PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Polymethacrylic Acids”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources
PubMed1978

The effect of synthetic polymers on the electrical and permeability properties of lipid membranes.

1. The effect of two series of hydrophilic and hydrophobic polymers on the stability, conductivity and permeability towards water and leucine of black lipid membranes and liposomes is reported. 2. The changes in properties of these membrane preparations is related to bulk phase viscosity and dielectric measurements together with monolayer studies. 3. The hydrophobic polymers dramatically increase membrane stability, had no effect on conductivity, but increased the permeability coefficient of leucine. 4. The hydrophilic polymers produced minor, but significant changes to membrane properties. 5. It is concluded that not only basic polymers but also neutral and acidic macromolecules can interact strongly with lipid membranes.

Acrylic Resins↗
PubMedDate not supplied

Synthesis and anticoagulant activity of sulfated glucoside-bearing polymer.

Poly(glucosyloxyethyl methacrylate) sulfate [poly(GEMA) sulfate], which contains sulfated glucoside residues, was prepared by the reaction with N,N-dimethylformamide (DMF)/sulfur trioxide (SO3) complex. The degree of sulfation was easily controlled by changing the amount of DMF/SO3 complex added and reaction time. The total human blood clotting time in the presence of poly(GEMA) sulfate was prolonged by increasing the dose or the degree of sulfation of the polymer. The anticoagulant activity of poly(GEMA) sulfate was also compared with that of dextran sulfate, poly(styrenesulfonic acid), poly(vinylsulfuric acid), and heparin. The result suggests that sulfated saccharide residues are essential for endowing anticoagulant activity to synthetic polymer.

Anticoagulants↗
PubMed2005

Effect of self-etching primer and adhesive formulations on the shear bond strength of orthodontic brackets.

PURPOSE: Despite many published articles on the bond strength of self-etching primers and adhesives in the restorative dentistry literature, there have been relatively few laboratory studies of the bond strength of new orthodontic materials, and, in most of these published studies, investigators used various methodologic approaches during different stages of the in vitro testing procedures. The aim of this study was to compare the shear bond strength of 4 self-etching primer and adhesive formulations, a nonrinse conditioner and acetone adhesive system, and a conventional system. MATERIAL: The self-etching products tested were Prompt L-Pop (3M ESPE, Seefeld, Germany), Clearfil SE Bond (Kuraray Dental, Osaka, Japan), FL Bond (Shofu Dental, Kyoto, Japan), and One-Up Bond F (Tokuyama, Tokyo, Japan); the nonrinse conditioner and acetone-based adhesive system was NRC and Prime&Bond NT (Dentsply International, Konstanz, Germany); the conventional acid-etch and bond system was Transbond XT (3M Unitek, Monrovia, Calif). Brackets were bonded to intact bovine mandibular incisors (n = 7 per group) according to each manufacturer's recommendations. The specimens were first stored in deionized water at 37 degrees C for 24 hours and then subjected to thermal cycling in deionized water at 5 degrees C +/- 2 degrees C to 55 degrees C +/- 2 degrees C for 1000 cycles. To facilitate degradation of bonds, the specimens were further stored in distilled water for 6 weeks before debonding procedures. RESULTS: The shear bond strengths of the 5 experimental groups were all significantly lower (P < .05) than that of the control group (Prompt L-Pop, 1.72 +/- 0.13 MPa; Clearfil SE Bond, 1.75 +/- 0.19 MPa; FL Bond, 1.71 +/- 0.22 MPa; One-Up Bond F, 1.77 +/- 0.14 MPa; control, 10.5 +/- 0.86 MPa) but not different from one another (P > .05). CONCLUSIONS: The tested self-etching primer and adhesive systems produced bond strength values much lower than that of the control product. Clinically, these products might not be suitable for orthodontic bracket bonding in terms of the shear bond strength achieved after thermal cycling and water storage.

Acid Etching, Dental↗
PubMed2003

Microtensile bond strength of total-etch and self-etching adhesives to caries-affected dentine.

