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PubMed2004

Evaluation of mechanical and thermal properties of commonly used denture base resins.

PURPOSE: The purpose of this investigation was to evaluate and compare the mechanical and thermal properties of 6 commonly used polymethyl methacrylate denture base resins. MATERIALS AND METHODS: Sorption, solubility, color stability, adaptation, flexural stiffness, and hardness were assessed to determine compliance with ADA Specification No. 12. Thermal assessments were performed using differential scanning calorimetry and dynamic mechanical analysis. Results were assessed using statistical and observational analyses. RESULTS: All materials satisfied ADA requirements for sorption, solubility, and color stability. Adaptation testing indicated that microwave-activated systems provided better adaptation to associated casts than conventional heat-activated resins. According to flexural testing results, microwaveable resins were relatively stiff, while rubber-modified resins were more flexible. Differential scanning calorimetry indicated that microwave-activated systems were more completely polymerized than conventional heat-activated materials. CONCLUSION: The microwaveable resins displayed better adaptation, greater stiffness, and greater surface hardness than other denture base resins included in this investigation. Elastomeric toughening agents yielded decreased stiffness, decreased surface hardness, and decreased glass transition temperatures.

Adsorption↗
PubMed1997

Clinical comparison of BACTEC 9240 plus aerobic/F resin bottles and the isolator aerobic culture system for detection of bloodstream infections.

The Plus Aerobic/F resin bottle of the BACTEC 9240 automated blood culture system (Becton Dickinson Diagnostic Instrument Systems, Sparks, Md.) was compared with aerobic culture of the Isolator system (Wampole Laboratories, Cranbury, N.J.) for the detection of bloodstream microorganisms from 6,145 blood cultures collected from adult patients with suspected septicemia. The BACTEC resin bottles were incubated for 7 days, and the sediment from the Isolator tube was inoculated to sheep blood and chocolate agars which were incubated for 72 h and to inhibitory mold, brain heart infusion, and Sabouraud agars which were incubated for 21 days. A total of 622 microorganisms were recovered from 583 blood cultures. The BACTEC resin bottle recovered statistically significantly more pathogens overall than the Isolator system (P = 0.0006). When individual pathogens isolated from either system for a 7-day study period were assessed, it was determined that the BACTEC resin bottle detected statistically significantly more isolates of Staphylococcus aureus (P = 0.0113) and coagulase-negative Staphylococcus spp. (P = 0.0029) than the Isolator system. The BACTEC resin bottle also detected statistically significantly more bloodstream infections (septic episodes) caused by coagulase-negative Staphylococcus spp. (P = 0.0146). The Isolator system recovered statistically significantly more contaminants overall (P < 0.0001), and among this group of microorganisms, recovered statistically significantly more Bacillus spp. (P < 0.0001), coagulase-negative Staphylococcus spp. (P < 0.0001), and viridans group Streptococcus spp. (P = 0.0156). The Isolator system detected statistically significantly more isolates of Histoplasma capsulatum (P = 0.004), but all of these isolates were detected at > or = 7 days of incubation of fungal plates, i.e., after the system to system comparison study period (7 days). In blood culture sets which produced growth of the same pathogen in both systems, there was a statistically significant difference in median time to detection for all pathogens combined favoring the BACTEC resin bottle over the Isolator tube (P < 0.05). When assessing individual microorganisms, the median times for detection of S. aureus, Enterococcus spp., and Pseudomonas spp. were all statistically significantly less for the BACTEC system (P < 0.05). The BACTEC instrument had 79 (1.3%) false positive signals. The BACTEC system required less processing time than the Isolator system and eliminates the hands-on time for detection of positive cultures required with the Isolator system.

Adult↗
PubMed1997

Microbiology and biodegradation of resin acids in pulp mill effluents: a minireview.

Resin acids, a group of diterpenoid carboxylic acids present mainly in softwood species, are present in many pulp mill effluents and toxic to fish in recipient waters. They are considered to be readily biodegradable. However, their removal across biological treatment systems has been shown to vary. Recent studies indicate that natural resin acids and transformation products may accumulate in sediments and pose acute and chronic toxicity to fish. Several resin acid biotransformation compounds have also been shown to bioaccumulate and to be more resistant to biodegradation than the original material. Until recently, the microbiology of resin-acid degradation has received only scant attention. Although wood-inhabiting fungi have been shown to decrease the level of resin present in wood, there is no conclusive evidence that fungi can completely degrade these compounds. In contrast, a number of bacterial isolates have recently been described which are able to utilize dehydroabietic or isopimaric acids as their sole carbon source. There appears to be an unusually high degree of substrate specificity with respect of the utilization of abietane congeners and the presence of substituents. Pimaranes do not appear to be attacked to the same extent as the abietanes. This paper reviews the occurrence, chemistry, toxicity, and biodegradation of resin acids in relation to the biological treatment of pulp and paper mill effluents.

