The effect of tooth bleaching on substance P expression in human dental pulp

Influence of dental bleaching on the pulp tissue: A systematic review of in vivo studies

BACKGROUND

Although several studies indicate the harmful effects of bleaching on pulp tissue, the demand for this procedure using high concentrations of hydrogen peroxide (HP) is high.

OBJECTIVES

To investigate the influence of bleaching on the pulp tissue.

METHODS

Electronic searches were conducted (PubMed/MEDLINE, Scopus, Cochrane Library and grey literature) until February 2021. Only in vivo studies that evaluated the effects of HP and/or carbamide peroxide (CP) bleaching gels on the inflammatory response in the pulp tissue compared with a non-bleached group were included. Risk of bias was performed according to a modified Methodological Index for Non-Randomized Studies scale for human studies and the Systematic Review Centre for Laboratory Animal Experimentation's RoB tool for animal studies. Meta-analysis was unfeasible.

RESULTS

Of the 1311 studies, 30 were eligible. Of these, 18 studies evaluated the inflammatory response in animal models. All these studies reported a moderate-to-strong inflammatory response in the superficial regions of pulp, characterized by cell disorganization and necrotic areas, particularly during the initial periods following exposure to 35%-38% HP, for 30-40 min. In the evaluation of human teeth across 11 studies, seven investigated inflammatory responses, with five observing significant inflammation in the pulp of bleached teeth. In terms of tertiary dentine deposition, 11 out of 12 studies noted its occurrence after bleaching with 35%-38% HP in long-term assessments. Additionally, three studies reported significant levels of osteocalcin/osteopontin at 2 or 10 days post-treatment. Other studies indicated an increase in pro-inflammatory cytokines ranging from immediately up to 10 days after bleaching. Studies using humans' teeth had a low risk of bias, whereas animal studies had a high risk of bias.

DISCUSSION

Despite the heterogeneity in bleaching protocols among studies, High-concentrations of HP shows the potential to induce significant pulp damage.

CONCLUSIONS

High-concentrations of bleaching gel increases inflammatory response and necrosis in the pulp tissue at short periods after bleaching, mainly in rat molars and in human incisors, in addition to greater hard tissue deposition over time. However, further well-described histological studies with long-term follow-up are encouraged due to the methodological limitations of these studies.

REGISTRATION

PROSPERO (CRD42021230937).

Effect of submucosal cryotherapy compared with steroids and NSAIDs injections on Substance P and Interleukin 6 pulpal release in experimentally induced pulpal inflammation in rabbits

OBJECTIVE

To compare the effect of submucosal cryotherapy using cold saline to dexamethasone sodium phosphate and diclofenac sodium injections on substance P and interleukin 6 release in experimentally induced pulpal inflammation in rabbits' molar teeth.

METHODOLOGY

Fifteen rabbits were randomly classified into 3 groups according to the submucosal injection given: cold saline, dexamethasone sodium phosphate, and diclofenac sodium. A split-mouth design was adopted, the right mandibular molars were experimental, and the left molars served as the control without injections. Intentional pulp exposures were created and left for 6 hours to induce pulpitis. Pulpal tissue was extracted and examined for SP and IL-6 levels using ELISA. Within each group, the level of cytokines released was measured for both control and experimental groups for intragroup comparison to determine the effect of injection. The percentage reduction of each mediator was calculated compared with the control side for intergroup comparison then the correlation between SP and IL-6 levels was analyzed using Spearman's rank order correlation coefficient. Statistical analysis was performed, and the significance level was set at p<0.05.

RESULTS

Submucosal cryotherapy, dexamethasone sodium phosphate, and diclofenac sodium significantly reduced SP and IL-6 pulpal release. Submucosal cryotherapy significantly reduced SP more than and IL-6 more than dexamethasone sodium phosphate and diclofenac sodium. Pulpal reduction of SP and IL-6 showed a strong positive significant correlation.

CONCLUSIONS

Submucosal cryotherapy reduces the pulpal release of SP and IL-6 and could be tested as an alternative to premedication to potentiate the effect of anesthesia and control postoperative endodontic pain.

Can carbamide peroxide be as effective as hydrogen peroxide for in-office tooth bleaching and cause less sensitivity? A systematic review

This study aimed to answer the question through a systematic review: Can carbamide peroxide be as effective as hydrogen peroxide and cause less in-office bleaching sensitivity? A literature survey was performed in PubMed/MEDLINE, Embase, Scopus, ISI Web of Science, and gray literature. Primary clinical trials that compared the efficacy or the in-office bleaching sensitivity between carbamide and hydrogen peroxides were included. The risk of bias was evaluated using the RoB2. The certainty of the evidence was assessed using the GRADE approach. DPI training significantly improved the mean scores of the dental undergraduates from 7.53 in the pre-DPI-training test to 9.01 in the post-DPI-training test (p < 0.001). After 6 weeks, the mean scores decreased marginally to 8.87 in the retention test (p = 0.563). DPI training increased their confidence level from 5.68 pre-DPI training to 7.09 post-DPI training. The limited evidence suggests that the 37% carbamide peroxide may be similarly effective to the 35% hydrogen peroxide for bleaching teeth in-office and causes less bleaching sensitivity. However, more well-designed split-mouth clinical trials are necessary to strengthen the evidence.

In-office Bleaching Activated With Violet LED: Effect on Pulpal and Tooth Temperature and Pulp Viability

OBJECTIVES

This study evaluated the influence of hydrogen peroxide (HP) with or without titanium dioxide nanotubes (TiO2) associated with violet LED (VL) regarding: a) the temperature change in the pulp chamber and facial surface; b) the decomposition of HP; and c) the cytotoxicity of the gels on pulp cells.

METHODS AND MATERIALS

The experimental groups were: HP35 (35% HP/Whiteness HP, FGM); HP35+VL; HP35T (HP35+TiO2); HP35T+VL; HP7 (7.5% HP/White Class 7.5%, FGM); HP7+VL; HP7T (HP7+TiO2); and HP7T+VL. TiO2 was incorporated into the bleaching gels at 1%. Eighty bovine incisors were evaluated to determine temperature change in 8 experimental groups (n=10/group). A k-type thermocouple was used to evaluate the temperatures of the facial surface and in the pulp chamber, achieved by enabling endodontic access to the palatal surface, throughout the 30-minute session. HP decomposition (n=3) of gels was evaluated by using an automatic potentiometric titrator at the initial and 30-minute time points. Trans-enamel and trans-dentinal cell viability were assessed with a pulp chamber device as well as enamel and dentin discs (n=6), and the treatment extracts (culture medium + diffused components) were collected and applied to MDPC-23 odontoblast cells to evaluate cell viability according to the MTT test.

RESULTS

A temperature increase in the pulp chamber was observed in the presence of VL at 30 minutes (p<0.05) (Mann-Whitney test). Also at 30 minutes, HP35 showed greater decomposition in the presence of VL rather than in its absence (p<0.05) (mixed linear models and the Tukey-Kramer test). HP7 provided greater cell viability than the groups treated with HP35 (p<0.05) (generalized linear models test). Cell viability was significantly lower for HP7 in the presence of VL (p<0.05).

CONCLUSION

Pulpal temperature increased with VL (maximum of 1.9°C), but did not exceed the critical limit to cause pulp damage. Less concentrated HP resulted in higher cell viability, even when associated with VL.

Can different agents reduce the damage caused by bleaching gel to pulp tissue? A systematic review of basic research

Objectives

This study aimed to investigate the effectiveness of different topical/systemic agents in reducing the damage caused by bleaching gel to pulp tissue or cells.

