Time of Application of Sodium Ascorbate on Bonding to Bleached Dentin.

Background: Restoration of the teeth immediately after bleaching with 35% hydrogen peroxide (H2O2) is contraindicated due to the remnant of free radicals that will stay inside enamel and dentin for 1-3 weeks and reduce the adhesion of composite resin. Sodium ascorbate is an antioxidant substance known to bind free radical residues, thereby shortening the delay in restoration. Purpose: The purpose of this study was to examine the resin bond strength of bleached dentin influenced by the application of 35% sodium ascorbate. Methods: Nine premolars were divided into their crown and root sections, with the crown subsequently being cut into four equal parts to obtain 36 samples. These were then divided into four groups, each containing nine samples. Group A (control): samples were bleached using35% hydrogen peroxide, immersed in an artificial saliva, stored in an incubator at 37°C for seven days and then filled with a composite resin. Group B:samples were also bleached by means of 35% H2O2 followed by one application of 0.025 ml 35% sodium ascorbate for 5 minutes and restored with composite resin. Group C: samples were bleached with 35% H2O2, followed by two applications of 0.025 ml 35% sodium ascorbate for 5 minutes, and restored with a composite resin. Group D: dentin was bleached with 35% H2O2 followed by three applications of 0.025 ml sodium ascorbate 35% for 5 minutes and restored with a composite resin. The shear bond strength of the composite resin was measured by a universal testing instrument (Zwick, USA). Data was analyzed by means of one-way Anova and LSD. Results: The highest mean shear bond strength of composite resin was in group C, while the lowest was in group B. The result of one-way Anova indicated a difference in the shear bond strength of composite resin in the four treatment groups (p < 0.05). An LSD test showed there to be a difference in shear bond strength of composite resin between group A and groups C and D or between group B and groups C and D. There was no difference in shear bond strength of composite resin between group A and group B or between group C and group D. Conclusion: Application frequency of 35% sodium ascorbate affect on shear bond strength of composite resin restoration in bleached dentin by 35% H2O2.

Background: There are various methods proposed to prevent the reduction of substrate micro tensile bond strength to bleached enamel. Therefore, this study aims to evaluate and compare the effectiveness of two common methods, namely 10% sodium ascorbate and Er:YAG laser irradiation, in increasing the microtensile bond strength of composite resins to bleached enamel. Methods: In this in vitro study, 72 maxillary premolar teeth were divided into four equal groups: bleached control group, unbleached control group, treated with 10% sodium ascorbate, and Er:YAG laser-treated group (60 mJ, frequency = 10 Hz, and power of 0.6 W with a 400-µm diameter tip). The samples were cut by a CNC cutting machine for a microtensile bond strength test. Results: The Er:YAG laser group showed the highest mean bond strength (27.3 MPa), while the bleached control group had the lowest (15.06 Mpa). There was a significant difference between the bleached and unbleached control groups (P<0.001). Samples prepared with 10% sodium ascorbate and the Er:YAG group had higher tensile bond strength than the bleached control group (P<0.0001). Tensile bond strengths were not significantly different between the 10% sodium ascorbate and the Er:YAG laser preparation groups (P=0.361). Conclusion: The findings of this study indicate that the microtensile bond strength of composite resins to bleached enamel can be increased by 10% sodium ascorbate and Er:YAG laser irradiation.

BackgroundRecently patients need faster treatments, and delaying restoration is not possible following bleaching treatment. The purpose of this study was to determine the effect of antioxidants, namely 10% sodium ascorbate, 10% alpha-tocopherol, 10% green tea and 10% Aloe vera extract on the shear bond strength of composite resin to enamel following extra-coronal bleaching using 40% hydrogen peroxide.Material and MethodsSeventy premolars were randomly assigned into 7 groups of 10 each. Group 1: bleaching treatment and no antioxidants application. Group 2: composite was built-up immediately after bleaching. Group 3: bleached specimens received composite build-up delayed by 2 weeks. Group 4, 5, 6 and 7: bleached specimens received an application of 10% sodium ascorbate, 10% alpha-tocopherol, 10% green tea, and 10% Aloe vera before composite build-up. Specimens were immersed in artificial saliva, stored in an incubator 37°C (24 hours), thermocycling, and tested using a universal testing machine. Data were analyzed by one-way ANOVA and Tukey’s test with 95% level of significance.ResultsBleaching caused significantly reduced shear bond strength (p<0.05), and application of 10% sodium ascorbate, 10% alpha-tocopherol, 10% green tea and 10% Aloe vera produced significantly greater shear bond strength compared to bleached group (P <0.05). However, no significant differences occurred between antioxidant groups (P >0.05).ConclusionsApplication of antioxidants increased the shear bond strength of composite resin to enamel following extra-coronal bleaching using 40% hydrogen peroxide. 10% sodium ascorbate, 10% alpha-tocopherol, 10% green tea and 10% Aloe vera extracts produced the same effect on the shear bond strength of composite resin to enamel following extra-coronal bleaching using 40% hydrogen peroxide. Key words:Antioxidants, shear bond strength, composite resin, extra-coronal bleaching.