Biodegradation, Environmental↗
PubMed2003

Adhesive resin induces apoptosis and cell-cycle arrest of pulp cells.

The application of an adhesive resin near or directly over the pulp was shown to induce pulp inflammation and lack of dentin regeneration. We hypothesize that the absence of dentin bridging is due to adhesive-resin-induced apoptosis of cells responsible for pulp healing and dentin regeneration. Mouse odontoblast-like cells (MDPC-23), undifferentiated pulp cells (OD-21), or macrophages (RAW 264.7) were exposed to SingleBond polymerized for 0-40 seconds. Annexin V and propidium iodide assays demonstrated that SingleBond induced apoptosis of MDPC-23, OD-21, and macrophages. The proportion of apoptotic cells was dependent on the degree of adhesive resin polymerization. Adhesive-resin-induced death of pulp cells was associated with activation of the pro-apoptotic cysteine protease Caspase-3. Interestingly, most cells exposed to adhesive resin that did not undergo apoptosis showed cell-cycle arrest. We conclude that an adhesive resin induces apoptosis and cell-cycle arrest of cells involved in the regeneration of the dentin-pulp complex in vitro.

Analysis of Variance↗
PubMed2006

Preparation and in vitro evaluation of polystyrene-coated diltiazem-resin complex by oil-in-water emulsion solvent evaporation method.

The purpose of this study was to examine the suitability of polystyrene-coated (PS-coated) microcapsules of drug-resin complex for achieving prolonged release of diltiazem-HCl, a highly water-soluble drug, in simulated gastric and intestinal fluid. The drug was bound to Indion 254, a cation-exchange resin, and the resulting resinate was microencapsulated with PS using an oil-in-water emulsion-solvent evaporation method. The effect of various formulation parameters on the characteristics of the microcapsules was studied. Mean diameter and encapsulation efficiency of the microcapsules rose with an increase in the concentration of emulsion stabilizer and the coat/core ratio, while the same characteristics tended to decrease with an increase in the volume of the organic disperse phase. The desorption of drug from the uncoated resinate was quite rapid and independent of the pH of the dissolution media. On the other hand, the drug release from the microcapsules was prolonged for different periods of time depending on the formulation parameters and was also found to be independent of the pH of the dissolution media. Both the encapsulation efficiency and the retardation of drug release were found to be dependent on the uniformity of coating, which in turn was influenced by the formulation parameters. Kinetic studies revealed that the desorption of drug from the resinate obeyed the typical particle diffusion process, whereas the drug release from the microencapsulated resinate followed the diffusion-controlled model in accordance with the Higuchi equation. PS appeared to be a suitable polymer to provide prolonged release of diltiazem independent of the pH of the dissolution media.

Absorption↗
PubMed2004

Determination of polymeric aluminum in soil extracted with a modified anion-exchange resin as a solid-phase adsorbent by ICP-AES.

In the present work, a new method was established by applying solid-phase extraction (SPE) to preconcentrate and separate polymeric aluminum (Al) and using ICP-AES to determine the polymeric Al, the total monomeric Al, and the total Al in soil extracts, respectively. A modified resin was prepared with impregnated 8-hydroxyquinoline-5-sulfoxinate (HQS) on the anion-exchange resin. It has good recognition ability for Al fractions, compared to the commonly used cation ion-exchange resin, which has a better ability to adsorb cations and a weak ability to recognize detailed Al species. The optimum conditions for Al fractionation sorption, elution and separation and the interference of foreign ions were studied with the prepared resin by continuous column and batch procedures. Monomeric Al was bound to Pyrocathecol Violet (PCV) at pH 6.2, whereas the polymeric Al species did not react with PCV for at least 15 min. Because a stable complex of Al-PCV was not absorbed on the HQS modified resin, the polymeric Al could be preconcentrated on-line by the HQS-modified resin. The adsorbed polymeric Al was eluted with 3 mL of 3 mol L(-1) of HCl, and then detected by ICP-AES. The method has been applied to directly determine polymeric Al in soil extracts with high selectivity as well as a high preconcentration factor. It gives a limit of detection of 0.6 ng mL(-1) with a relative standard deviation of less than 5.7% (n = 5, 0.24 microg mL(-1) Al).