OBJECTIVES: To evaluate the microtensile bond strength of total-etch or self-etch adhesives to caries-affected versus normal dentine, and to correlate these bond strengths with DIAGNOdent laser fluorescence and Knoop microhardness (KH) measurements of the substrates. METHODS: Extracted carious human molars were ground to expose flat surfaces where the caries lesion was surrounded by normal dentine. Surfaces were bonded with either Prime & Bond NT, Scotchbond 1, Clearfil SE Bond or Prompt L-Pop, according to manufacturers' recommendations. A crown was built up using resin composite (Tetric Ceram). After storage in water (37 degrees C, 24 h), teeth were vertically serially sectioned into 0.7 mm thick slabs and trimmed to yield 1 mm(2) test area that contained either caries-affected or normal dentine. Samples were tested in tension in an Instron machine at 1 mm/min. The quality of the dentine just beneath each fractured specimen was measured by laser fluorescence and KH. RESULTS: Total-etch adhesives yielded higher bond strengths than self-etching systems. Significantly lower results were obtained with Prompt L-Pop. All the adhesives attained higher strengths in normal than in caries-affected dentine, but the differences were only significant for Prime & Bond NT and Clearfil SE Bond. Higher laser fluorescence values and lower KH (p<0.001) were recorded in caries-affected dentine compared to normal dentine. CONCLUSIONS: The total-etch adhesives evaluated produced higher bond strengths to normal and caries-affected dentine than self-etching systems. Laser fluorescence measurements discriminated caries-affected dentine from normal dentine, and were strongly correlated with KH. However, laser fluorescence and KH did not permit high correlations with resin-dentine bond strengths in caries-affected dentine.

Acid Etching, Dental↗
PubMed2004

Effect of NaOCl on bond strengths of bonding agents to pulp chamber lateral walls.

The objective of this study was to evaluate the effects of 5% NaOCl on bond strengths of four bonding systems-Clearfil SE Bond, Prompt L-Pop, Prime&Bond NT, and Scotchbond Multi Purpose Plus-to pulp chamber mesial walls. Forty mandibular third molar teeth were used in the study. The pulp chambers of the first 20 teeth were restored with bonding agents and composite resins after 5% NaOCl irrigation, and the remaining teeth were restored without 5% NaOCl treatment. Each bonding group had five teeth. Three rectangular thin sticks (1+/-0.03 mm) were obtained from the mesial wall of restored pulp chambers by horizontal sectioning. In general, NaOCl application decreased the bond strength values of the bonding agents. Both Clearfil SE Bond and Prompt L-Pop without NaOCL showed higher bond strength values than the other bonding groups. In NaOCl-applied groups, Clearfil SE Bond had the highest bond strength. It can be concluded that self-etching bonding systems are more successful than the other systems in bonding to pulp chamber dentinal wall and that NaOCl reduces bond strength.

Acid Etching, Dental↗
PubMedDate not supplied

An in vitro investigation of a comparison of bond strengths of composite to etched and air-abraded human enamel surfaces.