This study aimed to evaluate the effect of the Nd: YAG laser on the tensile bond strength of composite resin to dentin with hypersensitivity using different universal bonding systems. After cutting the crown of 252 molars, buccal cervical enamel was removed at a thickness of approximately 2 mm, and 252 smooth dentin surfaces were exposed. Then they were etched with 0.5 M ethylenediaminetetraacetic acid (pH = 7.4) to stimulate hypersensitivity. The specimens were then randomly divided into 12 groups (n= 21) according to the surface treatments performed. After etching and bonding according to the manufacturer's recommendations in each group, the entire dentin surface was restored with Valux Plus composite resin. The samples were thermocycled and a universal test machine was used to measure the microtensile bond strength. The failure mode for each sample was observed under a stereomicroscope. For data analysis, the Bonferroni test, the independent t-test and the three-way anova test were used. The average microtensile bond strength in non-laser samples was higher than the average in laser samples (P<0.001). In comparison with the bonding agent type in both cases with and without laser, the highest average microtensile bond strength was related to ALL-BOND (P<0.001), meanwhile the lowest average tensile strength in samples without laser was related to G-Premio universal adhesive (P<0.001), and the lowest average microtensile strength in samples with laser belonged to Prime and Bond Elect group (P<0.001). Nd: YAG laser irradiation of the dentin surface before applying the adhesive significantly decreased the microtensile bond strength of the composite resin to the dentin surface. Key words:Nd:YAG laser, Bond strength, Dentin, hypersensitivity, Universal adhesives.

Introduction: The use of Sodium Hypochlorite (NaOCl) as an endodontic irrigant changes the properties of dentine and lowers the bond strength of resin cements to dentine. But it can be reversed by the use of antioxidants. Aim: To evaluate the effect of different antioxidants for restoring adhesion potential/reversal of microtensile bond strength of dentin of the pulp chamber treated with NaOCl and Ethylenediaminetetracetic Acid (EDTA). Materials and Methods: It was a laboratory based experimentalin-vitro study in which 40 freshly extracted human incisors were selected and cut to expose the pulp chamber dentin. The specimens were distributed into five groups: Group I samples were irrigated with 5.25% NaOCl for 30 minutes followed by 17% EDTA for 3 minutes and final rinse was done with 5.25% NaOCl (Positive control). Group II samples were treated with distilled water only (Negative control). In Group III, samples were treated same as in group I followed by 10% Sodium Ascorbate (SA) for 10 minute. Samples of group IV samples were also treated as in group I followed by application of 5% solution of Alpha tocopherol with for 10 minutes. Group V samples were treated same as in group I followed by rinse with 5% solution of Sodium Thiosulphate (Na2S2O3) for 10 minutes. Composite resin build up was performed and interface was tested by using Universal testing machine for Microtensile bond strength. The resulting data was analysed by one-way Analysis of Variance (ANOVA) and Mann-Whitney U test (p&lt;0.05). Results: The results demonstrated that irrigation with 5.25% NaOCl and 17% EDTA produce significant (p&lt;0.05) reduction in resin dentin bond strength but this can be reversed by application of 5% Na2S2O3. Highest bond strength was observed in group V (22.38±0.84) and lowest for group I (15.38±1.22). Conclusion: Dentin bond strength was significantly reduced when bonding was performed immediately after use of NaOCl. Use of antioxidants after final irrigation with NaOCl can be recommended for better bonding of composite resin.

