Simplified Application Procedures Research Articles

Maturation of restorative glass ionomers with simplified application procedure

ObjectivesRecent developments in glass ionomers (GI), including improved mechanical properties, allow the application of a filling without using a varnish to protect the initial setting reaction. Thus, this study aims to monitor the mechanical behavior of these new developments in comparison to traditional and clinically established GIs within one year of maturation by using generally accepted testing methodology along with a new test for determining chipping resistance. Materials and methodsFour GIs were characterized by assessing the variation in edge strength (ES), compressive strength (CS), Vickers hardness (HV) and indentation modulus (YHU). A special jig was constructed to examine ES, allowing a standardized positioning of the specimen during measurement to simulate clinical chipping, which is a commonly observed failure in brittle restoratives. ResultsThe properties analyzed herein progressively enhanced with maturation, but each properties followed different patterns. All applied tests were able to discriminate between different GI products and maturation stages. Depth-sensing indentation was evidenced as the most discriminatory testing methodology. Differences in chemical composition were better reflected by YHU, while the effect of maturation by HV. HV correlates moderate with CS (0.669) and ES (0.468). The correlation of YHU with the same parameters was lower (0.550 and 0.369). A very good correlation was identified between HV and YHU (0.843). ConclusionsThe new developed test was identified as reliable, sensitive to changes in the chemical composition of GIs and during maturation, easy-to-implement and may be used for ascertaining chipping resistance. The claimed improvement in mechanical properties in the absence of a protective varnish was generally confirmed.

Bonding effectiveness of self-etch adhesives to dentin after 24 h water storage.

Purpose:This study evaluated the immediate bonding effectiveness of five self-etch adhesive systems bonded to dentin.Materials and Methods:The microtensile bond strength of five self-etch adhesives systems, including one two-step and four one-step self-etch adhesives to dentin, was measured. Human third molars had their superficial dentin surface exposed, after which a standardized smear layer was produced using a medium-grit diamond bur. The selected adhesives were applied according to their respective manufacturer's instructions for μTBS measurement after storage in water at 37°C for 24 h.Results:The μTBS varied from 11.1 to 44.3 MPa; the highest bond strength was obtained with the two-step self-etch adhesive Clearfil SE Bond and the lowest with the one-step self-etch adhesive Adper Prompt L-Pop. Pretesting failures mainly occurring during sectioning with the slow-speed diamond saw were observed only with the one-step self-etch adhesive Adper Prompt L-Pop (4 out of 18).Conclusions:When bonded to dentin, the self-etch adhesives with simplified application procedures (one-step self-etch adhesives) still underperform as compared to the two-step self-etch adhesive Clearfil SE Bond.

Layering mechanism of MDP-Ca salt produced in demineralization of enamel and dentin apatite

ObjectiveThe 10-methacryloyloxydecyl dihydrogen phosphate (MDP) (EX adhesives)-based one-step self-etch adhesives have become widely utilized due to their simplified application procedures. The aim of this study was to determine the type of the molecular species of calcium salts of MDP (MDP-Ca salts) that form a layered structure and to understand the layering mechanism of MDP-Ca salts. MethodsThe EX adhesives were prepared by varying the amounts of MDP (25.6, 49.9, 80.5 and 116.1mg) added in 1g of the EX adhesive. Enamel and dentin reactant residues were obtained after the reaction of each EX adhesive to enamel or dentin particles for 30s. The chemical analyses of both reactant residues were then performed. ResultsThe molecular species of MDP-Ca salts that form a layered structure were determined as mono-calcium salt (MCS-MD) and di-calcium salts of the MDP dimer (DCS-MD). The dentin sample showed two types of characteristic XRD peaks assigned to the layer structure, since the dentin produced DCS-MD along with MCS-MD in contrast to the enamel sample. A mono-calcium salt of the MDP monomer (MCS-MM), a predominant molecular species, was not contributed to a layered-structure formation, since the intensities of characteristic XRD peaks are limited by the production of DCS-MD and MCS-MD. SignificanceThe self-assembled layering of MCS-MD and DCS-MD is associated by a hydrophobic bond between two 10-methylene groups in MCS-MD and DCS-MD. The MCS-MD may form a more tightly-packed layered structure than DCS-MD by the hydrogen bonded interaction between hydroxy groups bonded to each phosphorous atom.

