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PubMed1989

Olfactory function in chemical workers exposed to acrylate and methacrylate vapors.

An investigation of the olfactory function of 731 workers at a chemical facility which manufacturers acrylates and methacrylates was undertaken using a standardized quantitative test. In a cross-sectional analysis of the data, no associations of chemical exposure with olfactory test scores were observed. A nested case-control study designed to evaluate the cumulative effects of exposure on olfactory function, however, revealed elevated crude exposure odds ratios (95% confidence interval) of 2.0 (1.1, 3.8) for all workers and 6.0 (1.7, 21.5) for workers who never smoked cigarettes. Logistic regression analysis, adjusting for multiple confounders, revealed exposure odds ratios of 2.8 (1.1, 7.0) and 13.5 (2.1, 87.6) in these same groups, respectively, and a dose-response relationship between olfactory dysfunction and cumulative exposure scores--semi-quantitative indices of lifetime exposure to the acrylates. The data also revealed decreasing exposure odds ratios with increasing duration since last exposure to these chemicals, suggesting that the effects may be reversible.

Acrylates↗

PubMed2006

[Sectional acrylic dentures for a partially edentulous patient with microstomia: a clinical report].

PATIENT: The patient was a 48-year-old partially edentulous male with microstomia. His chief complaints were masticatory disturbance and aesthetic problems caused by missing teeth. After trayless impressions for diagnostic casts were made, sectional trays and a sectional record block were used for the definitive impression and maxillomandibular registration. Maxillary and mandibular acrylic sectional dentures were simultaneously delivered. DISCUSSION: Low caries activity, minimal occlusal force, appropriate plaque control, and simple designs for connecting portions of the two halves of the sectional dentures might lead to satisfactory results in this case. CONCLUSION: No problems have been observed for approximately 6 years after delivery of the acrylic sectional dentures for this microstomic patient.

Acrylic Resins↗

PubMedDate not supplied

Dynamic swelling behaviour of gelatin/poly(acrylic acid) bioadhesive microspheres loaded with oxprenolol.

The dynamic swelling of gelatin/poly(acrylic acid) microspheres loaded with oxprenolol has been evaluated. The movement of two distinct and characteristic swelling boundaries was measured directly using an optical microscope. Swelling rate constants associated with the inner moving front and the outer swelling boundary were determined. A polynomial equation incorporating both Fickian diffusion and case II relaxational models was used to fit the kinetics of liquid uptake. The influence of the concentration of the cross-linking agent, the poly(acrylic acid) load, the pH of the swelling medium and the particle size of the microspheres, on the swelling kinetics, was evaluated and discussed.

Acrylic Resins↗

PubMedDate not supplied

Oxprenolol release from bioadhesive gelatin/poly(acrylic acid) microspheres.

Drug release from gelatin/poly(acrylic acid) oxprenolol-loaded microspheres has been evaluated using an in situ sink immersion method and a wetting method. The kinetics of drug release were analysed by applying the empirical exponential equation and by the calculation of the approximate contribution of the diffusional and relaxational mechanism to the anomalous release process by fitting the data to the coupled Fickian/Case II equation. The influence of glutaraldehyde cross-linking agent concentration, the poly(acrylic acid) content, the pH of the release medium and the particle size of the beads on the drug release kinetics were evaluated and discussed.

Acrylic Resins↗

PubMed1990

Bone flap replacement vs acrylic cranioplasty: a clinical audit.

A 5-year retrospective study comparing bone flap replacement with acrylic cranioplasty was carried out. There was no significant difference in the high infection rates associated with the two procedures. We suggest that antibiotic-impregnated acrylic cranioplasty may be the safest and best surgical procedure based on the orthopaedic experience with gentamicin-impregnated cement in joint replacement surgery.

Acrylic Resins↗

PubMed1997

Assessment of the acrylic resin Technovit 7200 VLC for studying the gingival mucosa by light and electron microscopy.

