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PubMed1993

Complexoproductive and antiheparin properties of low density lipoproteins (LDL). III. Interaction of low density lipoproteins (LDL) with synthetic polyanionic compounds.

Low density lipoprotein (LDL) form insoluble complex bonds with polymetacrylic and polyvinylsulphonic acids in the presence of calcium chloride. Quantity of arising complexes depends on the concentrations of LDL, acids and calcium chloride and on pH. These complexes dissociate solutions of sodium chloride, urea and guanidine hydrochloride.

Calcium Chloride↗
PubMed2003

Morphological characterization of the resin-dentin interface in primary teeth.

The effects of self-etching adhesives on primary teeth were evaluated. Reports in the literature suggest differences between the first and second dentition regarding the composition and the morphology and, therefore, a possible difference in the performance of dental adhesives. The purpose of this study was to evaluate the effects of self-etching adhesives on primary dentin. Eight dentin disks were obtained from the occlusal surface of primary molars. The disks were divided between four dental adhesives [Prompt L-PoP (LP), Clearfil SE BOND (SE), Etch&Prime 3.0 (EP) and Prime&Bond NT (PB) + H(3)PO(4) (Control) and "restored" with a composite (Pertac II)]. After sectioning, fixation and HMDS drying, specimens were polished and Field Emission SEM examinations were carried out. Clearly visible hybrid layer formation was found for PB, LP and EP. An undoubtedly detectable interdiffusion zone was not evident after the use of SE. A clearly visible adhesive layer was recognizable for PB, EP and SE, but not continuously detectable for LP. Debonded regions were observed for all systems evaluated, but distinct differences in the failure mode were detected. The evaluated dental adhesives did not generate completely sealed interfaces between the composite resin and the dentin of primary teeth in vitro.

Acid Etching, Dental↗
PubMed1994

Effect of physical properties of direct bonding adhesives on bonding to etched enamel.

Five types of light-cured direct bonding adhesives with different volumes of microfiller were prepared for study of the relationships between bond strength to enamel, resinous tag length, and flexural strength, and between viscosity and resinous tag length. The resinous tag length was measured with the combination of 2,4,6-trichlorophenoxy methacrylate as a tracer and electron-probe microanalyzer. Correlating resinous tag length versus viscosity or bond strength after 1-day immersion, and flexural strength with bond strength after 1-day and 30-day immersion resulted in high correlation coefficients. However, the bond strength after thermocycling did not correlate with resinous tag length or flexural strength.

Acid Etching, Dental↗
PubMed2005

Investigations of step-growth thiol-ene polymerizations for novel dental restoratives.

OBJECTIVES: The goal of this work was to investigate the feasibility of formulating novel dental restorative materials that utilize a step-growth thiol-ene photopolymerization. Particularly, we are aiming to significantly reduce the polymerization shrinkage and shrinkage stress while retaining adequate physical properties as compared to current dimethacrylatre-based systems. METHODS: The thiol-ene system is composed of a 4:3 molar mixture of triallyl-1,3,5-triazine-2,4,6-trione (TATATO) and pentaerythritol tetramercaptopropionate (PETMP). The simultaneous measurement of shrinkage stress and functional group conversion was performed. Solvent extraction of unreacted monomers and dynamic mechanical analysis on the polymer networks that were formed were also studied. Flexural strength was measured for both filled and unfilled PETMP/TATATO and Bis-GMA/TEGDMA systems. RESULTS: Photopolymerization of PETMP/TATATO occurs at a much higher rate, with the maximum polymerization rate six times faster, than Bis-GMA/TEGDMA cured under the identical conditions. The results from the simultaneous measurement of shrinkage stress and conversion showed that the onset of shrinkage stress coincides with the delayed gel point conversion, which is predicted to be 41% for the 3:4 stoichiometric PETMP/TATATO resin composition. The maximum shrinkage stress developed for PETMP/TATATO was about 0.4 MPa, which was only approximately 14% of the maximum shrinkage stress of the Bis-GMA/TEGDMA system. Adequate flexural strength and flexural modulus values were obtained for both filled and unfilled PETMP/TATATO systems. SIGNIFICANCE: The dramatically reduced shrinkage stress, increased polymerization rate, significance increased functional group conversion, and decreased leachable species are all benefits for the use-of thiol-ene systems as potential dental restorative materials.

3-Mercaptopropionic Acid↗
PubMed2001

Heterogeneous distribution of single-bottle adhesive monomers in the resin-dentin interdiffusion zone.