Materials and Methods

Electronic searches were performed in July 2023. In vivo and in vitro studies evaluating the effects of different topical or systemic agents on pulp inflammation or cytotoxicity after exposure to bleaching agents were included. The risk of bias was assessed.

Results

Out of 1,112 articles, 27 were included. Nine animal studies evaluated remineralizing/anti-inflammatories agents in rat molars subjected to bleaching with 35%-38% hydrogen peroxide (HP). Five of these studies demonstrated a significant reduction in inflammation caused by HP when combined with bioglass or MI Paste Plus (GC America), or following KF-desensitizing or Otosporin treatment (n = 3). However, orally administered drugs did not reduce pulp inflammation (n = 4). Cytotoxicity (n = 17) was primarily assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay on human dental pulp cells and mouse dental papilla Cell-23 cells. Certain substances, including sodium ascorbate, butein, manganese chloride, and peroxidase, were found to reduce cytotoxicity, particularly when applied prior to bleaching. The risk of bias was high in animal studies and low in laboratory studies.

Conclusions

Few in vivo studies have evaluated agents to reduce the damage caused by bleaching gel to pulp tissue. Within the limitations of these studies, it was found that topical agents were effective in reducing pulp inflammation in animals and cytotoxicity. Further analyses with human pulp are required to substantiate these findings.

Trial Registration

PROSPERO Identifier: CRD42022337192.

Temporospatial Expression of Neuropeptide Substance P in Dental Pulp Stem Cells During Odontoblastic Differentiation in Vitro and Reparative Dentinogenesis in Vivo

INTRODUCTION

Substance P (SP) is a neuropeptide released from the nervous fibers in response to injury. In addition to its association with pain and reactions to anxiety and stress, SP exerts various physiological functions by binding to the neurokinin-1 receptor (NK1R). However, the expression and role of SP in reparative dentinogenesis remain elusive. Here, we explored whether SP is involved in odontoblastic differentiation during reparative dentinogenesis.

METHODS

Dental pulp stem cells (DPSCs) were isolated from healthy human dental pulp tissues and subjected to odontoblastic differentiation. The expression of SP and NK1R during odontoblastic differentiation was investigated in vitro. The effects of SP on odontoblastic differentiation of DPSCs were evaluated using alizarin red staining, alkaline phosphatase staining, and real-time polymerase chain reaction. After direct pulp capping with mineral trioxide aggregate, the expression of SP and NK1R during reparative dentin formation in rats were identified using histological and immunohistochemical staining.

RESULTS

SP and NK1R expression increased during the odontoblastic differentiation of DPSCs. SP translocated to the nucleus when DPSCs were exposed to differentiation medium. NK1R was always present in the nuclei of DPSCs and odontoblast-like cells. Additionally, we discovered that 10^-8 M SP marginally enhanced the odontoblastic differentiation of DPSCs, and that these effects could be impaired by the NK1R antagonist. Furthermore, SP and NK1R were expressed in odontoblast-like and dental pulp cells during reparative dentin formation in vivo.

CONCLUSIONS

SP contributes to odontoblastic differentiation during reparative dentin formation by binding to the NK1R.

Effect of bioactive glasses used as dentin desensitizers on the dentin-pulp complex in rats

Bioactive glasses have been recommended for the occlusion of dentinal tubules in treating cervical dentin hypersensitivity. This study evaluates an in vivo model of dentin exposure, and tests the efficacy of bioglass treatments. Thirty male Wistar rats received gingival recession surgery on the upper left first molar. The treatments were applied over the surface of the exposed dentin every 4 days for 28 days. The groups were as follows: Naive; Gingival recession; Cavity varnish; Biosilicate^®; Strontium bioglass; and Potassium bioglass. Changes in the dentin-pulp complex, and the presence of substance P, were evaluated through hematoxylin-eosin and immunohistochemical staining. The groups had similar results. Teeth with exposed dentinal tubules in rats showed a typical pattern in the dentin-pulp complex and immunotracing for substance P. The materials did not cause pulp damage. The effects of gingival recession and open dentinal tubules on pulp tissue require further clarification.

Effectiveness of Violet LED alone or in association with bleaching gel during dental photobleaching: A Systematic Review

AIMS

To conduct a systematic review to determine the efficacy of violet led in promoting dental bleaching itself or accelerating dental bleaching when associated with peroxides.

METHODS

Clinical and in vitro studies were identified by a search on November 27th 2020 in the PubMed and Scopus databases. Inclusion criteria were: 1) studies related to bleaching; 2) studies related to violet LED Light (405-410nm); and 3) studies that analyzed efficacy. The authors assessed the studies for risk of bias independently. Authors extracted outcomes including color change evaluation and pain assessment independently.

RESULTS

During the search process, 895 articles were found in the previously cited databases. After the first screening consisting of title and abstract evaluations, 18 articles were selected. Finally, 13 articles met the eligibility criteria and were included in this review, being 5 clinical trial/case series and 8 in vitro studies. In vitro studies showed a high risk of bias and interventional studies showed a low risk of bias.

CONCLUSION

The violet Led seems to have the potential to bleach teeth without peroxides, with a clinical perceptible color alteration. However, the effect is small in comparison to bleaching using peroxides. When Violet Led is used in association with peroxides, it seems to potentialize the bleaching result. However, due to the high heterogeneity between studies, a small number of clinical studies, and the high risk of bias of the in vitro included studies, the results are not definitive, and further well-designed studies are needed to reach safe evidence.

Influence of 35% hydrogen peroxide gel renewal on color change during in-office dental photobleaching with violet LED: A split-mouth randomized controlled clinical trial

BACKGROUND

To clinically evaluate the effect of 35% hydrogen peroxide gel renewal in association with violet LED (405-410nm) through a split-mouth randomized controlled clinical trial.

METHODS

The treatment consisted in 3 bleaching sessions of 15 min each, with an interval of 7 days between them, using 35% hydrogen peroxide combined to violet LED irradiation. Selected patients had two experimental segments for the split-mouth design: No change of the bleaching gel during each session (NBGR) and 3 changes of the bleaching gel every 5 min for each session (BGR). During the 3 bleaching sessions, the selected quadrant received the same treatment. Patients had their upper canines and central incisors teeth color measured with a subjective (color scale - VITA Classical) and an objective (spectrophotometer - VITA Easyshade) method and their teeth sensitivity measured using a Visual Analog Scale (VAS) before, immediately after each bleaching session, and 14 days and 2 months (60 days) after the end of the treatment.

RESULTS

The protocol adopted in the present study reached satisfactory results regarding color change. No statistical difference between groups was observed immediately after the end of the treatment and in the follow-up analysis for both subjective and objective color evaluation. No difference in tooth sensitivity between segments was observed.

CONCLUSION

There is no need for bleaching gel renewal when following the clinical protocol of 3 sessions of 15 min in a bleaching protocol of 35% hydrogen peroxide combined with violet LED.

Change of dental color and temperature through two bleaching agents boosted with light emitted by diodes

INTRODUCTION

The use of light sources during the application of bleaching can reduce the time and improve the results, but at the same time this can increase the dental temperature. The objective of this study was to evaluate the performance of two bleaching agents and the increase in dental temperature with the use of light emitted by diodes (LED)-unit.

MATERIALS AND METHODS

Forty third molars were obtained and randomized: the whiteness without lamp (WHN) and Pola office without lamp (PON) groups, two bleaching systems based on 35% hydrogen peroxide were used, according to manufacturer specifications. For the whiteness with lamp (WHL) and Pola office with lamp (POL) groups the same bleaching agents were light boosted. A spectrophotometer and ∆WI_D equation was used to record and analyzed teeth color. An infrared thermometer was used to record the external and internal temperature. A ∆T was obtained by the difference of the temperature of the groups with and without LED (WHN-WHL and PON-POL). For statistical analysis Kruskal-Wallis test and Anova test were performed.

