Effect Of Sodium Ascorbate Research Articles

Effect of Sodium Ascorbate, Grape Seed Extract, and Aloe Vera Application after In-Office Bleaching on the Bond Strength of Enamel: A 3-Year Evaluation

Introduction. Dental bleaching is the first choice to improve smile esthetics, but, in some cases, it needs to be associated with resin composite restoration to obtain a satisfactory result. Unfortunately, the bonding of resin-based materials can be impaired due to residual oxygen molecules, which can decrease the durability of the restoration. Objectives. To evaluate the effect of the antioxidant application on the bond strength of bleached enamel after 24 hr and 3 years of water storage. Methods. In total, 84 bovine teeth were used in this study. Of these, 77 were bleached with 35% hydrogen peroxide in a single session for three cycles of 15 min. Then, the specimens were divided into groups (n = 7 each): control (without bleaching), without antioxidant (WA) use; application of 10% sodium ascorbate (SA) gel, grape seed (GS) extract, and aloe vera (AV). The restorative procedure was performed immediately after bleaching, 7 and 14 days after bleaching. Specimens were sectioned and evaluated using microtensile bond strength (μTBS). Half of the resin-enamel sticks were tested after 24 hr, and the remaining half after 3 years of water storage. µTBS data were analyzed using a three-way analysis of variance, Tukey’s test, and Dunnett’s test. Results. The lowest µTBS values were observed when the restoration was performed immediately after bleaching in the AV, GS, and WA groups when compared with the SA group ( p < 0.005 ). However, no significant differences were observed among all groups after 3 years of water storage ( p < 0.001 ). Conclusions. SA at 10% was the most effective antioxidant agent for improving the immediate bond strength. However, independent of the antioxidant agent used, the bond strength values were maintained or recovered after 3 years of water storage. SA at 10% could be used to avoid delayed bonding procedures after in-office whitening without compromising bond strength over time. Clinical Significance. The use of antioxidants after dental bleaching can be effective in improving the bonding durability of the adhesive restorations.

Effect of Antioxidant and Buffering Agent Mixture on Dentin Shear Bond Strengths of Laminate Veneer and pH Change of External Medium After Intracoronal Bleaching

Aim: To investigate the effect of sodium ascorbate (SA), an antioxidant and calcium hydroxide (Ca(OH)2), a buffering agent mixture, on the shear bond strength of a luting resin to dentin, and pH changes of the extraradicular medium solution after intracoronal bleaching with hydrogen peroxide. Materials and Methods: In this in vitro study, 60 human maxillary central incisors were randomly assigned into six groups ( n: 10): Group 1: restored, no bleach; group 2: bleached, bonded immediately; group 3: bleached, treated with 10% SA applications before bonding; group 4: bleached, treated with calcium hydroxide applications before bonding; group 5: bleached, treated with CaOH2 and SA mixture applications before bonding; group 6: delay bonding by seven days. For bleach treatment in groups 2 to 6, intracoronal bleaching was performed with 35% hydrogen peroxide for four days. SA or CaOH2 or mixture of SA and CaOH2 were left in the access cavity for four days. Hybrid blocks, 4 mm × 4 mm wide × 2–mm thick, were luted with resin cements on dentin surface and then the specimens were subjected to shear bond strength testing. Analysis of variance and Tukey post hoc multiple comparison tests were applied ( P < .05). Results: G2 and G4 showed significantly low bond strength values and they were lower than the other groups ( P < .05). There were no significant differences between G1, G3, and G6 ( P > .05). The pH values had risen markedly in the groups containing calcium hydroxide (G4 and G5) after four days ( P < .05). Conclusion: The application of 10% SA or 10% SA and CaOH2 mixture were effective at reversing bleaching effects on bond strength. CaOH2 or CaOH2 and 10% SA mixture increased the external medium pH and were effective for alkalinization after intracoronal bleaching.

