scholarly journals Reversal of Compromised Bonding in Bleached Enamel

2002 ◽  
Vol 81 (7) ◽  
pp. 477-481 ◽  
Author(s):  
S.C.N. Lai ◽  
F.R. Tay ◽  
G.S.P. Cheung ◽  
Y.F. Mak ◽  
R.M. Carvalho ◽  
...  
Keyword(s):  
Sodium Ascorbate ◽  
Carbamide Peroxide ◽  
Water Control ◽  
Transmission Electron ◽  
Human Enamel ◽  
Silver Deposits ◽  
Anti Oxidant ◽  
Bond Strengths ◽  
Silver Grains ◽  
Ammoniacal Silver

Oxygen inhibits polymerization of resin-based materials. We hypothesized that compromised bonding to bleached enamel can be reversed with sodium ascorbate, an anti-oxidant. Sandblasted human enamel specimens were treated with distilled water (control) and 10% carbamide peroxide gel with or without further treatment with 10% sodium ascorbate. They were bonded with Single Bond (3M-ESPE) or Prime&Bond NT (Dentsply DeTrey) and restored with a composite. Specimens were prepared for microtensile bond testing and transmission electron microscopy after immersion in ammoniacal silver nitrate for nanoleakage evaluation. Bond strengths of both adhesives were reduced after bleaching but were reversed following sodium ascorbate treatment (P < 0.001). Resin-enamel interfaces in bleached enamel exhibited more extensive nanoleakage in the form of isolated silver grains and bubble-like silver deposits. Reduction of resin-enamel bond strength in bleached etched enamel is likely to be caused by a delayed release of oxygen that affects the polymerization of resin components.

Comparison of the Effect of Hydrogel and a Solution of Sodium Ascorbate on Dentincomposite Bond Strength After Bleaching

2008 ◽  
Vol 9 (2) ◽  
pp. 105-112 ◽  
Author(s):  
Soodabeh Kimyai ◽  
Hadi Valizadeh
Keyword(s):  
Bond Strength ◽  
Shear Bond Strength ◽  
Resin Composite ◽  
Sodium Ascorbate ◽  
Carbamide Peroxide ◽  
Treatment Groups ◽  
Bleaching Procedure ◽  
Bond Strengths ◽  
Composite Shear ◽  
Group 1

Abstract Aim The aim of this study was to compare the effects of solution and different sodium ascorbate hydrogels on dentin-resin composite shear bond strength subsequent to a bleaching procedure with 10% carbamide peroxide. Methods and Materials Sixty buccal dentin surfaces obtained from intact human third molars were randomly divided into five groups (n=12). Dentin surfaces received different treatments: (1) no treatment; (2) bleaching (10% carbamide peroxide gel); (3) bleaching + 10% sodium ascorbate solution; (4) bleaching + 10% sodium ascorbate hydrogel, and (5) bleaching + 20% sodium ascorbate hydrogel. Dentin surfaces were bonded with Single Bond™ and restored with a composite (Z100). The samples were tested for shear bond strengths. Data was analyzed using analysis of variance (ANOVA) and Tukey tests. Results Significantly higher bond strengths were observed subsequent to treatment with hydrogel and solution forms of sodium ascorbate (p<0.05). No significant differences were demonstrated between different forms of sodium ascorbate preparations. In addition, no significant differences were observed among groups with antioxidant treatment (Groups 3, 4, and 5) and Group 1 (no treatment). Conclusion Reduced bond strength to bleached dentin can be amended by the use of sodium ascorbate as an antioxidant. Clinical Significance Both hydrogel and solution forms of sodium ascorbate can significantly improve the reduced bond strength of resin composite to dentin subsequent to a bleaching procedure with 10% carbamide peroxide. Citation Kimyai S, Valizadeh H. Comparison of the Effect of Hydrogel and a Solution of Sodium Ascorbate on Dentin-composite Bond Strength After Bleaching. J Contemp Dent Pract 2008 February;(9)2:105-112.

scholarly journals Effects of an Antioxidant on the Shear Bond Strengths of Orthodontic Brackets After Conventional and Laser-Assisted Extra-Coronal Bleaching