RESULTS

The WHN, PON, WHL, and POL groups reported ∆WI_D values of 4.88 ± 1.08, 9.26 ± 3.27, 5.70 ± 2.48, 12.08 ± 5.44, respectively. The dates of internal temperature were 1.01 and 1.07°C, and for external temperature were 1.61 and 1.15°C respectively.

CONCLUSIONS

With the limitations of this study, both bleaching agents reported a significant increase in ∆WI_D with and without association of light. Significant temperature increases were also observed. The highest average temperature increase was approximately 1.61°C.

CLINICAL SIGNIFICANCE

Bleaching agents boosted with LED may improve the results of bleaching, but it is not essential to obtain good results.

A Spectrophotometric Study on Light Attenuation Properties of Dental Bleaching Gels: Potential Relevance to Irradiation Parameters

Background: During in-office bleaching, appropriate light sources are applied in order to enhance the activity of the bleaching gels applied onto teeth. For this method to be effective, a high absorption of light within the gel is necessary. Variation in the light attenuation capability of the gel, the duration of application and light activation can contribute towards safety hazards associated with this procedure. Methods: In this study, seven different gels and hydrogen peroxide have been evaluated for their optical properties by means of spectrophotometry (440–1000 nm). The transmitted light spectrum was used to estimate the intensity loss for each gel. The mean intensity decreases observed were statistically analysed using an analysis of variance (ANOVA). Results: The five more-pigmented gels tested indicated a very similar intensity loss of around 80%, whereas the remaining two gels showed significantly less attenuation (predominantly, p < 10⁻⁶). Conclusions: Throughout the spectrum of wavelengths examined, and according to the underlying studies evaluated, five of the gels assessed demonstrated an attenuation high enough to possibly avoid overheating of the underlying enamel dentine and pulp. An evaluation of appropriate irradiation parameters is proposed.

Effectiveness of Whitening Strips Use Compared With Supervised Dental Bleaching: A Systematic Review and Meta-analysis

CLINICAL RELEVANCE

Bleaching performed at home while under the supervision of a dentist provides greater color alteration compared with whitening strips when evaluated with a spectrophotometer, although the color alteration was undetectable by unaided human eyes.

SUMMARY

Objective: A systematic review and meta-analysis were performed to answer the following research question: Does the use of whitening strips (WS) lead to an equivalent color change compared with supervised dental bleaching in patients with permanent dentition?Methods: A search was performed on August 10, 2017 (updated on March 22, 2019), in PubMed, the Brazilian Library in Dentistry, Latin American and Caribbean Health Sciences Literature database, Cochrane Library, Scopus, Web of Science, and SIGLE, without restrictions regarding date or language. Abstracts from the International Association for Dental Research, unpublished and ongoing trial registries, dissertations, and theses were also searched. Only randomized clinical trials (parallel or split mouth) in patients with permanent dentition that compared WS with dentist-supervised dental bleaching performed at home (AH) or in office (IO) were included. The risk of bias (RoB) was evaluated using the Cochrane Collaboration tool. A meta-analysis with subgroup analysis (low and high peroxide concentration) was conducted for color change ΔE* (spectrophotometer) and ΔSGU (shade guide units), risk and intensity of tooth sensitivity (TS), gingival irritation (GI), and patient satisfaction using a random effects model. Heterogeneity was assessed with the Cochrane Q test and I2 statistics. GRADE (Grading of Recommendations, Assessment, Development and Evaluation) was used to assess the quality of the evidence.Results: After the removal of duplicates, followed by title and abstract screening, 20 studies remained. Only two studies were considered to have a low RoB; 11 had a high RoB, and seven had an unclear RoB. For WS versus IO, data were not available for the meta-analysis. For WS versus AH bleaching, a significant difference in ΔE* favoring the AH group was observed (standardized mean difference [SMD] = -0.50, 95% confidence interval [CI] -0.79 to 0.21), but the risk (risk ratio = 0.78, 95% CI 0.65 to 0.93) and intensity of TS (SMD = -0.30, 95% CI -0.56 to -0.04) were lower in the WS group. Color change in ΔSGU, risk and intensity of GI, and patient satisfaction were not significantly different between groups (p>0.20). The quality of evidence for ΔE*, risk and intensity of TS, and intensity of GI were graded as moderate.Conclusion: Although the risk and intensity of TS were lower in the WS group, dentist-supervised at-home bleaching led to a better color change when measured with a spectrophotometer, although the color alteration was undetectable by unaided human eyes.

A novel carbamide peroxide polymeric nanoparticle bleaching gel: Color change and hydrogen peroxide penetration inside the pulp cavity

OBJECTIVE

This study evaluated the hydrogen peroxide (HP) penetration inside the pulp cavity and the color change of teeth submitted to the 15% carbamide peroxide (CP) nanoparticle bleaching gel at several application times.

MATERIALS AND METHODS

Premolars were divided into nine groups (n = 6) according to 15% CP bleaching agents (nanoparticle and commercial) and to application times (15, 30, 45, and 60 minutes). A negative control was exposed to ultra-purified water. After a whitening procedure, the HP concentration (μg/mL) inside the pulp cavity was assessed via spectrophotometry. The color change (ΔE* and ΔE00*) was evaluated with a spectrophotometer. Data were analyzed via two-way ANOVA and Tukey (α = 0.05).

RESULTS

A lower concentration of HP was detected for CP nanoparticle gel after 30 and 45 minutes of whitening procedure (P = .001). The bleaching groups promoted a higher color change (ΔE* and ΔE00*) regardless of the application time (P = .0001).

CONCLUSIONS

The CP nanoparticle gel reduced HP inside the pulp cavity, and showed effective bleaching compared with CP commercial gel.

CLINICAL SIGNIFICANCE

Using 15% carbamide peroxide nanoparticle bleaching gel decreased the HP penetration inside the pulp cavity and may decrease bleaching-induced tooth sensitivity in at-home bleaching.

Influence of pain-relieving therapies on inflammation and the expression of proinflammatory neuropeptides after dental bleaching treatment

Objectives

To minimize the tooth sensitivity caused by in-office bleaching, many dentists use non-steroidal anti-inflammatory drugs and topical desensitizing gels containing potassium nitrate and sodium fluoride. This study aimed to evaluate the influence of these substances on inflammation and the expression of substance P and calcitonin gene-related peptide in pulp nerve fibers.

Materials and Methods

Seventy-two rats were divided into 6 groups as follows: GI, control; GII, only dental bleaching; GIII, only ibuprofen; GIV, ibuprofen administered 30 minutes before and after the bleaching treatment and every 12 hours until the analysis; GV, only topical application of a desensitizing agent; and GVI, topical application of a desensitizing agent before dental bleaching. Placebo gel was applied to the upper left jaw and the bleaching agent was applied to the upper right jaw in all groups. Subsequently, the groups were divided into 3 subgroups based on the time of analysis: 0, 24, and 48 hours after bleaching (n = 8). The rats were euthanized and the maxillae were processed and evaluated by histopathological and immunohistochemical analyses. The data were analyzed using the Kruskal-Wallis test, followed by the Dunn test (p < 0.05).

Results

In the bleaching groups, the inflammatory process and expression of neuropeptides decreased over time. The animals in which a desensitizing agent was applied showed better results within 24 hours.

Conclusions

The use of a desensitizing agent had positive effects on inflammation and pain-related neuropeptide expression, minimizing the painful effects of dental bleaching treatment.

