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PubMed2005

Conversion of a removable partial denture to a transitional complete denture: a clinical report.

A procedure is described for conversion of an existing removable partial denture into a complete denture using autopolymerizing tooth-colored acrylic resin, acrylic resin denture repair material, and a clear matrix template. The shape, color, and position of the lost natural teeth may be duplicated in the transitional denture, minimizing the psychological concerns of the patient regarding esthetics and social impact. Because the patient is never without teeth, an appropriate healing time can occur before fabrication of the definitive prosthesis.

Dental Prosthesis Design↗
PubMed1997

On the three-point flexural tests of dental polymeric resins.

Currently acrylic resins are commonly employed in many medical applications, especially for the fabrication of long span provisional restorations in dentistry and bone cement in orthopedics. On of the major problems associated with the conventional type of acrylic resins is their unsatisfactory mechanical properties. Among many attempts to strengthen acrylic resins, it has been demonstrated that they can be strengthened through the addition of reinforcement(s) as structural components of different size, shape and chemical composition, dispersed in the acrylic matrix, thus forming a composite structure. In the course of studies to strengthen dental polymeric resins by admixing various metallic oxide particles, PMMA-, PEMA-, and PIMA-based resins were reinforced by 2 vol.% added alumina, magnesia, zirconia, and silica powders. It was found that PMMA admixed with 2 vol.% zirconia exhibited the best improvement of mechanical properties (breaking strength, modulus of elasticity, offset yield strength, and fracture toughness as well). All tests were conducted under three-point bending. It was also found that the breaking strength based on the original sample dimension was, at most 20% less than those based on the final sample dimension. Moreover, this discrepancy was independent of the type of tested material, but dependent on the sample's modulus of elasticity.

Analysis of Variance↗
PubMed2005

Clinical evaluation of interocclusal recording materials in bilateral free end cases.

Five combinations of materials commonly used for intermaxillary records in cases of bilateral free end saddle were evaluated: acrylic resin base + wax; acrylic resin base + wax + ZOE paste; acrylic resin base + wax + Duralay resin; condensation silicone; and acrylic resin plate + irreversible hydrocolloid. The materials were evaluated by measuring the vertical distance between pairs of reference points located on the bases of the upper and lower articulated casts. The measurements obtained by manual articulation of the casts were used as the standards to which the measurements obtained with the recording materials were compared. ANOVA revealed significant differences among the materials and the Tukey's test showed that condensation silicone differed significantly (p<0.05) from the acrylic resin + wax combination, while no significant differences (p>0.05) were observed among the remaining materials. The condensation silicone presented the greatest differences from the measurements obtained by manual articulation of the casts whereas the acrylic resin base + wax combination presented the least differences. Based on the findings of this study, the following scale of fidelity can be settled from best to worst: acrylic resin base + wax; acrylic resin plate + alginate; acrylic resin base + wax + ZOE; acrylic resin base + wax + Duralay; and condensation silicone.

Acrylic Resins↗
PubMed2002

The effect of photo-activated glazes on the microhardness of acrylic baseplate resins.

OBJECTIVE: A comparative investigation of acrylic denture base surface microhardness, induced through glazing with different photo-activated liquids. MATERIALS AND METHODS: Thermopolymerized acrylic resin Paladon 65 (Kulzer) was used for this study. The samples were mechanically thinned by silicon carbide grinding papers and finally, mechanically polished by alumina pastes. The samples were then glazed with Palaseal, Plaquit and Lightplast-Lack photo-activated liquids. Microhardness tests were carried out via a Zeiss optical microscope equipped with an Anton Paar microhardness tester fitted with a Knoop indenter. RESULTS: Microhardness testing performed on surfaces glazed by Plaquit, Lightplast-Lack, and Palaseal photo-activated liquids showed enhanced microhardness values compared to the mechanically polished acrylic resin denture base material. CONCLUSIONS: Comparative microhardness tests performed on acrylic base resin treated with photo-activated acrylic glazes showed that all increases the surface microhardness. The enhancement of surface microhardness of acrylic denture bases suggests that they are likely to resist wear during service.

