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PubMed2006

Hydrophobic acrylic and plate-haptic silicone intraocular lens implantation in diabetic patients: pilot randomized clinical trial.

PURPOSE: To compare the capsular and uveal reaction after implantation of a plate-haptic silicone intraocular lens (IOL) (C11UB, Chiron) and a hydrophobic acrylic (AcrySof MA60, Alcon) IOL in diabetic patients. SETTING: Moorfields Eye Hospital and St. Thomas' Hospital, London, United Kingdom. METHODS: Thirty-five diabetic patients were recruited consecutively and randomly assigned to have implantation of either of the 2 IOLs. The percentage area of posterior capsule opacification (PCO), anterior capsule contraction (ACC), and postoperative inflammatory indices (flare and cells) were assessed objectively at 2 to 3 weeks, 6 months, and 1 year. Between-group and within-group analyses were conducted using the Student t test or Mann-Whitney test and Friedmann test, respectively. RESULTS: Between-group analysis showed the percentage area of PCO was significantly greater in patients with plate-haptic silicone IOLs at 6 and 12 months (P = .002). At 6 months, ACC was significantly greater in the plate-haptic group (P = .04), but the difference was not significant at 12 months. There was higher flare in the hydrophobic acrylic IOL group than in the plate-haptic silicone IOL group at 2 to 3 weeks (P = .08). Within-group analysis showed that over the follow-up period, the plate-haptic silicone group, but not the hydrophobic acrylic group, had a progressive increase in PCO (P = .003). In the hydrophobic acrylic group, but not the plate-haptic silicone group, there was a significant reduction in the mean anterior chamber flare value (P = .01). There was no significant difference in visual acuity or contrast sensitivity at any postoperative visit. CONCLUSION: In diabetic patients, hydrophobic acrylic IOLs can lead to an increased flare in the early postoperative period but they seem to be more favorable than plate-haptic silicone IOLs because the latter lead to more PCO.

Acrylic Resins↗
PubMed2004

The effect of reinforcement with woven E-glass fibers on the impact strength of complete dentures fabricated with high-impact acrylic resin.

STATEMENT OF PROBLEM: The fracture of acrylic maxillary complete dentures occurs frequently during service through heavy occlusal force or accidental damage. PURPOSE: The purposes of this study were to measure the impact strength of maxillary complete dentures fabricated with high-impact acrylic resin and to evaluate the effect of woven E-glass fiber-reinforcement on the impact strength of the complete dentures. MATERIAL AND METHODS: Preimpregnated woven E-glass fibers (Stick Net) were used to reinforce 10 complete denture bases fabricated with a heat-polymerized high-impact acrylic resin (Lucitone 199). Ten unreinforced complete dentures served as a control group. All specimens were stored in water at 37 degrees C for 2 months before testing. The impact strengths (J) of the dentures were measured with a falling-weight impact test. The impact strengths of both groups were compared by a repeated measures analysis of variance (alpha=.05). The Weibull distribution was also applied to calculate the cumulative fracture probability as a function of impact strength. RESULTS: The mean impact strength of the control dentures was 90.0+/-38.1 J at crack initiation, and 95.9+/-37.7 J at complete fracture, whereas the impact strength of reinforced dentures was 201.7+/-77.9 J and 277.9+/-102.5 J, respectively. Statistical analysis showed that impact strength of the high-impact acrylic complete denture was significantly increased by the addition of woven E-glass fiber (P<.0001). CONCLUSION: The impact strengths of maxillary complete dentures fabricated with high-impact acrylic resin increased by a factor greater than 2 when reinforced with woven E-glass fiber.

Acrylic Resins↗
PubMed1997

Reduction in the area of the anterior capsule opening after polymethylmethacrylate, silicone, and soft acrylic intraocular lens implantation.

