BACKGROUND: The clinical success of relining depends on the ability of reline resin to bond to denture base. Surface preparations may influence reline bond strength of urethane-based dimethacrylate denture base resin.
AIM: To investigate the effect of bur preparation on the surface roughness (R a ) of eclipse denture base resin and its shear bond strength (SBS) to an intra-oral self-curing reline material. The mode of reline bonding failure was also examined.
MATERIALS AND METHODS: Twenty-four cylindrical Eclipse™ specimens were prepared and separated into three groups of eight specimens each. Two groups were subjected to mechanical preparation using standard and fine tungsten carbide (TC) burs and the third group (control) was left unprepared. The R a of all specimens was measured using a contact stylus profilometer. Subsequently, relining was done on the prepared surface and SBS testing was carried out a day later using a universal testing machine.
RESULTS: One-way ANOVA revealed significant differences (P<0.05) in R a and SBS values for all the groups. Post-hoc Tukey's HSD test showed significant differences (P<0.05) between all the groups in the R a values. For SBS also there were significant differences (P<0.05), except between standard bur and control.
CONCLUSIONS: 1) There was a statistically significant difference in the R a of Eclipse™ specimens prepared using different carbide burs (P<0.05). 2) There was a statistically significant difference in the relined SBS (P<0.05) when prepared using different burs, but the difference between the standard bur and the control group was not statistically significant.
Dental rehabilitation of a completely edentulous geriatric patient has always been a challenge to the clinician, especially in treating those with higher expectations and demands. Treatment duration and the amount of residual alveolar bone available are often important considerations when planning for dental implant-based fixed treatment for these patients. With the introduction of zygomatic implants, a graftless alternative solution has emerged for deficient maxillary bone with provision for immediate loading. This article describes the treatment of a completely edentulous elderly patient using zygomatic implants in conjunction with conventional implants. The implants were immediately loaded using a definitive acrylic resin fixed denture reinforced with a cast metal framework, to provide function and aesthetics.
This study evaluated the shear bond strengths of light-polymerized urethane dimethacrylate (Eclipse) and heat-polymerized polymethylmethacrylate (Meliodent) denture base polymers to intraoral and laboratory-processed reline materials.
The interaction behaviours between components of polyacrylate (PAc)/poly(ethylene oxide) (PEO) and lithium perchlorate (LiClO(4)) were investigated in detail by Attenuated Total Reflectance (ATR)-Fourier Transformed Infrared (FTIR) spectroscopy. Solution cast films of the PAc/PEO and PAc/PEO/LiClO(4) were examined. No obvious shifting of the characteristic ether and ester group stretching modes of PEO and PAc was observed, indicating incompatibility of the binary PAc/PEO blend. The spectroscopic studies on the PAc/PEO/LiClO(4) blends reveal that Li(+) ions coordinate individually to the polymer components at the ether oxygen of PEO and the C-O of the ester group of PAc. Frequency changes observed on the nu(C-O-C) and omega(CH(2)) of PEO confirm the coordination between PEO and Li(+) ions resulting in crystallinity suppression of PEO. The absence of experimental evidence on the formation of PEO-Li(+)-PAc complexes suggests that LiClO(4) does not enhance the compatibility of PAc/PEO blend.
In this study, chitosan-poly(methacrylic acid-co-N-isopropylacrylamide) [chitosan-p(MAA-co-NIPAM)] hydrogels were synthesized by emulsion polymerization. In order to be used as a carrier for drug delivery systems, the hydrogels had to be biocompatible, biodegradable and multi-responsive. The polymerization was performed by copolymerize MAA and NIPAM with chitosan polymer to produce a chitosan-based hydrogel. Due to instability during synthesis and complexity of components to produce the hydrogel, further study at different times of reaction is important to observe the synthesis process, the effect of end product on swelling behaviour and the most important is to find the best way to control the hydrogel synthesis in order to have an optimal swelling behaviour for drug release application. Studied by using Fourier transform infra-red (FTIR) spectroscopy found that, the synthesized was successfully produced stable chitosan-based hydrogel with PNIPAM continuously covered the outer surface of hydrogel which influenced much on the stability during synthesis. The chitosan and PMAA increased the zeta potential of the hydrogel and the chitosan capable to control shrinkage above human body temperature. The chitosan-p(MAA-co-NIPAM) hydrogels also responses to pH and temperature thus improved the ability to performance as a drug carrier.