Effect of Sodium Ascorbate or Alpha-Tocopherol on the Resin-Dentin Interface and Bond Strength after Endodontic Treatment and Bleaching

Effect of Sodium Ascorbate or Alpha-Tocopherol on the Resin-Dentin Interface and Bond Strength after Endodontic Treatment and Bleaching

Effects of sodium ascorbate and delayed bonding after bleaching on shear bond strengts of orthodontic brackets

Introduction: The aim of the study was to determine the effects of sodium ascorbate and delaying bonding for 4 weeks after bleaching on SBS of orthodontic brackets.Methods: Sixty freshly extracted, noncarious, premolars were randomly assigned to 4 groups of 15 each. Orthodontic brackets were bonded with a composite resin and cured with a halogen light. After bonding, the shear bond strengths of the brackets were tested with a universal testing machine. Group I served as the control. In groups II, III, and IV, teeth were bleached with an office bleaching method. In group II, brackets bonded immediately after bleaching. In group III, teeth were immersed in artificial saliva of 4 weeks after bleaching before bonding brackets. In group IV, teeth were treated with 10% sodium ascorbate after bleaching before bonding brackets.Results: One-way analysis of variance indicated a significant difference between groups (P < .001). The highest values for SBS were measured in group I (11.92 ± 0.81 MPa). The SBS was significantly lower in groups II, III, and IV than in group I (P < .001). There was no statistically significant difference between groups III and IV.Conclusions: Bleaching significantly reduced the SBS of orthodontic brackets on human enamel. If bleaching is mandatory, teeth should be treated with sodium ascorbate before bonding.

Effect of sodium ascorbate and sodium nitrite on protein and lipid oxidation in dry fermented sausages

The effects of sodium nitrite and ascorbate on lipid and protein oxidation were studied during the ripening process of dry fermented sausages. Samples were taken at day 0, 2, 8, 14, 21 and 28 of ripening to assess lipid (malondialdehyde) and protein (carbonyls and sulfhydryl groups) oxidation. Sodium ascorbate and nitrite were separately able to reduce the formation of malondialdehyde. Their combined addition resulted in higher amounts of carbonyl compounds compared to their separate addition or the treatment without any of both compounds. Moreover, sodium nitrite limited the formation of γ-glutamic semialdehyde whereas sodium ascorbate showed a pro-oxidant effect. A loss of thiol groups was observed during ripening, which was not affected by the use of sodium ascorbate nor sodium nitrite. In conclusion, sodium nitrite and ascorbate affected protein and lipid oxidation in different manners. The possible pro-oxidant effect of their combined addition on carbonyl formation might influence the technological and sensory properties of these products.

Ascorbate and Apple Phenolics Affect Protein Oxidation in Emulsion-Type Sausages during Storage and in Vitro Digestion.

The effect of sodium ascorbate and apple phenolics on the oxidative stability of emulsion-type sausages during storage and digestion was investigated. Emulsion-type sausages containing 0.05% sodium ascorbate or 3% freeze-dried apple pomace were subjected to chilled illuminated storage and subsequent in vitro digestion. Lipid oxidation was assessed as TBARS, and protein oxidation was evaluated as thiol oxidation, total carbonyls, and γ-glutamic and α-amino adipic semialdehyde. Proteolysis was measured after digestion to evaluate protein digestibility. The results suggest the presence of protein-ascorbate and protein-phenol interactions, which may decrease protein digestibility and may interfere with spectrophotometric methods for measuring oxidation.

O ascorbato de sódio promove a resistência de união após técnicas de clareamento dental?

Objective: To summarize and discuss the available information concerning the effectiveness of sodium ascorbate in improving bond strength after dental bleaching procedures. Methods: Information of original articles or reviews listed in PubMed database using searching terms: (“sodium ascorbate” OR antioxidant) AND (bleaching OR hydrogen peroxide OR carbamide peroxide), were included in the review. Results: Most of studies revealed that sodium ascorbate could restore the altered redox potential of the oxidized bonding substrate, thus reversing the compromised bonding. However, several protocols of this antioxidant have been used in combination with different peroxide concentrations and exposure time to bleaching agents. Conclusion: Studies should be conducted to establish an appropriate application protocol and to evaluate the effect of sodium ascorbate in other dental properties.