Technovit 7200 VLC is an acrylic resin formulated for embedding undecalcified hard tissues which are prepared for light microscopy according to a cutting-grinding technique. To employ this resin for embedding and cutting soft tissues by ultramicrotomy, we carried out a qualitative study on biopsies of canine gingival mucosa using light and transmission electron microscopy. For a critical evaluation of this resin, some biopsies were embedded in Agar 100, an epoxy resin widely used in morphological studies. At the light microscopic level the samples embedded in Technovit 7200 VLC showed good morphology and excellent toluidine blue staining of different cell types and extra cellular matrix. At the ultrastructural level, nuclei, cytoplasmic organelles, collagen fibrils and ground substance appeared well preserved and showed high electron density. The acrylic resin was stable under the electron beam and its degree of shrinkage appeared to be very low. We conclude that Technovit 7200 VLC can be employed for ultramicrotomy for both light and electron microscopic investigation of soft tissues.

Acrylic Resins↗

PubMed1998

The synthesis and in vitro characterization of the mucoadhesion and swelling of poly(acrylic acid) hydrogels.

The purpose of this research was to synthesize insoluble, mucoadhesive hydrogels by crosslinking linear poly(acrylic acid) with sucrose and investigate the relationship between hydrogel crosslink density, swelling, and in vitro mucoadhesion. A condensation reaction was employed to synthesize the hydrogels and crosslink density was varied by altering sucrose concentration and cure time. Equilibrium swelling at pH 7.4 was measured both gravimetrically and geometrically. In vitro mucoadhesion was determined by a tensile technique. Equilibrium swelling studies indicated that the crosslink density was proportional to both sucrose concentration and duration of cure time. In vitro mucoadhesive properties of the hydrogels improved as crosslink density increased. This was attributed to an increase in poly(acrylic acid) chain density/unit area of the equilibrium swollen hydrogel, which promoted interaction of the mucoadhesive and glycoprotein polymer chains.

Acrylic Resins↗

PubMed1983

Penetration of acrylic bone cements into cancellous bone.

The depth of penetration of five commercial acrylic bone cements into cancellous bone was measured in vitro. Under standard, idealized conditions, cement penetration was found to vary significantly with different cements. Penetration was critically influenced by the coarseness of the cancellous bone and increased directly with the effective volume of the "cells" within the osseous matrix. An inverse correlation was determined between the mean cement viscosity during flow into the bone and final penetration depth. The dough time, set time and working time of each acrylic formulation was found to have no significant effect upon the depth of cement penetration. It is suggested that in addition to the techniques adopted for introduction of cement to the bone, the selection of the bone cement itself may critically influence the incidence of late loosening following total joint replacement.

Acrylic Resins↗

PubMed2001

Intraaneurysmal flow dynamics study featuring an acrylic aneurysm model manufactured using a computerized tomography angiogram as a mold.

OBJECT: To obtain precise flow profiles in patients' aneurysms, the authors developed a new in vitro study method featuring an aneurysm model manufactured using three-dimensional computerized tomography (3D CT) angiography. METHODS: A clear acrylic basilar artery (BA) tip aneurysm model manufactured from a patient's 3D CT angiogram was used to analyze flow modifications during one cardiac cycle. Stereolithography was utilized to create the aneurysm model. Three-dimensional flow profiles within the aneurysm model were obtained from velocity measurements by using laser Doppler velocimetry. The aneurysm inflow/outflow zones changed dynamically in their location, size of their cross-sectional area, and also in their shapes over one cardiac cycle. The flow velocity at the inflow zone was 16.8 to 81.9% of the highest axial velocity in the BA with a pulsatility index (PI) of 1.1. The flow velocity at the outflow zone was 16.8 to 34.3% of the highest axial velocity of the BA, with a PI of 0.68. The shear stress along the walls of the aneurysm was calculated from the fluid velocity measured at a distance of 0.5 mm from the wall. The highest value of shear stress was observed at the bleb of the aneurysm. CONCLUSIONS: This clear acrylic model of a BA tip aneurysm manufactured using a CT angiogram allowed qualitative and quantitative analysis of its flow during a cardiac cycle. Accumulated knowledge from this type of study may reveal pertinent information about aneurysmal flow dynamics that will help practitioners understand the relationship among anatomy, flow dynamics, and the natural history of aneurysms.