Bacillus licheniformis α-amylase (BLA) was chemically modified using 100-fold molar excess of succinic anhydride over protein or 0.66 M potassium cyanate to obtain 42 % succinylated and 81 % carbamylated BLAs. Size and charge homogeneity of modified preparations was established by Sephacryl S-200 HR gel chromatography and polyacrylamide gel electrophoresis. Conformational alteration in these preparations was evident by the larger Stokes radii (3.40 nm for carbamylated and 3.34 nm for succinylated BLAs) compared to 2.43 nm obtained for native BLA. Urea denaturation results using mean residue ellipticity (MRE) as a probe also showed conformational destabilization based on the early start of transition as well as ΔG(D)(H(2)O) values obtained for both modified derivatives and Ca-depleted BLA. Decrease in ΔG(D)(H(2)O) value from 5,930 cal/mol (for native BLA) to 3,957 cal/mol (for succinylated BLA), 3,336 cal/mol (for carbamylated BLA) and 3,430 cal/mol for Ca-depleted BLA suggested reduced conformational stability upon modification of amino groups of BLA or depletion of calcium. Since both succinylation and carbamylation reactions abolish the positive charge on amino groups (both α- and ε- amino), the decrease in conformational stability can be ascribed to the disruption of salt bridges present in the protein which might have released the intrinsic calcium from its binding site.
Multifunctional nanocarriers harbouring specific targeting moieties and with pH-responsive properties offer great potential for targeted cancer therapy. Several synthetic drug carriers have been studied extensively as drug delivery systems but not much information is available on the application of virus-like nanoparticles (VLNPs) as multifunctional nanocarriers. Here, we describe the development of pH-responsive VLNPs, based on truncated hepatitis B virus core antigen (tHBcAg), displaying folic acid (FA) for controlled drug delivery. FA was conjugated to a pentadecapeptide containing nanoglue bound on tHBcAg nanoparticles to increase the specificity and efficacy of the drug delivery system. The tHBcAg nanoparticles loaded with doxorubicin (DOX) and polyacrylic acid (PAA) demonstrated a sustained drug release profile in vitro under tumour tissue conditions in a controlled manner and improved the uptake of DOX in colorectal cancer cells, leading to enhanced antitumour effects. This study demonstrated that DOX-PAA can be packaged into VLNPs without any modification of the DOX molecules, preserving the pharmacological activity of the loaded DOX. The nanoglue can easily be used to display a tumour-targeting molecule on the exterior surface of VLNPs and can bypass the laborious and time-consuming genetic engineering approaches.
Adhesive bond strength studies for the tray adhesive of an addition vinyl polysiloxane (President) impression material were conducted with an acrylic resin, chromium-plated brass, and plastic trays. Tensile and shear stress studies were performed on the Instron Universal testing machine. Acrylic resin specimens roughened with 80-grit silicon carbide paper exhibited appreciably higher bond strengths compared with different types of tray material and methods of surface preparation.
PURPOSE: The impact strength and the flexural properties of denture base materials are of importance in predicting their clinical performance upon sudden loading. This study compares the impact and transverse strengths and the flexural modulus of three denture base polymers.
MATERIALS AND METHODS: The investigation included a relatively new microwave-polymerized polyurethane-based denture material processed by an injection-molding technique, a conventional microwave-polymerized denture material, and a heat-polymerized compression-molded poly(methyl methacrylate) (PMMA) denture material. Impact strength was determined using a Charpy-type impact tester. The transverse strength and the flexural modulus were assessed with a three-point bending test. The results were subjected to statistical analysis using a one-way analysis of variance and the Scheffé test for comparison.
RESULTS: The impact strength of the microwave-polymerized injection-molded polymer was 6.3 kl/m2, while its flexural strength was 66.2 MPa. These values were lower than those shown by the two compression-molded PMMA-based polymers. The differences were statistically significant. The flexural modulus of the new denture material was 2,832 MPa, which was higher than the conventional heat-polymerized polymer but was comparable to the other microwave-polymerized PMMA-based polymer. The difference in the flexural modulus was statistically significant.
CONCLUSION: In terms of the impact and flexural strengths, the new microwave-polymerized, injection-molded, polyurethane-based polymer offered no advantage over the existing heat- and microwave-polymerized PMMA-based denture base polymers. However, it has a rigidity comparable to that of the microwave-polymerized PMMA polymer.