OBJECTIVES: The purpose of this study was to investigate whether monomer separation occurs in single-bottle adhesives applied on acid-etched dentin surfaces. METHODS: Smear-layer covered dentin specimens produced from sound premolars, were acid-etched and analyzed by micro-MIR FTIR spectroscopy, before and after treatment with the single-bottle adhesives One-Step, Prime and Bond 2.1, Scotchbond 1 and Syntac-Sprint. The difference spectra (etched, and primed minus etched of the same dentin surfaces) were plotted and compared with original adhesive spectra. The C=C/C...C (aromatic adhesives) and C=C/C=O (aliphatic adhesives) peak area ratios were used to evaluate the extent of monomer separation relative to original adhesive spectra at the uppermost 2 microm of the resin-dentin interdiffusion zone. Three dentin specimens were used for each adhesive. One-way ANOVA and Newman-Keuls tests were performed to assess the statistically significant differences (alpha=0.05). RESULTS: All the adhesives demonstrated separation of monomer components on etched dentin ranging in mean values from 68.7 to 81.9% relative to reference. High molecular weight hydrophobic (i.e. BisDMA, BisGMA, BisGMA adducts) and hydrophilic monomers (i.e. BPDMA) predominated at the region probed. Prime and Bond 2.1 demonstrated the highest extent of monomer separation. SIGNIFICANCE: Heterogeneous monomer distribution following application to etched dentin may affect the curing performance of single-bottle adhesives within the resin infiltrated region and consequently, the mechanical and chemical stability of the network formed.

Acid Etching, Dental↗
PubMed1990

Shear bond strength of ceramic orthodontic brackets to enamel.

The recent introduction of ceramic orthodontic brackets has generated interest among orthodontists. The aim of this investigation was to evaluate the in vitro shear bond strengths to enamel of four ceramic orthodontic brackets and one stainless steel bracket in trials with two separate acid-etching times for enamel. Eighty extracted human central incisors were prepared for bonding to Starfire, Allure, Transcend, Quasar, and stainless steel (in the control group) orthodontic bracket systems. Enamel etching times of 15 seconds and 60 seconds were used. There was a total of 10 groups. After acid etching, one coat of low-viscosity bonding agent was applied and the brackets were bonded to etched enamel with Concise orthodontic bonding resin. The bonded test specimens were stored in distilled water at 37 degrees C for 14 days, after which they were thermocycled for 500 cycles (5 degrees C to 60 degrees C). The bonds were stressed to failure in an Instron machine at a crosshead speed of 0.02 inch per minute. The shear bond strengths were calculated and Weibull analysis was used to obtain a shape factor (the slope of the straight line and a measure of predictability) and the characteristic level (the 63.2% bond strength value of median rank on the strength line) for each group. Predictability and high bond strength, along with other factors, are important in the clinical selection of a bracket system. When either predictability or bond strength was considered independently, several bracket systems, coupled with a particular etch time, had either high predictability or high bond strength. The highest predictability and the highest bond strength were both found with the Allure bracket system.

Acid Etching, Dental↗
PubMedDate not supplied

Effect of cyclic loading on the microtensile bond strengths of total-etch and self-etch adhesives.

OBJECTIVE: To evaluate the effect of mechanical loading on the microtensile bond strength (MTBS) of five adhesive systems to dentin. METHODS: Flat dentin surfaces from human molars were divided into five groups and bonded with total-etch self-priming adhesives (Single Bond, Prime&Bond NT and Prime&Bond XP), two-step self-etching primer (Clearfil SE Bond) and an all-in-one adhesive (Etch&Prime 3.0), according to the manufacturers' instructions. Composite build-ups were constructed incrementally with Tetric Ceram. After 24 hours of water storage, half the specimens were load cycled (5000 cycles, 90 N). The teeth were then sectioned into beams of 1.0 mm2 cross-sectional area. Each beam was tested in tension in an Instron machine at 0.5 mm/minute. Data were analyzed by two-way ANOVA and Student Newman Keuls multiple comparisons tests (p<0.05). RESULTS: Clearfil SE Bond and Single Bond attained higher MTBS than the other three adhesives. Prime&Bond NT and Prime&Bond XP performed equally, and Etch&Prime 3.0 resulted in the lowest MTBS. After mechanical loading, MTBS decreased in all groups except Prime&Bond XP. Clearfil SE Bond, Single Bond and Prime&Bond XP obtained higher MTBS than Prime&Bond NT. Specimens bonded with Etch&Prime 3.0 resulted in premature failures and MTBS could not be measured. CLINICAL RELEVANCE: When using Etch&Prime 3.0, bond structures did not withstand mechanical loading, which may have an influence on the long-term success of restorations. If dentin is acid-etched, alcohol-based adhesive systems showed higher bond strength after mechanical loading.