Acrylic Resins↗
PubMed2000

Effectiveness of metal surface treatments in controlling microleakage of the acrylic resin-metal framework interface.

STATEMENT OF PROBLEM: Microleakage at the junction between the metal alloy and acrylic resin in a removable partial denture may result in discoloration, fluid percolation, and acrylic resin deterioration. The junction between a metal alloy and acrylic resin is an area of clinical concern. Failure of a removable partial denture may be linked to this interface. Enhancing resistance to microleakage at this interface may improve the long-term union between the 2 materials. PURPOSE: This investigation was designed to determine the effects of various metal surface treatment protocols on microleakage and bond strength between the metal alloy and acrylic resin used in the fabrication of a removable partial denture. MATERIAL AND METHODS: Ninety-six nickel-chromium-beryllium alloy specimens were randomly divided into 8 groups. After adaptation of baseplate wax, each specimen was invested. Subsequent to wax removal, each specimen was divided into a control half and an experimental half. Air abrasion, tinplating/oxidation, and silanation were evaluated individually and in all combinations. Heat-polymerized acrylic resin was processed against all specimens before storage in distilled water at 37 degrees C for 72 hours. Each specimen then was thermocycled in distilled water (3000 cycles) before immersion in sodium fluorescein dye for 24 hours. Counting grids that exhibited dye penetration under ultraviolet light exposure allowed assessment of microleakage. RESULTS: Air abrasion resulted in a significant decrease in microleakage when used individually and in all combinations (P<0.05). All experimental combinations that did not involve air abrasion demonstrated no significant reduction in measured microleakage between the experimental and control sides. Tukey's pair-wise comparison of the difference in the mean number of squares exhibiting microleakage between the control and treated sites for each experimental group revealed a significant difference, based on the involvement of air abrasion. Groups involving air abrasion did not differ significantly from each other (P<0.05). In addition, no significant difference was detected between groups not involving air abrasion (P<0.05). CONCLUSION: Air abrasion, alone and in combination with tinplating/oxidation and with silanation, resulted in a significant reduction in microleakage between the metal alloy and acrylic resin.

Acrylic Resins↗
PubMed2006

A comparison of two solder registration materials: a three-dimensional analysis.

STATEMENT OF PROBLEM: Use of a segmental indexing/soldering approach for assembly of complete arch implant frameworks has been advocated by some clinicians to achieve a passively fitting framework. To the authors' knowledge, a mathematical assessment using a 3-dimensional (3-D) distortion analysis has not been performed comparing segmental framework assembly to reassembly of 1-piece complete arch frameworks that required sectioning, indexing, and soldering. PURPOSE: The present study compared the use of 2 indexing materials, autopolymerizing acrylic resin and light-polymerized composite resin, for use in solder registration of complete-arch implant frameworks using 3 framework/indexing material combinations: gold/light-polymerized composite resin, silver palladium/autopolymerizing acrylic resin, and silver palladium/light-polymerized composite resin. MATERIAL AND METHODS: Five frameworks for each alloy/index combination were fabricated, for a total of 15 frameworks. Each framework was fitted to 5 implant abutments. Measurements were made of the initial gold cylinder/abutment positions for each of the 5 sites for the 15 frameworks. The 3-D spatial orientation of each gold cylinder/abutment was calculated prior to the gold cylinders being incorporated into the framework casting and served as the control against which all measurements were compared. After the indexing/soldering procedures, the 3-D spatial orientations of the cylinders were measured, first as 2- and 3-unit solder assembled framework segments and, finally, for complete-arch frameworks. These measurements were recorded in micrometers for linear distortions and degrees for angular distortions using a coordinate measurement machine (CMM). These data were compared and statistically assessed using a 1-way analysis of variance (ANOVA). A Student-Newman-Keuls test was used to determine significance between cylinders within each indexing combination. A repeated-measures ANOVA and a Student-Newman-Keuls test were used to determine significance between alloy/index group and cylinders for each of the measurement variables with statistical significance at alpha=.05 for all statistical analyses. RESULTS: Mean differences and SDs of total linear change for all groups found dR (total linear change) to be 33.56 +/- 27.70 mum for gold/light-polymerized composite resin, 34.87 +/- 27.99 mum for silver palladium/autopolymerizing acrylic resin, and 31.56 +/- 24.37 mum for silver palladium/light-polymerized composite resin. Total angular change, dtheta(R), was calculated to be 0.47 +/- 0.13 degrees for gold/light-polymerized composite resin, 0.46 +/- 0.17 degrees for silver palladium/autopolymerizing acrylic resin, and 0.52 +/- 0.15 degrees for silver palladium/light-polymerizing composite resin. CONCLUSIONS: No significant differences were found between alloy/index combinations, except for the measured variable dtheta(y), angular change about the Y axis.