Effect of sodium ascorbate and delayed treatment on the shear bond strength of composite resin to enamel following bleaching.

The effect of bleaching on enamel surfaces, as well as exploring methods of preventing the weakening of bond strength of two different adhesives to bleached enamel surfaces. This study compared the shear bond strength (SBS) of two different adhesives on bleached enamel immediately after bleaching, with a 1-week delay, and following application of an antioxidizing agent after bleaching. Materilas and Method: The enamel surfaces of 140 incisors were divided into 14 groups. Two unbleached enamel groups (n = 20) were prepared as negative controls of the Adper Single Bond 2 total-etch and Clearfil Tri S Bond self-etch adhesives. The remaining surfaces were randomly divided into two bleaching groups treated with 35% Beyond Max (n = 60) and 38% Opalescence Xtra Boost (n = 60). Each bleaching group was then divided into two subgroups using the total and self-etch adhesive systems. Specimens were bonded immediately after bleaching, after treatment with 10% sodium ascorbate (SA) gel, or after 1-week of immersion in artificial saliva. All groups were restored with composite resin. After thermocycling, SBS was measured and data were analyzed. In the control groups, there was no statistically-significant difference in SBS between self-and total-etch adhesives. Among all bleaching groups, no statistically-significant differences in SBS were noted, although the SA-treated delayed bonding (1-week) groups had the highest values. The lowest values were noted for the groups bonded immediately after bleaching.

Efeito do ascorbato de sódio na adesividade da resina composta em dentes clareados

Objective: The objective of this study was to evaluate the effect of sodium ascorbate on resin composite bond strength. Methods: Forty human premolars were used, which were divided into 4 groups: C – (control) unbleached teeth submitted to a restorative procedure; S – teeth bleached with 35% hydrogen peroxide and stored in artificial saliva for 48 hours; AS – teeth bleached with 35% hydrogen peroxide and irrigated with a 10% sodium ascorbate solution for 10 minutes; AG – teeth bleached with 35% hydrogen peroxide and immersed in 10% sodium ascorbate for 3 hours. After restoration, the samples were section and microtensile bond strength tests were performed in a universal test machine (Emic) at a speed of 1mm/min. The data were evaluated and submitted to the ANOVA and Tukey statistical tests (5% significance level). Results: Group C presented the highest bond strength value, differing statistically from Groups S and AG, however, without statistical difference in comparison with Group AS. Conclusion: Keeping teeth that have been bleached with 35% hydrogen peroxide in saliva for 48 hours is insufficient to recover bond strength. However, the use of 10% sodium ascorbate for 10 minutes may promote adequate bond strength, allowing immediate restoration of the teeth.

Effect of sodium ascorbate on the bond strength of all-in-one adhesive systems to NaOCl-treated dentin.

Background Ascorbic acid and its salts are low-toxicity products, which are routinely used in food industries as antioxidants. The aim of the present study was to evaluate the effect of 10% sodium ascorbate on the bond strength of two all-in-one adhesive systems to NaOCl-treated dentin. Material and Methods After exposing the dentin on the facial surface of 90 sound human premolars and mounting in an acrylic resin mold, the exposed dentin surfaces were polished with 600-grit SiC paper under running water. Then the samples were randomly divided into 6 groups of 15. Groups 1 and 4 were the controls, in which no surface preparation was carried out. In groups 2 and 5 the dentin surfaces were treated with 5.25% NaOCl alone for 10 minutes and in groups 3 and 6 with 5.25% NaOCl for 10 minutes followed by 10% sodium ascorbate for 10 minutes. Then composite resin cylinders, measuring 2 mm in diameter and 2 mm in height, were bonded on the dentin surfaces in groups 1, 2 and 3 with Clearfil S3 Bond and in groups 4, 5 and 6 with Adper Easy One adhesive systems according to manufacturers’ instructions. The samples were stored in distilled water for 24 hours at 37°C and then thermocycled. Finally, the samples underwent shear bond strength test in a universal testing machine at a strain rate of 1 mm/min. Data were analyzed with two-way ANOVA and post hoc Tukey tests at α=0.05. Results The differences between groups 1 and 2 (P=0.01), 1 and 5 (P=0.003). 1 and 6 (P=0.03) and 4 and 5 (P=0.03) were statistically significant. Two-by-two comparisons did not reveal any significant difference between other groups (P>0.05). Conclusions Use of 10% sodium ascorbate for 10 minutes restored the decreased bond strength of the adhesive systems to that of the control groups. Key words:Sodium ascorbate, adhesive systems, all-in-one, bond strength, sodium hypochlorite.

