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PubMedDate not supplied

Effect of disinfectants on the hardness and roughness of reline acrylic resins.

PURPOSE: Potential effects on hardness and roughness of a necessary and effective disinfecting regimen (1% sodium hypocholorite and 4% chlorhexidine) were investigated for two hard chairside reline resins versus a heat-polymerizing denture base acrylic resin. MATERIALS AND METHODS: Two standard hard chairside reliners (Kooliner and Duraliner II), one heat-treated chairside reliner (Duraliner II +10 minutes in water at 55 degrees C), and one standard denture base material (Lucitone 550) were exposed to two disinfecting solutions (1% sodium hypochlorite; 4% chlorhexidine gluconate), and tested for two surface properties [Vickers hardness number (VHN, kg/mm(2)); Roughness (Ra, microm)] for different times and conditions (1 hour after production, after 48 hours at 37 +/- 2 degrees C in water, after two disinfection cycles, after 7 days in disinfection solutions, after 7 days in water only). For each experimental condition, eight specimens were made from each material. Data were analyzed by analysis of variance followed by Tukey's test, and Student's t-test (p= 0.05). RESULTS: For Kooliner (from 6.2 +/- 0.3 to 6.5 +/- 0.5 VHN) and Lucitone 550 (from 16.5 +/- 0.4 to 18.4 +/- 1.7 VHN), no significant changes in hardness were observed either after the disinfection or after 7 days of immersion, regardless of the disinfectant solution used. For Duraliner II (from 4.0 +/- 0.1 to 4.2 +/- 0.1 VHN), with and without heat treatment, a small but significant increase in hardness was observed for the specimens immersed in the disinfectant solutions for 7 days (from 4.3 +/- 0.2 to 4.8 +/- 0.5 VHN). All materials showed no significant change in roughness (Kooliner: from 0.13 +/- 0.05 to 0.48 +/- 0.24 microm; Duraliner II, with and without heat treatment: from 0.15 +/- 0.04 to 0.29 +/- 0.07 microm; Lucitone 550: from 0.44 +/- 0.19 to 0.49 +/- 0.15 microm) after disinfection and after storage in water for 7 days. CONCLUSIONS: The disinfectant solutions, 1% sodium hypochlorite and 4% chlorhexidine gluconate, caused no apparent damage on hardness and roughness of the materials evaluated.

Acrylic Resins↗
PubMed1992

The effects of antimicrobial acrylic strips on the subgingival microflora in chronic periodontitis.

This study investigated the effects of root planing and/or the placement of acrylic strips containing chlorhexidine, metronidazole or tetracycline on the composition and antimicrobial susceptibility of the subgingival flora in chronic periodontitis. 101 periodontal pockets from 73 patients were entered into 6 treatment groups which were, chlorhexidine, metronidazole or tetracycline strips, root planing, root planing followed by metronidazole strips and a control, no treatment group. Total anaerobic counts and anaerobe/aerobe ratios were estimated from samples taken before treatment and 1, 2, 4, 8 and 12 weeks after treatment. In addition, a more detailed analysis of the effects of the treatments on the subgingival flora was carried out on 12 pockets in 12 patients. Tetracycline strips, metronidazole strips and root planing and metronidazole strips were more effective than chlorhexidine strips in causing reductions in total anaerobic count and anaerobe/aerobe ratio. However, the changes in microbial parameters rebounded to approach baseline levels 4 weeks after treatment. Chlorhexidine caused no detectable changes in the composition of the subgingival microflora, while metronidazole had a variable effect. Tetracycline appeared to effect major shifts in the composition of the microflora of treated pockets but caused a marked selection of tetracycline-resistant organisms.

Acrylic Resins↗
PubMed1977

Contact dermatitis from polyfunctional acrylic monomers.

Five out of 26 men employed formulating radiation drying printing ink developed eczematous dermatitis. Positive patch tests were obtained with two polyfunctional acrylic monomers, pentaerythritol triacrylate and trimethylol propane triacrylate and with formulations containing these in four affected employees. Cross sensitization was observed to dipentaerythritol monohydroxy pentaacrylate in each case. A fifth employee appeared to have developed irritant dermatitis from contact with these materials.

Acrylates↗
PubMed1984

The sensitizing potential of di-(meth)acrylates based on bisphenol A or epoxy resin in the guinea pig.

