching gel followed by 30 seconds of light curing. Groups B, C, and D were respectively treated with 0.24M oxalic acid followed by bleaching gel, 5.25% sodium hypochlorite followed by bleaching gel, and a combination of 0.24M oxalic acid, 5.25% sodium hypochlorite, and bleaching gel. The color was measured once more after the interventions (T3). Data were analyzed using two-way repeated measures ANOVA, paired sample t-test, and Tukey's test.

The mean color change (∆E2) between T2 and T3 was significantly higher in group D compared to group A (P<0.05). However, there was no significant difference in color change between groups A, B, and C. Additionally, there was no significant difference in color change between groups B, C, and D. The groups also showed significant differences in ∆L (P=0.007), with the only significant difference found between groups B and C (P=0.001).

The combined use of sodium hypochlorite and oxalic acid followed by in-office bleaching gel is more effective than bleaching alone in correcting tooth discoloration caused by tea. This protocol can further reduce yellow coloration.

This study aimed to evaluate the pH changes and penetration of hydrogen peroxide into radicular dentin when different protective bases were used with and without a bonding agent.

In this in-vitro experimental study, 70 single-rooted bovine teeth were instrumented and obturated with gutta-percha. The gutta-percha was removed 3mm below the cementoenamel junction (CEJ) and the teeth were divided into seven groups (n=10). In each group, 2mm base (1mm apical to the CEJ) was applied as follows:  TheraCal LC, TheraCal LC plus SE Bond, Lime-Lite, Lime-Lite plus SE Bond, Ionoseal, Ionoseal plus SE Bond, and resin-modified glass ionomer (RMGI). The teeth were placed in vials containing distilled water, and pH values and molar concentration of the medium surrounding the teeth were recorded immediately after internal bleaching with 35% hydrogen peroxide. The pH values were also recorded at 1, 7, and 14 days following renewal of the medium. Data were analyzed with t-test, one-way ANOVA, and Kruskal-Wallis test. 

After bleaching, the medium pH became acidic in all groups. There were no significant differences among groups in the mean pH of the medium after bleaching (P=0.189). Moreover, there were no significant differences among the study groups with respect to hydrogen peroxide concentration (P=0.895).

Intra-orifice barriers such as light-cure resin-modified calcium hydroxide, light-cure resin-reinforced glass ionomer, and light-cure calcium silicate can be as effective as RMGI in providing coronal seal during intracoronal bleaching.

Discoloration is an unfavorable side effect of regenerative endodontic procedures using mineral trioxide aggregate (MTA). The efficacy of home bleaching of discolored teeth with carbamide peroxide has not been well investigated, and the minimum required duration of home bleaching is still unclear. This study aimed to compare the effects of different durations of home bleaching on tooth discoloration caused by MTA.  

This in vitro, experimental study used 16 tooth blocks of bovine central incisors. To cause discoloration, white MTA was applied for 40 days in cavities drilled in blocks. The color parameters were measured at baseline and at 14, 28, and 42 days after the application of 20% carbamide peroxide using a spectrophotometer. Data were analyzed by repeated measures ANOVA and Tukey’s post-hoc test.

The color change (∆E) value was 22.9±10, 26.3±10.9, and 27.03±11 at 14, 28, and 42 days after bleaching, respectively.Significant color change occurred at 2, 4, and 6 weeks after the application of carbamide peroxide (P<0.001). The color change increased at 42 days (∆E of 3.1, or 13% compared with baseline), which was the highest amount among all time points. However, pairwise comparisons showed that it was not statistically significant (P=0.4).

It appears that 14 days is the required time for bleaching of teeth discolored by MTA. Longer bleaching times showed insignificantly higher efficacy for tooth whitening.

The prevalence of using different esthetic methods increases the possibility of close contact between them with potential adverse interactions. This study aimed to compare the surface changes (microhardness and roughness) in two types of feldspathic porcelain after laser bleaching and post-bleach polishing.

12 standardized rectangular specimens were prepared for each porcelain group (conventionally layered and CAD-CAM milled). Vickers microhardness and roughness were evaluated before and after the bleaching procedure and after polishing. Data were statistically analyzed using repeated measures ANOVA and t test (P<0.05).