Effect of Sodium Ascorbate and Ascorbic Acid Hydrogels on Microleakage of Composite Restorations after an Office Bleaching Protocol

Aim. This work evaluated the influence of 20% sodium ascorbate (SA) and 10% ascorbic acid (AA) hydrogels on microleakage of class V composite restorations after an office bleaching protocol (B). Methods : 60 bovine incisors were sectioned 8mm from the amelo-dentinal junction to incisal and 2mm to radicular directions. Root canals were sealed with a composite and teeth were divided into 5 groups: C (control group) – the teeth were prepared (P) (4 x 3mm diam. diamond bur 3131 – KG Sorensen) etched, rinsed (ER), adhesive system used (Ambar – FGM) and restored (R) with a microhybrid composite (Opallis – FGM); IR – B (2 sessions, 1 week interval - hydrogen peroxide 35% - Whitness HP Blue – FGM) + P + ER + R; SA - B + P + SA 20%/15 min + ER + R; AA – B + P + AA 10% /15min + ER + R; and MR – B + water storage (37°C/14d) + P + ER + R. Specimens were submitted to an aging process (thermocycling – 5/55°C/min, 5×10 4 cycles), varnish sealed, immersed in basic fuchsine (3h), washed and sectioned with a diamond disc. Microleakage was measured with the aid of ImageTool® software. ANOVA and a Tukey post hoc test were applied. Results. Microleakage (mm) and standard deviations per group were: C – 0.29 (0.06) A ; IR – 1.86 (0.15) C ; SA – 1.08 (0.09) B ; AA – 1.07 (0.10) B ; MR – 1.02 (0.12) B . Conclusions . Bleached teeth submitted to superficial treatment with 20% SA and 10% AA applied for 15 minutes prior to restoration presented reduced microleakage when compared to bleached teeth immediately restored. The use of these antioxidants led to a microleakage comparable to that observed after a waiting period of 14 days prior to restoration.

Effect of sodium ascorbate on dentin bond strength after treatment with oxidizing root canal irrigants

Background/purposeThe aim of this study was to evaluate the effect of 10% sodium ascorbate solution on dentin bond strength after being treated with different oxygen-releasing root canal irrigants. Materials and methodsTwenty-one human third molars were used in this study. The specimens were randomly divided into seven groups according to irrigation solutions, as follows: Group C (control group), distilled water; Group SH, 5.25% sodium hypochlorite (NaOCl); Group SHA, 5.25% NaOCl + 10% sodium ascorbate solution; Group HP, 10% hydrogen peroxide (H2O2); Group HPA, 10% H2O2 + 10% sodium ascorbate solution; and Group OW, ozonated water; Group OWA, ozonated water + 10% sodium ascorbate solution. A two-step self-etching adhesive system (CLEARFIL SE Bond) was applied to the surfaces, and resin core buildups (Filtek Z550) were placed. The specimens were sectioned into 1-mm2 beams and tested in a microtensile bond-strength (μTBS) testing machine at a cross-head speed of 1 mm/minute. Fractured specimens were examined with a stereomicroscope to determine the mode of failure (adhesive, cohesive, or mixed). The data were analyzed by one-way analysis of variance and Tukey tests (P < 0.05). ResultsThe ozonatedwater-treated groups showed the lowest μTBS values among all the groups. Although the 10% sodium ascorbate application increased dentin bond strength in Group OW, the difference was not significant (P > 0.05). ConclusionAlthough 10% sodium ascorbate application for 10 minutes is an effective method to reverse the compromised bond strength of NaOCl- and H2O2-treated dentin, it might not have a sufficient effect when the dentin is treated with ozonated water.