Most composite materials in dentistry used today, contain resins based on dimethacrylates. BIS-GMA [2,2-bis-(4-(2-hydroxy-3-methacryloxypropoxy)phenyl)propane], the addition reaction product of bisphenol A and glycidyl methacrylate or an epoxy resin and methacrylic acid, is used most extensively. More recently, dimethacrylates based on bisphenol A, with various chain lengths have appeared on the market as a substitute for or in addition to BIS-GMA. Such compounds are BIS-MA [2,2-bis-(4-(methacryloxy)phenyl)propane], BIS-EMA [2,2-bis-(4-(2-methacryloxyethoxy)phenyl)propane] and BIS-PMA [2,2-bis-(4-(3-methacryloxypropoxy)phenyl)propane]. Increasing interest in the radiaton cure of coatings and printing inks have focused attention on these substances and on epoxy diacrylates as radiation-curable resins. The sensitizing capacity of the different acrylates based on bisphenol A or epoxy resin have been investigated with the guinea pig maximization test. The pattern of simultaneous reactivity of the compounds was also studied. Epoxy diacrylate [2,2-bis-(4-(2-hydroxy-3-acryloxy-propoxy)phenyl)propane], BIS-EMA and BIS-MA are shown to be strong sensitizers, while the linear fraction of BIS-GMA and its isomers and BIS-PMA have none or a low sensitizing capacity. The impurities in the BIS-GMA and BIS-MA batches seem to have high allergenic potential. These results stress the importance of a pure substance when discussing allergenicity and cross reactions.

Acrylates↗
PubMed1984

In vivo and in vitro testing of gloves for protection against UV-curable acrylate resin systems.

In vitro data demonstrated that the permeation of a UV-curable urethane acrylate resin system through glove materials was greatest for latex and neoprene gloves and less for two nitrile gloves. Permeation in vitro for the resin system took longer than 480 min. Individual components of the resin permeated faster when tested separately than when in the formulated system. In vivo 48-h patch test data suggested that neither nitrile glove would be adequate for worker protection, but the in vivo test exaggerated the duration of contact between resin, glove, and skin. Both nitrile gloves provide adequate protection under use conditions, provided the gloves were not re-used within 8 h.

Acrylates↗
PubMed1988

Occupational allergic contact dermatitis from anaerobic acrylic sealants.

Anaerobic sealants are acrylates that polymerize in the absence of oxygen. They are used principally in the engineering and electronic industries. Their use can cause occupational dermatitis in the workers who handle them. In this work, we report our experience with 6 patients who presented with allergic contact dermatitis to these sealants.

Acrylates↗
PubMed1995

Rapid increase in skin problems among dental technician trainees working with acrylates.

A panel of trainees at The Danish School of Dental Technicians was asked to fill in questionnaires 2X a year, to elucidate whether the prevalence of skin problems on their hands increased during the study and to compare the results to the general population. At the beginning of the study, trainees had a prevalence of skin problems not statistically significantly different from that in the general population. 8 months later, an increase of 23% in the prevalence was observed. Compared to the general population the standardized prevalence ratio (SPR) increased to 4.78, and compared to dental technicians at work, an SPR of 0.71 was found after 1 year of study. Very few trainees experienced relief in symptoms during the 1st year of study (5%), whereas 33% developed worse symptoms. The results demonstrate that trainees shortly after beginning their education have the same very high magnitude of skin problems as dental technicians at work. Trainees were exposed to acrylates more extensively than dental technicians. It is far from acceptable that this educational experience involves such a great risk to individuals with no experience or knowledge of the hazards of their occupational environment. Preventive actions are called for, e.g., increased use of encapsulated systems, use of gloves with a well documented protective effect and mandatory courses on the hazardous effects of dental materials.

Acrylates↗
PubMed1990

A method of determining residual monomer in acrylic resin using methyl ethyl ketone.

An improved method of extraction of residual monomer from acrylic resin has been described for determination of the concentration of residual monomer by gas chromatography. Four kinds of organic solvent selected according to their physicochemical properties (methanol, N,N-dimethylformamide, ethyl acetate and methyl ethyl ketone) were tested for their capacity to extract residual monomer at varying temperatures and time periods. Extraction with methyl ethyl ketone at 4 degrees C was found to be the most effective. The method is simpler and more effective than others reported so far, and therefore seems to be suitable for clinical laboratory use.

Acetates↗
PubMed1992

Acrylic resins reinforced with woven highly drawn linear polyethylene fibres. 2. Water sorption and clinical trials.

The results reported in this paper are part of a continuing study of the reinforcement of acrylic denture base resins with highly drawn linear polyethylene fibres. Water sorption is significantly reduced by incorporation of these fibres, even though the water diffusion processes as such remain broadly unaffected. Clinical trials are encouraging and the reinforced dentures have been well accepted by all the patients.

Acrylic Resins↗
PubMed1993

Acrylic resins reinforced with woven highly drawn linear polyethylene fibres. 3. Mechanical properties and further aspects of denture construction.

