Intracoronal Bleaching Agents Research Articles

Evaluation of the penetration of intracoronal bleaching agents into the cervical region using different intraorifice barriers

BackgroundThe present study aimed to make a comparison between the effects of 35% hydrogen peroxide gel (HP) and sodium perborate with distilled water (SP) bleaching agents on the sealing characteristics of glass ionomer cement (GIC), TheraBase, ProRoot MTA and Biodentine intraorifice barriers.MethodsOne hundred and twelve single-rooted mandibular human premolar teeth extracted from young patients (14–25 years) were chosen. Root cement and cementoenamel junction (CEJ) of teeth were examined under a stereomicroscope at 10 × magnification to ensure there was no cement defect or dentin gap in CEJ. After the endodontic access cavities were opened on the occlusal surfaces of the teeth, the working length was determined. Instrumentation of each root canal was performed with a ProTaper Gold rotary system in the determined working length and filled with gutta-percha + AH Plus with a single cone technique using. Root fillings were removed 3 mm short of the CEJ and sealed with one of the following intraorifice barrier materials (n = 30/group): 1. GIC; 2. TheraBase; 3. ProProot-MTA; 4. Biodentine. In each of the sub-groups, either HP or SP was used to perform intracoronal bleaching on days 1, 4, and 7. All outer surfaces of the specimens except the 3 mm cervical region were covered with nail polish and modeling wax layers. Specimens were immersed in a 5 ml Eppendorf tube that contained 2 mL of distilled water. The penetration of peroxide release was measured using the colorimetric ferric thiocyanate method. Statistical analysis of the data was performed with Three-way ANOVA and Tukey’s test (P = 0.05).ResultsIn the HP groups, GIC showed the greatest peroxide release when compared with other tested groups on day 1 (P < 0.05). Biodentine and ProRoot MTA displayed a significantly lower peroxide leakage when compared to GIC and TheraBase on days 1 and 4 (P < 0.05). While GIC and TheraBase were used, HP observed higher peroxide penetration when compared with SP on days 1 and 4 (P < 0.05).ConclusionsPeroxide diffusion was significantly influenced by the kind of intracoronal bleaching agents and intraorifice barrier materials used.

Influence of intracoronal bleaching agents on the bond strength of MTA cements to composite resin and their surface morphology.

The objective of the present in vitro study was to evaluate micro-tensile bond strength (µSBS) of MTA cements to composite resin using a universal adhesive after internal bleaching procedure, and to examine surface characteristics of MTA cements exposed to bleaching agents. MTA specimens were divided into three subgroups according to the bleaching agent used which were, 37% carbamide peroxide (CP), 35% hydrogen peroxide (HP), and no exposure as a control group (n = 12). After exposure to bleaching agent, composite resins were applied to MTA surfaces using a universal adhesive in self-etch mode. The specimens were exposed to a shear force until failure to evaluate bond strength. MTA surfaces were investigated using scanning electron microscopy (SEM) to observe the effects of the bleaching agents. Differences between groups were analyzed using two-way ANOVA test and intergroup comparisons were assessed with Tukey test (p < 0.05). Although there was a slight difference in bond strength between bleaching agents (CP and HP), no significant difference was found, irrespective of MTA cement. After the HP application, the bond strength values decreased approximately by half compared with the controls. SEM results demonstrated distinct morphological differences between the intact MTA surface (control) and treated MTA surface. Distinct micro-cracks, surface irregularities, and capillary voids formed due to the superficial dissolution caused by peroxides. Exposure to the intra-coronal bleaching agents had a negative influence on the surface morphology of MTA cements and their bond strength to composite resin.

