Intracoronal Bleaching Research Articles

Clinical efficiency of a sodium perborate - hydrogen peroxide mixture for intracoronal non-vital teeth bleaching

Introduction/Objective. The aim was to evaluate initial efficiency of sodium perborate (tetrahydrate) and 30% hydrogen peroxide mixture for intracoronal non-vital teeth bleaching (?walking bleach? technique). Methods. Forty patients with discolored teeth were included in the study. Based on their history and clinical examination, causes of discoloration were classified as necrotic pulp, ?endo-sealer? or unknown. The ?walking bleach? technique was performed by applying sodium perborate (tetrahydrate) and 30% hydrogen peroxide mixture intracoronally to cavity dentin walls. The mixture was renewed in seven-day intervals. Tooth color was assessed visually before, during, and after the procedure using the Vita Classical shade guide (Vita Zahnfabrik, Bad Sackingen, Germany). Numerical values or shade guide units (SGU) were assigned to Vita shade tabs on a bright-dark scale. Analysis of variance, t-test, correlation and regression analysis were used to analyze the data (p < 0.05). Results. On average, 26 ? 9 days or 3?4 appointments were required for intracoronal bleaching to achieve the desired or best possible shade. Better clinical efficiency was found in the necrotic pulp group (17 ? 6 days; 8 ? 3 SGU) than in the ?endo-sealer? group (42 ? 13 days; 4 ? 2 SGU) (p < 0.05). Age significantly influenced bleaching efficiency (p < 0.05). There was no significant correlation between bleaching efficiency and initial shade (p > 0.05). Conclusion. Intracoronal, non-vital teeth bleaching (?walking bleach? technique) using sodium perborate (tetrahydrate) and 30% hydrogen peroxide mixture showed satisfactory clinical efficiency. Discoloration caused by pulp necrosis was treated more efficiently than that caused by endodontic sealers. Younger age had a positive effect and discoloration intensity had no effect on bleaching efficiency.

Six-month Follow-up of the Effect of Nonvital Bleaching on IL-1β and RANK-L: A Randomized Clinical Trial.

It has been reported that bleaching generates an increase in the activity of osteoclasts in vitro. We quantified the RANK-L and IL-1β biomarkers in a double-blind, randomized clinical trial evaluating the in vivo effect of hydrogen peroxide (35%) and peroxide carbamide (37%) six months after whitening. Fifty volunteers participated, each with color change in a nonvital tooth. Fifty teeth were randomly divided into two groups (n=25), and the teeth were bleached using either 35% hydrogen peroxide (G1) or 37% carbamide peroxide (G2). Intracoronal bleaching was carried out by a technical "walking bleach" over four sessions. Gingival crevicular fluid samples were collected and used to quantify the IL-1β and RANK-L secreted levels. Samples of six periodontal sites (three vestibular and three palatal) were collected for up to six months (at the beginning of the study [baseline] and at one week, one month, and six months posttreatment). The color change was visually monitored using the Vita Bleached Guide (ΔSGU). Comparing each time to baseline assessment, a significant increase in the levels of IL-1β and RANK-L across time points was detected (p<0.05). The color change was 4 in G1 and G2, and a statistically significant difference (p<0.05) was found at the month time point between the groups. Using the Spearman test, a strong correlation (>0.8) between the IL-1β and RANK-L levels in both groups at all time points was detected. Nonvital bleaching using a technical walking bleach induces an increase in the IL-1β and RANKL production in periodontal tissues, which persists for six months after treatment. Both biomarkers were highly correlated in both groups and at all time points.