Acid Etching, Dental↗
PubMed1991

Marginal leakage in occlusally loaded, etched, class-II composite resin restorations.

Microleakage was studied in class-II cavities restored with a calcium hydroxide liner and an adhesive system combined with two different posterior composite resins. The restorations were exposed to repeated loading when immersed in dye solution. The teeth were cut, and microleakage along the cavity walls and into dentin was evaluated by light microscopy. Dye penetration at the interface between the cavity and the restoration was recorded in 61% of the loaded and in 30% of the unloaded teeth. The difference between loaded and unloaded was greater for the teeth lined with Life than with Gluma dentin bonding.

Acid Etching, Dental↗
PubMedDate not supplied

Effect of bonding variables on the shear bond strength and interfacial morphology of a one-bottle adhesive.

This study's objectives were: 1) to determine the combination of bonding procedures (with or without acid etching, moist or dry substrate, one or two applications of primer/adhesive) that would produce the highest shear bond strength of Prime & Bond and Dyract AP and 2) to characterize the resin-dentin/enamel interface produced by these bonding procedures. Ninety-six bovine incisors were randomly assigned to eight groups for shear bond testing to enamel (n = 6) and dentin (n = 6). Prime & Bond and Dyract AP were applied and cured following manufacturers' instructions. Shear bond testing was conducted in a Universal Testing Machine. Thirty-two bovine incisors were sectioned to produce blocks with enamel and dentin, then bonded in pairs for evaluation of interfacial morphology. They were polished and argon ion-etched using a high-speed argon ion-etching machine and examined by SEM. The groups where enamel was etched, kept moist or dry and received a single application of Prime & Bond produced the highest shear bond strength. Dentin bond strengths were high in the groups where dentin was etched and kept moist. The number of Prime & Bond applications had no effect on dentin bond strength. Acid etching results in better adaptation of Prime & Bond to enamel and dentin regardless of whether moisture is present.

Acid Etching, Dental↗
PubMed2001

Bonding strength to two different surfaces of dentin under simulated pulpal pressure.

PURPOSE: The purpose of this in vitro study was to measure and compare the in vitro shear bond strengths (SBS) of the following dentin bonding systems to different dentin surfaces under simulated pulpal pressure: Liner Bond 2 (self-etching) (LB2), Liner Bond 2V (self-etching) (LB2V), Opti Bond Solo (single component) (OBS), Fuji Bond LC (filled) (FBLC), Prime & Bond 2-1 (single component) (P&B2-1), and Solid Bond (total etching) (SB). MATERIALS AND METHODS: Occlusal and buccal surfaces of 60 extracted human molars were prepared to expose the dentin bonding surface. After being wet ground with 600-grit abrasive papers, teeth were randomly assigned to 6 equal groups of 10 each. The dentin surfaces were treated with the bonding systems mentioned above, and resin composite cylinders (Clearfil AP-X) were built up under simulated pulpal pressure when diluted bovine serum was used as the pulpal fluid. After one day of storage in 37 degrees C water, the specimens were shear tested to failure on an Instron machine. RESULTS: The data were statistically analyzed with the Student's t-test and a post hoc Tukey test. Comparing buccal surfaces, the post hoc Tukey test indicated no significant differences among all the test groups (p > 0.05). On occlusal surfaces, the post hoc Tukey test indicated significant differences among the tested groups (p < 0.05). The Student's t test revealed significant differences between the occlusal and buccal shear bond strength values in LB 2, LB2V, and SB groups (p < 0.05). CONCLUSION: The strength of adhesion to dentin depends upon both the adhesive system used - with self-etching systems tending to show higher bond strengths than the other materials tested - and the location of the dentin, with significantly higher SBS being found on buccal surfaces in 3 of the 7 tested bonding systems.

Acid Etching, Dental↗
PubMed2000

Shear bond strength to moist and dry dentin of four dentin bonding systems.

PURPOSE: To compare the shear bond strength of four single-bottle adhesive systems (Prime & Bond NT, Single Bond, Gluma Comfort Bond, Gluma Comfort Bond + Desensitizer) bonded to moist and dry dentin. MATERIALS AND METHODS: A column of resin-based composite was bonded to human dentin using the dentin bonding systems following manufacturers' directions (n= 12). For half the specimens, the dentin was dried completely after acid etching (air dried for 10 s). For the remaining specimens, the dentin was left moist (glistening appearance with no puddles) after acid etching. All specimens were thermocycled for 1,000 cycles at 6-60 degrees C, placed in a fixture on an MTS machine and loaded in shear until failure. RESULTS: Statistical analysis revealed that dentin condition (moist or dry) was significant for Prime & Bond NT, Single Bond, and Gluma Comfort Bond. Bonding to moist dentin produced higher bond strengths than bonding to dry dentin. For Gluma Comfort Bond + Desensitizer, no statistical difference was found between bonding to moist vs. dry dentin. Over all, Single Bond and Gluma Comfort Bond bonded to moist dentin produced significantly higher bond strengths than all other groups.