An in-vitro Comparison of the Bleaching Efficacy of 35 Percent Carbamide Peroxide with Established Intracoronal Bleaching Agents

Introduction: Intracoronal bleaching is the simplest, least invasive, and least expensive means available to lighten non-vital discolored teeth. The objective of the study: To evaluate the intra coronal bleaching efficacy of 35% Carbamide peroxide relative to 35% Hydrogen peroxide and Sodium perborate using artificially stained extracted human teeth. Materials and Methods: Eighty extracted human permanent maxillary and mandibular anterior teeth and single-rooted premolars were artificially stained using whole human blood and root canal treatment was completed. They were bleached twice 7 days apart using: Group I (n=20) – 35% Carbamide peroxide gel, Group II (n=20) – 35% Hydrogen peroxide gel, Group III (n=20) – 2 gm Sodium perborate mixed with per ml of distilled water, Group IV (n=20)– Distilled water only (control). Evaluation of shade was performed on day 0,7,14. Results: On day 7, In Groups I and Group II, there was a reduction in the shade by 2 vita tab positions, whereas Group IIIlightened by 1-tab position only. On day 14, CP and HP lightened by overall 3-tab positions and SP by 2-tab positions. There were no statistical differences between the groups on day 7 and day 14. Conclusion: 35% Carbamide peroxide, 35% Hydrogen peroxide and Sodiumperborate were equally effective for Intra coronal bleaching.

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.

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.

Effects of Three Different Types of Intracoronal Bleaching Agents on Shear Bond Strength of Stainless Steel and Sapphire Brackets Bonded to Endodontically Treated Teeth : An in Vitro Study

Effects of Three Different Types of Intracoronal Bleaching Agents on Shear Bond Strength of Stainless Steel and Sapphire Brackets Bonded to Endodontically Treated Teeth : An in Vitro Study

Effects of conventional and laser activated intracoronal bleaching agents on ultrastructure and mineral content of dentin

Aims and Objectives: The purpose of this in vitro study was to evaluate the ultra structural changes induced in dentin after exposure to different conventiona and laser-activated intracoronal bleaching agents . Materials and Methods: Forty human maxillary teeth were taken and were decoronated through the cemento-enamel junction (CEJ) perpendicular to the long axis of tooth, the crown part was then cut parallel to long axis dividing the tooth into mesial and distal half. Experimental specimen were then divided into two groups (n = 20) in which group 1-35% hydrogen peroxide (Pola office SDI limited Australia) Group 2-30% hydrogen peroxide (J White Heydent GmbH Germany), the groups were further sub-divided into sub-group A - conventional application and Subgroup B - laser activation (Nd: Yag laser Fotona Fidellis III). The specimens were then evaluated under scanning electron microscope (FEI quanta 200 North America) to determine diameter of dentinal tubules and chemical analysis of the same was done. Results : Within the limits of this in vitro study, higher concentration of hydrogen peroxide used as intracoronal bleaching agent: (1) increases dentinal tubule diameter. (2) And also promote alteration in organic and inorganic components of dentin with reduction in calcium/phosphorous ratio leading to demineralization with insignificant difference between conventional application and laser activation. Conclusion : Laser activation of hydrogen peroxide bleaching agent can be added to the present treatment modalities for intracoronal bleaching techniques for faster and more accurate results.

Effect of intracoronal bleaching agents on ultrastructure and mineral content of dentin

Aim:The purpose of this in vitro study was to evaluate the ultrastructural changes of dentin induced after exposure to different intracoronal tooth bleaching agents.Materials and Methods:Dental discs of 1 mm thickness were prepared from coronal dentin of sixty-four human maxillary premolars. Experimental specimens were divided into four subgroups: 45% carbamide peroxide, 35% hydrogen peroxide, sodium perborate + 30% hydrogen peroxide, sodium perborate + water. The specimens were then evaluated under scanning electron microscope to determine diameter of dentinal tubules and chemical analysis.Results:There was significant difference between dentinal tubule diameter of all test and control groups with the exception of sodium perborate + water. Chemical analysis revealed that there was no significant difference between experimental subgroups regarding calcium and sulfur wt%.Conclusions:All bleaching agents increased dentinal tubule diameter and promote alterations in mineral content of dentin with the exception of Sodium perborate mixed with water.