РЕЗУЛЬТАТЫ ВНУТРИКОРОНКОВОГО ОТБЕЛИВАНИЯ ДЕПУЛЬПИРОВАННЫХ ЗУБОВ

&#x0D; Изменение в цвете депульпированного зуба – весьма распространенное и многофакторное по этиологии явление, являющееся частой причиной обращения к стоматологу, особенно если потемневший зуб находится в линии улыбки. Цвет зубов, в свою очередь, наряду с их формой и оптическими свойствами, является важнейшим эстетическим критерием современного человека. Одним из способов исправления цвета таких зубов является внутрикоронковое отбеливание. Целью исследования было оценить эффективность внутрикоронкового отбеливания и восстановления флуоресцентных свойств депульпированных зубов в зависимости от типа используемого силлера при эндодонтическом лечении и причин депульпирования. Для изучения эффективности внутрикоронкового отбеливания депульпированных зубов провели отбеливание 194 зубов 190 пациентам, обратившихся в Клинику ВГМУ и на кафедру терапевтической стоматологии с курсом ФПК и ПК УО «ВГМУ» в период 2014–2018 гг. с жалобами на изменение в цвете зубов после эндодонтического лечения. Средний возраст пациентов составил 34,6±8,2 года. Результаты полученных данных свидетельствуют о том, что эффект отбеливания с восстановлением цвета и флуоресцентных свойств до исходных характеристик витального зуба был достигнут у 72 зубов из 194 (37,11%). У 122 зубов (62,89%) необходимого отбеливания и восстановления флуоресценции не произошло. Из них частично отбелилось 68 зубов (35,05%), не отбелилось 54 зуба (27,84%). В зубах, корневые каналы которых были обтурированы материалами на основе эвгенола, цветовые и флуоресцентные параметры восстановлены в 50% случаев. При обтурации корневых каналов депульпированных зубов силлером на основе резорцин-формалина восстановления цвета и флуоресценции не произошло ни в одном из случаев. Зависимости эффективности отбеливания депульпированных зубов от причины, вызвавшей дисколорит, не выявлено. Однако наиболее частой причиной возникновения изменения в цвете депульпированного зуба был осложненный кариес.&#x0D;

Effects of intracoronal bleaching agents on the surface properties of mineral trioxide aggregate.

Bleaching agents may affect surface properties of mineral trioxide aggregate (MTA) as a coronal barrier. The purpose of this study was to investigate surface properties of MTA after exposure to intracoronal bleaching agents. MTA was set in acrylic molds with a 4mm high central hole and a 6mm diameter. Specimens were divided into four groups (n = 10); three groups were exposed to bleaching agents three times on every fourth day (carbamide peroxide-CP, hydrogen peroxide-HP, sodium perborate-SP) and a control group-C. The surface roughness and Vickers surface microhardness were measured. Differences between groups were analyzed using a Kruskal-Wallis test and intergroup comparisons were assessed with a Mann-Whitney U test with a Bonferroni correction (p < 0.0001). The microstructure and elemental composition were observed using a scanning electron microscope (SEM) and an energy-dispersive X-ray microanalysis (EDX) system. In terms of microhardness, the decrease in the HP group was significantly greater than that of the CP and SP groups; CP group significantly greater than that of the SP group, however, there was no significant difference between the SP and C groups. Surface roughness values were compared between groups, and no significant differences were observed between the CP and HP groups, and they exhibited significantly higher roughness values than the SP and C groups. SEM/EDX showed that the bleaching agents affected the elemental distribution. Bleaching agents adversely affected the surface roughness, surface microhardness and elemental distribution of MTA, with exposure to SP causing fewer changes on the surface properties than CP or HP.

Radicular Peroxide Penetration from Different Concentrations of Carbamide Peroxide Gel during Intracoronal Bleaching—An In vitro Study

The aim of this study is to evaluate and compare the amount of radicular peroxide penetration when various concentrations of carbamide peroxide (CP) bleaching gels (10, 15, and 35%) and a mixture of 30% hydrogen peroxide (HP) with sodium perborate are used for intracoronal bleaching. Fifty extracted single-rooted premolars from young adults were used. The specimens were then divided into five groups such that teeth with varying sizes were equally distributed in all groups. Group I-distilled water (control group), group II-10% CP, group III-15% CP, group IV-35% CP, and group V-30% HP with sodium perborate. Intermediate restorative material (IRM) was used to seal access cavities and left for a week at 37 °C in an incubator. Following the bleaching process, suspended teeth from plastic tubes containing distilled water were removed and the water was used to determine the amount of peroxide levels. A UV-visible spectrophotometer at a wavelength of 480 nm was used to determine the quantity of peroxide based on the optical density. Results showed the highest peroxide leakage in group V, followed by group IV, and then group III, whereas the least peroxide penetration was found in group II, and the control group or group I showed no penetration. The Kruskal-Wallis test showed a significant difference between the various groups tested. The Mann-Whitney test was done to find in which pair of groups there exists a significant difference. It was found that all the groups when compared among themselves showed a significant difference. The present study concluded that lower concentrations of CP 10 and 15% produced lower peroxide leakage. Hence, it could be tried as an alternate to traditional agents in cases with compromised tooth which shows cervical tooth defects where the risk of external root resorption is higher. The management of discolored teeth involves different techniques; among various techniques, bleaching is considered to be a safe, effective, and relatively noninvasive technique to lighten discolored teeth and it also conserves dental hard tissue.