2018 ◽  
Vol 20 (3) ◽  
pp. 71-79
Author(s):  
Funda Fundaoĝlu Küçükekenci DDS ◽  
Ahmet Serkan Küçükekenci DDS, PhD ◽  
Süleyman Kutalmiş Büyük DDS, PhD
Keyword(s):  
Bond Strength ◽  
Orthodontic Brackets ◽  
Sodium Ascorbate ◽  
Control Group ◽  
Bleaching Procedure ◽  
Human Enamel ◽  
Negative Effect ◽  
Group 3 ◽  
Bond Strengths ◽  
Group 2

Purpose: The purpose of this study was to evaluate the effects of the application of antioxidant on the shear bond strengths (SBS) of orthodontic brackets bonded to human enamel after extra-coronal bleaching with hydrogen peroxide (HP). Materials and methods: Fifty freshly extracted premolars were randomly divided into three groups. One group (Group 1) was bleached with 40% HP (n=20), another group (Group 2) was bleached with 40% HP and activated with an Nd: YAG laser (n=20), and a control group (Group 3) received no treatment (n=10). After the bleaching procedure, Groups 1 and 2 were further divided into two subgroups (Group 1a, Group 1b, Group 2a, and Group 2b). Specimens in Groups 1a and 2a (n=10) received no antioxidant application. A 10% sodium ascorbate solution was applied to specimens in Groups 1b and 2b (n=10). The brackets were then bonded with light-cure adhesive paste to the enamel surfaces of all experimental groups. Specimens were subjected to SBS tests for debonding. Results: The SBS of brackets bonded in Groups 1 and 2 were significantly lower than those of brackets bonded to the control group (p<0.001); however, no statistically significant differences in SBS were noted in Groups 1 and 2 (p>0.001). The antioxidant-treated SBS of brackets in Groups 1b and 2b were significantly higher than those of Groups 1a and 2a (p<0.001). Conclusions: The application of 40% HP had a negative effect on the bond strength. The use of antioxidant for 15 min resulted in the reversal of failed bond strength.

Electron Micro Technology Study on BN Fiber’s Microcosmic Structure and Mechanics Properties

2012 ◽  
Vol 588-589 ◽  
pp. 104-107
Author(s):  
Qing Tian Li
Keyword(s):  
Mechanical Properties ◽  
Scientific Basis ◽  
Manufacturing Technology ◽  
Technology Study ◽  
Compound Material ◽  
Transmission Electron ◽  
Anti Oxidant ◽  
Micro Technology ◽  
Compound Materials ◽  
Analytical Technology

This paper uses transmission electron microscope technology, studies microcosmic structure’ s feature of BN fiber, clarifies existing crystal structure’s state of BN fiber during its producing and transform course. It is studied that BN fiber has a sound mechanical properties, which most of crystalline phase is turbine layer phase and whose nitrogen is high and size is small .During the course of BN fiber’s producing, adding suitable tension from axial can promote directional arrange of BN fiber’s surface crystalline grain and put forward the improving direction of manufacturing technology in order to improve materials’ mechanical properties. BN fiber(indicated by BNf) is a kind of new inorganic material. Because of its fine stable, corrosion-resisting, anti-oxidant properties and high ability of absorbing neutron and so on, it is attached more and more importance and it get constant development and usefulness. BNf and ceramics, metal, various compound materials made of resin material can be used in metallurgy, electron, aviation etc science and technology fields. But the intensity of BNf and its elasticity modulus are lower than basic fundamental material. When BNf’s compound material get fine properties above mentioned, the mechanics properties of the material will drop. So its application degree will be limited to a certain extent. In order to improve and raise BNf’s mechanics properties, this essay makes use of electron micro analytical technology to study its microcosmic structure and mechanics properties, providing scientific basis for designing reasonable manufacturing technology.

scholarly journals Adhesion of Two Bonding Systems to Air-Abraded or Bur-Abraded Human Enamel Surfaces

2008 ◽  
Vol 02 (03) ◽  
pp. 167-175 ◽  
Author(s):  
Abdulkadir Sengun ◽  
Hasan Orucoglu ◽  
Ilknur Ipekdal ◽  
Fusun Ozer
Keyword(s):  
Bond Strength ◽  
Composite Resin ◽  
In Vitro Study ◽  
Air Abrasion ◽  
Adhesive Resin ◽  
Bonding Performance ◽  
Human Enamel ◽  
Bond Strengths ◽  
Bonding Systems