Effect of bleaching agents on sealing properties of different intraorifice barriers and root filling materials

Objective: To evaluate the effect of intracoronal bleaching agents on the sealing properties of different intraorifice barriers and root filling materials. Study Design: The root canals of extracted human premolars (n=180) were prepared by using System GT rotary files and filled with either gutta-percha+AH Plus or Resilon+Epiphany sealer. In both groups, the coronal 3mm of root filling was removed and replaced with one of the following materials applied as intraorifice barriers (n=30/group): 1. ProProot-MTA; 2. Conventional Glass ionomer cement; and 3. Hybrid resin composite. In each subgroup, intracoronal bleaching was performed using either sodium perborate with distilled water or 35% hydrogen peroxide gel for 3 weeks. The leakage of specimens was measured using fluid-filtration and dye penetration tests. The data were analyzed statistically with One-way ANOVA, Repeated Measures t-test and Independent Samples t-test (p=0.05). Results: The fluid conductance values of the test groups were not influenced by the type of the bleaching agent, the intraorifice barrier, or the root filling material (all p>0.05). However, the extent of dye leakage was significantly affected by the type of intraorifice barrier material (p<0.05), which showed the following statistical ranking: glass ionomer cement > resin composite > ProRoot-MTA (p<0.05). Conclusions: The effect of 35% hydrogen peroxide gel or sodium perborate/distilled water on the sealing properties of tested intraorifice barriers and root filling materials varied conforming leakage assessment. These properties were not affected by using fluid filtration test, while the glass ionomer barrier showed the greatest amount of dye leakage in both gutta-percha and Resilon root-filled teeth. Key words:Tooth Bleaching, root canal filling materials, glass ionomer cement, mineral trioxide aggregate, micro leakage

PH-changes during Intracoronal Bleaching: An in vivo Study

This study aimed to measure pH changes during 14 days intracoronal bleaching with hydrogen peroxide/sodium perborate and carbamide peroxide/sodium perborate. Twenty patients presenting endodontically treated central maxillary incisors with color alterations were divided in two groups (n = 10): Group CP + SP: 37% carbamide peroxide + sodium perborate paste; Group HP + SP: 30% hydrogen peroxide + sodium perborate paste. The pH values were measured using a digital microprocessor at different times: Baseline, 2, 7 and 14 days. Data were analyzed with two-way ANOVA followed by Tukey's test (α = 0.05). ANOVA showed p < 0.00 which indicated significant difference between the groups. The mean values (± sd) and the results of the Tukey´s test were: HP + SP/14 days-7.98 (±0.58)a; HP + SP/7 days-8.59 (±0.18)b; HP + SP/2 days- 8.83 (±0.32)bc; HP + SP/Baseline-8.83 (±0.01)bc; CP + SP/ Baseline-8.89 (±0.01)bc; CP + SP/14 days-9.11 (±0.58)cd; CP + SP/7 days-9.54 (±0.16)de; CP + SP/2 days-9.66 (±0.08) de. The group HP + SP resulted in significantly lower pH values compared with group CP + SP. It can be concluded that both associations showed alkaline pH values; however, there was significant reduction in the pH values of the 30% hydrogen peroxide associated with sodium perborate after 14 days. The association of hydrogen peroxide and carbamide peroxide with sodium perborate paste presented alkaline characteristics during the 14-day evaluated period. Thus, regarding pH changes, both associations can be considered safe as intracoronal bleaching agents.

Influence of intracoronal bleaching agents on the ultimate strength and ultrastructure morphology of dentine