Acrylic Resins↗

PubMed1993

Effect of an ultraviolet light-activated coating material on reduction of the leaching of methyl methacrylate and formaldehyde from denture acrylic resins.

Effect of glazing with an ultraviolet light-activated coating material on reduction of the leaching of methyl methacrylate and formaldehyde from denture acrylic resins was quantitatively evaluated. Disks prepared from auto-polymerized resins were painted with the material and radiated with ultraviolet light. The disks were immersed in artificial saliva and the concentrations of methyl methacrylate and formaldehyde leached were determined by high-performance liquid chromatography and flow injection analysis. Compared to untreated controls, the glaze significantly decreased concentrations of both leachable substances. Treatment with an ultraviolet light-activated coating material is effective in suppressing the leaching of methyl methacrylate and formaldehyde from acrylic resins as well as in smoothing the denture surfaces.

Acrylic Resins↗

PubMed1991

Mortality from cancer of the colon or rectum among workers exposed to ethyl acrylate and methyl methacrylate.

Mortality from colon and rectum cancer has been reviewed in three cohorts working in 1933-1982 in two plants manufacturing and polymerizing acrylate monomers. The two cohorts with later dates of hire showed no excess mortality. In the earliest cohort, excess colon cancer seemed restricted to men employed extensively in the early 1940s in jobs entailing the highest exposures to vapor-phase ethyl acrylate (EA) and methyl methacrylate (MMA) monomer and volatile by-products of the EA/MMA polymerization process. The excess mortality appeared only some two decades after the equivalent of three years' employment in jobs with the most intense exposures. A smaller elevation in colon cancer mortality also appeared in a low-exposure group in the early cohort. Rectal cancer mortality was elevated in the same categories that showed excess rates of colon cancer death. Because of the lower rates, the rectal cancer results are more imprecise.

Acrylates↗

PubMed1976

An acrylic dental protector in peroral endoscopy.

A simple acrylic dental prosthesis is described which achieves successful dental protection during peroral endoscopy. This prosthesis is not advocated for all cases, but certainly is well warranted for those patients whose upper dentition is at risk during endoscopy because of the prominence of the incisors, the presence of loose teeth, or with extensive restorative work. In present experience, approximately 10 per cent of patients undergoing endoscopy have such an acrylic prosthesis prepared pre-operatively. The commercially available flexible plastic dental guard is used in approximately 25 per cent of cases, and the remaining cases need no specific attention. It is felt that this prosthesis could be constructed by any dentist conversant with the technique.

Acrylic Resins↗

PubMed1999

Evaluation of a bitemark using clear acrylic replicas of the suspect's dentition--a case report.

An assault occurred during which a bite was inflicted on the left ear of the victim, producing a laceration and severing a portion of tissue from the ear. During the course of their investigation police recovered a lacerated fragment of tissue thought to be of a person's left ear. Impressions of a suspect's dentition were made and cast in dental stone. Positive replicas of the occlusal surfaces of the suspect's dentition were subsequently made using acrylic resin. The ear fragment displayed a lacerated border and a surface which exhibited indentations. When compared with the details of the suspect's lower anterior teeth, correspondence was visible between the shape of the indentations and characteristics of the suspect's dentition. The use of transparent acrylic replicas of the suspect's dentition facilitated the interpretation and comparison between the marks retained in the ear fragment and the features of the suspect's dentition.

Acrylic Resins↗

PubMed1975

The acrylic jacket crown.

An attempt has been made to cover briefly the many applications of the acrylic jacket crown. It is readily understandable that this type of restoration has many shortcomings but at the same time it has many useful and important applications in dentistry when properly employed. It is hoped that the specialist and generalist alike will have found some new and useful applications of the acrylic jacket crown.

Acrylic Resins↗

PubMedDate not supplied

Clinical survey of acrylic resin removable denture repairs with glass-fiber reinforcement.