Effect of Sodium Ascorbate on Dentin Bonding After Two Bleaching Techniques

The purpose of this study was to analyze the influence of 10% sodium ascorbate (SA) on the hybrid layer, resin tag length, and bond strength to dentin after bleaching. Six groups were tested: G C, control; G SA, sodium ascorbate (SA) + restoration; G CP, bleaching with carbamide peroxide (CP) + restoration; G CP+SA, bleaching with CP + SA+ restoration; G HP, bleaching with 35% hydrogen peroxide (HP) + restoration; and G HP+SA, HP + SA + restoration. After dental bleaching, the dentin was exposed and the antioxidant solution was applied to groups G SA, G CP+SA, and G HP+SA, before bonding procedures. The teeth were sectioned in the mesiodistal direction. One section was decalcified, and the specimens were embedded in paraffin and sectioned in the longitudinal direction with a thickness of 6 μm. Fifteen slices of each specimen were selected according to a systematic sample of slices with an interval proportional to the total number of slices obtained for each tooth. The specimens were stained using the Brown & Brenn method, and an optic microscope was used to analyze the hybrid layer thickness and resin tag length. The remaining tooth segment was sectioned into stick-shaped specimens and used for microtensile bond strength testing (0.5 mm/min). Statistical analysis was performed using two-way analysis of variance and Fisher test. The results for hybrid layer + tag formation (in micrometers) were G C, 13.27 Aa; G SA, 11.85 Ba; G CP, 6.84 Bb; G CP+SA, 9.02 Ab; G HP, 7.28 Bb; and G HP+SA, 9.22 Ab; bond strength results (in MPa) were G C, 49.5 Aa; G SA, 51.7 Aa; G CP, 37.16 Bb; G CP+SA, 47.69 Aa; G HP, 32.39 Ab; and G HP+SA, 39.67 Ab. Tooth bleaching with CP or HP impairs the formation of the hybrid layer and resin tags and reduces the microtensile bond strength. Statistically, the use of SA significantly increases the hybrid layer thickness and resin tag length. The microtensile bond strength values for carbamide peroxide increased, but the microtensile bond strength for hydrogen peroxide was not affected.

Effect of sodium ascorbate on the bond strength of silorane and methacrylate composites after vital bleaching

We investigated the effect of sodium ascorbate (SA) on the microtensile bond strengths (MTBSs) of different composites to bovine enamel after vital bleaching with hydrogen peroxide (HP) or carbamide peroxide (CP). Thirty bovine incisors were randomly divided into five groups and treated with no bleaching application (control), 35% HP alone, 35% HP+10% SA for 10 minutes (HP+SA), 16% CP alone, or 16% CP+10% SA for 10 minutes (CP+SA). Specimens were restored with Silorane adhesive and Filtek Silorane composite (designated as S/group) or with Clearfil SE bond and Filtek Supreme XT (designated as F/group). Composite build-up was created on the enamel. Sectioned specimens (n=10 per group; 1 mm2; cross-sectional area) were created and stressed in a universal testing machine at 1 mm/min crosshead speed. The application of 10% SA immediately after bleaching with 16% CP or 35% HP increased the enamel MTBS, regardless of the adhesive/composite resin used. The resulting MTBS values were similar to those of the control groups. Use of 16% CP and 35% HP alone decreased the enamel MTBS, regardless of the adhesive/composite resin used, with F/CP+SA=F/HP+SA=F/CP=S/CP+SA=S/HP+SA=S/C>S/CP=S/HP=F/CP=F/HP (p<0.05). We concluded that the application of SA for 10 minutes immediately after vital bleaching increases the enamel BS for dimethacrylate- and silorane-based composites.