Sodium percarbonate as a novel intracoronal bleaching agent: assessment of the associated risk of cervical root resorption.

To evaluate the extraradicular peroxide release from sodium percarbonate compared to sodium perborate as an intracoronal bleaching agent. Sixty mandibular single-rooted premolars with intact CEJ were selected. After root filling, gutta-percha was removed 4mm apical to CEJ and 2mm of GIC was condensed over the root filling. Intracoronal bleaching agents were placed into six groups of teeth (n=10): sodium perborate with distilled water (SPW); sodium percarbonate with distilled water (SPCW); sodium perborate with 30% hydrogen peroxide (SPHP); sodium percarbonate with 30% hydrogen peroxide (SPCHP); 30% hydrogen peroxide as positive control (HP) and distilled water as negative control (CL). The teeth were then mounted in vials filled with distilled water, kept in an incubator and taken out at 1, 3 and 6days for spectrophotometric analysis. Extraradicular peroxide release was quantified by the ferrothiocyanate method. Statistical analysis was undertaken with one-way anova and Scheffe post hoc tests. The greatest peroxide release occurred in the HP group, followed by the SPCHP and SPHP groups, and then by the SPCW and SPW groups. Intergroup comparison revealed that there was no significant difference in peroxide release among the groups SPCW and SPW on days 1, 3 and 6 (P>0.05). Similarly, no significant difference was found between the SPCHP and SPHP treated groups on days 1, 3 and 6 (P>0.05). Extraradicular peroxide release from sodium percarbonate was comparable to that of sodium perborate, as the differences were not significant.

In-office and walking bleach dental treatments on endodontically-treated teeth: 25 years follow-up.

Many techniques have been evolved for the purpose of managing discoloured non-vital tooth such as dental bleaching, restorative and prosthetic treatment. In order to achieve better control on the patients, in-office and intra-coronal bleaching procedures were introduced in clinical practice. Such techniques usually use higher whitening agent concentrations activated by means of heat or light sources, resulting in improved color stability in the long term. The aim of this study was to evaluate the color stability, after 25 years, of endodontically-treated teeth subjected to in-office and walking bleach dental treatments with carbamide peroxide. A population of patients with a single endodontic treatment on an incisor teeth was recruited. All the teeth selected for the study were subjected to both in-office intra-coronal dental bleaching and walking bleach technique with 10% carbamide peroxide gel. The patients were recalled at follow-up every 12 months for a total observational period of 25 years. After 25 years of clinical service on 40 patients, an optimal tooth color stability in relation to adjacent teeth was evidenced in 34 patients, while 6 patients were classified as failures, since a color mismatch of two or more shades were noticed. Consequently, a success rate of 85% was reported after 25 years. Ten percent carbamide peroxide proved to be an effective dental whitening agent in the long-term for endodontically-treated.

Color Regression and Maintenance Effect of Intracoronal Whitening on the Quality of Life: RCT—A One-year Follow-up Study

This randomized clinical study evaluated two parameters: 1) the clinical color rebound of whitening patients' tooth discoloration using the walking bleaching technique and 2) the impact on psychological and aesthetic self-perception at the one-year follow-up of patients who underwent bleaching of nonvital teeth. Fifty study participants with nonvital tooth discoloration were recruited. Teeth were assigned randomly into one of two groups: 1) 35% hydrogen peroxide (n=25) and 2) 37% carbamide peroxide (n=25). Intracoronal bleaching was carried out over the course of four sessions using the walking bleach technique. Tooth color was evaluated after each session in order to measure the total color variation (ΔE). The guide was arranged from highest (B1) to lowest values (C4) for evaluating color, and color changes using Vita Classical Shade (ΔSGUs) units were calculated. Subjective and objective assessments were compared with the counterpart of the tooth. Aesthetic perception and psychosocial factors were evaluated before and after treatment by the Oral Health Impact Profile (OHIP) and Psychological Impact of Dental Impact Questionnaire (PIDAQ) surveys. Color changes (ΔE) were 15.48 ± 5.17 and 14.02 ± 4.85 for carbamide and hydrogen peroxide groups, respectively. There were no significant differences ( p>0.05) between these two groups at the one-year follow-up. There was a decrease in the PIDAQ scores after treatment compared to baseline values ( p<0.05). The majority of OHIP values regressed to baseline values. The technique of walking bleaching was highly effective and showed minimal color rebound in nonvital teeth and had a positive effect on patients' psychological impact at the one-year follow-up.