PURPOSE: The purposes of the study were to measure the tensile bond strength of composite resin to human enamel specimens that had been either etched or air-abraded, and to compare the quality of the marginal seal, through the assessment of microleakage, of composite resin to human enamel specimens that had been either etched or air-abraded. MATERIALS AND METHODS: Thirty mandibular molar teeth were decoronated and sectioned mesio-distally to produce six groups, each containing ten specimens that were embedded in acrylic resin using a jig. In each of the four treatment groups, the specimen surfaces were treated by either abrasion with 27 or 50 microm alumina at 4 mm or 20 mm distance, and a composite resin was bonded to the treated surfaces in a standardized manner. In the two control groups the specimens were treated with 15 seconds exposure to 36% phosphoric acid gel and then similarly treated before being stored in sterile water for 1 week. All specimens were then subjected to tensile bond strength testing at either 1 or 5 mm/min crosshead speed. For the microleakage study, the degree of dye penetration was measured 32 times for each treatment group, using a neutral methylene blue dye at the interface between composite and either 27 or 50 microm air-abraded tooth structure or etched enamel surfaces. RESULTS: The mean bond strength values recorded for Group 1 (phosphoric acid etch, 5 mm/min crosshead speed) was 25.4 MPa; Group 2 (phosphoric acid etch, 1 mm/min), 22.2 MPa; Group 3 (27 microm alumina at 4 mm distance), 16.8 MPa; Group 4 (50 microm alumina at 4 mm distance), 16.9 MPa; Group 5 (27 microm alumina at 20 mm distance), 4.2 MPa; and for Group 6 (50 microm alumina at 20 mm distance) 3.4 MPa. An analysis of variance (ANOVA) demonstrated significant differences among the groups, and a multiple comparison test (Tukey) demonstrated that conventionally etched specimens had a greater bond strength than air-abraded specimen groups. No significant difference in dye penetration could be demonstrated among the groups (p= 0.58). CONCLUSIONS: Composite resin applied to enamel surfaces prepared using an acid etch procedure exhibited higher bond strengths than those prepared with air abrasion technology. The abrasion particle size did not affect the bond strength produced, but the latter was adversely affected by the distance of the air abrasion nozzle from the enamel surface. The crosshead speed of the bond testing apparatus had no effect on the bond strengths recorded. The marginal seal of composite to prepared enamel was unaffected by the method of enamel preparation.

Acid Etching, Dental↗
PubMed1993

Resistance to vertical fracture of roots, previously fractured and bonded with glass ionomer cement, composite resin and cyanoacrylate cement.

A recently developed glass ionomer bone cement (Ionos) may be suitable for bonding vertically fractured teeth, but the resulting resistance to repeated fracture of the bonded teeth is unknown. The purpose of this study was to assess in vitro the resistance to repeated fracture of roots which were previously fractured and bonded with Ionos cement and other bonding agents. Thirty-six roots were separated at the cervix and grooved on the coronal surface. Each root was mounted in an Instron machine and a vertical force was exerted until fracture occurred. Both the force required to fracture the root (F) and the root surface area (A) were recorded, and the root halves were bonded with one of the following materials: Ionos bone cement without dentin etching, Permabond 910 cyanoacrylate adhesive, and Gluma bonding system. The bonded roots were maintained in a wet sponge. One week later the roots were re-fractured in the Instron machine, and the forces were recorded (RF). Each one of F, RF, A, and the ratios RF/F and RF/A were compared statistically among the three experimental groups. Overall, RF was at the most 20% of F. Statistically significant differences were obtained only in RF, RF/F, and RF/A (p < 0.0003). Roots bonded with Ionos cement demonstrated significantly lower values than roots bonded with Permabond and Gluma, both of which did not differ significantly. It was concluded that roots bonded with Ionos cement were the least resistant to re-fracture, due to a lesser bonding strength of Ionos bone cement as compared with Permabond and Gluma.

Acid Etching, Dental↗
PubMed1995

Variability in microleakage observed in a total-etch wet-bonding technique under different handling conditions.

Using a stereoscopic clearing protocol and scanning electron microscopy, we investigated the extent and nature of microleakage in a total-etch, current-generation dentin adhesive by a wet-bonding technique under different handling conditions. The hypotheses were that inadequate light curing of the primer or incomplete drying of the primer solvent might adversely affect the sealing ability of an acetone-containing adhesive system. The study consisted of three experimental groups: (I) a control group with an adequate light source and with the primer solvent completely dried; (II) an "inadequate-light" group; and (III) an "incomplete evaporation of primer solvent" group. The extent of microleakage after silver staining and clearing of the specimens was scored based on a modified five-point scale. Nonparametric statistical analysis (Kruskal-Wallis ANOVA) followed by a multiple comparison test (Dunn test) indicated significant differences among the three groups (p < 0.05). SEM examination of the restorative interface revealed that microleakage appeared to be initiated from the bonding resin-hybrid layer interface in all three groups, representing the weak link in the adhesive system. In addition, microleakage was characterized by 5 zones, each delineating a stage in a continuous array of progressively deleterious microleakage patterns variously distributed among the three groups. It was suggested that, while the bonding resin-hybrid layer interface represented the intrinsic weakness in an already much improved dentin adhesive, extrinsic factors such as the adequacy of the curing light and, more importantly, complete removal of the primer solvents can and should be avoided to preserve the structural integrity of the marginal seal.