Journal Article↗
PubMed1990

Intracellular calcium measurements with PVC-resin Ca-selective microelectrodes in frog proximal tubules and sartorius muscle fibers.

To measure ion activity of intracellular calcium, (Ca)i, we manufactured a Ca2(+)-selective microelectrode based on a neutral carrier, ETH-1001, with or without polyvinylchloride column (PVC-resin). Before and after cell impalements (n = 7), PVC-resin Ca2(+)-selective microelectrodes exhibited Nernstian slopes in the range of p(Ca) from 3 to 7 (the mean slope constant: 29.1 and 29.4 mV/p(Ca), respectively) and sub-Nernstian slopes between p(Ca) = 7 and 8 (21.6 and 21.1 mV/p(Ca]. Individual detection limits of PVC-resin microelectrodes averaged p(Ca) = 8.5 before and 8.3 after cell impalements. In contrast, the non-PVC-resin microelectrode exhibited a poor response between p(Ca) = 7 and 8 especially after cell impalements. Normal values obtained with the PVC-resin microelectrode for (Ca)i of proximal tubule cells and resting sartorius muscle fibers in the bullfrog averaged 18 +/- 2 (n = 10) and 12 +/- 2 (n = 7) nM (mean +/- S.E., number of observations), respectively. We conclude that 1) the PVC-resin microelectrode is a useful tool for measuring intracellular ion activities, and 2) the values of intracellular Ca2+ activity of the proximal tubule and skeletal muscle fibers measured with this microelectrode are in a lower range among the various values reported before with the other methods.

Animals↗
PubMed1990

Immunohistochemical detection of DNA replication in mouse uterine cells by bromodeoxyuridine labeling of wax- and resin-embedded tissue sections.

To apply the bromodeoxyuridine (BrdU) labeling method using a monoclonal antibody to the study of cell proliferation in the mouse uterus, methods of fixation and embedding of tissues and of immunofluorescent staining were compared in terms of the rate of detection of labeled cells and specificity and stability of fluorescence obtained. BrdU was administered intravenously 2 hr before death and uterine blocks were embedded in polyester wax and Technovit resin after fixation in formalin and periodate-lysine-paraformaldehyde, respectively. The indirect method with anti-BrdU and fluorescein isothiocyanate (FITC) conjugated antimouse IgG antisera and the direct method with FITC conjugated anti-BrdU antibody were applied to both wax- and resin-embedded sections. Labeled and total cells were counted in luminal and glandular epithelia and stomata adjoining them. Counterstaining with hematoxylin for counting total cells produced intense fluorescence over the whole of resin sections and made counting of labeled cells impossible. On wax sections, on the other hand, the results were satisfactory, although the number of labeled cells detected was decreased slightly. In wax sections fluorescence due to nuclear incorporation of BrdU in the indirect method could be easily distinguished from the cytoplasmic or extracellular emission seen in some cells by its location and characteristic color. In resin sections, however, more careful observation was needed since the second antibody used in the indirect method cross-reacted with IgG in eosinophils and produced cytoplasmic fluorescence of the same color. By the indirect method greater numbers of labeled cells were detected in wax sections than in resin sections. The difference was distinct in tissues with extensive cell proliferation. By the direct method the fluorescence obtained was weaker and apt to fade more quickly than that obtained by the indirect method; use of the direct method reduced the number of labeled cells detected in both wax- and resin-embedded sections.

Animals↗
PubMed1991

The use of visible light-curing resin for vertebral body replacement.

The technology of visible light-curing resin has recently been developed for use in removable prosthodontics. A quartz halogen lamp producing a 400- to 500-nanometer wave-length spectrum of visible light is used to polymerize high-molecular-weight acrylic resin monomers. While several in vitro and in vivo studies of visible light-curing resin are found in the dental literature, no studies have yet been performed to evaluate it as an intracorporeal implant in surgery. The authors have designed a rat model of microcervical corpectomy to assess vertebral body replacement with visible light-curing resin in comparison to conventional autopolymerizing methyl methacrylate. Spinal cord function tests, spinal-implant stability assessments, and histological evaluations were made in a total of 41 rats at 2, 4, or 6 months postimplant. No animal developed a neurological deficit or radiographic instability, and at sacrifice there was no evidence of implant fracture-extrusion. In addition, there were no signs of adverse reaction in the surrounding tissues. Morphological investigation of the resin/bone interface at 6 months revealed very good implant anchorage. Visible light-curing resin was found to be far superior to methyl methacrylate for construction of spinal implants. Its waxy consistency makes it easy to handle. It remains pliable until light is applied, allowing adjustments in shape for a well-fitted implant without time constraints. Applied in layers, adjustments can be made even after polymerization of a previous layer. This new implantable resin will allow safer, immediate stabilization in patients with neoplastic destruction of the spine, and may also be advantageous for other neurosurgical applications, such as cranioplasty.