Comparison of Shear Bond Strength of Composite Restoration to Intact Enamel of Primary Incisors using Different Conditioners, and Adhesive Systems

Background: Esthetic demands among patients have led to the introduction of tooth-colored restorations. Composite resins bond to enamel applying acid etch technique. Total etch adhesion systems are still considered as golden standard among bonding systems. However, clinicians have tendency towards using adhesive systems with a simplified application procedure. The aim of the present study is to compare the shear-bond strength of composite restoration to intact enamel of primary incisors using different conditioners, and adhesive systems.
 Materials and Methods: This experimental study was conducted in Shiraz University of Medical Sciences. 53 teeth were classified into 5 groups based on the bonding procedure. After composite build-up, specimens were placed in a universal testing machine at a cross-head speed of 1mm/min. Inter-group comparison of the shear-bond strength to enamel was analyzed employing One-way-ANOVA and Tukey post-hoc test. Data were statistically analyzed using SPSS (Version 17, Chicago, IL, USA).
 Results: The highest shear-bond strength was related to the second (37% phosphoric acid etching + Margin Bond adhesive system), and the fifth group (37% phosphoric acid etch + Tokuyama Bond Force adhesive system), and the lowest bond strength was related to the third group (Tokuyama Bond Force adhesive system alone) (p value = 0.00).
 Conclusion: Based on the results of the present study, surface pre-treatment with 37% PA accompanied with self-etching adhesive system, increased the shear-bond strength in vitro. This method can be further studied in clinical settings.

Effect of adhesive system type and root region on the push‐out bond strength of glass–fibre posts to radicular dentine

To compare interfacial strength in different thirds of the root canal amongst glass-fibre posts luted with four different adhesive luting agents. A total of 44 extracted human single-rooted teeth were randomly divided in four groups and restored using glass-fibre posts and the following luting agents: All Bond SE/Duo-Link (ABSE), All Bond 3/Duo-Link (AB3), BisCem (BC), Clearfil ED primer II/Clearfil Esthetic Cement (CLF). One week after luting, the samples were thermocycled in water, and then embedded in acrylic resin. Three sections (cervical, middle and apical) of 2 mm thickness were prepared from each specimen, and the post in each section was subjected to a push-out test. One additional specimen for each group was prepared for scanning electron microscopy analysis and the bonding effectiveness to dentine was assessed. The data were analysed using the Kolmogorov-Smirnov test, two-way anova, one-way anova, and the Scheffe test (P < 0.05). The push-out bond strength values for BC and ABSE were not significantly different (P > 0.05), but both were significantly higher than the means for AB3 and CLF (P < 0.05) in the cervical and middle regions. The same trend was observed in the apical region, except for the AB3 and ABSE which were not significantly different (P > 0.05) from each other. There were significant differences in bond strength amongst root thirds, with a reduction in values from the cervical to apical third (P < 0.05). The use of BisCem and All Bond SE/Duo-Link combination with their simplified application procedures may be considered an alternative to the currently used systems for luting glass-fibre posts in root canal.