Acrylic Resins↗
PubMed1979

Adhesion between copper-plated acrylic tray resin and a polysulfide rubber impression material.

The method of copper plating on acrylic resin was developed, and the bond strength to polysulfide rubber was measured in comparison with that of the adhesive coating. The bond strength with copper plating was greater than with adhesive coating. The specimens with adhesive coating failed due to a rupture occurring at the elastomer-adhesive interface, while those with copper plating had cohesive-adhesive failure. The method of copper plating on acrylic resin improved the adhesion between the polysulfide rubber and the custom-built acrylic resin tray.

Acrylic Resins↗
PubMed1982

The surface finish of the new microfill restorative materials. A scanning electron microscope study.

Surface smoothness is an important requirement for restorative materials. Recently, restorative materials claimed to be inherently smooth in surface characteristics have been developed. Matrix-formed and finished surfaces of five new microfill restorative materials were compared with two composite resins, an acrylic resin and a silicate cement by means of scanning electron microscopy. The results of this investigation indicated that the matrix-formed surfaces of all the restorative materials studied were not altogether perfect. Polishing using sandpaper and cuttlefish discs produced a very smooth surface finish in the new microfill restorative materials, Estic microfill, Estilux microfill, Isopast, Isolux and Silar which was comparable to that of the acrylic resin, Sevriton. The composite resins, Adaptic and Estilux exhibited the worst surface finish and the silicate cement, Bio-trey was intermediate. Finishing, using other finer polishing devices on four of the materials produced a further improvement in the surface finish.

Acrylic Resins↗
PubMedDate not supplied

The effect of veneering materials on stress distribution in implant-supported fixed prosthetic restorations.

In this study, the effect of various materials used in fabricating superstructures for implant-retained fixed partial dentures on stress distribution around implant tissues was investigated. Five different mathematical models consisting of 11,361 nodes and 54,598 elements were constructed to study porcelain, gold alloy, composite resin, reinforced composite resin, and acrylic resin veneering materials using the 3-dimensional finite element analysis method. MARC K7.2/Mentat 3.2 software was used for the analysis. Reference points were determined on the cortical bone, where perpendicular, oblique, and horizontal forces were applied. Stress values created by oblique and horizontal forces appeared to be higher than those created by vertical forces. Stress seemed to be concentrated at the cortical bone around the cervical region of the implant. Gold alloy and porcelain produced the highest stress values in this region. Stresses created by acrylic resin and reinforced composite resin were 25% and 15% less, respectively, than porcelain or gold alloy. Porcelain and gold alloy produced stress values at the lingual implant sites that reached the ultimate strength values of the cortical bone.

Acrylic Resins↗
PubMed2006

Adsorption of branched alkylbenzene sulfonate onto styrene and acrylic ester resins.