Animals↗
PubMed2002

Improving a self-curing dental resin by eliminating oxygen, hydroquinone and water from its curing process.

Self-curing dental resins are always manipulated in the presence of curing inhibitory factors such as oxygen, hydroquinone, water and another contaminants such as saliva and blood. The purpose of this study was to elucidate the effects of eliminating these curing inhibitory factors on resin properties. Several clinically relevant characteristics of an experimental resin cured in the absence of inhibitory factors (purified group) were determined and compared with the resin cured conventionally (control group). The purified group showed a significantly shorter induction period and higher reaction exotherm. It also showed significantly higher tensile strength and lower strain to failure. With regard to the amount of residual monomer, fracture toughness and fatigue strength the improvements were not significant. These findings suggest that the polymerization outcomes and mechanical properties of the purified group resin can be improved in general. Dental clinicians should pay attention to the storage and curing environments while manipulating the self-curing resin.

Benzoyl Peroxide↗
PubMedDate not supplied

Effects of aging on repair bond strengths of a polyacid-modified composite resin.

The effect of age of a poly-acid-modified composite resin on repair bond strength after different methods of surface conditioning was studied. Surface conditioning methods included the following: maleic acid with resin application; polyacrylic acid with resin application; sand-blasting with resin application. Shear bond testing between the aged and new material was carried out with an Instron Universal Testing Machine. Although repair bonds strengths after all surface conditioning methods were significantly higher than the control group at 1 week, no statistically significant differences in bond strengths were noted after aging the material for 6 months. After all aging periods, surface conditioning with sand-blasting and resin application resulted in the highest repair bond for poly-acid-modified composite resins. Specimens with cohesive failure in the material gave significantly higher repair bond strengths than specimens with adhesive failure at the repaired interface.

Analysis of Variance↗
PubMed2002

[Study on the infinity optical thickness of light-cured composite resins and attached shade guides].

OBJECTIVE: This study compared the opaque characteristics of light-cured composite resins and attached shade guides. METHODS: Three kinds of light-cured composite resins and attached shads guides were used. A plastic mold (10mm in diameter and 4mm in height) was used to prepare disk specimens. Color was measured by CIE L*a*b* relative to CIE source against a white and a black background, using a colorimeter. Color change (DeltaE)was calculated as DeltaE=[(DeltaL*)(2)+(Deltaa*)(2)+(Deltab*)(2)](1/2). The heights of composite resins were recorded as DeltaE is approximately 1.5. The infinity optical thickness of composite resins when delta E*=1.5 was calculated by regression formulation. RESULTS: There was significant difference in color difference and the infinity optical thickness among materials and shades. The infinity optical thickness gradual decreased in the same shade mark from 1 to 4, and from A to D the results was not simple. CONCLUSION: There was significant difference in the infinity optical thickness between the attached shade guides and the resins materials. Composite resins contain micro-filler were inferior in infinity optical thickness.

English Abstract↗
PubMed1993

[Stress analysis with a laser microscope analyzer for acrylic base resin]

Acrylic resin are applied widely as a denture resin,its residual stress is closely related with aging and mechanical properties of denture resin.The authors tested the stress level of the base resin with a laser microscope stress analyzer in the study.The results indicated that there was not statistical differences between two curing methods is in water bath or under pressure.The residual stress in base resin can be concentrated at the area near to clasp wire which was embedded in base resin for reinforcing strength of denture base.The vibration caused by grind with stone wheel or impact in disc lasting with a hammer may increase the stress level in base.The authors pointed out some methods for reducing residual stress resin.