Influence of low-level laser therapy on inflammation, collagen fiber maturation, and tertiary dentin deposition in the pulp of bleached teeth

OBJECTIVES

We evaluated the effects of low-level laser therapy (LLLT) using an infrared laser (IRL) and a red laser (RL) on the pulp of molar teeth in rats after dental bleaching to assess inflammation, collagen fiber maturation, and tertiary dentin formation.

MATERIALS AND METHODS

Eighty Wistar rats (Rattus norvegicus, albinus) were randomly divided into eight groups with 10 hemimaxillae in each of the following: control; bleached (Ble, 35% hydrogen peroxide [H₂O₂]); Ble-1IRL and Ble-1RL (one IRL [808 nm, 30 s, 3 J] or RL [660 nm, 15 s, 1.5 J] application immediately after H₂O₂); Ble-3IRL and Ble-3RL (three [immediately, 24 h, and 48 h] IRL or RL applications after H₂O₂); and 3IRL and 3RL (three IRL or RL applications without bleaching). The rats were euthanized after 2 and 30 days for histological evaluation of inflammation (hematoxylin-eosin) and maturation of collagen fibers (picrosirius red). Additionally, the dentin deposition in the specimens obtained at 30 days was quantified via microtomography of the pulp chamber volume. Statistical analyses were performed (P < 0.05).

RESULTS

Initially, severe damages to the pulp were observed in the Ble and Ble-1RL groups. Ble-1IRL and Ble-3RL groups showed lower inflammation. The bleached groups had a greater amount of mature collagen fibers than the control group. The Ble-3IRL group had a greater number of immature fibers than the Ble group. At 30 days, there was an absence of inflammation and equal proportion of mature and immature collagen fibers. All bleached groups showed a reduction in the volume of the pulp chamber.

CONCLUSION

Three consecutive applications of RL and one IRL application can minimize damage to the pulp of bleached teeth, whereas three IRL applications can minimize pulp fibrosis. However, LLLT did not prevent deposition of tertiary dentin.

CLINICAL RELEVANCE

This study describes LLLT protocols capable of minimizing inflammation and maturation of collagen fibers in pulp tissue after dental bleaching. However, the protocols proved insufficient for reducing the formation of tertiary dentin in bleached teeth.

Effects of Exposure to Cola-Based Soft Drink on Bleaching Effectiveness and Tooth Sensitivity of In-Office Bleaching: A Blind Clinical Trial

OBJECTIVE

The purpose of this single-blind (evaluators) and parallel design study was to evaluate whether exposure to a cola-based soft drink during bleaching treatment with 35% hydrogen peroxide (HP) affects color change and bleaching-induced tooth sensitivity.

MATERIAL AND METHODS

Forty-four patients with central incisors darker than A2 were selected. Participants who did not drink cola-based soft drinks were assigned to the control group (CG), while participants who drank a cola-based soft drink at least twice a day were assigned to the experimental group (EG). For the CG, foods with staining dyes were restricted. For the EG, there was no restriction on food and patients were asked to rinse their mouths with a cola-based soft drink for 30 s, 4 times daily. For both groups, 2 sessions with three 15 min applications of 35% HP were performed. Shade evaluation was assessed via subjective (VITA classical and VITA bleacheguide shade guides) and objective methods (Easyshade spectrophotometer) at baseline, during bleaching (first, second, and third weeks), and post bleaching (1 week and 1 month). Patients recorded their sensitivity perceptions using a numerical rating scale and 0-10 visual analog scales. Variation in shade guide units and the 2 colors (DE) were evaluated with a Student's t-test (α = 0.05) and Mann-Whitney test (α = 0.05). Absolute risk of tooth sensitivity and intensity of tooth sensitivity were evaluated by a Chi-square test (α=0.05).

RESULTS

Effective bleaching was observed for both groups after 30 days, without statistical difference (p > 0.08). There was no significant difference in absolute risk of bleaching-induced tooth sensitivity between the 2 groups (p = 0.74). Higher and significant scores in pain scales were detected for the EG in comparison to the CG (p < 0.05).

CONCLUSION

Even that the cola-based soft drink exposure during in-office bleaching treatments did not affect the bleaching's effectiveness; patients reported a higher intensity in bleaching-induced tooth sensitivity.

Effect of Analgesic Drugs on Tooth Sensitivity Induced by In-office Dental Bleaching: A Systematic Review and Meta-analysis

OBJECTIVE

This systematic review evaluates the effect of preemptive analgesia on tooth sensitivity induced by in-office tooth bleaching.

METHODS

The review was structured based on the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) checklist. The methods were recorded at PROSPERO (CRD42018095440). Randomized clinical trials, studies published in English, and studies in which the efficacy of preemptive analgesia with analgesic and anti-inflammatory medications prior to in-office tooth bleaching was compared with that of placebo were included. PubMed/MEDLINE, Scopus, Web of Science, and Cochrane Library were used for searching. The electronic search provided 373 articles, and seven of them were selected based on the inclusion criteria.

RESULTS

Immediately after time point, a significant reduction of dental sensitivity was observed in the drug group compared to the control group (p=0.02; mean difference [MD]: -0.90; confidence interval [CI]: -1.63 to -0.16), while there was no significant difference at up to one-hour (p=0.22; MD: -0.42; CI: -1.09 to -0.25), at 1-24-hour (p=0.88; MD: -0.05; CI: -0.61 to 0.72), or 24-48-hour (p=0.69; MD: 0.05; CI: -0.21 to 0.32) time points. The incidence of sensitivity during the procedure was not statistically different between the groups (p=0.64; MD: 0.91; CI: 0.92 to 1.15). The nonsteroidal anti-inflammatory drug group showed a statistically significant reduction (p=0.04; MD: -0.69; CI: -1.36 to -0.03) in tooth sensitivity compared with the other groups.

CONCLUSIONS

This systematic review and meta-analysis demonstrated that the medications analyzed did not interfere with the incidence of sensitivity symptoms. Regarding the intensity, no difference was observed between the drug and placebo groups at the up to one-hour, 1-24-hour, or 24-48-hour time points, and there was a statistically significant difference at the zero-hour time point in favor of the drug group. However, based on the variables that influenced this result, it should be considered with prudence because a small difference was observed.

Preemptive Use of Piroxicam on Tooth Sensitivity Caused By In-Office Bleaching: A Randomized Clinical Trial

This clinical trial evaluated the effect of preemptive use of the non-steroidal anti-inflammatory drug piroxicam in a single dose 30 min prior to in-office bleaching on the prevention of tooth sensitivity (TS) reported by patients. Fifty patients were submitted to two sessions of in-office tooth bleaching with 35% hydrogen peroxide used for 2 sessions, each consisting of a single 45-min application, with an interval of 7 days between session. Thirty minutes prior to the procedure, the patient randomly received a single dose of piroxicam (200 mg) or placebo in a double-blind, randomized, crossover design. The TS was evaluated using verbal rate (VRS) and visual analog (VAS) scales during the bleaching procedure and at 24 h after each session. The color changes were assessed by the Vita Bleachedguide scale 1 week after each bleaching session. Risk of TS was calculated from the VRS and analyzed by the McNemar test, while the level of TS was analyzed by the Mann-Whitney test. For the VAS, t-tests were used to compare data from the treatments at each assessment time. Data regarding color changes were subjected to Wilcoxon and Mann-Whitney tests (α=0.05). The preemptive administration of piroxicam did not affect the risk and level of TS compared to placebo, irrespective of the assessment time. The treatment sequence did not affect bleaching effectiveness. In conclusion, the administration of a single dose of piroxicam prior to in-office tooth bleaching was unable to significantly reduce the risk and level of TS.