Glass Ionomer Derivates Have Better Retention Rates in Cervical Restorations Compared to Self-Etching Adhesive Systems

MEDLINE search and search of abstracts of IADR/AADR and ConsEuro conferences published between January 1998 and May 2004 revealed 85 prospective clinical trials on the clinical effectiveness of 57 different adhesive systems (or restoratives) in Class V restorations; 35 of these trials were published in peer-reviewed journals and 50 as conference abstracts. No further selection was made. All studies had to include information on the retention rates. Five types of adhesives were differentiated: 3 and 2 step etch-and-etch adhesives, 2 and 1 step self-etch adhesives, and glass ionomer derivates. No minimal or maximal exposure limit was set. The main outcome was the annual retention loss in relation to one of the 5 adhesive systems used in non-carious Class V restorations. The observation period of the studies varied between 0.5 years and 6 years. Restorations with glass ionomer derivates showed the highest success rate in regard to retention with a mean annual loss of retention of 1.9% (range 0%-7.6%). Three-step etch-and-rinse adhesive systems and 2-step self-etch adhesive systems showed a clinically reliable and predictably good clinical performance with a mean annual retention loss of 4.8% (range 0%-16%) and 4.7%(range 0%-19%) respectively, whereas the mean annual retention loss of 2-step etch-and-rinse adhesive systems was 6.2% (range 0%-19.5%) and that of 1-step self-etching adhesives 8.1% (range 0%-48%). However, due to the great variability a statistically significant difference was found only for glass ionomer versus 2-step etch-and-rinse and glass ionomer versus 1-step self-etch adhesive systems when the Kruskall-Wallis and Dwass-Steel-Chritchlow-Fligner test for multiple comparisons was applied. The percentage of adhesive systems--according to the adhesive category--which would get the full ADA acceptance was as follows: glass ionomer derivates 96%, 3-step etch-and-rinse 81%, 2-step self-etch 71%, 1-step self-etch 68%, 2-step etch-and-rinse 51%. The authors concluded that although there is a tendency towards adhesives with simplified application procedures, simplification appears to induce loss of effectiveness.

Microtensile Bond Strength and Interfacial Characterization of 11 Contemporary Adhesives Bonded to Bur-cut Dentin

This study evaluated mechanically and ultra-morphologically 11 different adhesive systems bonded to dentin. The microtensile bond strength (microTBS) of 11 contemporary adhesives, including two three-step etch&rinse, three two-step etch&rinse, two two-step self-etch and four one-step self-etch adhesives to dentin, were measured. The resultant interfacial ultra-structure at dentin was characterized by transmission electron microscopy (TEM). Human third molars had their superficial dentin surface exposed, after which a standardized smear layer was produced using a medium-grit diamond bur. The selected adhesives were applied according to their respective manufacturer's instructions for microTBS measurement after storage in water at 37 degrees C for 24 hours or for TEM interfacial characterization. The microTBS varied from 11.1 to 63.6 MPa; the highest bond strengths were obtained with the three-step etch&rinse adhesives and the lowest with one-step self-etch adhesives. TEM evaluation showed very different interaction patterns, especially for the self-etch adhesives. "Mild" self-etch adhesives demineralized the dentin surface sufficiently to provide micro-mechanical retention, while preserving hydroxyapatite within the hybrid layer to enable additional chemical interaction. When bonded to dentin, the adhesives with simplified application procedures (in particular, one-step self-etch adhesives) still underperform as compared to conventional three-step adhesives. "Mild" two-step self-etch adhesives that provide additional chemical bonding appear to most optimally combine bonding effectiveness with a simplified application protocol.

Bond strength and morphology of enamel using self-etching adhesive systems with different acidities

Objectives:To assess the bond strength and the morphology of enamel after application of self-etching adhesive systems with different acidities. The tested hypothesis was that the performance of the self-etching adhesive systems does not vary for the studied parameters.Material and methods:Composite resin (Filtek Z250) buildups were bonded to untreated (prophylaxis) and treated (burcut or SiC-paper) enamel surfaces of third molars after application of four self-etching and two etch-and-rinse adhesive systems (n=6/condition): Clearfil SE Bond (CSE); OptiBond Solo Plus Self-Etch (OP); AdheSe (AD); Tyrian Self Priming Etching (TY), Adper Scotchbond Multi-Purpose Plus (SBMP) and Adper Single Bond (SB). After storage in water (24 h/37°C), the bonded specimens were sectioned into sticks with 0.8 mm2 cross-sectional area and the microtensile bond strength was tested at a crosshead speed of 0.5 mm/min. The mean bond strength values (MPa) were subjected to two-way ANOVA and Tukey's test (α=0.05). The etching patterns of the adhesive systems were also observed with a scanning electron microscope.Results:The main factor adhesive system was statistically significant (p<0.05). The mean bond strength values (MPa) and standard deviations were: CSE (20.5±3.5), OP (11.3±2.3), AD (11.2±2.8), TY (11.1±3.0), SBMP (21.9±4.0) and SB (24.9±3.0). Different etching patterns were observed for the self-etching primers depending on the enamel treatment and the pH of the adhesive system.Conclusion:Although there is a tendency towards using adhesive systems with simplified application procedures, this may compromise the bonding performance of some systems to enamel, even when the prismless enamel is removed.