Acid Etching, Dental↗
PubMedDate not supplied

The influence of a dentin desensitizer on the microtensile bond strength of two bonding systems.

A laboratory study evaluated the influence of a dentin desensitizer (D/Sense 2) on the microtensile bond strength of two adhesive systems: a self-etching primer (Bistite II SC) and a one-bottle adhesive (Prime & Bond 2.1). Sixteen crown dentin discs were obtained from extracted sound human third molars. Dentin surfaces were ground with 600 grit silicon carbide (SiC) abrasive papers to produce a standardized smear layer. Teeth were randomly divided into four groups (n=4). G1-D/Sense 2 + Prime & Bond 2.1; G2-D/Sense 2 + Bistite II SC; G3- and G4-dentin surfaces were bonded with Prime & Bond 2.1 and Bistite II SC, respectively, with no previous treatment with D/Sense 2. Eight mm high resin composite crowns (TPH Spectrum) were incrementally built-up on the treated surfaces. One sample from each group was prepared for evaluation of the hybrid layer on SEM. The specimens for the microtensile test were serially sectioned perpendicular to the adhesive layer to obtain 1 mm2 bounded sticks. Then, each stick was submitted to the microtensile test performed at a 0.5 mm/min crosshead speed. One-way ANOVA and Tukey test showed statistically significant differences among the groups (p<0.05). Values in MPa were: G1-17.85; G2-9.88; G3-35.16; G4-15.57. Based on the results of this study, it can be concluded that the D/Sense 2 desensitizer decreased the bond strength of Prime & Bond 2.1 and Bistite II SC bonding systems.

Acetone↗
PubMedDate not supplied

Occlusal loading evaluation in the cervical integrity of Class II cavities filled with composite.

There are many doubts about the clinical behavior of condensable composite restorations in Class II cavities, particularly when they are submitted to axial mechanical loads. This study evaluated cervical microleakage in Class II direct fillings in composite, whether or not they were submitted to an occlusal load cycling. Twenty-three human molars with standardized cavities (proximal vertical "slot") were treated with enamel and cement endings. After completion of the filling process with condensable composite (Surefil), they were separated into two groups: control (without occlusal loading) and test, where 4,000 one-second cycles of 150 N occlusal loading were applied. Twenty teeth were submitted to a microleakage test and then evaluated according to dye penetration. Significant statistical differences (Wilcoxon test, p=0.005<0.05) of leakage degree in enamel and cement were found in the control group. Significant statistical differences at <0.05 were also found in the test group, with p=0.045. After paired comparison of the control and test groups, a significant statistical difference was found at the enamel level (Mann-Whitney test, p=0.03). However, no significant statistical differences were found at the cement level (p=0.28). Therefore, it could be concluded that there was greater microleakage in cement compared to enamel, and occlusal loading has a decisive influence, as it increases the rate of microleakage.

Acid Etching, Dental↗
PubMed1990

[Relationship between length of resin tag and bond strength of bonding adhesive].

It is well known that the bond strength of direct bonding adhesive to etched enamel is dependent upon the formation of resin tags. So it is considered that there is a significant correlation between the bond strength and the length and shape of resin tags. However, there are very few reports on this correlation. In this study, a method of combining halogenated methacrylate and electron-probe microanalyzer (EPMA) was applied for measurement of resin tag length in order to investigate the correlation between the bond strength and resin tag length. Two experimental light cured adhesives were prepared for this study. One (CI-U) was prepared by blending microfiller (30 wt%) to the mixture of di (1-methacryloyl-oxyethyl-2-chloromethyl)-2,2,4-trimethylhexamethylene dicarbamate (50 wt%) and triethylene glycol dimethacrylate (TEGDMA: 59 wt%) and the other (Br-B) was prepared by blending microfiller (30 wt%) to the mixture of Bis-GMA (22.2 wt%), TEGDMA (65.9 wt%) and tetrabromobisphenol-A-glycidyl methacrylate (4Br-Bis GMA: 11.9 wt%). Preparation of 2%, 10%, 37%, and 60% phosphoric acid solutions, 2%, 5%, 10%, and 30% maleic acid solutions and 2%, 5%, 10%, and 30% citric acid solutions was carried out for use as etchants. The consistency and the bond strength to etched enamel for the adhesives and the amount of decalcification for the etchants were measured. The etched enamel surfaces, the resin tags on resin surfaces and the interfaces between the resin and enamel were observed with a SEM. The results were as follows: 1) The consistency of Cl-U was higher than that of Br-B. 2) The amount of decalcification was proportional to acid concentration, except for phosphoric acid solution. The amount of decalcification decreased in the order of citric acid solution, maleic acid solution and phosphoric acid solution when the concentration was 2% and 10%. 3) The SEM micrographs revealed that the enamel surface treated with the etchants containing a high concentration of acid was rougher. 4) The bond strength increased with increasing the concentration of the etchants except for the bond strength of Cl-U after being immersed in 37 degrees C water for 30 days and being thermal cycled. The bond strength for Cl-U was reduced greater than that of Br-B by long-term water immersion and thermal cycling.(ABSTRACT TRUNCATED AT 400 WORDS)