PURPOSE: The aim of this study was to evaluate clinical usefulness and durability of continuous glass-fiber reinforcement in repair of acrylic resin removable dentures. MATERIALS AND METHODS: Fractured removable dentures without reinforcement, with conventional metal-wire reinforcement, or with mesh reinforcement were collected from two dental schools in Finland. The total number of dentures was 51 and the number of patients was 48. During the repair, the dentures were reinforced with a polymer-preimpregnated E-glass fiber at the region of the fracture. The fibers were used as partial fiber reinforcement, i.e., only the weakest part of the denture was reinforced. Follow-up time varied from 4 months to 4.1 years. After the follow-up period, possible fractures and discoloring were visually inspected. Possible irritation of oral mucosa by glass fibers and the general shape of the denture were also evaluated. RESULTS: In 88% of the cases, there was no need for adjustment at the region of partial fiber reinforcement, and the clinical condition of the dentures was good. Glass fibers did not irritate the oral mucosa. In the case of refracture or hairline fracture, positioning of the partial fiber reinforcement was incorrect or the reinforcement had been used incorrectly (the wetting of the reinforcement with denture base resin was inadequate). CONCLUSION: Polymer-preimpregnated partial fiber reinforcement seems to be useful in eliminating fractures of acrylic resin removable dentures. However, this study emphasizes the importance of correct positioning and accurate laboratory technique when partial fiber reinforcement is used.

Acrylic Resins↗

PubMed2001

The effect of powder/liquid mixing ratio on the stiffness and impact strength of autopolymerising dental acrylic resins.

The stiffness of representative cured autopolymerising dental acrylic resins was determined by calculation of a secant modulus from measurements in tension of load and extension, and related to the powder/liquid mixing ratio. The impact strengths of autopolymerising, heat-cure and commercial resins were compared. It was found that while the stiffness of autopolymerising resins was unaffected by variations in powder/liquid mixing ratio, extension to failure was greater with lower powder/liquid ratios. The impact strength of autopolymerising resins was found to be greater than that of heat-cure resins, and a tentative explanation is offered. These findings may help to explain the pattern of failure of acrylic resin denture bases.

Acrylic Resins↗

PubMed2002

Prevention of allergy to acrylates and latex in dental personnel.

Contact allergy to acrylate monomers and immediate hypersensitivity to latex gloves in dental personnel calls for preventive measures to reduce the risks. The aim of the study was to evaluate the preventive effect of an information campaign after a 3-year follow-up. The campaign included instructions and training according to an ordinance, both in writing and orally, e.g. concerning the choice of products and protection devices and the proper handling of the materials. The follow-up was carried out through 1997-2000 and included all eligible 513 subjects. Information on new cases was ascertained by a questionnaire and reports from the occupational health service and the department of dermatology. The number of expected new cases was based on the incidence rate, derived from a preceding prevalence study in the same county, and the exposed years at risk in the follow-up period. No new case of allergy to acrylates or latex rubber was found in the follow-up period as against 4.91 expected (p = 0.007). In conclusion, this study indicates that occupational allergies can be prevented successfully, but requires vigorous measures to influence the behaviour and the routines of daily work in dental practice.

Acrylates↗

PubMed2001

Clinical effects of removable acrylic appliance design on gingival tissues: a short-term study.

The aim of this study was to assess the effects on the gingiva when an experimental palatal acrylic removable appliance, was worn for 3 weeks. Clinical parameters were reassessed after a 3 week recovery period when the appliance was no longer worn. The appliance design featured a base plate on the right side which extended to the gingival margin, but which on the left, was relieved from the gingival margin by 6mm. Plaque index, gingival index, and probing depth were recorded on days 0, 7, and 21, and at day 42. Results indicated that there was increasing gingival inflammation in the right palatal gingiva by day 7, and this became worse by day 21. Statistically significant differences in gingival inflammation were evident when right and left sides were compared at day 7 and 21, although there were no significant differences in plaque accumulation during this period. Probing depth measurements also increased significantly on the right side by day 21. All these gingival changes reversed to baseline levels during the recovery period by day 42. This paper demonstrates the rapid effect of acrylic denture design on gingival tissues.

Acrylic Resins↗