PURPOSE: To report reduction in the area of anterior capsule opening at various postoperative intervals after continuous capsulorrhexis and to compare any differences in the area reduction between polymethylmethacrylate, silicone, and soft acrylic intraocular lenses. METHODS: Prospectively, 240 eyes of 240 patients undergoing phacoemulsification and intraocular lens implant surgery were randomized into three groups based on the type of intraocular lens used: polymethylmethacrylate, silicone, and soft acrylic. The area of the anterior capsule opening was quantitated, and examinations were performed at 1 week and 1, 3, and 6 months postoperatively. RESULTS: After intraocular lens implantation, the mean anterior capsule opening area 3 months postoperatively was significantly smaller than that at 1 week in all groups (polymethylmethacrylate, P = .0090; silicone, P < .0001; soft acrylic, P = .0127). Mean percentages in area reduction at both 3 and 6 months postoperatively were significantly greater than those at 1 week and 1 month (P < .0001). In comparing the three intraocular lenses at 1 week postoperatively, no statistical significance was observed regarding the anterior capsule opening area between the three groups. However, the mean anterior capsule opening areas in the polymethylmethacrylate and soft acrylic intraocular lens groups were significantly larger than those in the silicone intraocular lens group at 1 month (P = .0024), and 3 months (P = .0032), and 6 months (P = .0022) postoperatively. CONCLUSIONS: After continuous capsulorrhexis and intraocular lens implant surgery, the area of the anterior capsule opening gradually decreased for up to 3 months postoperatively. The contraction of the anterior capsule opening was greater in the silicone group than in either the polymethylmethacrylate or the soft acrylic groups.

Acrylates↗
PubMed2003

Capillary electrochromatography with monolithic stationary phases. II. Preparation of cationic stearyl-acrylate monoliths and their electrochromatographic characterization.

A novel cationic monolithic stationary phase based on the co-polymerization of pentaerythritol diacrylate monostearate (PEDAS) with a selected quaternary amine acrylic monomer was designed for performing capillary electrochromatography at high flow velocity. While PEDAS functioned as both the ligand provider and the cross-linker, the quaternary amine acrylic monomer was introduced to control the magnitude of the electroosmotic flow (EOF). The fabrication of the cationic stearyl-acrylate monolith (designated as cationic C17 monolith) with controlled porosity was achieved by free radical polymerization using the initiator 2,2'-azobisisobutyronitrile in the presence of a ternary porogenic solvent composed of cyclohexanol, ethylene glycol and water. Four different quaternary amine acrylic monomers were investigated in order to find the optimum monomer for achieving maximum electroosmotic flow (EOF) velocity. Both photo- and thermally-initiated polymerization proved effective in producing the cationic C17 monolith, and the best monolith was achieved when [2-(acryloyloxy)ethyl]trimethyl ammonium methyl sulfate (AETA) was used as the quaternary amine acrylic monomer. Although the zeta potential of the resulting cationic C17 monolith is positive with respect to water, the magnitude and direction of the EOF was markedly affected by the nature of the electrolyte in the mobile phase. Consequently, anodal, zero or cathodal EOF was observed depending on the nature of the electrolyte, and this was attributed to the adsorption of the ionic components of the electrolyte on to the solid stationary phase, which is characterized by its amphiphilic nature consisting of C17 chains, ester functions, hydroxyl groups and quaternary amine moieties. Optimized PEDAS-AETA monoliths yielded columns with high separation efficiency and allowed rapid separations on the time scale of seconds to be achieved with short capillaries.

Acrylates↗
PubMed1998

New acrylic resin composite with improved thermal diffusivity.

STATEMENT OF PROBLEM: Studies have shown that physical characteristics of denture base materials may affect patient acceptance of denture prostheses by altering sensory experience of food during mastication. Thermal diffusivity is one material property that has been cited as being important in determining gustatory response, with denture base acrylic resins having low thermal diffusivity compared with denture base metal alloys. PURPOSE: This study prepared and characterized experimental acrylic resin composite material with increased thermal diffusivity. MATERIAL AND METHODS: Sapphire (Al2O3) whiskers were added to conventional denture base acrylic resin during processing to achieve loadings of 9.35% and 15% by volume. Cylindrical test specimens containing an embedded thermocouple were used to determine thermal diffusivity over a physiologic temperature range (0 degree to 70 degrees C). RESULTS: Thermal diffusivities of the sapphire containing composites were found to be significantly higher than the unmodified acrylic resin. Thermal diffusivity was found to increase in proportion to the volume percentage of sapphire filler, which suggested that the high aspect ratio ceramic particles formed a pathway for heat conduction through the insulating polymer matrix. CONCLUSION: The thermal diffusivity of denture base acrylic resin was increased by the addition of thermally conducting sapphire whiskers.