The Effects of Antioxidant Application and Time Factor on Fiber Post Bonding to Root Dentin after Intracoronal Bleaching

Aim: The aim was to evaluate the effects of antioxidant application and delayed cementation on the bond strength of fiber posts after intracoronal bleaching.&#x0D; Methodology: Fifty-five maxillary central incisors were used. Root canals were enlarged using Reciproc system up to R40 instrument. Root canals were irrigated, dried with paper-points, and obturated with gutta-percha and a sealer. In 44 teeth, root canal fillings were removed 2-mm coronally and canal orificies were sealed with glass-ionomer-cement. A 37% CP gel was used to bleach the teeth. Five experimental groups were defined (n=11). G1: No bleaching, G2: Immediate FPC, G3: Immediate FPC after SA application, G4: 14-days delayed FPC, G5: 14-days delayed FPC after SA application. Push-out tests were performed. Statistical interpretations were made (α=0.05).&#x0D; Results: There was no significant difference among the groups in apical thirds (p&gt;0.05). However, significant differences were detected among the groups in middle and coronal thirds (p&lt;0.05).&#x0D; Conclusion: The 14-days delayed cementation seems to be a more reliable method than the SA application before FPC procedure after intracoronal bleaching.

Effect of Various Bleaching Agents on the Surface Composition and Bond Strength of a Calcium Silicate-based Cement.

This study aimed to evaluate the morphological and elemental changes that occur on the surface of calcium silicate-based cement (CSC) and to analyze the bond strength of composite resin to CSC after application of various bleaching agents. One hundred twenty-five CSC blocks (Biodentine) were prepared and randomly divided into five groups according to the bleaching agent applied over the material surface (n=25): SP-DW (sodium perborate-distilled water mixture), SP-HP (sodium perborate-3% hydrogen peroxide [H2O2] mixture), CP (37% carbamide peroxide gel), HP (35% H2O2 gel), and a control group (no bleaching agent). After 1 week, scanning electron microscopy provided an analysis of the surface morphology and elemental composition for 10 specimens from each group. Composite resin was placed at the center of each cement surface in the remaining specimens (n=15). A universal testing machine determined shear bond strength (SBS) and fracture patterns were identified with a dental operating microscope. Data were analyzed using one-way analysis of variance and Tukey HSD tests. The cement surface in the CP and HP groups presented changes in structure and elemental distribution compared with the remaining groups. The former groups exhibited a decrease in the calcium level and an increase in the silicon level and presented significantly fewer SBS values than the remaining groups ( p<0.05). Most failures were adhesive in the CP and HP groups, while they were predominantly cohesive in the remaining groups. The bleaching agents with higher concentration induced deterioration of the cement surface and negatively affected the bond strength of the composite resin to CSC. The use of CSC is recommended as a cervical barrier when intracoronal bleaching is performed with a mixture of sodium perborate with water or 3% H2O2.

Aferição do pH de diferentes agentes clareadores indicados para o clareamento intracoronário

Objetivo: Aferir os valores de pH de diferentes produtos clareadores indicados para uso na técnica intracoronária em diferentes intervalos de tempo. Materiais e métodos: Para cada grupo experimental (G), foram preparadas cinco amostras (n=5): G1 – água destilada (AD); G2 – peróxido de hidrogênio (H2O2) a 30%; G3 – perborato de sódio (PbS) + AD; G4 – PbS + H2O2 a 30%; G5 – percarbonato de sódio (PcS) + AD; e G6 – PcS + H2O2 a 30%. O pH foi determinado por um pHmetro digital, em diferentes intervalos de tempo: imediatamente após a manipulação (T0), 24 horas (T1) e 168 horas após a manipulação (T2). Os dados obtidos foram submetidos à análise estatística por meio do teste de Kruskal-Wallis, seguido pelo teste de Mann Whitney para comparações múltiplas entre os grupos. Para verificar o efeito do tempo em cada grupo, foi aplicado o teste de Friedman. Resultados: Na avaliação do efeito do tempo em cada grupo, observou-se que G2 apresentou comportamento ácido, enquanto os demais grupos exibiram valores de pH próximos da neutralidade ou alcalinos. Conclusão: H2O2 30% foi o único agente que apresentou comportamento ácido em todos os tempos de avaliação, e a mistura PcS + H2O foi a que apresentou os maiores valores de pH.