A New Approach for Dental Bleaching Using Violet Light With or Without the Use of Whitening Gel: Study of Bleaching Effectiveness

The objective of this study was to evaluate the effectiveness of violet light-emitting diodes (LEDs) in dental bleaching treatment when used in conjunction with bleaching gels containing different concentrations of hydrogen peroxide (HP). Here, 90 bovine teeth (n=15) were randomly assigned to the following groups: GI, placebo without light; GII, 35% HP without light; GIII, 17.5% HP without light; GIV, placebo with violet LED; GV, 35% HP with violet LED; and GVI, 17.5% HP with violet LEDs. Three bleaching sessions of 45 minutes were conducted; 21 cycles involving one minute of irradiation by violet LEDs with 30-second intervals were performed during each session of bleaching (GIV, GV, and GVI). Color changes (ΔE, ΔL, Δa, and Δb) were analyzed using a visible ultraviolet light spectrophotometer 7 days after each bleaching session. The mean ΔE, ΔL, Δa, and Δb values were compared between groups by analysis of variance and Tukey tests, with a significance level of 5%. The groups treated with 35% HP had higher ΔE and ΔL and lower Δb values, regardless of whether violet light was used. The group that received only violet LED differed from the control group in terms of ΔE, and the group treated with 17.5% HP and violet LED presented higher ΔE values than the group treated with 17.5% HP only. Thus, violet light did not influence bleaching efficacy when using 35% HP, but when used in conjunction with 17.5% HP, it increased the bleaching efficacy. Moreover, use of the violet LED only also prompted a bleaching effect, although it was less marked.

In Vivo Study of the Action of a Topical Anti-Inflammatory Drug In Rat Teeth Submitted To Dental Bleaching

Bleaching gel containing hydrogen peroxide (H2O2) cause damages in pulp tissue. This study investigated the action of a topical anti-inflammatory, the Otosporin®, in rats' bleached teeth with the null hypothesis of which the Otosporin® is no able to minimize the pulp inflammation that bleaching gel generates. The rat's molars were divided into groups: BLE: bleached (35% H2O2 concentration /single application of 30 min); BLE-O: bleached followed by Otosporin® (10 min); and control: placebo gel. In the second day after dental bleaching, the rats were killed, and the jaws were processed for hematoxylin-eosin and immunohistochemistry analysis for tumor necrosis factor alpha (TNF-α), interleukin (IL)-6 and IL-17. The data collected were subjected to Kruskal-Wallis and Dunn statistical tests with at a 5% level of significance (p<0.05). The BLE group had moderate to strong inflammation in the occlusal third of the coronary pulp, with necrotic areas; and BLE-O, mild inflammation (p<0.05). There was a significant difference in the occlusal and middle thirds of the coronary pulp between the BLE with BLE-O and control groups (p<0.05). There was no difference in the cervical third (p>0.05). The BLE group had a high immunoexpression of TNF-α than BLE-O and control groups (p<0.05), with moderate and mild immunoexpression, respectively. Regarding IL-6 and IL-17, the BLE group had higher immunoexpression than control (p<0.05); the BLE-O was similar to the control (p>0.05). The topical anti-inflammatory Otosporin® can reduce pulp inflammation after dental bleaching in the rat teeth.

Anti-inflammatory potential of a carvedilol gel in the pulpal tissue of rats after dental bleaching: A histopathological evaluation

AIM

Carvedilol is an antioxidant that decreases inflammation in periodontitis. The hydrogen peroxide (H₂ O₂ ) of bleaching gel causes inflammation and necrosis of the dental pulp. In the present study, we evaluated the anti-inflammatory potential of carvedilol in the pulp of rats after bleaching.

METHODS

The right upper molars of rats received 35% H₂ O₂ (1× 30 minutes), and the left upper molars were used as the control. Half of the rats received carvedilol gel (1× 10 minutes), forming the following groups: bleached, bleached followed by carvedilol (bleached+carvedilol), and control. After 2 and 30 days (N = 7 hemi-maxillae/group), the rats were killed for histological evaluation, and statistical tests were performed (P < 0.05).

RESULTS

After 2 days, the bleached group showed necrosis in the occlusal third of the coronal pulp, and in the bleached+carvedilol group, severe inflammation (P > 0.05), both different from the control (P < 0.05). In the middle third, the bleached group showed severe inflammation, and the bleached+carvedilol group showed moderate inflammation (P > 0.05), with the only difference between the bleached and control groups (P < 0.05). In the cervical third, the bleached group showed moderate inflammation, and the bleached+carvedilol group showed mild inflammation (P > 0.05). The difference again was only between the bleached and control groups (P < 0.05). At 30 days, there was no inflammation and a marked amount of tertiary dentin in bleached teeth (P > 0.05).

CONCLUSION

Carvedilol gel has the potential of minimizing H₂ O₂ damage, especially in deep regions of the dental pulp of rats after bleaching.

Association Between In-Office And At-Home Tooth Bleaching: A Single Blind Randomized Clinical Trial

This controlled randomized clinical trial evaluated the effect of associating at-home and in-office bleaching procedures on tooth sensitivity (TS) and bleaching effectiveness. Forty patients subjected to on session of in-office bleaching with 38% peroxide hydrogen. Subsequently, the patients were randomly allocated to receive a second session of in-office bleaching or to use a tray containing 10% carbamide peroxide delivered during 7 consecutive days. The worst TS score reported during or after each bleaching procedure was recorded using a verbal rating scale and TS risk (score different from 0) was calculated. Color changes were measured 7 days after each in-office session (for patients receiving in-office procedures only) or after the end of at-home bleaching (for the combined protocol), and 6 months after the last procedure for both bleaching protocols. Color was assessed by a spectrophotometer and by color match with the Vita Classical and Bleach guide scales. Statistical analyses were carried out to assess possible differences between the protocols regarding the outcomes and to analyze the effect of time of assessment on color changes. The bleaching protocol did not affect the risk for and the maximum level of TS reported, irrespective of the time of assessment. In the color evaluation, the bleaching protocol also did not affect the ultimate tooth color. In conclusion, after one in-office bleaching session, there was no difference in bleaching effectiveness and TS between performing a second in-office session and associating it with 1-week at-home bleaching.

Combination of Acetaminophen/Codeine Analgesics Does Not Avoid Bleaching-Induced Tooth Sensitivity: A Randomized, Triple-Blind Two-Center Clinical Trial

Bleaching-induced tooth sensitivity (TS) is highly prevalent.

OBJECTIVE

This study aimed to determine if the combination of opioids and nonopioids analgesics (Tylex) may provide a better analgesic effect.

METHOD

A triple-blind, parallel, randomized two-center clinical trial was conducted with 105 healthy patients who received either a placebo or a combination of acetaminophen/codeine. The first dose of Tylex 30 mg (acetaminophen 500 mg/codeine 30 mg) or placebo was administered one hour before the in-office bleaching (35% hydrogen peroxide), and extra doses were administered every six hours for 48 hours. The TS was recorded using a visual analog scale of 0 to 10 and a numeric rating scale of 0 to 4 in different periods: during bleaching, one hour up to 24 hours, and 24 hours up to 48 hours postbleaching. The color was measured before and one month after dental bleaching with a visual shade guide (Vita Classical), Vita Bleachedguide 3D-MASTER, and the spectrophotometer Vita Easyshade. The absolute risk of TS was evaluated using the Fisher exact test. Data of TS intensity with numeric rating scale of the two groups were compared with the Mann-Whitney U-test and the Friedman test, while data from the visual analog scale were evaluated by two-way repeated measures analysis of variance and the Tukey test for pairwise comparison. The color changes between groups were compared using the Student t-test (α=0.05).

RESULTS

No significant differences between the groups were observed in the risk and intensity of TS. The overall absolute risk of TS was approximately 96%. No significant differences between groups were observed in terms of color change ( p>0.05) for any scale.