Acid Etching, Dental↗
PubMed2004

Fluid movement across the resin-dentin interface during and after bonding.

This study evaluated the extent of water penetration through resin-dentin interfaces before and after being sealed with adhesives. Four adhesive resin systems (2 total-etch adhesives and 2 self-etching primer adhesives) were used in this study. Dentin disks were placed in a split-chamber device, and in situ fluid movement across dentin was measured, with and without physiological pressure, during bonding procedures or 24 hrs after bonding. The fluid movement across dentin occurs via dentin tubules after acid-etching. Large outward or inward fluid shifts across dentin were observed during air-drying and light-curing for resin application. The amount of fluid movement across resin-bonded dentin when total-etch adhesives were used was significantly greater than that with self-etching adhesives. The milder acid-etching effects of self-etching primers may retain hybridized smear plugs within the tubules that reduce outward fluid flow, resulting in superior dentin sealing.

Acid Etching, Dental↗
PubMed2000

Dentine bonding systems: 1. Mode of action.

The achievement of a reliable bond to dentine has been more difficult than bonding to enamel, due principally to the anatomy of the dentine substrate. The mechanisms of bonding are now much better understood than a decade ago and clinically-viable bond strengths to dentine are now achieved with many dentine bonding systems.

Acid Etching, Dental↗
PubMed1985

Three-year evaluation of sealant: effect of isolation on efficacy.

This study analyzes the clinical effectiveness of a sealant (Delton) and its requirements for retreatment to maintain the optimum protection from pit and fissure caries. One hundred paired occlusal surfaces were treated in 29 patients. Two contralateral, partially erupted, noncarious molars with deep occlusal fissures were randomly selected to receive a sealant; one had a rubber dam and the other, cotton rolls for isolation. Each tooth received a prophylaxis with a rubber cup and a pumice slurry. The dryness of the field was evaluated. Each tooth was etched with 37% phosphoric acid for 60 seconds, rinsed for 15 seconds, and dried for 30 seconds. Sealant (Delton Tinted) was applied with a syringe according to manufacturer's instructions. Sealants were evaluated and reapplied where indicated at 6-month intervals. The average 6-month retention rate over 36 months was 95%, regardless of the method of isolation used when the sealant was applied initially. No tooth under treatment with a sealant became carious. The retreatment rate was highest at baseline (8%) and at 6 months (11.3%). Of the total number of retreated sealants, 61% were from the mandibular arch. During the 36 months of this study, 31% of the treated teeth required at least one retreatment.

Acid Etching, Dental↗
PubMed2003

Total-etch versus self-etch adhesive: effect on postoperative sensitivity.

BACKGROUND: Self-etching adhesives are believed to prevent postoperative sensitivity when used under posterior resin-based composite restorations. The authors tested a twofold hypothesis: a self-etch, or SE, adhesive would result in less postoperative sensitivity than a total-etch, or TE, adhesive; an SE adhesive would result in poorer enamel marginal integrity than a TE adhesive. METHODS: Patients were selected on the basis of requiring Class I and II restorations in molars and premolars. The authors placed 30 restorations with the SE material (Clearfil SE Bond, Kuraray America, New York) and 36 restorations with Prime & Bond NT (Dentsply Caulk, Milford, Del.), which uses 34 percent phosphoric acid to etch enamel and dentin simultaneously. Preparations were of standard design, with all margins in enamel without beveling. Upon rubber dam isolation, the authors conditioned the enamel and dentin walls with the self-etching primer (for Clearfil SE Bond) or etched with the proprietary 34 percent phosphoric acid (for Prime & Bond NT), followed by application of the corresponding dentin adhesive. Teeth were restored with the proprietary hybrid resin-based composite indicated for posterior restorations: Clearfil AP-X for Clearfil SE Bond or Esthet-X Micro Matrix Restorative for Prime & Bond NT. The restored teeth were evaluated preoperatively and at two weeks, eight weeks and six months postoperatively for sensitivity to cold (ice), air and masticatory forces, as well as for marginal discoloration. RESULTS: Analysis of variance revealed no statistically significant differences in postoperative sensitivity between the SE and TE materials at any recall time. Marginal discoloration was rated as "absent" for all restorations at six months. Only one tooth displayed sensitivity to occlusal forces at six months. CONCLUSION: The SE adhesive did not differ from the TE adhesive in regard to sensitivity and marginal discoloration. CLINICAL IMPLICATIONS: Postoperative sensitivity may depend on the restorative technique rather than on the type of dentin adhesive used.