Previous work has established the feasibility of producing acrylic denture bases reinforced with layers of highly drawn linear polyethylene fibres in a woven form. This paper reports on the mechanical properties of the system, including the effect of water conditioning. It is confirmed that substantial improvements in impact strength can be obtained by the incorporation of the polyethylene fibres in woven form. The fibre/resin integration within the dentures has also been studied by optical microscopy. It was found that delamination may occur during some processing stages and steps are suggested to avoid this problem.

Acrylic Resins↗
PubMed1976

The influence of casting solvent composition on structure and permeability of acrylic-methacrylic ester copolymer films.

Decrease in the solvation of polymer by inclusion of ethanol in the acetone casting solution resulted in greater permeability to urea of cast acrylate-methacrylate film. The greater permeability was accompanied particularly by a decrease in pore size and increase in pore number, despite the absence of change in pore area. A decrease in cohesiveness in the film was suggested by the decrease in tortuosity of the pores as seen by scanning electron microscopy; also, water uptake was increased when the film was cast from an ethanolic solution. The results support the view that, in practice, the composition of the solvent, by its effect on microstructure, can affect the function of the film cast from it.

Acetone↗
PubMed1960

Acrylic acid, an "antibiotic" principle in Phaeocystis blooms in antarctic waters.

An acidic algal substance has been isolated and characterized as the sodium salt. Synthetic sodium acrylate possesses chemical and antibacterial properties identical with those of the natural product. This observation identifies the algal substance in the stomach contents of euphausids, the diet of pygoscelid penguins, which inhibits the penguin gastrointestinal microflora.

Acrylates↗
PubMed2006

The course of surface deposits on a hydrophilic acrylic intraocular lens after implantation through a hexagonal cartridge.

AIM: To evaluate the outcome of surface deposits that occurred during implantation of hydrophylic acrylic intraocular lenses (IOLs) through a hexagonal cartridge. METHODS: Surface deposits were observed on the posterior surface of the ACR6D SE IOLs that were injected through a hexagonal cartridge filled with sodium hyaluronate 1%. All the patients were examined 1 day, 1 week, 1 month, 6 months and 1 year postoperatively. The location of the deposits was recorded and photographed. The patients were questioned about blurred vision, glare or halos. RESULTS: Linear or curly deposits were detected on the posterior surface of the IOL in six patients. In four patients, the deposits were peripheral and were observed 1 week postoperatively. In two patients, the deposits were noticed immediately after implantation. In one eye, they were misinterpreted as a crack in the IOL's optic and were left in the eye. In the second patient the deposits were removed immediately after implantation with forceps. The deposits that were left after implantation (five eyes) did not resolve during 1 year of follow-up. None of the eyes developed abnormal inflammatory reaction. In three eyes the best-corrected visual acuity (BCVA) was 6/6. In the other three eyes the BCVA was 6/12. None of the patients experienced any visual disturbance. CONCLUSIONS: Implantation of the ACR6D SE IOL through a hexagonal cartridge can lead to the formation of deposits on the posterior surface of the lens. The deposits do not resolve and may resemble a crack in the IOL. The deposits left on the IOL had no clinical relevance in our patients.

Acrylic Resins↗
PubMed2004

Water-dispersed lamellar phases of symmetric poly(styrene)-block-poly(acrylic acid) diblock copolymers: model systems for flat dense polyelectrolyte brushes.

We investigate the static properties of a water-dispersed lamellar ( L) phase formed in the melt state with a nearly symmetric poly(styrene)-block-poly(acrylic acid) (PS- b-PAA) diblock copolymer. The PAA brush is considered as a model flat polyelectrolyte ( PE) brush of controlled surface density. Thanks to small-angle X-ray scattering, its behavior in water is studied as a function of (i) its ionization, through the pH of the dispersions which is increased by an addition of a known amount of a base, i.e. sodium hydroxyde NaOH, and (ii) in the presence of a monovalent salt, i.e. sodium chloride NaCl, of concentration C(S). At low pH, we find that the brush effectively behaves as a neutral brush. At high pH, the brush is in the so-called "osmotic regime", in which all sodium counterions are trapped within the brush volume and stretch the chains via an osmotic effect. The properties of such a brush in the presence of a monovalent salt, confirm this result, showing a C(S)(-1/3) dependence in the brush height L(O), in agreement with mean-field predictions. The L(O)- C(S) profiles at different ionizations give access to the actual brush internal charge fraction f. The results are found to be in very good quantitative agreement with experimental measures found in the literature, and can be completely and quantitatively described by Oosawa's approach to counterion condensation in a semi-dilute to concentrated solution of charged, rod-like chains.

Acrylic Resins↗