In this study, a series of acrylic ester resins were prepared and characterized. The adsorption behaviors of sodium 6-dodecyl benzenesulfonate (6-NaDBS) on styrene resin XAD-4 and acrylic ester resins have been studied. As compared to commercial acrylic ester resins Amberlite XAD-7 and Diaion HP2MG, YWB-38, one of the as-prepared resins, exhibits better adsorption properties toward 6-NaDBS. The experimental equilibrium data were fitted to the Langmuir and double-Langmuir models. The two models provide very good fit for all acrylic ester resins over the temperature range studied, whereas fitted results for styrene resin XAD-4 are less accurate. The investigation indicates that the adsorbate molecules are directly adsorbed on acrylic ester resins as a bi-layer, while the molecules are adsorbed on XAD-4 as monolayer formation followed by the establishment of bi-layer. Adsorption kinetics and elution processes were also investigated for further exploring the adsorption behavior and mechanism on styrene resin XAD-4 and YWB-38.

Acrylates↗
PubMed1990

Chromogranin A as a marker of neuroendocrine histogenesis of tumours: an immunoelectron microscopic study with considerations about the influence of fixation and embedding media on immunolabelling.

The ultrastructural localization of chromogranin A (Chr A) was studied in eleven neoplasias of the diffuse neuroendocrine system (3 pancreatic islet-cell tumours, 1 medullary carcinoma of the thyroid, 1 large bowel and 1 small bowel carcinoid tumours, 2 carcinoid tumours of the lung, 1 adenoma of the parathyroid gland, 2 pheochromocytomas of the adrenal gland). On account of the great influence of the technical treatment of the samples on the immunolocalization of Chr A, the effect of the following variables was studied in a case of pheochromocytoma: fixation in glutaraldehyde versus paraformaldehyde, postfixation in osmium tetroxide versus omission, embedding in epoxy resin versus acrylic resin. The method of choice for the better preservation of the antigenic character of the tissue was found to be fixation in 4% paraformaldehyde, omission of osmium postfixation and embedding in LRWhite acrylic resin; by this procedure we were able to find Chr A in the neurosecretory granules of all the studied cases, using three commercially available antibodies directed against Chr A. These findings further confirm that Chr A is a reliable marker for the study of neuroendocrine neoplasias by electron microscopy.

Adrenal Gland Neoplasms↗
PubMed2004

The in vitro effect of pulpal pressure and luting agent on tensile bond strength of complete cast crowns.

STATEMENT OF PROBLEM: The degree to which pulpal pressure may affect bond strength of complete cast crowns is unknown. PURPOSE: The aim of this in vitro study was to evaluate the effect of simulated pulpal pressure on the tensile bond strength of complete cast crowns luted with 2 different cements. MATERIAL AND METHODS: Forty-eight human mandibular canine teeth were cleaned and stored in saline solution. The crowns were prepared by 1 investigator, and standardization of the preparation was accomplished by fixing a dental handpiece in a parallelometer. Uniform grooves, 0.5 mm in depth, were prepared with burs with depth guides. The complete crowns were prepared with a 0.5-mm shoulder margin. Teeth were randomly divided into 2 groups of 24 teeth each (Group I and Group II). In Group I, bonding and tensile test procedures of the teeth were carried out under simulated pulpal pressure (15 cm of saline solution). In Group II, simulated pulpal pressure was not used. The roots were removed 1 mm below the cementoenamel junction to create direct communication with the pulp chamber. The remaining pulpal tissues were carefully removed, and crowns were embedded in acrylic resin. The acrylic resin was then penetrated by a stainless steel tube that connected the pulp chamber and the barrel of a disposable plastic 5-ml syringe. The pulp chambers were filled with physiological saline solution under elevated pressure to locate the area of greatest permeability on the dentinal surface. Crowns were cast (Co-Cr alloy) with a 20-mm bar to allow testing of the bond strength. Each of the 2 groups were further divided into 2 luting cement groups of 12 each (Group I, A and B, and Group II, A and B). Group IA/IIA and Group IB/IIB specimens were luted with a polycarboxylate luting cement (Poly-F Plus) and an adhesive luting cement (Superbond C&B), respectively. After storage in distilled water for 24 hours, all specimens were subjected to a tensile bond test in a universal testing machine at a crosshead speed of 0.5 mm/min until failure. The maximum load at fracture (Newton) was recorded. The results were then evaluated with 2-way analysis of variance and Tukey's honestly significant difference tests (alpha=.05). RESULTS: Simulated pulpal pressure increased the bond strength of cast complete crowns cemented with an adhesive luting agent (P=.01). No significant difference was found in the bond strength of complete cast crowns cemented with polycarboxylate cement with or without pulpal pressure. Superbond C&B adhesive luting agent showed significantly higher bond strength values for Group I (388.9+/-32.7) and Group II (300.9+/-66.8), when compared with polycarboxylate cement for Group I (221.3+/-17.3) and Group II (186.8+/-38.5) (P=.001). CONCLUSION: Simulated pulpal pressure had a positive effect on the retention of complete cast crowns when cemented with Superbond C&B adhesive luting agent. Superbond C&B significantly increased the retention of crowns in either the presence or absence of pulpal pressure.