Acrylic Resins↗
PubMed1999

Time-related wettability characteristic of acrylic resin surfaces treated by glow discharge.

STATEMENT OF PROBLEM: Adhesion and cohesion have important roles in denture retention, and attempts have been made to improve the wettability of the acrylic resin material by surface treatments. PURPOSE: This study examined the initial and subsequent wettability of an acrylic resin denture base material treated under air or argon plasma atmosphere before and after exposure to air or distilled water. MATERIAL AND METHODS: Acrylic resin specimens were treated with plasma under air or argon atmosphere and were either exposed to air or distilled water for up to 60 days. Wettability characteristics of the acrylic resin specimens were determined by contact-angle measurements after 2 hours and after 60 days. Surface composition of the specimens also was analyzed with x-ray photoelectron spectroscopic (XPS) measurements. RESULTS: Statistically significant difference was found between control and each of the plasma treatment groups (P <.05). Although the storage condition and storage period caused statistically significant difference on contact angle values (P <.05), atmosphere type did not have any effect on the results (P >.05). XPS spectra of the plasma-treated specimens differed from control specimens only in the O1s region with a narrower and more intense peak that could be assigned to -COH groups. During 60 days of exposure, the O/C atomic ratios decreased within the first 2 weeks but settled to 0.40 and 0. 32 up to 60 days compared with 0.26 for untreated control specimens. CONCLUSION: Glow discharge plasma altered the surfaces of the acrylic resin and increased thc wettability as shown both by XPS and contact-angle measurements, and plasma treatment seemed to offer a durable (at least up to 60 days) wettability.

Acrylic Resins↗
PubMed2001

Comparative toxicity of acrylic acid to marine and freshwater microalgae and the significance for environmental effects assessments.

In this study, we compared the sensitivity of freshwater and marine organisms to two structurally similar substances, acrylic acid and methacrylic acid. Reported acute toxicity data (L(E)C50-values) for freshwater organisms range from 0.1 to 222 mg/l and 85 to >130 mg/l for acrylic acid and methacrylic acid, respectively. The large variation in toxicity data for acrylic acid is due to a specific toxicity to certain species of freshwater microalgae, with algae EC50-values being two to three orders of magnitude lower than L(E)C50-values reported for fish and invertebrates. To evaluate the sensitivity of marine organisms, ecotoxicity data was generated for ten species of microalgae, one invertebrate species and one fish species. For methacrylic acid, we found a marine acute toxicity that ranged from 110 to >1260 mg/l, which is comparable to reported data on freshwater organisms. In strong contrast, the resulting L(E)C50-values for acrylic acid ranged from 50 to >1000 mg/l, and there was no specific sensitivity of marine algae when compared to marine invertebrates and fish. For acrylic acid, therefore, use of the available freshwater toxicity data for an effects assessment for the marine environment is likely to overestimate the hazard and risk from this substance. Overall, the results of the study suggest that ecotoxicity data generated on freshwater species may not always be appropriate for the effects assessments of organic chemicals in the marine environment, thus emphasising the importance of using ecologically relevant data to assess environmental risk.

Acrylates↗
PubMed2000

Comparison of artificial eye amplitudes with acrylic and hydroxyapatite spherical enucleation implants.