ABSTRACTAim and objectivesThe aim of this study was to evaluate and compare the deproteinizing effect of sodium hypochlorite, bromelain, and papain on microtensile bond strength of composite resin to etched dentin.Materials and methodsEighty freshly extracted permanent molars were wet grounded into a flat surface using a diamond disk to expose the superficial dentinal surface. Teeth were etched with 37% phosphoric acid for 15 seconds and rinsed with water and blot dried. Teeth were divided into four groups (n = 20) based on the method of dentin deproteinization. Group I: only etching; group II: deproteinized with 5.25% sodium hypochlorite for 1 minute; group III: deproteinized with 8% bromelain enzyme for 1 minute; and group IV: deproteinized with 8% papain enzyme for 1 minute. All the samples were washed off with distilled water to remove deproteinizing agents. Sample surfaces were blot dried and bonding of the dentin surface was performed and restored with light cure bulk fill composite. Samples were stored in distilled water (37°C/24 hours) and thermocycled. Then, the teeth were longitudinally sectioned and individually fixed to a sectioning block using acrylic resin. The block was mounted on hard tissue microtome and sectioned to get one to three slabs of 1 mm thick sections. The beam was then attached to a custom-made jig using screws subjected to the Instron universal testing machine. A tensile load was applied at a crosshead speed of 0.5 mm/minute until the beam fractured.ResultsHigher mean bond strength was recorded in group IV followed by group III, group II, and group I, respectively. Group III presented a statistically significant highest mean score compared to other study groups with group I and group II (p < 0.001), followed by group IV having significantly higher mean score compared to group I and group II (p < 0.001) and finally a significant difference was observed between group II and group I (p < 0.001). However, the mean microtensile bond strength score did not differ significantly between group III and group IV (p = 0.20).ConclusionWithin the limitations of this present in vitro study, the following conclusions were drawn. The microtensile bond strength of dentine tested in various deproteinizing agents is as follows: 8% bromelain > 8% papain > 5.25% NaOCl > control group. Naturally occurring deproteinizing agents, such as bromelain and papain, used in this study have resulted in greater bond strength values when compared to that of traditionally used chemical agent such as NaOCl.How to cite this articleKhatib MS, Devarasanahalli SV, Aswathanarayana RM, et al. Microtensile Bond Strength of Composite Resin Following the Use of Bromelain and Papain as Deproteinizing Agents on Etched Dentin: An In Vitro Study. Int J Clin Pediatr Dent 2020;13(1):43–47.

This study evaluated the effect of propolis as an antioxidant agent on bond strength to enamel after intracoronal bleaching. A total of 160 incisors were endodontically treated. Sixteen teeth were served as control, and the remaining teeth were randomly divided into three main groups according to the bleaching agent used; group 1: Sodium perborate (SP); group 2: Carbamide peroxide (CP); group 3: Hydrogen peroxide (HP). After bleaching, the samples were divided into three subgroups; subgroup A: no antioxidant agent application, subgroup B: sodium ascorbate (SA), subgroup C: propolis (PP). After the antioxidant agents application, the sample's surfaces were washed and dried. After adhesive application, composite resin cylinders were applied to enamel surfaces using tygon tubes and a shear bond strength test was performed. The use of PP significantly decreased the bond strength of composite resin to the enamel (p < 0.05). Using propolis as an antioxidant agent adversely affects the bond strength to enamel after intracoronal bleaching.

Several studies have shown that compromised bonding to bleached enamel can be reversed with antioxidants. Aim: The aim of this study was investigate the effect of the antioxidant treatment on the micro-shear bond strength of a composite resin with a clinically acceptable antioxidant usage time taken into account. Methods: Using in vitro techniques, the effect of the antioxidant sodium ascorbate (SA) was evaluated on the micro-shear bond strength of a hybrid composite resin (Tetric® A2 Ivoclar Vivadent) to dentin, which was bleached with 35% carbamide peroxide (Opalescence Quick, Ultradent Products Inc). Thirty-five intact flat buccal dentin surfaces from bovine incisors were randomly assigned to five groups which were subjected to the following treatment protocols: group 1, bleached for 45 min and bonded immediately afterwards; groups 2 and 3, bleached and then treated with 10% SA for 10 and 5 min before bonding, respectively; group 4, stored in distilled water for seven days after bleaching and before bonding; group 5, received no bleaching or antioxidant treatment. After the bonding procedure, specimens were subjected to a micro-shear bonding test. Data were analyzed by ANOVA and a post-hoc Tukey’s test. Results: One-way ANOVA revealed significant differences in bond strength among the five groups. Conclusions: It was found that the shear bond strength was reduced by carbamide peroxide bleaching, and that the antioxidant SA was ineffective at reversing the composite strength at the concentrations and treatment times examined.