Dentin bond strength and nanoleakage of the adhesive interface after intracoronal bleaching.

This study evaluated dentin bond strength (BS) and nanoleakage of non- and pre-etched dentin immediately (T0 ,), 7 days (T7 ), and 14 days (T14 ) after bleaching. Bovine incisors (150) were selected and half of them submitted to intrapulpal dentin etching (e). Non- and pre-etched dentin were subjected to the following (n = 15): no bleaching/control (C); 35% carbamide peroxide (CP); 35% hydrogen peroxide (35% HP); 25% hydrogen peroxide (25% HP); and sodium perborate (SP). Bleaching agents were applied to the pulp chamber four times within a 72-h interval. Afterwards, pulp chamber dentin was prepared for the BS test at different evaluation times (n = 5): T0 , T7 , and T14 . Composite blocks were built on pulp chamber and sectioned in slices. Slices were reduced to an hour-glass shape with a cross-sectional area of 0.8 mm2 and submitted to microtensile BS test. Two additional specimens for each group were prepared for nanoleakage evaluation by transmission electron microscopy (TEM). Results were analyzed by ANOVA (two-way) and Dunnett's test (p < .05). BS decreased immediately after intracoronal bleaching for both sound and pre-etched dentin (p < .05). At T14 , the BS of non-etched bleached dentin increased for all groups, whereas the pre-etched SPe group presented BS similar to the Ce. Nanoleakage within the hybrid layer was perceptible immediately after bleaching, although a decrease in nanoleakage was observed for all groups at T14 . Adhesive restorations should be performed 7-14 days after bleaching, according to the bleaching agent used. Intracoronal bleaching should be performed preferably with sodium perborate if previous dentin etching is applied.

Effectiveness and Impact of the Walking Bleach Technique on Esthetic Self-perception and Psychosocial Factors: A Randomized Double-blind Clinical Trial.

This trial evaluates the impact of psychosocial and esthetic self-perceptions of patients undergoing nonvital tooth bleaching using the walking bleach technique. We also assessed the clinical effectiveness of bleaching tooth discoloration. Fifty volunteers with nonvital tooth discoloration were enrolled. Teeth were randomized into two groups: 35% hydrogen peroxide (n=25) and 37% carbamide peroxide (n=25). Intracoronal bleaching was performed over four sessions using the walking bleach technique. Tooth color was evaluated at each session to measure total color variation. The shade guide was arranged from highest (B1) to lowest (C4) values to assess the color and calculate the color change in the number of shade guide units. Subjective and objective assessments were compared with the tooth counterpart. Esthetic self-perception and psychosocial factors were assessed before and after treatment. Color change was 15.48<5.17 for hydrogen peroxide and 14.02<4.85 for carbamide peroxide. There was no significant difference at any time point (p>0.05) except at sessions 3 and 4 (p<0.05). Overall, whitened teeth values were similar to those of counterpart teeth (p>0.05). There was a decrease in Oral Health Impact Profile and Psychosocial Impact of Dental Esthetics questionnaire scores after treatment compared with baseline (p<0.05). The walking bleach technique was highly effective on nonvital teeth and had a positive effect on self-esthetic perception and psychological impact for the patients.

Effect of access design on intracoronal bleaching of endodontically treated teeth: An ex vivo study.