Analysis of Variance↗
PubMedDate not supplied

Shock absorbability and hardness of commercially available denture teeth.

PURPOSE: Composite resin teeth are more widely used than porcelain or acrylic resin teeth in the fabrication of removable dentures because of their high fracture toughness and high abrasion resistance. The purpose of this study was to evaluate the shock absorbability of commercially available artificial posterior teeth by the free drop-ball test with an accelerometer and to evaluate the Vickers hardness at the surface. MATERIALS AND METHODS: The tested artificial teeth included seven composite resin teeth, one acrylic resin tooth, and one porcelain tooth. Specimens were tested 50 hours after immersion in distilled water at 37 degrees C. The impact value and Vickers hardness were measured. A one-way analysis of variance was used to analyzed the data (P = .05). RESULTS: The composite resin teeth showed an intermediate impact value between that of the acrylic resin tooth and the porcelain tooth. Among the artificial teeth investigated, the porcelain tooth showed the highest impact value. A significant difference in the impact value was observed between the porcelain tooth and the composite resin and acrylic resin teeth. However, no significant difference was observed among the composite resin teeth tested. A significant correlation was found between the impact values and the Vickers hardness of the artificial teeth. CONCLUSION: The present findings suggest that composite resin teeth and acrylic resin teeth have a higher shock absorbability than porcelain teeth.

Absorption↗
PubMed1992

Effect of repair surface design, repair material, and processing method on the transverse strength of repaired acrylic denture resin.

The transverse strengths of blocks of denture base acrylic resin repaired with autopolymerizing monomer and polymer and autopolymerizing monomer and heat-cured polymer were measured with a three-point bending test. Three repair joints were studied: butt, round, and 45-degree bevel. Three processing methods were used: bench cure, hydroflask with hot water for 10 minutes, and hydroflask with hot water for 30 minutes. The strengths of repairs made with round and 45-degree bevel joint designs were similar and significantly greater than those with a butt joint design. The strengths of repairs processed in a hydroflask for 10 minutes and 30 minutes were similar and significantly greater than those cured on the bench top. There was no difference in the strength of repairs made with autopolymerizing monomer and polymer and autopolymerizing monomer and heat-cured polymer.

Acrylic Resins↗
PubMed1998

A comparison between the wear resistance of three types of denture resin to three different dentifrices.

This study compares the abrasive effects of three dentifrices on three different denture base resins, a heat cured acrylic resin, a self cured acrylic resin and a light activated urethane dimethacrylate-based resin. Specimens of the resins were subjected to a regimen of mechanical brushing using measured amounts of paste on standard toothbrushes driven by a reciprocating device. The apparent wear of each specimen was assessed qualitatively using scanning electron microscopy and quantitatively using profilometry and reflex microscopy. The study showed that cleaning pastes play a significant role in the wear of conventional acrylic resins, the relative abrasivity of the dentifrices being substrate related. However, wear was less evident on the light activated urethane dimethacrylate resin. Brushing with water alone produced no detectable wear on any of the specimens.

Acrylic Resins↗