Clinical effectiveness of contemporary adhesives: A systematic review of current clinical trials

Objectives The purpose of this paper was to review current literature on the clinical effectiveness of contemporary adhesives when used to restore cervical non-carious class-V lesions. Restoration retention in function of time was recorded in order to find out if adhesives with a simplified application procedure are as clinically effective as conventional three-step adhesives. Data Sources Literature published from January 1998 up to May 2004 was reviewed for university-centred clinical trials that tested the clinical effectiveness of adhesives in non-carious class-V lesions. Restoration-retention rates per adhesive reported in peer-reviewed papers as well as IADR-AADR abstracts and ConsEuro abstracts were included and depicted as a function of time in graphs for each of the five adhesive classes (three- and two-step etch-and-rinse adhesives, two- and one-step self-etch adhesives, and glass ionomers). The guidelines for dentin and enamel adhesive materials advanced by the American Dental Association were used as a reference. Per class, the annual failure rate (%) was calculated. Kruskal–Wallis analysis and Dwass–Steel–Chritchlow–Fligner pairwise comparisons were used to determine statistical differences between the annual failure percentages of the five adhesive categories. Results Comparison of retention of class-V adhesive restorations as a measure to determine clinical bonding effectiveness of adhesives revealed that glass ionomers most effectively and durably bond to tooth tissue. Three-step etch-and-rinse adhesives and two-step self-etch adhesives showed a clinically reliable and predictably good clinical performance. The clinical effectiveness of two-step etch-and-rinse adhesives was less favourable, while an inefficient clinical performance was noted for the one-step self-etch adhesives. Significance Although there is a tendency toward adhesives with simplified application procedures, simplification so far appears to induce loss of effectiveness. Clinical performance can be correlated with, and predicted by, appropriate types of laboratory study.— Reprinted with permission of The Academy of Dental Materials.

Clinical effectiveness of contemporary adhesives: A systematic review of current clinical trials

The purpose of this paper was to review current literature on the clinical effectiveness of contemporary adhesives when used to restore cervical non-carious class-V lesions. Restoration retention in function of time was recorded in order to find out if adhesives with a simplified application procedure are as clinically effective as conventional three-step adhesives. Literature published from January 1998 up to May 2004 was reviewed for university-centred clinical trials that tested the clinical effectiveness of adhesives in non-carious class-V lesions. Restoration-retention rates per adhesive reported in peer-reviewed papers as well as IADR-AADR abstracts and ConsEuro abstracts were included and depicted as a function of time in graphs for each of the five adhesive classes (three- and two-step etch-and-rinse adhesives, two- and one-step self-etch adhesives, and glass-ionomers). The guidelines for dentin and enamel adhesive materials advanced by the American Dental Association were used as a reference. Per class, the annual failure rate (%) was calculated. Kruskal-Wallis analysis and Dwass-Steel-Chritchlow-Fligner pairwise comparisons were used to determine statistical differences between the annual failure percentages of the five adhesive categories. Comparison of retention of class-V adhesive restorations as a measure to determine clinical bonding effectiveness of adhesives revealed that glass-ionomers most effectively and durably bond to tooth tissue. Three-step etch-and-rinse adhesives and two-step self-etch adhesives showed a clinically reliable and predictably good clinical performance. The clinical effectiveness of two-step etch-and-rinse adhesives was less favourable, while an inefficient clinical performance was noted for the one-step self-etch adhesives. Although there is a tendency towards adhesives with simplified application procedures, simplification so far appears to induce loss of effectiveness. Clinical performance can be correlated with, and predicted by, appropriate types of laboratory study.