CONCLUSION

The use of an acetaminophen/codeine combination prior to in-office bleaching does not reduce the risk and intensity of bleaching-induced TS.

Effect of photobiomodulation with low-level laser therapy combined with potassium nitrate on controlling post-bleaching tooth sensitivity: clinical, randomized, controlled, double-blind, and split-mouth study

OBJECTIVES

To evaluate the effect of photobiomodulation with low-level laser therapy (PBM-LLLT) combined with 5% potassium nitrate (KNO₃) on controlling tooth sensitivity (TS) after in-office tooth bleaching.

MATERIALS AND METHODS

Fifty volunteers were selected based on the inclusion and exclusion criteria and were randomly allocated into four groups: G1 (control): placebo gel application, 35% hydrogen peroxide bleaching (HP35) and mock PBM-LLLT without light emission; G2: placebo gel application, bleaching with HP35 and PBM-LLLT; G3: application of KNO₃, bleaching with HP35 and mock PBM-LLLT; and G4: application of KNO₃, bleaching with HP35 and PBM-LLLT. A pain assessment questionnaire was used to evaluate TS during the 21 days of treatment. The Friedman test was used for intragroup analysis, and the Wilcoxon and Mann-Whitney tests were used for intergroup comparisons.

RESULTS

The intragroup evaluation showed significant differences among the evaluation times in all groups (p ≤ 0.05). The highest pain sensitivity levels were recorded on the 1st, 8th, and 15th days. In G1, TS manifested for up to 3 days after each bleaching session, while G2, G3, and G4 presented TS only on the days of the bleaching sessions. Intergroup analysis showed that TS manifestation differed significantly between G1 and the other groups (p ≤ 0.05) but did not differ significantly among G2, G3, and G4 (p ≥ 0.05).

CONCLUSION

PBM-LLLT and KNO₃ are effective at reducing pain sensitivity after tooth bleaching, but no synergistic effect between these treatments was observed for the different evaluation periods.

CLINICAL RELEVANCE

The effect of PBM-LLLT combined with KNO₃ on post-bleaching tooth sensitivity is similar to their individual use alone.

Effect of low-level laser therapy combined with 5000 parts per million fluoride dentifrice on postbleaching sensitivity: A clinical, randomized, and double-blind study

OBJECTIVE

The aim of this double-blind, randomized, controlled clinical study was to assess the efficacy of low-level laser therapy (LLLT) combined with 5000 ppm fluoride dentifrice on postbleaching sensitivity in teeth exposed to 35% hydrogen peroxide for four weeks.

MATERIALS AND METHODS

Twenty-five volunteers were evaluated using the split-mouth model in which the right and left maxillary/mandibular quadrants were randomized and allocated to one of two groups: GPLACEBO, in which the laser tip was positioned without the emission of light (placebo effect) + 5000 ppm sodium fluoride, or GLASER, which comprised LLLT + 5000 ppm sodium fluoride. For both groups, LLLT and placebo were used before bleaching, whereas fluoride was applied after bleaching. LLLT was applied at two points: on the central cervical and medial regions of the incisors, canines, and premolars in the corresponding hemi-arch. At each point, 60 J/cm² was applied for 16 seconds with an irradiance of 3.75 W/cm² using the therapeutic infrared device. To assess tooth sensitivity, a modified visual analogue scale was used after an evaporative stimulus, and a daily pain questionnaire was also applied.

RESULTS

The Wilcoxon and Friedman tests demonstrated a significant difference in the incidence of sensitivity pain between GPLACEBO and GLASER (P ≤ .05), with different evaluation times.

CONCLUSION

Teeth treated with laser therapy in combination with the topical use of sodium fluoride at each bleaching session demonstrated less sensitivity compared with the application of sodium fluoride only.

CLINICAL SIGNIFICANCE

The use of a low-level laser therapy in combination with topical use of sodium fluoride improves symptoms of dentin sensitivity at each bleaching session.

At-home Bleaching With 10% vs More Concentrated Carbamide Peroxide Gels: A Systematic Review and Meta-analysis

Objective:

To perform a systematic review to answer the following research question: Is at-home bleaching in adults with more concentrated carbamide peroxide (CP) gels as effective and safe as bleaching performed with 10% carbamide peroxide gels?

Methods and Materials:

A comprehensive search was carried out in the MEDLINE via PubMed, Scopus, Web of Science, LILACS, BBO, Cochrane Library and SIGLE, without restrictions. IADR abstracts (1990 to 2016) and unpublished and ongoing trial registries, dissertations and theses (ProQuest Dissertations and Periodicos Capes Theses Databases) were also searched. The risk of bias of the included studies was analyzed using the Cochrane Risk of Bias tool from the Cochrane Collaboration. We meta-analyzed the data using the random effects model to compare 10% CP and more concentrated CP gels in terms of color change (ΔSGU or ΔE) and risk and intensity of tooth sensitivity (TS). The quality of the evidence was rated using the GRADE approach.

Results:

After the database screening, 182 articles remained, and this number was reduced to 17 after examination of the abstracts and/or full texts. Four articles were follow-ups of earlier studies, and thus we collected 13 studies. Ten studies were at unclear risk of bias, while three were at low risk of bias. Lower risk and intensity of TS was observed for 10% CP. The odds ratio for the risk of TS was 0.41 (95% CI 0.20 to 0.84, p=0.01), and the difference in means for TS intensity was 0.44 (95% CI 0.67 to −0.20, p=0.0003). No significant difference was observed in terms of color change in ΔSGU (difference in means 0.29; 95% CI 0.25 to 0.83, p=0.29) and for ΔE (difference in means −0.16; 95% CI 0.38 to 0.06, p=0.16). Except from the ΔSGU, for which the evidence was graded as low quality, the other outcomes were considered at moderate quality.

Conclusions:

At-home bleaching with 10% CP showed similar bleaching efficacy with lower risk and intensity of TS in comparison with more concentrated carbamide peroxide gels.

Randomized controlled clinical trial on bleaching sensitivity and whitening efficacy of hydrogen peroxide versus combinations of hydrogen peroxide and ozone

The clinical efficacy regarding bleaching sensitivity and tooth shade lightening using a standard hydrogen peroxide (H₂O₂) bleaching gel was compared with the additional use of ozone either before or after application of H₂O₂. Using computer-generated tables, 45 participants were randomly allocated into three groups (n = 15 each) in this investigator-driven, single-centre trial. In Group 1, upper anterior teeth were bleached using ozone (produced via a healOzone X4 device) for 60 seconds, then 38% H₂O₂ for 20 minutes; in Group 2, 38% H₂O₂ application (20 min) was followed by ozone (60 s); air produced by the healOzone machine (60 s) followed by 38% H₂O₂ (20 min) was used in Group 3 (control). Bleaching sensitivity was evaluated via visual analogue scales, and a treatment-blinded reader objectively recorded tooth shades using a colorimeter before and 24 hours after bleaching (at α = 0.05). The H₂O₂/ozone combination did not result in pain sensations, while both ozone/H₂O₂ and H₂O₂ alone increased bleaching sensitivity (p < 0.001). Teeth achieved lighter shades (higher L*/lower b* values) after bleaching in all groups (p < 0.001), while Ozone boosted lighter tooth shades, irrespective of its use before or after H₂O₂ (p < 0.05). Due to the complimentary effects, applying ozone after H₂O₂ seems preferable for bleaching.

Preemptive use of etodolac on tooth sensitivity after in-office bleaching: a randomized clinical trial

Purpose

This study determined the effectiveness of the preemptive administration of etodolac on risk and intensity of tooth sensitivity and the bleaching effect caused by in-office bleaching using 35% hydrogen peroxide.