PURPOSE: To compare artificial eye amplitudes in patients who randomly received either a hydroxyapatite or an acrylic, scleral-covered spherical implant after enucleation. DESIGN: Randomized, controlled trial. PARTICIPANTS: Thirty-four consecutive patients who underwent enucleation because of an intraocular melanoma and 21 healthy control participants from the hospital staff. METHODS: Eligible patients randomly received a hydroxyapatite or an acrylic, scleral-covered spherical orbital implant. Fourteen patients were fitted with a hydroxyapatite implant, and 16 were fitted with an acrylic implant. We measured horizontal and vertical saccadic amplitudes of both the artificial eye and the healthy eye. Measurements were performed with the magnetic search coils technique. Saccadic amplitudes of the artificial eye were compared with the healthy eye of the patient. The amplitudes of the healthy eyes were compared with saccadic amplitudes of control participants. The interval from surgery to measurements was at least 3 months in all patients. Saccadic gain (artificial eye and eye amplitude divided by target amplitude) and saccadic symmetry (artificial eye amplitude divided by healthy eye amplitude) were calculated. MAIN OUTCOME MEASURES: Saccadic gain and saccadic symmetry. RESULTS: The gain in the healthy eyes of the patients was comparable with the gain of the control eyes. Saccadic symmetry was 1.0 in control participants. In patients, it was 0.334 in horizontal saccades and 0.577 in vertical saccades. However, saccadic symmetry did not differ significantly between the acrylic group and the hydroxyapatite group (P: > 0.1 for any saccadic direction). Equivalence was detectable with a power more than 90% for horizontal saccades and more than 80% for vertical saccades. Curvilinearity was rejected for both patient groups and for all saccadic directions (P: > 0.5). CONCLUSIONS: When no motility peg is placed, acrylic and hydroxyapatite spherical implants yield comparable saccadic amplitudes of the artificial eye. Artificial eye amplitudes were markedly more restricted horizontally than vertically. In all saccadic directions, the relation between target amplitude and artificial eye amplitude was linear.

Acrylic Resins↗
PubMed1997

Developmental toxicity study of inhaled acrylic acid in New Zealand White rabbits.

In range-finding and definitive developmental toxicity studies, timed pregnant New Zealand White rabbits were exposed to acrylic acid (CAS No. 79-10-7) vapour for 13 consecutive days during pregnancy. In the range-finding study, eight pregnant does/group were exposed to 30, 60, 125 or 250 ppm acrylic acid vapour on gestation days (gd) 10-22 of pregnancy. Monitors of toxicity included body weight measurements, daily food consumption measurements and clinical observations. Three of the eight does/group were killed on the day following the last exposure (gd 23), and the remaining does were killed and autopsied on gd 29. At autopsy, special attention was given to gross observation of maternal nasal turbinates, and nasal turbinates from all does were evaluated histologically. No evaluation of foetuses was performed in the range-finding study. In the definitive study, 16 does/group were exposed to concentrations of 25, 75 or 225 ppm acrylic acid vapour from gd 6 to 18, the major period of organogenesis. Monitors of maternal toxicity included clinical observations and measurements of body weight and daily food consumption measurements. Does were killed and autopsied on gd 29. Maternal liver and kidney weights were measured and external, visceral and skeletal evaluations of foetuses were conducted. Maternal nasal turbinates were not evaluated histologically in the definitive study. Effects in does from both studies included consistent concentration-related reductions in food consumption and body weight gains throughout the exposure period at concentrations of acrylic acid vapour above 60 ppm. Characteristic clinical signs of sensory irritation, including perinasal and perioral wetness and severe nasal congestion, were noted in does from both studies at or above vapour concentrations of 75 ppm. Gross observation of nasal turbinates immediately following exposures in the range-finding study indicated colour changes in the nasal turbinates of does in the 60 and 250 ppm groups. Colour changes in the nasal turbinates were noted in one doe from the 250 ppm exposure group killed on gd 29. Pertinent autopsy findings in the does from the definitive study included ulceration of the nasal turbinates of a single doe in the 225 ppm group. Histological evaluation of turbinates from does killed the day following exposures in the range-finding study revealed lesions in the nasal epithelium in all acrylic acid-exposed groups. The severity of the lesions was concentration related. Microscopic evaluation of turbinates from does killed on gd 29 showed the presence of nasal lesions in the 60, 125 and 250 ppm groups. However, the nasal tissues had recovered considerably during the post-exposure interval. Despite the severe effects on the nasal mucosa of does in both studies, there was no evidence of developmental toxicity including teratogenicity at any exposure concentration used in the definitive study.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

Metabolic pathways of 1-butyl [3-13C]acrylate. Identification of urinary metabolites in rat using nuclear magnetic resonance and mass spectroscopy.