Acid Etching, Dental↗
PubMedDate not supplied

Influence of surface conditions and silane agent on the bond of resin to IPS Empress 2 ceramic.

PURPOSE: The aim of this study was to evaluate the effect of different ceramic surface treatments on the tensile bond strength between IPS Empress 2 ceramic framework and Rely X adhesive resin cement, with or without the application of a silane coupling agent. MATERIALS AND METHODS: One hundred twenty disks were made, embedded in resin, and randomly divided into six groups: group 1 = sandblasting (100 microm), no silanation; group 2 = sandblasting (100 microm), silane treatment; group 3 = sandblasting (50 microm), no silanation; group 4 = sandblasting (50 microm), silane treatment; group 5 = hydrofluoric acid etching, no silanation; and group 6 = hydrofluoric acid etching, silane treatment. The disks were bonded into pairs with adhesive resin cement. All samples were stored in distilled water at 37 degrees C for 24 hours and then thermocycled. The samples were submitted to tensile testing. RESULTS: The use of silane improved the bond strength in relation to the groups in which silane was not applied (P < .05). The most effective surface treatment was etching with 10% hydrofluoric acid, both with (25.6 MPa) and without silane application (16.4 MPa); these values showed a statistically significant difference compared to sandblasting with 50- and 100-microm Al2O3. Sandblasting with 50-microm Al2O3, with (11.8 MPa) and without silane (5.4 MPa), demonstrated significantly higher tensile bond strength than sandblasting with 100-microm Al2O3, with (8.3 MPa) and without silane (3.8 MPa). CONCLUSION: Combined application of 10% hydrofluoric acid and silane enhanced the bond strength between the IPS Empress 2 ceramic framework and resin agent.

Acid Etching, Dental↗
PubMed2005

Hydrolytic stability of self-etching adhesive systems.

PURPOSE: The aim of this investigation was to determine the hydrolytic stability of conventional methacrylates in comparison with a new acrylic ether phosphonic acid and a bis(acrylamide) cross-linking monomer under acidic aqueous conditions and to confirm the potential of these new monomers as components in a self-etching enamel-dentin primer, based on shear bond strength measurements. MATERIALS AND METHODS: Two new monomers were synthesized, an acrylic ether phosphonic acid and a bis(acrylamide). Characterization of the two monomers was carried out by 1H-NMR, and 13C-NMR spectroscopy and of the phosphonic acid by 31P-NMR spectroscopy. The hydrolytic stability of these monomers was evaluated by 1H-NMR spectroscopy or high performance liquid chromatography (HPLC), and was compared with the hydrolytic stability of conventional adhesive methacrylates, ie, MDP, 4-META, TEGDMA and GDMA. Shear bond strength to enamel and dentin was determined using the acrylic ether phosphonic acid and bis(acrylamide) formulated into what is now being marketed as a self-etching primer (AdheSE, Ivoclar Vivadent), and compared with the total-etch adhesives Prime & Bond NT (Dentsply) and Excite (Ivoclar Vivadent) and the self-etching systems One-Up Bond F (Tokuyama), Touch & Bond (Parkell), i-Bond (Heraeus Kulzer), Prompt-L-Pop (3M ESPE), and Clearfil SE Bond (Kuraray). Initial and 24-h bond strength values of AdheSE were compared with those after 16 weeks of storage at 42 degrees C. RESULTS: Stability studies have shown that conventional methacrylate monomers undergo rapid hydrolysis under acidic aqueous conditions (up to 90% degradation after 16 weeks at 42 degrees C). However, the newly formulated strongly acidic acrylic phosphonic acid and cross-linking bis(acrylamide) are stable under these conditions. Moreover, a self-etching enamel-dentin primer based on these new monomers showed high bond strength values. CONCLUSION: The shelf life of dental adhesives can be increased by using ether- or amide-linked polymerizable analogues instead of conventional, less stable ester derivatives. This should improve the performance of adhesive bonds made with these more hydrolytically stable comonomers.