Material and methods

Fifty patients were selected for this tripleblind, randomized, crossover, and placebo-controlled clinical trial. Etodolac (400 mg) or placebo was administrated in a single-dose 1 hour prior to the bleaching procedure. The whitening treatment with 35% hydrogen peroxide was carried out in two sessions with a 7-day interval. Tooth sensitivity was assessed before, during, and 24 hours after the procedure using the analog visual scale and the verbal rating scale. Color alteration was assessed by a bleach guide scale, 7 days after each session. Relative risk of sensitivity was calculated and adjusted by session, while overall risk was compared by the McNemar's test. Data on the sensitivity level of both scales and color shade were subjected to Friedman, Wilcoxon, and Mann-Whitney tests, respectively (α=0.05).

Results

The preemptive administration of etodolac did not affect the risk of tooth sensitivity and the level of sensitivity reported, regardless of the time of evaluation and scale used. The sequence of treatment allocation did not affect bleaching effectiveness, while the second session resulted in additional color modification. The preemptive administration of etodolac in a single dose 1 hour prior to in-office tooth bleaching did not alter tooth color, and the risk and intensity of tooth sensitivity reported by patients.

Conclusion

A single-dose preemptive administration of 400 mg of etodolac did not affect either risk of tooth sensitivity or level of sensitivity reported by patients, during or after the in-office tooth bleaching procedure.

Influence of different types of light on the response of the pulp tissue in dental bleaching: a systematic review

OBJECTIVES

This systematic review (PROSPERO register: CRD42016053140) investigated the influence of different types of light on the pulp tissue during dental bleaching.

MATERIALS AND METHODS

Two independent authors conducted a systematic search and risk of bias evaluations. An electronic search was undertaken (PubMed/Medline, Embase, The Cochrane Library, and other databases) until May 2017. The population, intervention, comparison, outcomes (PICO) question was: "Does the light in dental bleaching change the response of the pulp to the bleaching procedure?" The intervention involved pulp tissue/cells after bleaching with light, while the comparison involved pulp tissue/cells after bleaching without light. The primary outcome was the inflammation/cytotoxicity observed in pulp after bleaching.

RESULTS

Out of 2210 articles found, 12 articles were included in the review; four were in vivo studies (one study in dogs/others in human), and eight were in vitro studies (cell culture/with artificial pulp chamber or not). The light source used was halogen, light-emitting diode (LED), and laser. Only one in vivo study that used heat to simulate light effects showed significant pulp inflammation. Only two in vitro studies demonstrated that light influenced cell metabolism; one using halogen light indicated negative effects, and the other using laser therapy indicated positive effects. Given that animal and in vitro studies have been identified, there remain some limitations for extrapolation to the human situation. Furthermore, different light parameters were used.

CONCLUSIONS

The effects of dental bleaching on the pulp are not influenced by different types of light, but different light parameters can influence these properties.

CLINICAL RELEVANCE

There is insufficient evidence about the influence of different types of light on inflammation/cytotoxicity of the pulp.

Randomized clinical trial of the effect of NovaMin and CPP-ACPF in combination with dental bleaching

OBJECTIVE

This randomized, controlled, double-blind clinical study evaluated the effect of calcium sodium phosphosilicate (NovaMin) and casein phosphopeptide-amorphous calcium phosphate with fluoride (CPP-ACPF) on the prevention of post-operative sensitivity and on the effects of clinical bleaching treatment.

MATERIAL AND METHODS

Sixty volunteers were selected according to inclusion and exclusion criteria and were randomly assigned into three groups (n=20): CG (control group) patients, who were treated with 35% hydrogen peroxide; NOVAG (NovaMin group) patients, who were treated with 35% hydrogen peroxide followed by the application of NovaMin; and CPPG (CPP group) patients, who were treated with 35% hydrogen peroxide followed by the application of CPP-ACPF. Both bioactive agents were applied for five minutes. An evaporative stimulus associated with a modified visual scale was used to analyze sensitivity 24 hours after each bleaching session. The color evaluation was performed on the maxillary central incisors using a spectrophotometer. Associations between the intervention group, bleaching session, and reported sensitivity were tested using Chi-square partitioning.

RESULTS

Color change values (ΔE) were analyzed using analysis of variance (ANOVA). The significance level used for both tests was 5%. In the intragroup assessment, the Friedman test showed that only the CPP-ACPF group showed no statistically significant difference (p<0.05) between baseline and first bleaching session. In the intergroup assessment, the Kruskal-Wallis test showed that the CPPG had less postoperative sensitivity after the first session, when compared to the other groups (p<0.05). Color change analysis (ΔE) showed a significant difference between the means obtained in the different bleaching sessions in all groups (p<0.05).

CONCLUSIONS

This study showed that the combination of CPP-ACPF with 35% hydrogen peroxide significantly reduced post-operative sensitivity in the first session, compared with the other evaluated treatments. The association of CPP-ACPF and NovaMin did not affect the color change induced by tooth bleaching.

Comparison of Effectiveness and Sensitivity Using Two In-Office Bleaching Protocols for a 6% Hydrogen Peroxide Gel in a Randomized Clinical Trial

Objective:

The aim of this blinded and randomized clinical trial was to compare two application protocols (one 36-minute application vs three 12-minute applications). We then assessed the effectiveness of the bleaching and any increase in sensitivity that was induced by bleaching via a split-mouth design.

Methods and Materials:

Thirty patients were treated. One group had a half arch of teeth treated with a traditional application protocol (group A: 3 × 12 minutes for two sessions). The other received an abbreviated protocol (group B: 1 × 36 minutes over two sessions). Two sessions were appointed with a two-day interval between them. The tooth color was registered at each session, as well as one week and one month after completing the treatment via a spectrophotometer. This measured L*, a*, and b*. This was also evaluated subjectively using the VITA classical A1-D4 guide and VITA Bleachedguide 3D-MASTER. Tooth sensitivity was registered according to the visual analogue scale (VAS) scale. Tooth color variation and sensitivity were compared between groups.

Results:

Both treatments changed tooth color vs baseline. The ΔE* = 5.71 ± 2.62 in group A, and ΔE* = 4.93 ± 2.09 in group B one month after completing the bleaching (p=0.20). No statistical differences were seen via subjective evaluations. There were no differences in tooth sensitivity between the groups. The absolute risk of sensitivity reported for both groups was 6.25% (p=0.298). The intensity by VAS was mild (p=1.00).

Conclusions:

We used hydrogen peroxide (6%) that was light activated with a hybrid LED/laser and two different protocols (one 36-minute application vs three 12-minute applications each for two sessions). These approaches were equally effective. There were no differences in absolute risk of sensitivity; both groups reported mild sensitivity.

Effect of Adhesive Restoration and Bleaching Technique on the Concentration of Hydrogen Peroxide In the Pulp Chamber

This study aimed to quantify the concentration of hydrogen peroxide into the pulp chamber in the presence or absence of adhesive enamel restorations and to analyze the resin-dentin interface of bleached groups. Bovine incisors (120) were randomly divided into three groups according to enamel treatment (n=40 each): (1) enamel without restoration (control); (2) enamel cavities (3 mm diameter × 1.5 mm depth) restored with a silorane-based (SB) system; or (3) enamel cavities (3 mm diameter × 1.5 mm depth) restored with a dimethacrylate-based (DB) system. Restorations were thermocycled, and all groups were submitted to one application of 35% hydrogen peroxide (HP) agent for 45 minutes and subjected to four light activation methods (n=10 each): without light, light-emitting diode (LED), LED/diode laser, or halogen light. Acetate buffer solution was placed into the pulp chamber before bleaching, and this solution was collected to spectrophotometrically determine the concentration of HP that reached the pulp chamber after bleaching. Rhodamine B was added to the HP agent and applied on additional enamel samples of each group for 24 hours. Samples were sectioned mesiodistally, and the bleaching agent was traced using confocal microscopy. According to two-way analysis of variance and Tukey test (α=0.05), the HP concentration in the pulp chamber of the control group was significantly lower than that of the SB group (p&lt;0.05), regardless of light activation. No differences were observed between DB and SB groups and between control and DB groups, except for the DB halogen light activated group, which exhibited higher HP intrapulpal concentration (p&lt;0.05). Confocal microscopy exhibited HP diffusion through the interface of the SB and DB restored groups as well as enamel prisms in the control group. The SB restorative system increased the HP diffusion into the pulp chamber, but HP was able to diffuse even in the absence of enamel restorations.