1-Butylacrylate, an industrial monomer, is rapidly metabolized by carboxylesterase-catalyzed hydrolysis to acrylic acid and 1-butanol. Acrylic acid enters the intermediary metabolism and is efficiently degraded to carbon dioxide as the metabolic end product. To obtain a virtually complete metabolic pattern, rats were dosed by a single intraperitoneal dose of 1 mmol/kg 1-butyl [3-13C]acrylate. The urine was then analyzed by a one-dimensional 1H-detected and two-dimensional 1H-13C shift-correlated heteronuclear multiple-quantum NMR experiment. In this experiment, three urinary metabolites, namely, 3-hydroxypropanoic acid, N-acetyl-S-(2-carboxyethyl)cysteine, and N-acetyl-S-(2-carboxyethyl)cysteine sulfoxide, were identified comparing their 1H and 13C chemical shifts with those of authentic standards. In another experiment, to enhance minor metabolic pathways, rats were dosed with 0.25 mmol/kg of a carboxylesterase inhibitor, tri-o-tolyl phosphate, prior to 0.5 mmol/kg butyl [3-13C]acrylate. Under these conditions, N-acetyl-S-(2-carboxyethyl)cysteine, N-acetyl-S-[2-(butoxycarbonyl)-ethyl]cysteine, and N-acetyl-S-(2-carboxyethyl)cysteine sulfoxide were found in urine. No metabolites which would arise from a possible metabolic activation of 1-butyl acrylate to 1-butyl oxiranecarboxylate and its subsequent hydrolysis or glutathione conjugation were found. It is estimated that any metabolite amounting to more than 1% of the dose should be detected under these conditions. To study the routes by which BA enters the intermediary metabolism, incorporation of the label into urinary carboxylic acids was followed by GC/MS. Significant enrichment was found in 3-hydroxypropanoic acid and citric and isocitric acid but not in lactic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcysteine↗
PubMed2002

Visual discrimination testing of ultraviolet transmitting and ultraviolet blocking acrylic thermoplastics.

BACKGROUND: Visual perception has hindered the development of blinded, placebo-controlled ultraviolet light exposure conditions in humans. New acrylic thermoplastics that block or transmit ultraviolet light have visual properties that may provide a solution. METHODS: In a series of triangle taste tests, 60 subjects were tested for the ability to visually perceive ultraviolet light transmission by two of four types of acrylic thermoplastics. RESULTS: Forty-six of sixty (67%) subjects were unable to visually detect ultraviolet light transmitting acrylics among ultraviolet blocking acrylics in both an ambient light background condition and an ambient light background condition with ultraviolet A light supplementation. CONCLUSION: Acrylic thermoplastics allow for the production of blinded, placebo-controlled ultraviolet light exposure conditions by eliminating visual discrimination differences between active and control groups.

Acrylic Resins↗
PubMed1999

A method for measuring dermal exposure to multifunctional acrylates.