Acid Etching, Dental↗
PubMed2006

A new solution for a chronic problem; aqueous enteric coating.

In this research, we have reconsidered the current enteric coating techniques and offered a new solution using both theoretical and practical approaches. This approach is based on the fact that salt formation can solubilize the pH-sensitive polymers in water. However, having applied the polymer solution onto the dosage form's surface, the polymer should be converted to the nonionized form for delayed release action. Ammonium hydrogen carbonate (AHC) is used as a buffering agent with dual actions of salting in and desalting the polymer. Following the application of the coating medium onto the dosage form's surface and drying, AHC dissociate completely to ammonia, carbon dioxide, and water converting the polymer to its nonionized form. FT-IR studies on free film samples further confirmed the proposed mechanism. A range of pH-sensitive polymers and other ingredients in water have been successfully applied at the surface of a model ASA tablets, using pan coating technique. According to the SEM observation, the coating layer is very dense and rigid, despite the fact that, the coated amount of the polymers is quit small. The enteric tablets maintain their shapes in acid medium and passed the USP dissolution test for DR ASA tablets.

Aspirin↗
PubMed2005

Controlled grafting of comb copolymer brushes on poly(tetrafluoroethylene) films by surface-initiated living radical polymerizations.

Surface modification of poly(tetrafluoroethylene) (PTFE) films by well-defined comb copolymer brushes was carried out. Peroxide initiators were generated directly on the PTFE film surface via radio frequency Ar plasma pretreatment, followed by air exposure. Poly(glycidyl methacrylate) (PGMA) brushes were first prepared by surface-initiated reversible addition-fragmentation chain transfer polymerization from the peroxide initiators on the PTFE surface in the presence of a chain transfer agent. Kinetics study revealed a linear increase in the graft concentration of PGMA with the reaction time, indicating that the chain growth from the surface was consistent with a "controlled" or "living" process. alpha-Bromoester moieties were attached to the grafted PGMA by reaction of the epoxide groups with 2-bromo-2-methylpropionic acid. The comb copolymer brushes were subsequently prepared via surface-initiated atom transfer radical polymerization of two hydrophilic vinyl monomers, including poly(ethylene glycol) methyl ether methacrylate and sodium salt of 4-styrenesulfonic acid. The chemical composition of the modified PTFE surfaces was characterized by X-ray photoelectron spectroscopy.

Chromatography, High Pressure Liquid↗
PubMed1991

Preparation and evaluation of Eudragit gels. II: In vitro release of salicylic acid, sodium salicylate, and ketoprofen from Eudragit L and S organogels.

The in vitro dissolution characteristic of salicylic acid, sodium salicylate, and ketoprofen from Eudragit L and S organogels was investigated by the rotation disk method. The dissolution pattern of salicylic acid and erosion of Eudragit L polymer from the organogels followed apparent zero-order kinetics, providing strong evidence for a surface erosion mechanism and negligible diffusional release of salicylic acid. On the other hand, the dissolution of salicylic acid from Eudragit S organogels was a linear function of the square root of time. The apparent dissolution rate of salicylic acid from Eudragit S organogels increased with increasing temperature from 32 to 42 degrees C and agitation rate from 50 to 200 rpm. A linear relationship was obtained between the logarithm of apparent dissolution rate constants and the reciprocal of absolute temperatures. The activation energy for release of salicylic acid from Eudragit S organogels was in the range of 2.99 to 5.57 kcal/mol. From various experimental results, it was concluded that the release process of salicylic acid from Eudragit S organogels was diffusion controlled through the organogels matrix.

Acrylic Resins↗