A Proposal of Fracture Control Design Procedure

In order to make the fracture mechanics analysis readily applicable at design levels with efforts normally required in design for stress analysis, this paper proposes its simplified application procedure. The key point of this procedure is the estimation of the crack propagation path and K value from the stress analysis results on crackless model.The proposed crack path estimation criteria are based on the study of the relationship between the direction of principal stress in a flat plate as well as the K value when the crack reaches a normal crossing member and the crack propagation path. The proposal also includes simplified K value estimation methods by grouping actual forms of cracking into several typical patterns, so that the designer can estimate the K value for almost any type of structural members which he will face in his design. To verify the validity of the proposed procedure, the bottom transverse damage of a large tanker was analyzed for comparison with the actual cracks. The analysis results are consistent in explaining the actual damage phenomena and this procedure has been proved quite practical through examination of the design measures taken.

The Transient Recovery Voltage Application of Power Circuit Breakers

The proposed transient recovery voltage standard for high voltage circuit breakers will specify application requirements on a recovery voltage basis. This paper studies the inherent circuit parameters required to generate the required TRV envelope. A simplified application procedure is developed based on miles to the first line discontinuity and the number of lines connected on the bus side of the circuit breaker.

The X/R Method of Applying Power Circuit Breakers

A NEW BASIS for rating power circuit breakers was proposed at the January 1954 AIEE Winter General Meeting by the Working Group on Methods of Rating Power Circuit Breakers. This group proposed that the making, latching, and interrupting current ratings of circuit breakers be combined into one rating, rated short-circuit current, having specified characteristics which a breaker shall be able to close, carry, and interrupt with any permissible delay in tripping on a predominantly resistive or inductive circuit. To compare these specified characteristics with the decrement rates for asymmetrical fault currents on high-voltage systems, a so-called X/R method has been developed and is intended for use as the basis for a simplified application procedure for power circuit breakers rated on the proposed new basis.

Corrosion Resistant Coatings — Properties and Uses

The use of organic coatings to control severe corrosion and contamination conditions in industry has grown considerably during the past ten years. Because the resin research chemist has made available to the coating formulators new and improved resins, this progress has been expedited considerably. Application of coatings formulated from the four newer resins discussed in this paper has resulted in considerable savings and has reduced shutdown, due to equipment failure from corrosion, by a large percentage. Structural steel in paper and pulp and chemical plant environments has been completely protected for period of four years and more where formerly repainting was required every six months and replacement about every five years. Coating of steel headers and piping in cooling towers will give satisfactory protection for three to four years where as formerly three to four months was the average life of the protaction afforded by best paints and enamels. The wide range of resistance of the new type catalyzed coatings has made possible the lining of tanks cars to insure freedom from product contamination for a wide range of products including sugar syrups, solvents, alkalies, plasticizers, transformer ois, and various food products. Beer and wine storage tanks, either of steel or concrete can now be coated to prevent all product contamination, and the linings will withstand the various cleaning operations which are normally used in these industries. Such linings can be easily repaired in the field in case of mechanical damage. The simplified application procedures of these new coating materials has extended their uses many fold and has decreased the failure incident. Higher or greater film thickness has enabled the customer to use more accurate inspection methods such as electrical spark testing or electrical continuity testing. The thin film coatings could not be inspected in this manner due to their inability to withstand such fasts. Fexibility has been increased without sacrificing any resistance thus making the coatings more resistant to mechanical damage during cleaning operations or in normal use. Research and development will continue to produce new resins and coating materials so that the useful range of organic coatings can be further extended.