Aceclofenac is a new generation non-steroidal anti-inflammatory drug showing effective anti-inflammatory and analgesic properties. It is available in the form of tablets of 100 mg. Importance of aceclofenac as a NSAID has inspired development of topical dosage forms. This mode of administration may help avoid typical side effects associated with oral administration of NSAIDs, which have led to its withdrawal. Furthermore, aceclofenac topical dosage forms can be used as a supplement to oral therapy for better treatment of conditions such as arthritis. Ointments, creams, and gels containing 1% (m/m) aceclofenac have been prepared. They were tested for physical appearance, pH, spreadability, extrudability, drug content uniformity, in vitro diffusion and in vitro permeation. Gels prepared using Carbopol 940 (AF2, AF3) and macrogol bases (AF7) were selected after the analysis of the results. They were evaluated for acute skin irritancy, anti-inflammatory and analgesic effects using the carrageenan-induced thermal hyperalgesia and paw edema method. AF2 was shown to be significantly (p < 0.05) more effective in inhibiting hyperalgesia associated with inflammation, compared to AF3 and AF7. Hence, AF2 may be suggested as an alternative to oral preparations.
Abstract This article describes the clinical and laboratory procedures involved in the fabrication of laboratory-processed, provisional, screw-retained, implant-supported maxillary and mandibular fixed complete dentures incorporating a cast metal reinforcement for immediate loading of implants. Precise fit is achieved by intraoral luting of the cast frame to milled abutments. Effective splinting of all implants is attained by the metal substructure and retrievability is provided by the screw-retention of the prosthesis.
This study assessed the nature of the adhesion in repaired glass-ionomer restorative materials. Two chemically different glass-ionomer cements, Ketac Fil and Chemfil II Cap, and three different methods of conditioning the surface for repair were employed. Specimens of each material were prepared and the cut surfaces were then treated with either 35% phosphoric acid, 35% polyacrylic acid or a combination of phosphoric acid followed by polyacrylic acid. Freshly mixed material was injected against these treated surfaces and allowed to set under simulated intraoral conditions. The specimens were tested to failure in flexion after seven days storage. Assessment of the fractured surfaces was then carried out using the scanning electron microscope. The results showed the occurrence of both adhesive and cohesive failure.
Imatinib mesylate is an antineoplastic agent which has high absorption in the upper part of the gastrointestinal tract (GIT). Conventional imatinib mesylate (Gleevec) tablets produce rapid and relatively high peak blood levels and requires frequent administration to keep the plasma drug level at an effective range. This might cause side effects, reduced effectiveness and poor therapeutic management. Therefore, floating sustained-release Imatinib tablets were developed to allow the tablets to be released in the upper part of the GIT and overcome the inadequacy of conventional tablets.
As a topical delivery system, a nanoscaled emulsion is considered a good carrier of several active ingredients that convey several side effects upon oral administration, such as nonsteroidal anti-inflammatory drugs (NSAIDs).
Micro-emulsions and sometimes nano-emulsions are well known candidates to deliver drugs locally. However, the poor rheological properties are marginally affecting their acceptance pharmaceutically. This work aimed to modify the poor flow properties of a nano-scaled emulsion comprising palm olein esters as the oil phase and ibuprofen as the active ingredient for topical delivery. Three Carbopol ® resins: 934, 940 and Ultrez 10, were utilized in various concentrations to achieve these goals. Moreover, phosphate buffer and triethanolamine solutions pH 7.4 were used as neutralizing agents to assess their effects on the gel-forming and swelling properties of Carbopol ® 940. The addition of these polymers caused the produced nano-scaled emulsion to show a dramatic droplets enlargement of the dispersed globules, increased intrinsic viscosity, consistent zeta potential and transparent-to-opaque change in appearance. These changes were relatively influenced by the type and the concentration of the resin used. Carbopol ® 940 and triethanolamine appeared to be superior in achieving the proposed tasks compared to other materials. The higher the pH of triethanolamine solution, the stronger the flow-modifying properties of Carbopol ® 940. Transmission electron microscopy confirmed the formation of a well-arranged gel network of Carbopol ® 940, which was the major cause for all realized changes. Later in vitro permeation studies showed a significant decrease in the drug penetration, thus further modification using 10% w/w menthol or limonene as permeation promoters was performed. This resulted in in vitro and in vivo pharmacodynamics properties that are comparably higher than the reference chosen for this study.
The flocculation performances of nine cationic and anionic polyacrylamides with different molecular weights and different charge densities in the treatment of pulp and paper mill wastewater have been studied. The experiments were carried out in jar tests with the polyacrylamide dosages range of 0.5-15 mg l(-1), rapid mixing at 200 rpm for 2 min, followed by slow mixing at 40 rpm for 15 min and settling time of 30 min. The effectiveness of the polyacrylamides was measured based on the reduction of turbidity, the removal of total suspended solids (TSS) and the reduction of chemical oxygen demand (COD). Cationic polyacrlyamide Organopol 5415 with very high molecular weight and low charge density is found to give the highest flocculation efficiency in the treatment of the paper mill wastewater. It can achieve 95% of turbidity reduction, 98% of TSS removal, 93% of COD reduction and sludge volume index (SVI) of 14 ml g(-1) at the optimum dosage of 5 mg l(-1). SVI values of less than 70 m lg(-1) are found for all polyacrylamide at their respective optimum dosage. Based on the cost evaluation, the use of the polyacrylamides is economically feasible to treat the pulp and paper mill wastewaters. This result suggests that single-polymer system can be used alone in the coagulation-flocculation process due to the efficiency of the polyacrylamide. Sedimentation of the sludge by gravity thickening with settling time of 30 min is possible based on the settling characteristics of the sludge produced by Organopol 5415 that can achieve 91% water recovery and 99% TSS removal after 30 min settling.