To evaluate the effects of intracoronal bleaching on ultimate tensile strength (UTS) of sound and etched dentine and its ultrastructure morphology. Bovine dentine specimens with (e) or without previous etching with 37% phosphoric acid for 15 s were used for the intracoronal bleaching experiments. Teeth were randomly assigned to five treatments (n = 10): (C) control--no bleaching, (SP) sodium perborate, (CP) 35% carbamide peroxide, (25% HP) 25% hydrogen peroxide and (35% HP) 35% hydrogen peroxide. Bleaching was performed four times within a 72 h interval and afterwards, dentine pulp chamber blocks were obtained. The blocks were sectioned in 0.7 mm-thick slices and these were trimmed to reduce the inner dentine to a dumbbell shape with a cross-sectional area of 0.8 mm(2). Specimens were tested with the microtensile method (0.5 mm min(-1)) and data were analysed (two-way ANOVA-Tukey test, P < 0.05). Additional teeth were prepared for transmission electron microscopy (TEM) to evaluate dentine ultramorphology. The mean values of the UTS (SD) in MPa for sound dentine were: C = 48.3(8.5)a, SP = 34.6 (8.2)b, CP = 32.9 (8.9)b, 25% HP = 28.0(4.6)b, 35% HP = 26.4(6.6)b, and pre-etched dentine: Ce = 38.9(13.8)a, SPe = 31.3 (9.3)ab, CPe = 28.4 (6.2)ab, 25% HPe = 30.0 (7.9)ab, 35% HPe = 19.9(4.6)b. Significant differences between the means are indicated by the letters. TEM observations exhibited demineralization areas for all bleaching treatments. Bleaching decreased dentine UTS after treatment. Pre-etched not-bleached dentine (Ce) presented UTS similar to pre-etched bleached dentine, except for 35% HPe. The decrease of UTS of bleached dentine could be attributed to ultrastructural alterations such as loss of inorganic components.

Radicular penetration of hydrogen peroxide from various intracoronal bleaching agents: an vitro study

External cervical resorption has been reported to occur when bleaching of root filled teeth is done with 30% H2O2 alone or mixed with sodium perborate. H2O2 leakage through dentinal tubules has been speculated as one of the reasons for the resorption. External cervical root resorption has not been reported with the bleaching agent sodium perborate mixed with bidistilled water. Purpose of this study was to comparatively evaluate the H2O, leakage from three bleaching agents i.e. sodiumperborate mixed with 30% H2O2 or bidistilled water or 30% H2O2 alone. 21 human freshly extracted premolars were taken and root canal treatment was completed. Pulp chambers were prepared to receive bleaching agents. The teeth were divided into experimental and control groups. Experimental group was again divided into subgroups : A, B, C according to bleaching agents used. Resulls showed that maximum H2O2 leakage occurred from 30% H2O2 while minimum from sodium perborate mixed with bidistilled water.

Effect of Intracoronal Bleaching Agents on Dentin Microhardness

The purpose of this in vitro study was to compare the effect of intracoronal bleaching agents associated or unassociated with chlorhexidine gel on dentin microhardness. Sixty human maxillary incisor crowns were divided into six groups, and bleaching agents were sealed into the pulp chambers as follows: sodium perborate + water (SPW), sodium perborate + 2% chlorhexidine gel (SP + CHX), sodium perborate + 30% hydrogen peroxide solution (SP + HP), 37% carbamide peroxide gel (CP), 37% carbamide peroxide gel + 2% chlorhexidine gel (CP+CHX), and water (W). After the bleaching procedure, microhardness testing was carried out on the dentin surface at three different levels: inner, middle, and outer dentin. The greatest reduction in microhardness was observed for the SP + HP group. No differences were observed between the SPW and SP + CHX group. The 2% chlorhexidine gel did not adversely affect dentin microhardness when associated with the tested bleaching agents. CHX might be considered as an antimicrobial vehicle during intracoronal bleaching.