Response of human pulps to different in-office bleaching techniques: preliminary findings

This study evaluated a whitening effect and the likely side effect (tooth sensitivity and pulp response) of human teeth subjected to different in-office bleaching (IOB) techniques and materials, mainly the presence of calcium in the IOB materials. A calcium-free (CF) and a calcium-containing (CC) 35% hydrogen peroxide (HP) gels were evaluated. The CF was refreshed every 15 minutes, three times (CF 3-15) or in a single 45-min application (CF 1-45) at one bleaching appointment. The CC was used only in a single 45-min application (CC 1-45). Each technique was applied in 5 mandibular incisors scheduled for extraction for different patients. In control group, no tooth bleaching was performed. The tooth colour (TC) and tooth sensitivity (TS) were recorded at baseline and after IOB. The teeth were extracted 2 days after the application of IOB and subjected to histological analysis. The data was submitted to appropriate statistical analysis (α=0.05). The changes of TC were similar between groups and statistically different from the control (p<0.05). However, TS of groups bleached with CF was statistically higher than that recorded for CC and the control (p<0.05). In CF 3-15 and CF 1-45 groups, the coronal pulp tissue exhibited partial necrosis associated with tertiary dentin deposition. In CC 1-45 group smaller area of necrosis occurred only in three bleached teeth in which tertiary dentin deposition was observed. The calcium-containing 35%HP gel could be preferable for in-office bleaching because it caused less tooth sensibility and pulp damage.

Inflammatory response of human dental pulp to at-home and in-office tooth bleaching

Tooth bleaching is a technique of choice to obtain a harmonious smile, but bleaching agents may damage the dental pulp.

Evaluation of temperature increase during in-office bleaching

The use of light sources in the bleaching process reduces the time required and promotes satisfactory results. However, these light sources can cause an increase in the pulp temperature.

Clinical Evaluation of Genotoxicity of In-office Bleaching

Objective: The aim of this study was to evaluate the genotoxicity of in-office bleaching with 35% hydrogen peroxide in epithelial cells from the gingival and lip tissues.

Methods and Materials: Thirty volunteers with central incisors shade A1 or darker were selected for this study. The gingival tissue of the teeth to be bleached was isolated with a light-polymerized resin dam, and the 35% hydrogen peroxide gel was administered during three 15-minute applications over the course of the 45-minute application period. Two bleaching sessions with a one-week interval in between were performed. Exfoliated oral mucosa gingival epithelial cells and upper lip lining were collected at baseline and one month after the in-office dental bleaching. The scraped cells were placed on clean glass slides and smears were prepared. After staining with Giemsa solution, two blinded examiners performed cell and micronuclei counts under a 100× optical microscope. Tooth sensitivity was evaluated using the Visual Analogue Scale (VAS). Shade evaluation was recorded before and one month after the bleaching treatment with the value-oriented shade guide Vita Bleachedguide 3D-MASTER and the spectrophotometer Vita Easyshade. Data from the shade guide units and the micronuclei (MN) frequency were subjected to a Mann-Whitney test (α=0.05). The overall difference between before and one month after the bleaching treatment (ΔE and ΔSGU), absolute risk, and intensity of tooth sensitivity (TS) were calculated, as was the 95% confidence interval (CI).

Results: The frequency of MN was not increased after bleaching with 35% hydrogen peroxide in both study groups (p&gt;0.05). The absolute risk of TS of the participants was 93% (95% CI, 79%-98%), with a mean VAS intensity of 5.7 ± 2.9 (95% CI, 4.6-6.8). Meaningful whitening was observed after bleaching. The change in shade guide units in the Bleachedguide 3D-MASTER was 2.3 ± 1.4. In terms of ΔE, the change in color was 7.7 ± 3.5.

Conclusions: The in-office bleaching did not induce DNA damage to the gingival and lip tissue during the bleaching period. Although effective whitening was observed, most of the participants experienced TS.

Experimentally Induced Pulpal Lesion and Substance P Expression: Effect of Ketoprofen-A Preliminary Study

Objectives. To evaluate substance P (SP) and the effect of ketoprofen administration, a nonsteroidal anti-inflammatory drug (NSAID), on SP in the pulp of upper third molars with experimentally induced pulpal lesion. Materials and Methods. A sample of 20 young systemically healthy adults of both sexes, nonsmokers, with a healthy upper third molar to extract for orthodontic purposes, was selected. Prior to the procedure, an inflammatory process was generated by mechanical exposure of the pulp. After 15 minutes, the pulp was collected using a sterile barbed broach. SP levels were determined by using a commercially available enzyme immunoassay (ELISA) kit. The subjects were randomly divided into two groups: group 1 received a dose of ketoprofen 30 minutes prior to the experimental procedure. The subjects of group 2 did not receive any kind of drug administration. The patients were asked to complete a diary on the postoperative pain. Results. No statistically significant difference could be detected in SP expression between the two groups. In group 1, pain manifestation was significantly delayed in comparison with group 2. Conclusions. Preventive administration of ketoprofen did not significantly affect the pulpal levels of SP but resulted in a significantly postponed manifestation of pain after extraction.

Effectiveness of a desensitizing agent before in-office tooth bleaching in restored teeth

OBJECTIVES

The aim of this clinical trial was to evaluate the effectiveness and tooth sensitivity associated with bleaching in patients with composite restorations in anterior teeth after the application of a desensitizing agent.

MATERIAL AND METHODS

Bleaching was performed with 35 % hydrogen peroxide gel in 30 patients with composite restorations in anterior teeth, divided according to the prior application of a desensitizing agent (De), or a placebo (Pl), on maxillary superior teeth. Color was recorded at baseline, 1 week after each session and 6 months after treatment. The experience of tooth sensitivity (TS) was recorded on an NRS (0-4) during bleaching and 24 h after each session. Bleaching effectiveness was evaluated by one-way ANOVA and Tukey's tests (α = 0.05). The percentage of TS was evaluated by Fisher's exact test. For each treatment, periods were compared using the Wilcoxon signed-rank test (α = 0.05), and at each period, treatments were compared using Mann-Whitney U test.

RESULTS

Both groups showed similar tooth color enhancement and color stability after 6 months (p < 0.05). No significant difference in prevalence of sensitivity was detected between groups (p < 0.001). Higher TS intensity (median [first/third quartiles]) was observed for Pl (1.5 [1/1.75]) compared with De (0.5 [0/1]) during treatment (p < 0.05).

CONCLUSIONS

The use of a desensitizing gel (5 % potassium nitrate, 2 % sodium fluoride) before tooth bleaching in patients with composite restorations did not reduce the prevalence of tooth sensitivity, but reduced the intensity of TS during bleaching.

CLINICAL RELEVANCE

Although the use of a desensitizing agent before bleaching, in patients with composite resin restorations, did not reduce the prevalence of TS, a reduction of the TS intensity during the protocol was observed without jeopardizing the whitening outcome.