To determine the effect of access design on intracoronal bleaching with 35% carbamide peroxide on discolored teeth. Forty-two intact maxillary central incisors were selected, sectioned and artificially stained using whole blood. Color measurements were performed with a spectrophotometer: before staining (T1), after staining (T2), at 7 (T3), and 14 (T4)days postbleaching. After T1, specimens were stratified and divided randomly into two groups according to access design (N=20): G1: contracted endodontic cavity (CEC) access performed with a #848-010M bur and G2: traditional endodontic cavity (TEC) access done with a #1157bur. Canals were obturated, a cervical barrier was placed and 35% carbamide peroxide was sealed in the chamber for 7days and replaced at 7days for an additional 7days. Data were collected based on CIELAB-CIE1976 (L* a* b* ) system. Repeated measures SNK anova was used to evaluate the effects of access design and time on color change (ΔE* ) and luminosity (L* ) (α<0.05). For CEC, L* was significantly different at all times points (P<.05). For TEC, L* values were significantly different at all time points (P<.05) except for T0 and T4, which were similar (P>.05). There was no statistical difference for ΔE* between CEC and TEC designs at any time point (P>.05). In general, teeth accessed with CEC or TEC designs showed statistically similar bleaching when using 35% carbamide peroxide. However, lightness values were only reestablished with bleaching through a TEC access design. Despite the current trend to conserve tooth structure when performing endodontic access cavities, the use of conservative access designs for bleaching discolored maxillary central incisors affected the acceptability threshold when compared with a traditional access design. These smaller accesses might not be an alternative treatment option when internal bleaching in the esthetic zone is anticipated.

Concurrent Effects of Bleaching Materials and the Size of Root Canal Preparation on Cervical Dentin Microhardness.

Introduction:The aim of the present study was to evaluate the concurrent effect of root canal preparation size and intra coronal bleaching on dentin microhardness. Methods and Materials:Seventy-two intact anterior teeth were root canal treated and randomly divided into two groups (n=36) according to the size of coronal root canal preparation. The coronal portions of the canals were then enlarged with #2 and 4 Peeso reamers, respectively. Following root canal obturation, teeth were assigned into three groups (n=12) to be treated with bleaching agents containing 35% hydrogen peroxide (HP), sodium perborate (SP) and distilled water as control group. The teeth were stored at 37ºC and 100% humidity for 7 days. Dentinal blocks with 3 mm thickness were obtained from the cervical region and Vickers microhardness number (VHN) were measured for outer and inner dentin in each tooth sample. Data were analyzed using two-way ANOVA and Tukey’s HSD tests.Results:In the outer dentin, the mean VHN in the HP and control groups showed statistically significant differences (P=0.047). The mean VHN of inner dentin for the large preparation size was statistically higher in comparison to the small preparation size (P=0.042). There was a statistically significant difference in the mean VHN of inner dentin with small preparation size between HP and SP groups (P=0.029) and HP and control groups (P=0.021). Conclusion:Intra coronal bleaching with 35% hydrogen peroxide, affects the inner and outer dentin significantly. Excessive removal of cervical dentin, following root canal preparation, alongside the adverse effect of bleaching materials on dentin could result in the tooth fracture.

In Vitro Sealing Properties of Calcium-Enriched Mixture and Mineral Trioxide Aggregate Orifice Barriers during Intra-Coronal Bleaching.

Introduction:This study aimed at evaluating the sealing properties of calcium-enriched mixture (CEM) compared to mineral trioxide aggregate (MTA) as a cervical barriers in intra-coronal bleaching. Methods and Materials:In this in vitro study, endodontic treatment was performed on 60 extracted human incisors and canines without canal calcification, caries, restorations, resorption or cracks. The teeth were then randomly divided into two experimental groups and two control groups (n=15). Then, CEM cement and MTA were applied as 3-mm intra-orifice barriers in the test groups; a mixture of sodium perborate and 30% hydrogen peroxide bleaching agents were placed within the pulp chamber for one week. Dye penetration method was used to evaluate the sealing ability of agents. Statistical analysis was performed using SPSS software. The Kendall coefficient was used to evaluate inter-observer agreement. The chi-squared test was used for statistical analysis. Results:The results showed that the penetration rates of CEM and MTA were the same as positive control group, with no significant differences (P=0.673 and P=0.408, respectively). However, there was a significant difference between the negative control group and CEM and MTA groups (P=0.001 for both groups). In addition, the sealing ability of MTA and CEM cement were not significantly different (P=0.682). Conclusion:During intra-coronal bleaching procedures CEM cement can be used as a cervical barrier with sealing properties comparable to that of MTA.

Effect of different intracoronal bleaching methods on shear bond strength of ceramic brackets bonded to bleached enamel: An in-vitro study.

