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PubMed2004

Effects of water storage of E-glass fiber reinforced denture base polymers on residual methyl methacrylate content.

This study investigated the effect of water storage on residual methyl methacrylate (MMA) content of continuous E-glass fiber (Wetrotex International) reinforced denture base polymers. Heat-polymerization (short- and long-term boiling and conventional curing cycle using Meliodent), autopolymerization (processed in air at room temperature and in water at 60 degrees C with the use of Meliodent Rapid Repair), and microwave-polymerization (3 min at 500 W with the use of Acron MC) were employed. The residual MMA contents of 120 specimens were analyzed by high-performance liquid chromatography at deflasking (control) and after water (37 degrees C) storage of 1 day, 1 week, and 1 month. Bonferroni's pairwise comparison test was used for statistical analysis. Significant reduction were determined only in the long-term terminal boiled heat-polymerized test group at the end of 1 day (p < 0.01), 1 week (p < 0.05) and also 1 month of water storage (p < 0.01). Significant reduction in autopolymerized test groups started even after 1 week of water storage (p < 0.05). Microwave-polymerized test groups did not show a significant residual MMA reduction in all time intervals (p > 0.05). The polymerization methods and cycles applied to the glass fiber reinforced denture base polymers influence both the content and the reduction of residual MMA after water storage.

Acrylic Resins↗
PubMed1992

Reinforcement of complete denture bases with continuous high performance polyethylene fibers.

Clinical literature details the causes for deformation and failure of acrylic resin complete denture bases. These findings are used to select patterns of high performance polyethylene fiber reinforcement that would best use the properties of the material and improve the mechanical behavior of the prostheses. A technique is described for making reinforced maxillary and mandibular bases with the fibers placed as suggested by the analysis. Microscopic observations of cross sections of reinforced bases revealed good fiber/resin integration and polish.

Composite Resins↗
PubMed1992

The effect of interface adhesion, water immersion and anatomical notches on the mechanical properties of denture base resins reinforced with continuous high performance polyethylene fibres.

Previous work has presented a study of the mechanical properties of denture base resins reinforced with a new type of high performance fibre. It is now shown that the substantial improvements demonstrated in those composites remain largely unaffected by a watery environment, anatomical notches, moulding pressure and other factors of denture construction. The understanding of the reinforced resins is here complemented with a detailed study of the interface strength, taking into account the various couplings occurring within the system.

Acrylic Resins↗
PubMed2005

Effect of microwave treatments on dimensional accuracy of maxillary acrylic resin denture base.

Microwave energy has been used as an alternative method for disinfection and sterilization of dental prostheses. This study evaluated the influence of microwave treatment on dimensional accuracy along the posterior palatal border of maxillary acrylic resin denture bases processed by water-bath curing. Thirty maxillary acrylic bases (3-mm-thick) were made on cast models with Clássico acrylic resin using routine technique. After polymerization and cooling, the sets were deflasked and the bases were stored in water for 30 days. Thereafter, the specimens were assigned to 3 groups (n=10), as follows: group I (control) was not submitted to any disinfection cycle; group II was submitted to microwave disinfection for 3 min at 500 W; and in group III microwaving was done for 10 min at 604 W. The acrylic bases were fixed on their respective casts with instant adhesive (Super Bonder) and the base/cast sets were sectioned transversally in the posterior palatal zone. The existence of gaps between the casts and acrylic bases was assessed using a profile projector at 5 points. No statistically significant differences were observed between the control group and group II. However, group III differed statistically from the others (p<0.05). Treatment in microwave oven at 604 W for 10 min produced the greatest discrepancies in the adaptation of maxillary acrylic resin denture bases to the stone casts.

Acrylic Resins↗
PubMed1996

Composition and effect of denture base resin surface primers for reline acrylic resins.

This study investigated the effect of resin surface primers for reline acrylic resins on the surface texture of denture base resin by use of scanning electron microscopy. Analysis of the composition of the primers was also conducted. The composition of the primers was classified into three groups: solvent based, monomer based, and monomer and polymer based. Scanning electron microscopic observation revealed various effects of the primers on the denture base resin surface, which depended on the composition of primers.