Journal Article↗
PubMed1996

[The influence of masking agent on adhesion of composite resin]

In this study we used light cured resin,opaque resin and composite resin/masking agent to bond 24 teeth in vitro and then we tested their bonding stress.We also used these three materials to treat 240 tetracycline stained teeth in clinic.After half a year,one year,two years follow-up we found:in vitro study,the highest stress of composite resin is 144.3kG/cm(2).There is no significant difference in statistics among these three materials if we used the masking agent or opaque resin or not.In clinical follow-up,there is no significant difference in shed,partial shed,margin stain,gingival inflammation,and unsatisfied rate in three groups.The author believed the masking agent or opaque resin has no influence on the stress of resin restoration.So when we treated tetracycline stained teeth,we could choose it to increase aesthetic feeling.

Journal Article↗
PubMed1992

Pulp reactions to resin cements.

Several formulas of a resin-filled cement that successfully passed a series of laboratory tests were evaluated for their pulp reactions in primates. Their performance was compared to three controls: a positive control (silicate cement), a negative control (zinc oxide-eugenol) and a control group with the protection of calcium hydroxide. The chemical cure resin cement scored the lowest reactions for the 5-day evaluation. The intermediate and prolonged periods demonstrated no significant differences while average, acceptable responses were recorded. No resin cement formula scored as low as the negative control for the three time periods. Silicate cement, the positive control, scored the greatest inflammatory reaction of any material in the intermediate period, but this response was resolved after 60 days. When the resin cements were used with calcium hydroxide, the traditional reactions to calcium hydroxide were observed; an initial mild irritation that diminished with time and was completely resolved after 60 days. The resin cements, with or without the calcium hydroxide, compared favorably to the negative control IRM after 60 days. If the resin cements are appropriately applied, they are expected to be well tolerated by the human pulp. The microorganisms associated with microleakage (MLM) were minimal and there appeared to be no correlation between the MLM and pulp inflammation.

Analysis of Variance↗
PubMed1990

A new type ceramic bracket for suppression of resin remaining in debonding.

A new type of ceramic bracket was prepared to minimize the destruction at the bracket-resin interface and to suppress resin remaining on the tooth surface in debonding. The brackets were of a chemical bonding type, and had a box-formed cavity in the bracket base to hold resin, a 0.018 inch slot, and twin-type wings. Impact strengths and debonding aspects of the residual resin were studied. The impact strengths of the brackets seemed to exceed the desired level, compared to other control ceramic brackets or metal brackets. A resin remaining ratio (RRR) was adopted as the quantitative evaluation for the residual resin condition. Mean RRR's of the brackets were about 10%, which was a very low value in comparison to the other brackets.

Ceramics↗
PubMed1990

[Effect of physically hard labor on the locomotor system--results of an epidemiological cross-sectional study of resin tappers].

Resin tapping involves a high physical workload. We found the mean working-energy expenditure to be 21 +/- 5 kJ min-1. The mean heart-rate amounted to 127 +/- 18 beats min-1. It is the upper extremities where the work-related strain is particularly high. The clinical, function-diagnostic and X-ray examinations (X-ray only for resin tappers) covered 110 resin tappers and a control group of the same size (for pair-matching purposes). The main finding of the examinations was that both the pain and the degree of elbow-joint arthrosis deformans significantly increase in the course of the work years in resin tapping. Arthrosis deformans of the elbow joints is regarded by us to be a "resin-tapping related health risk", which is found in one in four resin tappers after about 18 work years.

Adult↗
PubMed1984

Evaluation of MMA-4-META-TBB resin as a dental adhesive material.

A new adhesive resin containing a reactive monomer, 4-methacryloxyethyl trimellitate anhydride (4-META) was prepared, and its application to hard tooth tissues and metals was studied. Scanning electron microscopy showed that the average length of 4-META resin tags in enamel and dentin was 22 mu and 40 mu respectively. The tensile adhesive strength between 4-META resin and enamel was about 130 kg/cm2 after etching with 65% phosphoric acid. Its bond strength to dentin treated with a cleaning solution of 10% citric acid and 3% ferric chloride was about 190 kg/cm2. In precious alloys heated at 500 degrees C for 5-10 minutes, a bond strength of more than 100 kg/cm2 was obtained. The precious alloys containing Au, Ag, Pt and Cu should be selected especially for dental restorations. In polished non-precious alloys, the bond strength was greater than 100 kg/cm2. If non-precious alloys were oxidized with HNO3, the bond strength increased to 150-200 kg/cm2. The results suggest that the nickel-chromium alloy used in fixed prosthodontics must be treated chemically before adhesion with 4-META resin, but cobalt-chromium alloy used in removable partial dentures bonds well with 4-META resin without chemical treatment. In conclusion, MMA-4-META-TBB resin seems to be a promising adhesive material in dentistry.

Acrylates↗