The surface roughness of both groups increased significantly after laser bleaching (P<0.001 for conventional and P=0.004 for CAD-CAM porcelains). The polishing process reduced the roughness of both groups; the reduction was significant in conventional specimens (P=0.020). The surface hardness values did not change significantly in the groups after the bleaching and post-bleach polishing stages (P=0.142). Generally, the average surface roughness of CAD-CAM specimens was significantly lower (P<0.001), and the surface microhardness of the CAD-CAM group was significantly higher than conventional porcelains (P=0.011).

Laser bleaching significantly increased the surface roughness of feldspathic porcelains; however, it did not affect the surface microhardness significantly. Unlike CAD-CAM specimens, polishing significantly improved the surface smoothness of conventional porcelains.

Reports indicate that lasers accelerate tooth bleaching by activating bleaching agents. Due to the lack of sufficient information about the application of the Er, Cr:YSGG laser, the present study was conducted to compare the degree of enamel color changes after teeth bleaching treatment using chemical whitening agents alone and with Er, Cr:YSGG laser.

In this laboratory study, several human molars were cut into 4 parts after cutting and removing the pulp. Based on laser application, the samples were randomly divided into two groups (N=20), including the chemical bleaching group (G1) and the chemical bleaching group with activated laser (G2). In G1, the bleaching process was performed only with 35% hydrogen peroxide for two weeks (3 times, 15 minutes each week). In G2, the gel bleaching was activated by the Er, Cr:YSGG laser with a wavelength of 2780 nm. It was placed 2.5 cm from the sample surface with bleaching agents and applied twice for 15 seconds. Color changes were recorded using a spectrophotometer before bleaching, immediately after, 1 month, and 3 months after bleaching. Data were analyzed by SPSS software (version 18), Repeated measures ANOVA, and Tukey’s tests (α=0.05).

Mean and standard deviation of changes in Δa showed a significant difference between the gel group and the gel group with laser over time (P<0.05), but this difference was not observed in ΔL and ΔB (P>0.05). However, the intragroup comparison demonstrated significant changes in Δa and Δb in both groups over time, but not in ΔL (P>0.05). The ΔE changes in both the laser and bleaching gel groups were above the threshold of 3.3. The results indicated no significant difference between G1 and G2 in terms of the ΔE (P>0.05). Finally, the results revealed that 1 and 3 months after teeth whitening, ΔE changes in both groups were greater than 3.3.

Overall, the application of the Er, Cr:YSGG laser had no positive effect on bleaching efficacy when using a 35% hydrogen peroxide gel. Based on the findings, color changes were stable in the studied groups for up to 3 months after teeth bleaching.

This study evaluated the effect of pomegranate peel and green tea extracts on shear bond strength (SBS) of a microhybrid composite to bleached enamel.

In this in vitro, experimental study, 44 maxillary premolars were divided into 4 groups of control A (composite cylinders bonded to teeth without bleaching), group B (composite bonding immediately after bleaching), group C (5 g of green tea extract was dissolved in 100 mL of distilled water, applied for 10 minutes, and rinsed for 30 seconds, followed by bleaching and composite bonding) and group D (5 g of pomegranate peel extract was dissolved in 100 mL of distilled water; the rest was similar to group C). In groups B, C and D, 35% hydrogen peroxide was applied on the teeth for 20 minutes and rinsed. This process was repeated two more times. The teeth were etched with 35% phosphoric acid for 15 seconds and rinsed for 15 seconds. A microhybrid composite was applied in Tygon tubes, bonded to the teeth with single Bond, and light-cured. Mode of failure was also determined. SBS was measured by a universal testing machine and data were analyzed by one-way ANOVA and Tukey’s test.

A statistically significant difference was found in the mean SBS of the groups (P<0.001). The mean SBS of group B (not treated with antioxidant after bleaching) was significantly lower than that in other groups (P<0.05).

Application of 5% pomegranate peel and green tea extracts increase the SBS of composite to bleached enamel.