Acetone↗
PubMedDate not supplied

Construction of an interim obturator using a microwave-polymerized denture base resin.

This article describes a technique for fabricating an interim obturator for maxillectomy patients using a microwave-polymerized denture base resin. The use of microwave irradiation to polymerize this type of resin reduces the time required to fabricate interim obturators and results in prostheses comparable in physical properties and superior in dimensional accuracy to prostheses made with conventional heat-polymerized acrylic denture base resin. The technique is simple and time efficient, and it does not require any special or elaborate laboratory equipment.

Acrylic Resins↗
PubMed1999

Microwave polymerization of denture base materials. A comparative study.

A comparison of some properties of denture base polymers processed by both microwave and water-bath methods demonstrated that, in general, water-bath polymerization with a long curing cycle and a 3-h terminal boil produced superior properties. Although these two methods were inter-changeable for the conventionally heat cured material, consistently superior results were produced by following the method recommended by the manufacturer. Microwaving of autopolymerizing resin improved mechanical properties and reduced residual monomer. The clinical significance of these results remains to be tested.

Chromatography, Gas↗
PubMed1993

Flow injection analysis of formaldehyde leached from denture-base acrylic resins.

Formaldehyde is responsible for allergic inflammation in acrylic denture wearers and the quantitation of formaldehyde is necessary to study its leaching from denture-base materials. Flow injection analysis was developed to quantify the formaldehyde leached from acrylic resins. Different resins were immersed in aqueous solvents at 37 degrees C and the immersion solutions were directly injected into the flow system, in which formaldehyde was converted on-line to a fluorescent derivative and its fluorescence was detected. Under the optimized conditions, the leached formaldehyde could be quantified in a short time (within 4 min) with high sensitivity (pmol levels per injection) and high specificity (no fluorescent response to the other leachables). In leaching experiments, significant amounts of formaldehyde were leached from autopolymerized resins, but not from heat- and microwave-polymerized resins.

Acrylic Resins↗
PubMed1989

[Influences of remelting on physical properties of denture base metal alloys].

This research was designed in order to evaluate the mechanical properties, such as tensile strength, compressive strength, surface hardness and the elongation and reduction percentages of the length, of the metal specimens prepared from first, second and third generation castings of a denture base metal. The results revealed only a proportional decrease on surface hardnesses of the specimens casted from first, second and third meltings. While the other properties of all specimens had showed no significant differences between themselves, it was concluded that the denture base metals could be melted and used again at least three times.

Dental Alloys↗
PubMed1989

[Development of a light curing denture base resin].

We developed the light cured direct relining material and used it clinically. In this study, a partial change in its components was made to improve both its strength and manipulability with the aim of using it as a denture base material. The physical properties of the new material, bonding to resin teeth, fit, as well as procedure were discussed. As for physical properties, the bending strength of the new material was increased by improving its organic filler, it becoming comparable to that of heat curing resin. The water absorption of the new material was the lowest of compared materials. The bonding strength of this material to resin teeth was increased by treatment with a light cured bonding agent and the fit of the new material to a test model was comparable to that of heat curing resin. Thus, the new material seems to be quite clinically effective as a denture base resin.

Composite Resins↗
PubMed2002

An investigation into the transverse and impact strength of "high strength" denture base acrylic resins.

A range of materials, often marketed as high strength resins is available. These materials are often expensive options to conventional heat-cured acrylic resin. The aim of this study was to investigate transverse and impact strength of five "high strength" acrylic resin denture base materials. A conventional heat-cured acrylic resin was used as a control. Specimens were prepared as specified in the International Standard Organization (ISO 1567: 1988) and British standards for the Testing of Denture Base Resins (BS 2487: 1989) and the British Standard Specification for Orthodontic resins (BS 6747: 1987) for transverse bend and impact testing. The impact strength was measured using a Zwick pendulum impact tester and the transverse bend strength measured using a Lloyds Instruments testing machine. The results showed that Metrocryl Hi, Luctitone 199 and N.D.S. Hi all had an impact strength which was significantly higher than the control. For the modulus of rupture, there was a significant difference between Sledgehammer and the other groups. There was no significant difference between the other groups and the control. For the modulus of elasticity, Sledgehammer produced the highest value followed by the control. The remaining four materials had a modulus of elasticity less than the control.