ABSTRACTObjectives: The purpose of this in vitro study was to evaluate whether mechanical alteration of the enamel surfaces with air abrasion and bur abrasion techniques could enhance the bonding performance of a three step and a self etching adhesive resin systems to enamel.Methods: 126 extracted lower human incisor teeth were used. The teeth were divided into three groups including 40 teeth each. First group; teeth were used as control and no preparation was made on enamel surfaces, 2nd group; outer enamel surfaces were air abraded, 3rd group; outer enamel surfaces were abraded mechanically with a diamond fissure bur. Cylinder composite resin blocks were bonded to the buccal enamel surfaces with two bonding systems (20 specimens in each group). Bond strengths to enamel surfaces were measured at a cross-head speed of 1 mm/min. The data were analyzed by ANOVA and Duncan Tests. To examine interface composite resin/enamel surfaces at scanning electron microscopy, remaining 6 teeth were used. Fracture analysis was performed using an optical stereomicroscope.Results: Bond strengths values of Solid Bond were significantly higher than bond strengths of Clearfil SE Bond for all types of enamel (P<.05). Shear bond strength values obtained with Solid Bond (three step system) to three types of enamel surfaces [air-abraded (30.25±7.00 MPa), bur-abraded (29.07±3.53 MPa), control (31.74±7.35 MPa)] were close to each other (P>.05). The macroscopic mode of failures for bonding systems, SB and SE Bond appeared to be adhesive and cohesive in nature.Conclusions: In order to get better bond strength values with self etching systems, it is advisable to prepare enamel surfaces with bur or air abrasion, but it enamel preparation is not necessary for three step systems. (Eur J Dent 2008;2:167-175)

scholarly journals Two Modes of Nanoleakage Expression in Single-step Adhesives

2002 ◽  
Vol 81 (7) ◽  
pp. 472-476 ◽  
Author(s):  
F.R. Tay ◽  
D.H. Pashley ◽  
M. Yoshiyama
Keyword(s):  
Silver Nitrate ◽  
Silver Ions ◽  
Single Step ◽  
Mineral Dissolution ◽  
Resin Infiltration ◽  
Transmission Electron ◽  
Hybrid Layers ◽  
Self Etch ◽  
Ammoniacal Silver ◽  
Spotted Pattern

Self-etch adhesives that etch, prime, and bond simultaneously should not exhibit incomplete resin infiltration within hybrid layers. We hypothesized that nanoleakage patterns in these systems are artifacts caused by mineral dissolution in mildly acidic silver nitrate. Resin-dentin interfaces bonded with four single-step, self-etch adhesives were examined for nanoleakage by conventional (pH 4.2) and basic ammoniacal (pH 9.5) silver nitrate and prepared for transmission electron microscopy. All adhesives exhibited a reticular mode of nanoleakage within hybrid layers when conventional silver nitrate was used. With ammoniacal silver nitrate, an additional spotted pattern of nanoleakage was observed within adhesive and hybrid layers. The reticular mode of nanoleakage in self-etch adhesives probably represents sites of incomplete water removal that leads to regional suboptimal polymerization. The spotted pattern identified with the use of ammoniacal silver nitrate probably represents potentially permeable regions in the adhesive and hybrid layers that result from the interaction of the basic diamine silver ions with acidic/hydrophilic resin components.

Direct Bonding in Orthodontics: A Comparison of Attachments

1977 ◽  
Vol 4 (2) ◽  
pp. 65-69 ◽  
Author(s):  
I. R. Reynolds ◽  
J. A. von Fraunhofer
Keyword(s):  
Clinical Practice ◽  
Human Enamel ◽  
Bond Strengths ◽  
Tensile Bond Strengths

The tensile bond strengths to human enamel of metallic and non-metallic direct bonding attachments used with their recommended adhesives are reported. The results obtained are compared and contrasted and the findings are discussed in relation to clinical practice.