OBJECTIVE:To investigate the effect of different intracoronal bleaching methods on the shear bond strength and site of failure of ceramic brackets.MATERIALS AND METHODS:Sixty freshly extracted human maxillary incisors were randomly divided into four groups (n = 15). Endodontic access cavity was prepared and root canals were filled, root fillings were removed 2mm apical to the cementoenamel junction, and a 2-mmthick layer of glass ionomer cement base was applied. Group 1 served as the control. Intracoronal bleaching was performed with 35% carbamide peroxide in group 2, sodium perborate in group 3, and 37.5% hydrogen peroxide in group 4. The teeth were immersed in artificial saliva for 4 weeks before bracket bonding. Ceramic brackets were bonded with composite resin and cured with LED light. After bonding, the shear bond strength of the brackets was tested with a universal testing machine. The site of bond failure was determined by modified ARI (Adhesive Remnant Index).RESULTS:The highest value of shear bond strength was measured in control group (18.67 ± 1.59 MPa), which was statistically significant from groups 2,3, and 4. There was no significant difference between groups 2 and 4. The lowest shear bond strength was measured in group 3. ARI scores were not significant from each other.CONCLUSIONS:Intracoronal bleaching significantly affected the shear bond strength of ceramic brackets even after 4 weeks of bleaching. Bleaching with sodium perborate affects shear bond strength more adversely than does bleaching with other agents like hydrogen peroxide and carbamide peroxide.

Antioxidant effectivity to decrease coronal microleakage of composite resin restoration after intra-coronal bleaching

This study aimed to compare the ability of the three antioxidant ingredients and a minimal application to decrease microleakage of composite resin restoration after intracoronal bleaching. Fifty maxillary first incisor that met the inclusion criteria were prepared endodontic treatment. They are divided into 10 groups: control group (no antioxidant), sodium ascorbate 10%, catalase 10% and sodium ascorbate 10% with Tween 80 0.2% and an application period of 1 hour, 24 hours and 48 hours. Applied hydrogen peroxide 35% for 5 days. Samples were restored with composite resin and coated with nail polish, placed China ink for 24 hours. Coronal microleakage was assessed using a stereomicroscope, which showed presented a significant different (ρ&lt;0.05) in 48 hours. It was concluded that sodium ascorbate 10% with Tween 80 0.2% had a significant effect in decreasing coronal microleakage in 48 hours.

Comparison of the Shear Bond Strengths of Ceramic Brackets Using either a Self-Etching Primer or the Conventional Method after Intracoronal Bleaching

Comparison of the Shear Bond Strengths of Ceramic Brackets Using either a Self-Etching Primer or the Conventional Method after Intracoronal Bleaching

Evaluation of Hydroxyl Radical Diffusion and Acidified Thiourea as a Scavenger during Intracoronal Bleaching

IntroductionThe diffusion of hydroxyl radicals in intracoronal bleaching is associated with a risk of invasive cervical resorption. The use of acidified thiourea has been recommended as a scavenger of residual radicals generated during intracoronal bleaching. The aims of this study were to quantify hydroxyl radical diffusion to external root surfaces after intracoronal bleaching with commonly used materials and to evaluate the effect of using acidified thiourea with hydrogen peroxide (H2O2) on hydroxyl radical diffusion. MethodsEighty-two human premolars were prepared, stained, root filled, and allocated to experimental and control groups as follows: group 1: sodium perborate (SP) and water (n = 21), group 2: H2O2 (n = 21), group 3: acidified thiourea and H2O2 (n = 21), group 4: neutral thiourea and H2O2 (n = 10), control group 1: negative control (water) (n = 10), and control group 2: positive control (SP and H2O2) (n = 10). Materials were placed into the pulp chamber, sealed, and placed in 5 mmol/L terephthalic acid at 37°C for 48 hours. Hydroxyl radicals were quantified using a fluorescence microplate reader and high-performance liquid chromatography with fluorescence detection. ResultsThe H2O2 and SP mixture resulted in the greatest hydroxyl radical diffusion and was significantly greater than SP and water (P < .05) and H2O2 (P < .05). The addition of acidified thiourea resulted in higher radical diffusion, whereas the addition of neutral thiourea resulted in lower diffusion than H2O2 alone. ConclusionsThe SP and water mixture resulted in the lowest hydroxyl radical diffusion, and the H2O2 and SP mixture resulted in the greatest. Although the addition of acidified thiourea to H2O2 did not reduce radicals detected, the addition of neutral thiourea had a positive effect.