Acrylic Resins↗
PubMed1990

Effect of retention grooves on tooth-denture base bond.

The bond strength of acrylic resin teeth with and without retention grooves processed onto standard and high-impact denture base resin was investigated. A shear compressive force was applied at an angle of 130 degrees to the lingual surface of the teeth until fracture occurred. The values were subjected to a two-way analysis of variance with repeated measures. Canine teeth bonded better than central or lateral incisors (p less than 0.01). A significantly greater force was required to fracture teeth from high-impact resin (p less than 0.01). Vertical retention grooves enhanced bond strength (p less than 0.01).

Acrylic Resins↗
PubMed1989

Adhesion characteristics of visible light-cured denture base material bonded to resilient lining materials.

This investigation compared the adhesion of resilient lining materials to Triad visible light-cured denture base material. The liners used were Tru-Soft, Molloplast-B, and Esscheem. Cylindrical samples were made from Triad VLC material and were sectioned to produce a flat bonding surface, which was roughened and treated with Triad bonding agent. Resilient liners 3 mm thick were processed according to the manufacturer's recommendations and samples were stored at 37 degrees +/- 1 degree C in distilled water for 48 hours and 30 days. Tensile bond strength was determined by using an Instron Universal testing machine for the three resilient liners.

Acrylic Resins↗
PubMed1989

[Development of a new system for measuring the mean film thickness of the white silicone on the fitness test of the denture base].

A new system is developed for measuring the mean film thickness of the white silicone on the fitness test of the denture base. This system is based on analysing the B/W film density replaced from the thickness of the silicone. The detective feature of this system is as follows: 1. An adequate correlation between the logarithm of the thickness of the white silicone and the logarithm of the B/W film density was estimated from the results of experimental values. 2. With use of the computer assembled into the system, it is capable to quickly process data. 3. Compared with the conventional method, the proper suggestion was gotten to the clinical data. 4. The system is available to use of investigating the bite force and the mean film thickness of the white silicone.

Bite Force↗
PubMed1988

Bond strength of 4-META acrylic resin denture base to cobalt chromium alloy.

This study was designed to compare the bond strength of a conventional poly(methyl methacrylate) acrylic resin denture base (Lucitone 199) with a recently developed acrylic resin base containing 4-META (Meta-Dent) to CoCr metal alloy by using various designs representative of clinical situations. The mechanical bond strength of Lucitone 199 resin was compared with the chemical and combination chemical and mechanical bond strength of Meta-Dent resin. The following conclusions may be extrapolated from the results. 1. The highest bond strength was observed between Meta-Dent resin and the plain flat metal plate. 2. The second highest bond strength was observed between Meta-Dent resin and the flat metal plate with two posts. 3. The lowest bond strengths were observed between Meta-Dent resin and the samples containing mesh retentive mechanisms. 4. The mean bond strength of Lucitone 199 resin was highest for the flat metal plate with two posts, followed by the large mesh. Bond strength with the small-mesh samples was lowest. These differences were not statistically significant. 5. The mean bond strengths of Meta-Dent resin to flat metal plates with or without posts was significantly higher than any of the Lucitone 199 resin metal bond strengths, to the 99% confidence level. Additional studies will be necessary to confirm the validity of these conclusions with respect to clinical removable partial dentures. Longitudinal investigations will be required to reveal clinical performance of these resin systems.

Acrylic Resins↗
PubMed2000

Shear bond strength of resin teeth to heat-cured and light-cured denture base resin.

The failure of the bond between acrylic resin teeth and denture base material remains a considerable problem. Previous research has indicated that the introduction of a bonding agent to the tooth-resin interface significantly increased the tensile bond strength. To further investigate this finding, and to complement the earlier study, a shear strength assessment was carried out. Both a commercial and an experimental bonding agent were evaluated for tooth retention when applied to heat-cured and visible light-cured (VLC) resin. A significant increase in shear bond strength was obtained when bonding agents were applied. The experimental cement gave the greatest increase in strength, although the VLC resin failed to achieve the same degree of tooth attachment as the heat-cured resin.

Acrylic Resins↗