Natural extracts versus sodium ascorbate to extend the shelf life of meat-based ready-to-eat meals

The effect of grape seed and green tea extracts was compared with effect of sodium ascorbate on bacterial spoilage, lipid stability and sensory quality in cooked pork meatballs during refrigerated storage. Meatballs were stored at 4 in aerobic packaging for 0, 4, 8, 12 and 16 days under retail display conditions. Lipid oxidation was evaluated as thiobarbituric acid reactive substances, volatile compounds and cholesterol oxidation products. Colour stability was assessed through CIELab parameters. Microbiological spoilage was determined through total viable, mould and yeast and coliform counts. The samples containing green tea and grape seed extracts showed lower levels of thiobarbituric acid reacting substances, major volatile compounds and microbiological counts than the samples with sodium ascorbate. Formation of cholesterol oxidation products was also inhibited to a greater extent. Colour of meatballs and pork meatballs was not affected by refrigerated storage; however, the addition of extracts provided brown shades. The addition of antioxidants did not modify the sensory attributes except for the colour. Green tea and grape seed extracts were more effective than sodium ascorbate at preventing lipid oxidation.

Effect of Sodium Ascorbate on Resin Bonding to Sodium Perborate–bleached Dentin

SUMMARY This was an in vitro study to evaluate the effect of sodium ascorbate on the microshear bond strength (MSBS) of resin composite to sodium perborate-bleached dentin. Molar dentin sections were divided into six groups: 1) control, 2) sodium perborate (SP) bleach and immediate bonding, 3) SP and 30 second sodium ascorbate (SA); 4) SP and 1 minute SA; 5) SP and 2 minute SA; and 6) SP and 7 day delay before bonding. They were further divided into two-step self-etching (Clearfil SE Bond) or all-in-one self-etching (Xeno IV) adhesive systems. Resin composite microtubes were bonded according to dentin location-center, pulp horn, and peripheral positions-and an MSBS test was carried out. Failure mode was determined using light microscopy and scanning electron microscopy. There were no significant differences between the treatment types/groups. MSBSs were significantly higher for two-step self-etching adhesive compared with all-in-one self-etching adhesive (p=0.028). For the all-in-one adhesive, MSBSs at the center and pulp horn positions were significantly lower than the peripheral positions (p<0.001). All-in-one groups had significantly more adhesive failures than two-step adhesive groups (p=0.015). The odds of adhesive failure were higher at the pulp horn position than the peripheral position (p=0.004). Sodium perborate bleaching of dentin had no effect on MSBS or mode of failure for either two-step or all-in-one self-etching adhesives; therefore, the effect of sodium ascorbate was negligible. The two-step adhesive groups demonstrated the highest MSBS, and the all-in-one groups, when bonded to center and pulp horn dentin, exhibited the lowest MSBS.

Effect of sodium ascorbate dose on the shelf life stability of reduced nitrite liver pâtés

The effect of sodium ascorbate (SA; 500, 750, 1000mg/kg) and sodium nitrite (SN; 40, 80, 120mg/kg) doses on the shelf-life stability of liver pâtés was investigated in a full factorial design. Clear dose-dependent responses of the added SN or SA were found for the concentrations of nitrite, ascorbic acid and dehydroascorbic acid in the raw batters and in the cooked pâtés before and after 48h of chilled display. Decreasing the SN dose to 80mg/kg had no negative impact on the colour stability (a* value) and lipid oxidation (TBARS), and no additional antioxidant effect of SA was noticed. Lowering SN to 40mg/kg resulted in proper colour formation, but the colour stability was inferior and lipid oxidation increased. Yet, increasing the amount of SA, at this low SN dose, resulted in lower TBARS values. Decreasing the SN dose to 80 or 40mg/kg had no distinct effect on protein oxidation, which was however only measured by carbonyl content.