UV-curable acrylates are used increasingly for coating wood surfaces in the furniture industry. One of the active components, tripropylene glycol diacrylate (TPGDA), is known to be both an allergen and irritant to the skin. Methods to measure dermal exposure to skin irritants and allergens, such as acrylates, are insufficient for exposure assessment and there is none for this compound. The aim of this investigation was to develop a skin and surface sampling method, based on tape stripping, and a gas chromatographic method for quantitative analysis for assessing occupational skin exposure to multifunctional acrylates. Twelve adhesives were tested for their efficiency to remove TPGDA and UV-coating from a glass surface, the skin of guinea pigs and human volunteers employing the tape-stripping method in order to find the best performing tape. Variables that affect removal efficiency such as the applied dose and its retention time on the skin, tape adhesion time on the skin, and the number of strippings required to detect the contaminant from the skin were studied. Fixomull tape performed the best during sampling and analysis and had the most consistent removal efficiencies for the studied substances. The average removal efficiency with a single stripping at the 2 microliters TPGDA exposed skin sites was 85% (RSD = 14.1), and for UV-resin exposed sites 63% (RSD = 20.2). The results indicated that this method can be used for measuring dermal exposure to multifunctional acrylates efficiently, accurately, and economically. This method provides a sensitive and powerful tool for the assessment of dermal exposure to multifunctional acrylates both from the skin and from other contaminated surfaces in occupational field settings.

Acrylates↗
PubMed2005

Effect of storage duration on tensile bond strength of acrylic or silicone-based soft denture liners to a processed denture base polymer.

OBJECTIVE: To investigate the effect of storage duration on the tensile bond strength of acrylic and silicone-based denture base materials with liners either heat-cured or auto-cured. MATERIAL AND METHODS: The denture liners investigated were Vertex soft (acrylic-based, heat-cured), Coe soft (acrylic-based, auto-cured), Molloplast-B (silicone-based, heat-cured), and Mollosil plus (silicone-based, auto-cured). The soft liner specimens were 10 x 10 x 3 mm and were processed between two PMMA blocks. They were tested following immersion in water at 37 degrees C for 1 day, 1 week, and 1, 3, and 6 months. Tensile bond strength was measured using a universal testing machine (Testometric Micro 500) at a crosshead speed of 20 mm/min (n = 10 specimens per experimental group). Multiple ANOVA and Tukey HSD were used to analyse the data at a pre-set alpha of 0.05. RESULTS: The results indicate that the tensile bond strength of acrylic-based soft liners is greater than that of silicone-based materials. The bond strength of all lining materials decreases with storage duration; the decrease being greatest for the acrylic-based soft liners. The decrease in bond strength of the auto-cured materials is greater than that of the heat-cured products. CLINICAL SIGNIFICANCE: Comparison of the materials in this study indicates that the silicone-based, heat-cured soft liner is superior, based on the tensile bond strength property. Use of silicone-based, heat-cured soft liners may provide better clinical success over a long period. These laboratory results need to be verified by clinical testing.

Acrylic Resins↗
PubMed1985

LC50 values for rats acutely exposed to vapors of acrylic and methacrylic acid esters.

Acute exposure studies were conducted using adult male Sprague-Dawley rats to obtain LC50/24 concentrations for the common esters of acrylic and methacrylic acids. The order of acute toxicity was determined to be methyl acrylate greater than ethyl acrylate greater than butyl acrylate greater than butyl methacrylate greater than methyl methacrylate greater than ethyl methacrylate. Four-hour daily exposures (excluding weekends) of young adult male rats to 110 ppm methyl acrylate in air over a period of 32 d failed to produce significant differences in body or tissue weights, blood chemistries, gross metabolic performance, and spontaneous small-intestinal motor activities when compared with a sham-exposed group.

Acrylates↗
PubMed2006

Evaluation of tris-acryl gelatin microsphere embolization with monochromatic X Rays: comparison with polyvinyl alcohol particles.

PURPOSE: Imaging of blood vessels 30 mum or smaller can be achieved with use of monochromatic x rays. The purpose of the present investigation was to use this method to evaluate the in vivo primary embolic effect of tris-acryl gelatin microspheres and polyvinyl alcohol (PVA) particles in small blood vessels, and specifically to assess the distribution of these particles and the resulting changes in circulation. MATERIALS AND METHODS: Twelve rabbits were divided into four groups: group 1 (PVA particles, 90-180 mum; n = 3), group 2 (tris-acryl gelatin microspheres, 40-120 mum; n = 3), group 3 (PVA, 300-500 mum; n = 3), and group 4 (tris-acryl gelatin microspheres, 300-500 mum; n = 3). After microangiography with monochromatic x rays, embolization was performed in normal auricular blood vessels, and immediately thereafter, postembolization microangiography was performed. Images acquired before and after embolization with the four embolic agents were compared, and the diameters of embolized blood vessels were measured. The mean embolized vascular diameter and its ratio to the midrange particle size of the embolic agent were calculated. RESULTS: Tris-acryl gelatin microspheres did not aggregate and tended to lodge in vessels close in size to the individual particle size, whereas PVA particles aggregated in vessels larger than the individual particle size. For tris-acryl gelatin microspheres, no blood flow was noted peripheral to the embolized region, whereas for PVA particles, blood flow was noted in regions peripheral to the embolized region. CONCLUSIONS: Monochromatic x rays allow direct visualization of in vivo embolic properties. This technique holds promise for comparative studies of embolic agents.