Objective:The aim of this study was to comparatively investigate the neutralizing effect of antioxidant treatment and delayed bonding after bleaching with hydrogen peroxide on the shear bond strength of a composite resin (CR) and resin-modified glass ionomer (RmGI) to enamel.Materials and Methods:Ninety-six freshly extracted human 3rd molars with flat enamel surfaces were divided into six experimental groups (n=12/group) and two control groups (n=12/group). After initial preparation, specimens in Groups 1 and 5 (control groups) were not bleached and the buccal enamel surface of specimens were bonded immediately with CR and RmGI. The samples of the remaining groups were all bleached six hours a day for seven days consecutively. Immediately after bleaching, groups two and six specimens were bonded with CR and RmGI. Groups 3 and 7 specimens were immersed in distilled water at 37°C for 7 days and the specimens in Groups 4 and 8 were treated with 10% sodium ascorbate as an antioxidant agent after bleaching. Specimens in Groups 3 and 4 were bonded with CR and Groups 7 and 8 specimens were bonded with RmGI immediately. After specimens were bonded, the shear bond strength (SBS) was measured. The SBS data analyses were subjected to one-way analysis of variance (ANOVA) followed by Tukey test for comparison of specific mean values.Results:The mean SBS value in Group 2 (immediately bonded with CR after bleaching) was significantly lower than other CR groups (P=0.045). RmGI did not bond to buccal enamel surface of specimens in group 6. There was no significant difference between other groups bonded with RmGI (P>0.05).Conclusions:Applying 10% sodium ascorbate hydrogel and one week delay before bonding resulted in reversal of reduced bond strength of CR and RmGI to bleached enamel.

Objective:Application of sodium ascorbate as an antioxidant and calcium hydroxide as a buffering agent following intracoronal bleaching has been recommended. The aim of this study was to investigate the effect of using the mentioned materials on shear bond strength of composite resin to the bleached dentin.Materials and Methods:In this in vitro investigation, sixty human sound premolars were divided randomly into five groups (n=12). Occlusal dentin surfaces were exposed. The negative control (NC) group was not bleached and the other groups were bleached with 35% hydrogen peroxide gel for 5 days. Afterwards, composite cylinders were built up in the positive control (PC) group immediately after bleaching, in the delay bonding (DB) group after one week, in the sodium ascorbate (SA) and calcium hydroxide (CH) groups after 40 hours of treatment with the materials. Then, the samples were stored in 37°C for 24 hours. The specimens were thermocycled (5–55°C, 500 cycles), subjected to shear bond testing by universal machine. The data were analyzed by One-Way ANOVA and Duncan tests (α =0.05).Results:There was a significant difference between PC and CH groups in comparison with the other groups (p<0.05), but the difference among other groups was not significant (p>0.05).Conclusion:Application of sodium ascorbate could significantly increase the bond strength of composite resin to bleached dentin, while the use of calcium hydroxide did not affect bond strength.

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.

Objective:The objective of this in - vitro study was to evaluate the effect of different antioxidants in reversal of of deleterious effect of bleaching on shear bond strength of composite resin to bleached enamel.Materials and methods: Seventy bovine incisors were used. The specimens were randomly divided into seven groups (10 specimens each) as follow: Group 1: no bleaching treatment and no antioxidant application. Group 2: bleaching only without antioxidant application and immediate composite resin application after bleaching. Group 3: bleaching only without antioxidant application and delayed composite application (after 2 weeks) of storage. Group 4: bleaching and application of 10% Alpha-tocopherol.Group 5: bleaching and application of 6% cranberry extract. Group 6:bleaching and application of 10% sodium ascorbate. Group 7: bleaching and application of 10% green tea. 40% hydrogen peroxide (Opalescence Xtra Boost 40%, Ultradent, South Jourdan, UT, USA) was used. Composite resin Tetric N -Ceram was used. The shear bond strength was measured using a universal testing machine. Results: one-way ANOVA test revealed significant differences in shear bond strength among the tested groups (p < 0.001). Bond strength significantly decreased after bleaching. There was no significant difference in shear bond strength reversed using10% Alpha-tocopherol, 10% sodium ascorbate and 10% green tea and delayed restoration. Whereas the difference was significant between group 5(6% cranberry extract) and other antioxidants groups. Conclusion: The results obtained from the use of antioxidants using (10% Alpha-tocopherol, 10% sodium ascorbate and 10% green tea extract) is approximately the same as the delayed restoration.