Acid Etching, Dental↗
PubMed2002

Direct posterior resin composite restorations: new techniques and clinical possibilities. Case reports.

Direct adhesive resin composite restorations in posterior teeth are now a reality thanks to improvements in these restorative materials and adhesive techniques. However, correct selection and application of materials are vastly important to clinical success. Two restorative techniques are described in detail, in one, a low-viscosity resin composite is placed incrementally, and in the other a condensable resin composite is placed in bulk. The former allows for greater security, because it is more traditional and has already proved to have clinical longevity; the latter has the advantage of being a quicker and simpler procedure. However, both techniques provide restorations that faithfully copy the dental tissues and have all the advantages of adhesive procedures.

Acid Etching, Dental↗
PubMedDate not supplied

Evaluation of microleakage using different bonding agents.

This study evaluated microleakage in vitro using different bonding agents. Forty-two freshly extracted caries-free human teeth were randomly divided into seven groups of six teeth and restored with different adhesive systems: Single Bond, Prime&Bond NT, Excite, Durafill Bond, Etch&Prime 3.0, Prompt L-Pop and Vitremer as the control group. All groups were treated according to manufacturers' instructions. Class V cavities were prepared on buccal and lingual surfaces (3 x 2.5 x 1.5 mm) of each tooth (12 restorations per group), with gingival margins in dentin. The teeth were restored with Charisma resin composite. After finishing and polishing with Denco-Flex disks, the teeth were thermocycled for 200 cycles (5 degrees C-55 degrees C +/- 2 degrees C, 60-second dwell time). Apical foramina and surfaces around restorations were coated with nail varnish, stained in 50% AgNO3 solution for 12 hours and longitudinally sectioned. Microleakage was evaluated with a stereomicroscope. Marginal penetration was scored on a 0-4 scale. Statistical analysis using the Kruskal-Wallis test revealed significant (p < or = 0.05) leakage at dentin margins for all adhesive systems when compared to the control. Except for Durafill Bond, no significant difference was found between the self-etching adhesives and one-bottle adhesives.

Acid Etching, Dental↗
PubMed2003

Microtensile bond strength of several adhesive systems to different dentin depths.

PURPOSE: To determine the bond strength of five adhesives systems to either superficial or deep dentin. METHODS: Extracted human third molars had their crowns transversally sectioned either next to the occlusal DEJ or next to the pulp, to expose flat, superficial or deep dentin surfaces. The surfaces were bonded with: 1) three two-step, total-etch, self-priming adhesives (Single Bond, Prime&Bond NT, and Excite), 2) a two-step, self-etching primer (Clearfil SE Bond), and 3) a single-step, self-etching all-in-one adhesive (Etch & Prime 3.0) according to manufacturers' directions. Composite build-ups were constructed incrementally with Z250. After storage for 24 hours in water at 37 degrees C, the teeth were sectioned to obtain several bonded beams of 1.0 mm2 cross-sectional area. Each beam was tested in tension in an Instron machine at 0.5 mm/minute. Results were analyzed by two-way ANOVA and post-hoc multiple comparisons (P = 0.05). Bonded interfaces were also examined by TEM. Nanoleakage was examined using a silver-staining technique. RESULTS: Single Bond, Prime&Bond NT and Clearfil SE Bond performed equally when were bonded to superficial dentin; the lowest value was obtained with Etch & Prime 3.0. On deep dentin, the highest bond strengths were attained with Clearfil SE Bond and Prime & Bond NT. The bond strengths of Prime & Bond NT and Excite were significantly higher to deep than to superficial dentin and the rest of the adhesives showed similar bond strength to both dentin depths. Nanoleakage was manifested to variable extent within all hybrid layers examined.

Acid Etching, Dental↗