Effect of bleaching agents on bonding to pulp chamber dentine

To determine the effect of intracoronal bleaching agents on adhesion of bonding agents to pulp chamber dentine. Forty extracted human maxillary anterior teeth were randomly divided into four groups of 10 teeth each. Bleaching agents were sealed in pulp chambers for 7 days, as in clinical use. Group 1 (control): distilled water, group 2: 35% hydrogen peroxide, group 3: sodium perborate mixed with water, and group 4: sodium perborate mixed with 35% hydrogen peroxide. Teeth were stored in saline at 37 degrees C for 7 days. After the bleaching agent was removed, teeth were leached in water for a further 7 days prior to bonding. The crown was cut vertically from mesial to distal and the labial pulp chamber dentine was prepared for bonding with Clearfil SE-Bond and filled with resin composite (Clearfil AP-X). The bonded specimens were kept moist at 37 degrees C for 24 h. Microtensile bond strengths were determined using a universal testing machine. Additional teeth were prepared using the same bleaching procedures to investigate the scanning electron microscopic appearance of the dentine surface. Mean values (+/-SD) of microtensile bond strength for the experimental groups were: group 1: 5.29 +/- 2.21 MPa, group 2: 5.99 +/- 1.51 MPa, group 3: 9.17 +/- 1.65 MPa and group 4: 3.99 +/- 1.31 MPa. Dentine treated with sodium perborate in water (group 3) had significantly higher mean bond strength when compared with the other three groups (P < 0.05, Tukey's test). Mean bond strength was lowest when dentine was treated with sodium perborate plus hydrogen peroxide (group 4). In terms of subsequent bond strength during restoration, sodium perborate mixed with distilled water appears to be the best intracoronal bleaching agent.

Extraradicular diffusion of hydrogen peroxide and pH changes associated with intracoronal bleaching of discoloured teeth using different bleaching agents.

To evaluate the extraradicular pH and hydrogen peroxide (HP) diffusion when either 35% carbamide peroxide (CP), 35% HP or sodium perborate (SP) is used for intracoronal bleaching of artificially discoloured teeth. Single rooted extracted human premolars were stained with whole blood cells. After shaping and cleaning, they were root filled and a base cement placed 1 mm below the buccal cementoenamel junction (CEJ). Four cemental defects were prepared just below the CEJ on each root surface. The teeth were randomly divided into four groups of 11 specimens, and intracoronally bleached using CP, HP, SP or distilled water (CL). Each tooth was suspended in a vial of distilled water and bleached for 7 days. The pH of the extraradicular distilled water was tested at 0, 1, 2 and 7 days and the HP that diffused through the root quantified using the Ferrous Oxidation-Xylenol Orange 2 Assay. The results were analysed using the one-way anova and Scheffe tests. Carbamide peroxide produced the greatest increase and HP the least pH change (P < 0.05 except day 1), SP was intermediate. From day 1 onwards, radicular diffusion of HP was greatest with HP and least with CP (P < 0.01), again SP was intermediate. There was no significant difference between CP and SP. Carbamide peroxide had very low levels of extraradicular diffusion of HP, in the presence of cemental defects. It could be an alternative to the other intracoronal bleaching agents.

Effect of internal bleaching agents on dentinal permeability of non-vital teeth: quantitative assessment.

The aim of this in vitro study was to assess quantitatively dentin permeability of pulpless teeth after intracoronal bleaching therapy with three different agents. Twenty-four maxillary central incisors were randomly assigned to four groups according to the bleaching agent used: I--non-bleached control; II--37% carbamide peroxide; III--sodium perborate/20% hydrogen peroxide paste; IV--27% carbamide peroxide. After standard access and root-canal preparation the access opening, biomechanical preparation and root-canal filling, a cervical glass ionomer plug was prepared and intracoronal bleaching procedures were carried out in a standardized fashion. The access cavities were opened and the teeth were externally sealed and immersed in a 10% copper sulfate aqueous solution for 30 min, in vacuum for the first 5 min. Then, samples were removed, dried with absorbing paper and immersed in a 1% rubianic acid alcohol solution, for the same above-mentioned period in solution and in vacuum. Copper ion penetration was indicated by the rubianic acid staining. Mean values and SD for the experimental groups were: I--7.88% (+/-1.33), II--16.94% (+/-5.72); III--11.45% (+/-3.90) and IV--8.98% (+/-4.19). Data were submitted to one-way anova. The results showed that the 37% carbamide peroxide provided the highest increase in dentin permeability, followed by sodium perborate with 20% hydrogen peroxide. The 27% carbamide peroxide provided the lowest results and showed statistical similarity to the control group. On basis of these findings, it may be concluded that, among the tested intracoronal bleaching agents, 37% carbamide peroxide presented an optimized overall performance in increasing dentinal permeability.