Acrylic Resins↗
PubMed1981

The effects of the incorporation of chlorhexidine acetate on some physical properties of polymerized and plasticized acrylics.

The effects on the water uptake and weight loss of the incorporation of chlorhexidine acetate in heat cured acrylic and an acrylic gel soft liner was determined. Hardness and transverse bend measurement were similarly made for admixtures to heat and cold cured acrylics. Following soaking in water for 87 days the heat cured test specimens demonstrated an initial weight gain followed by a progressive loss, the soft liner test specimens however all showed weight gains. Drying back specimens to constant weight revealed significantly greater weight losses in test compared to control specimens for both the cured acrylic and gel liner. However these weight losses were less than the chlorhexidine content for 5 and 10% admixtures. Hardness and moduli of elasticity measurements were significantly reduced for heat and cold cured acrylics containing chlorhexidine. The property changes observed in the materials would be consistent with the pattern of incorporation of chlorhexidine into the matrix. However, these do not negate the carriage of medicaments in these materials for prolonged delivery within the oral cavity, if employed as rebase or reline materials in existing prostheses.

Acrylates↗
PubMed1993

Effect of some properties of metal strengtheners on the fracture resistance of acrylic denture base material construction.

In this study we investigated the effect of metal wire bonding to acrylic resin on the fracture resistance of an acrylic denture base material construction. Two different bonding methods were tested, and after measuring the resistance, the surface of the wires were examined by a scanning electron microscope. The effect that the placing of metal strengtheners in different positions in the acrylic resin had on the fracture resistance of the denture base material construction was also clarified. When three different positions of the metal wires in the acrylic resin were compared, the results showed that bonding of metal wire to acrylic resin somewhat enhanced the fracture resistance of test specimens, while the different positions of the wires had no effect on the fracture resistance.

Acrylic Resins↗
PubMed2006

Effect of enzymatic and NaOCl treatments on acrylic roughness and on biofilm accumulation.

As denture cleansers should be able to reduce biofilm accumulation without changing the acrylic resin surface structure, this study evaluated the effect of denture cleansers on surface roughness of acrylic resin and on biofilm accumulation. It was conducted a crossover study of three phases of 4 days each and 13 volunteers wore palatal appliances containing four specimens of acrylic resin of known surface roughness which were extra-orally submitted once a day to three groups of separated treatments: (i) negative control, (ii) enzymatic commercial solution (Ortoform) or (iii) 0.5% sodium hypochlorite (NaOCl). The appliances were immersed eight times a day in a 20% sucrose solution to enhance biofilm formation. On morning of the fifth day of each phase, the amount of biofilm formed on the specimens was estimated by the amount of protein extracted with alkali and the surface roughness of the specimens was again measured. New palatal appliances with new specimens were worn by the volunteers in the following phases, but the treatments were changed. The roughness of the resin increased after the treatments (P < 0.05) but the difference among the cleansers was not statistically significant (P = 0.85). The lowest amount of biofilm formed on acrylic resin specimens was found for the treatment with NaOCl (P < 0.05) but the enzymatic product did not differ from the negative control group (P > 0.05). The data suggest that the roughness of acrylic resin was not changed by the cleansers, but the ability to reduce biofilm accumulation depended on the product used.

Acrylic Resins↗