The purpose of this study was to evaluate the effect of timing of dentin sealing and provisional restoration methods on the bond strength of composite resin to dentin. Flat dentin surfaces were prepared and the teeth were divided into three groups: control, resinrestoration with immediate dentin sealing (IDS), and resin restoration with delayed dentin sealing (DDS). For the control group, a dentin surface was bonded by using dual-curing dentin adhesive (Excite DSC) and restored with resin immediately. For the IDS groups, a dentin was sealed with OptiBond FL (OB) or Hybrid Coat (HC), and it was restored with following 3 provisional restoration methods: SQ/PQ/CQ {SQ, water-soluble separator (SEP) + provisional resin; PQ, petroleum jelly + provisional resin; CQ, temporary cement (Cavitec) + provisional resin}. For the DDS groups, a dentin was temporized with 2 provisional restoration methods: Q/CQ (Q, provisional resin only) without dentin sealing. After a week, the provisional restoration was removed and cleaned. The treated dentin surface was bonded using Excite DSC and restored with resin, followed by microtensile bond strength (μTBS) tests. The μTBS of control and the IDS-OB groups were not significantly different (P>0.05). The DDS groups presented lower μTBS than control and the IDS-OB groups (P 0.05). However, using CQ significantly lower the μTBS than using Q in the DDS groups (P<0.05). IDS with a etch-and-rinse type dentin bonding agent improved the bond strength. The use of ZOE-containing cement on the unsealed dentin surface decreased the μTBS.

Materials like carbamide peroxide or hydrogen peroxide are commonly used for vital teeth bleaching. However, there have been concerns regarding their effect on composite-to-bleached enamel bonding strength. The study investigated the impact of organic and antioxidant agents on composite bond strength in bleached enamel with different dental adhesive solvents. Human third molar teeth were sectioned into buccal and lingual halves. The two main adhesive solvent groups evaluated were acetone and alcohol. Each main group was divided into six groups. The positive control group received no bleaching, the negative control group consisted of bleaching with no surface deoxidization; and other experimental categories involved post-bleach treatments with 95% ethanol, sodium ascorbate (10%), acetone solution, or sodium fluoride solution (1.1%). Following the surface treatment and enamel bonding procedure, nano-hybrid composite cylinders measuring 3 × 2 mm were directly cured over the bleached enamel substrate. The shear bond test was performed after 24-h storage and 12,000 thermocycles on a universal testing machine. In this study, one-way ANOVA was used along with Tukey's HSD tests at a significance level of 0.05. The negative control groups showed significantly lower bond strength than the positive control group. Ethanol surface treatment had superior mean bonding strength in acetone and alcohol-based adhesive solvent groups. The utilization of sodium ascorbate for surface treatment resulted in a significant enhancement of adhesion between the composite material and bleached enamel surface. Sodium fluoride application showed no significant recovery in shear bond strength in both dental adhesive groups. It was concluded that hydrogen peroxide severely compromised the immediate bond strength of composite resin. Surface treatment of bleached enamel with ethanol, sodium ascorbate, and acetone solutions is an effective option for restoring bond strength.

Studies have shown that bleaching agents interfere with the adhesion of composite resin placed immediately after bleaching. The aim of this study was to evaluate the shear bond strengths of composite resin after four different durations since the time of nonvital bleaching (1 d and 1, 2, and 3 wk). Two hundred seventy bovine teeth were assigned to nine groups (n = 30) according to the bleach used and the time between bleaching and restoration: group 1--sodium perborate (SP), 1 day after bleaching (AB); group 2--SP, 1 week AB; group 3--SP, 2 weeks AB; group 4--SP, 3 weeks AB; group 5--37% carbamide peroxide (CP), 1 day AB; group 6--CP, 1 week AB; group 7--CP, 2 weeks AB; group 8--CP, 3 weeks AB; group 9--control group (no treatment). After the bleaching treatment, the teeth in each group were sectioned and the enamel and dentin were separated. The teeth were cut, embedded in polyester resin, and polished to obtain flat enamel and dentin surfaces. The adhesive system was applied and a cylinder of composite resin was bonded on each flat surface. The specimens were stored in distilled water for 7 days at 37 degrees C. The shear bond strength test was performed in a universal test machine (Emic DL-500, São José dos Pinhais, São Paulo, Brazil) at a crosshead speed of 0.5 mm/min. The data were subjected to analysis of variance, Dunnett's t-test, and Tukey's least significant difference at p < or = .05 and showed a statistically significant decrease in bond strengths of composite resin for enamel and dentin 1 day after the nonvital bleaching. The decrease in shear bond strength values is time dependent. A delay in bonding procedures for composite resin restoration is recommended. According to the results, a satisfactory time to perform the restoration of composite resin for both enamel and dentin is 2 weeks after bleaching.