Novel pH sensitive N-succinyl chitosan-g-poly (acrylic acid) hydrogels were synthesized through free radical mechanism. Rheometer was used to observe the mechanical strength of the hydrogels. In vitro degradation was conducted in SIF (pH 7.4). The effect of concentration of monomers, initiator, and crosslinking agent and pH and ionic strength of NaCl, CaCl2, and AlCl3 on swelling of the hydrogels was observed. The results showed that equilibrium swelling ratio was highly influenced by concentration of monomers, initiator, and crosslinking agent concentration, and pH and salt solutions of NaCl, CaCl2, and AlCl3. The swelling kinetics revealed that swelling followed non-Fickian anomalous transport. Furthermore, theophylline loading (DL %) and encapsulation efficiency (EE %) of the hydrogels was in the range of 15.5 ± 0.15-22.8 ± 0.06% and 62 ± 0.15-91 ± 0.26%, respectively. The release of theophylline in physiological mediums was strongly influenced by the pH. The theophylline release was in the range of 51 ± 0.20-92 ± 0.12% in SIF and 7.4 ± 0.02-14.9 ± 0.03% in SGF (pH 1.2), respectively. The release data fitted well to Korsmeyer-Peppas model. The chemical activity of the theophylline suggested that drug maintained its chemical activity after release in vitro. The results suggest that synthesized hydrogels are excellent drug carriers.
Commercial low-density polyethylene (LDPE) films were UV/ozone treated and coated using a layer-by-layer (LbL) technique by alternating the deposition of polyethyleneimine (PEI) and poly(acrylic acid) (PAA) polymer solutions and antimicrobial silver (Ag). The effects of the initial pH of the PEI/PAA polymer solutions alternating layers (pH 10.5/4 or 9/6.5) on the antimicrobial activity of the developed LbL coatings combined with Ag against Gram-negative and Gram-positive bacteria were investigated. The results from fourier transform infrared spectroscopy and toluidine blue O assay showed that LDPE LbL coated using PEI/PAA polymer solutions with initial pH of 10.5/4 significantly increased the presence of carboxylic acid groups and after Ag attachment the coating had higher antimicrobial activity against both Gram-negative and Gram-positive bacteria compared to the LDPE LbL coated using PEI/PAA polymer solutions with initial pH of 9/6.5. The LDPE LbL coated films using non-modified pH PEI/PAA polymer solutions decreased the water contact-angle indicating an increased hydrophilicity of the film, also increased the tensile strength and roughness of LDPE LbL coated films compared to uncoated LbL samples. The LDPE LbL coated films attached with Ag(+) were UV/ozone treated for 20 min to oxidise Ag(+) to Ag(0). The presence of Ag(0) (Ag nanoparticles (NPs)) on the LDPE LbL coated films was confirmed by XRD, UV-vis spectrophotometer and colour changes. The overall results demonstrated that the LbL technique has the potential to be used as a coating method containing antimicrobial Ag NPs and that the manufactured films could potentially be applied as antimicrobial packaging.
Polyacrylamide (PAM), a commonly used organic synthetic flocculant, is known to have high reduction in turbidity treatment. However, PAM is not readily degradable. In this paper, pectin as a biopolymeric flocculant is used. The objectives are (i) to determine the characteristics of both flocculants (ii) to optimize the treatment processes of both flocculants in synthetic turbid waste water. The results obtained indicated that pectin has a lower average molecular weight at 1.63 x 10(5) and PAM at 6.00 x 10(7). However, the thermal degradation results showed that the onset temperature for pectin is at 165.58 degrees C, while the highest onset temperature obtained for PAM is at 235.39 degrees C. The optimum treatment conditions for the biopolymeric flocculant for flocculating activity was at pH 3, cation concentration at 0.55 mM, and pectin concentration at 3 mg/L. In contrast, PAM was at pH 4, cation concentration >0.05 mM and PAM concentration between 13 and 30 mg/L.