Acid-rain-induced changes in cuticles and Ca distribution in Scots pine and Norway spruce seedlings

1995 ◽  
Vol 25 (8) ◽  
pp. 1313-1325 ◽  
Author(s):  
Minna Turunen ◽  
Satu Huttunen ◽  
Jaana Back ◽  
Jukka Lamppu
Keyword(s):  
Acid Rain ◽  
Norway Spruce ◽  
Scots Pine ◽  
Crystal Formation ◽  
Water Control ◽  
Growing Seasons ◽  
Physicochemical Changes ◽  
Transmission Electron ◽  
Pine Seedlings ◽  
Induced Changes

Seedlings of Scots pine (Pinussylvestris L.) and Norway spruce (Piceaabies (L.) Karst.) were subjected to acid rain irrigation at pH 7, pH 4, and pH 3 three times a week during the growing seasons of 1986–1989 in a field experiment. Scanning and transmission electron microscopy, energy dispersive spectrometry, contact angle measurements, and chloroform extraction of waxes were used to detect physicochemical changes in the needle cuticles. The first detectable symptoms of acid rain were observed after 5 weeks of acid rain treatment at pH 3 and pH 4, which resulted in few CaSO4 crystallites on visibly undamaged pine and spruce needle surfaces. After 7 weeks of acid rain treatment there were CaSO4 crystallites scattered over the whole needle surface area and erosion of the epicuticular waxes could be observed occasionally. CaSO4 crystal formation later decreased, especially on the needles of seedlings treated at pH 3. Ca concentrations in the needles and roots of the seedlings and in the soil in the boxes were higher in the pH 3 treatments than elsewhere. The more abundant deposition of Ca oxalate crystallites on the inner walls of the epidermal and hypodermal cells of the spruce needles than on their outer walls was probably also connected with Ca leaching, caused by acid rain. Acid rain also delayed wax synthesis, as 2-month-old pine needles exposed to pH 3 and pH 4 had about 50% less wax than the water controls in early August. The needle surfaces of the southern provenances of spruce and pine seedlings were slightly less wettable after pH 4 treatment than after the control water treatment, because they probably benefited from N and S compounds in the irrigation water. The needle surfaces were more wettable in the pH 3 and water control seedlings than in the other treatments.

scholarly journals Eudragit S100 Entrapped Liposome for Curcumin Delivery: Anti-Oxidative Effect in Caco-2 Cells

Coatings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 114 ◽  
Author(s):  
Vincenzo De Leo ◽  
Sante Di Gioia ◽  
Francesco Milano ◽  
Paola Fini ◽  
Roberto Comparelli ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Polymeric Coating ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Physico Chemical ◽  
Eudragit S100 ◽  
Natural Polyphenol ◽  
Anti Oxidant ◽  
Small Unilamellar Vesicles

Curcumin is a natural polyphenol with strong antioxidant activity. However, this molecule shows a very poor bioavailability, instability, and rapid metabolism in vivo. In this work curcumin was loaded in Eudragit-coated liposomes to create a gastroresistant carrier, able to protect its load from degradation and free it at the site of absorption in the colon region. Small unilamellar vesicles were prepared and coated with Eudragit by a pH-driven method. The physico-chemical properties of the prepared systems were assessed by light scattering, transmission electron microscopy, infrared spectroscopy, and differential scanning calorimetry. The uptake of vesicles by Caco-2 cells and the anti-oxidant activity in cells were evaluated. The produced vesicles showed dimensions of about forty nanometers that after covering with Eudragit resulted to have micrometric dimensions at acid pH. The experiments showed that at pH > 7.0 the polymeric coating dissolves, releasing the nanometric liposomes and allowing them to enter Caco-2 cells. Delivered curcumin loaded vesicles were then able to decrease significantly ROS levels as induced by H2O2 in Caco-2 cells. The proposed work showed the possibility of realizing effective gastroresistant curcumin liposome formulations for the delivery of antioxidant molecules to Caco-2 cells, potentially applicable to the treatment of pathological conditions related to intestinal oxidative stress.

Effects of Time and Concentration of Sodium Ascorbate on Reversal of NaOCl-Induced Reduction in Bond Strengths

2007 ◽  
Vol 33 (7) ◽  
pp. 879-881 ◽  
Author(s):  
C WESTON ◽  
S ITO ◽  
B WADGAONKAR ◽  
D PASHLEY
Keyword(s):  
Sodium Ascorbate ◽  
Bond Strengths
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