Effect of Sodium Ascorbate and the Time Lapse before Cementation after Internal Bleaching on Bond Strength between Dentin and Ceramic

To evaluate the effects of the elapsed time (ET) after nonvital bleaching (NVB) and sodium ascorbate application (10%) (SAA) on the shear bond strength of dentin to ceramic. Bovine incisors were selected, internally bleached (35% carbamide peroxide) for 9 days and submitted to the following treatments (n = 10): G1, G2, G3-luting after 1, 7, and 14 days; G4, G5, and G6-luting after SAA, 1, 7, and 14 days, respectively. G7 and G8 were not bleached: G7-luting 24 hours after access cavity sealing; G8-luting 24 hours after access cavity sealing after SAA. After NVB, the vestibular dentin was exposed and flattened. The SAA was applied to the dentin (G4, G5, G6, G8) for 10 minutes, and it was then washed and dried. The dentin was etched (37% phosphoric acid), and an adhesive system (Single Bond 2) was applied. Feldspathic ceramic discs (VM7; 4-mm diameter, 3-mm thick) were luted with a dual-resin agent (RelyX ARC, 3M ESPE Dental Products, St. Paul, MN). After 24 hours, specimens were submitted to shear test on a universal testing machine. The data (MPa) were submitted to ANOVA and Dunnet's test (5%). The means (+/- SD) obtained were (MPa): G1 (14 +/- 4.5), G2 (14.6 +/- 3.1), G3 (14 +/- 3.7), G4 (15.5 +/- 4.6), G5 (19.87 +/- 4.5), G6 (16.5 +/- 3.7), G7 (22.8 +/- 6.2), and G8 (18.9 +/- 5.4). SAA had a significant effect on bond strength (p= 0.0054). The effect of ET was not significant (p= 0.1519). G5 and G6 presented higher values than the other bleached groups (p < 0.05) and similar to G7 and G8 (p > 0.05). After NVB, adhesive luting to dentin is recommended after 7 days if sodium ascorbate has been applied prior to dentin hybridization.

Effect of sodium ascorbate on bond strength of different adhesive systems to NaOCl‐treated dentin

The aim of this study was to evaluate the effects of sodium ascorbate on bond strength of different adhesive systems to NaOCl-treated dentin. Eighty extracted molar teeth were used in the study. The buccal enamel surfaces were removed to obtain a flat dentin surface. The teeth were mounted in self-curing resin and dentin surfaces were irrigated with NaOCl for 10 min. Half of the specimens were treated with sodium ascorbate for 10 min. The teeth were randomly assigned to four subgroups according to the adhesive systems used (Clearfil SE Bond, Clearfil Tri-S Bond, Adper Prompt-L-Pop, Adper Single Bond 2). Bond strengths were determined with a Universal Testing Machine, at a crosshead speed of 0.5 mm/min. Data were statistically analysed using anova at a significance level of 0.05. Two-way ANOVA revealed that the effect of sodium ascorbate application on bond strength of adhesive systems to NaOCl-treated dentin was statistically significant (P < 0.05). The bond strength results were significantly influenced by the application of sodium ascorbate (P < 0.05) and there was a significant difference between the adhesive systems (P < 0.05). Although statistically significant differences were not demonstrated in all adhesive resin groups, sodium ascorbate application after NaOCl treatment improved the bond strength values.

The effect of sodium ascorbate on the mechanical properties of hyaluronan-based vascular constructs

Esterified hyaluronic acid (HYAFF) is routinely used for clinical tissue engineering applications such as skin and cartilage. In a previous study we developed a technique for in vitro generation of cylindrical constructs from cellularized HYAFF flat sheets. In the present investigation we studied the possibility to improve mechanical properties of this vascular construct by the addition of sodium ascorbate (SA). Non-woven HYAFF flat sheets were seeded with porcine aortic smooth muscle cells (SMCs) and cultured for 14 or 28 days with standard medium or medium additioned with SA. In selected experiments HYAFF sheets seeded with SMCs were wrapped to obtain cylindrical shape and then cultured in control medium or SA additioned medium for up to 28 days. We estimated cell viability for flat sheets, and performed histological examination, analysis of extracellular matrix (ECM) deposition and mechanical tests on tubular constructs. The number of viable cells and ECM deposition increased with time in constructs cultured in the presence of SA, as compared to control group. Moreover, SA improved mechanical properties of the vascular construct lowering material stiffness and increasing tensile strength as compared to untreated controls. The addition of SA to the medium improved cell proliferation and ECM synthesis on this biodegradable material, which leads to the formation of well organized, mechanical resistant tissue-engineered structure.