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PubMedDate not supplied

The effect of flowable resin composite on microleakage in class V cavities.

This in vitro study investigated the microleakage of flowable resin composite as a restorative material and as a liner (either light cured separately or co-cured with hybrid resin composite) in Class V cavities. A light-cured hybrid resin composite was used as a control. Twenty extracted human premolars were prepared with standardized Class V cavity outlines on the buccal and lingual surfaces. The occlusal margin of the cavities was on enamel and the gingival margin was on dentin. One bottle adhesive system (Single Bond) was used after etching enamel and dentin with 34.5% phosphoric acid for 15 seconds. The cavities were randomly divided into four groups of 10 each and restored according to the manufacturers' instructions: Group I-Hybrid resin composite (Z100); Group II-Flowable resin composite (Filtek Flow); Group III-Flowable resin composite (Filtek Flow)+Hybrid resin composite (Z100); light cured separately; Group IV-Flowable resin composite (Filtek Flow)+Hybrid resin composite (Z100); co-cured. The samples were thermocycled 200 times with a 30-second dwell time. They were then immersed in a 0.5% basic fuchsin solution for 24 hours, sectioned and analyzed by stereomicroscopy. The degree of dye penetration was recorded and analyzed with the Kruskal-Wallis and Mann-Whitney U tests. The results of this study indicate that there was no leakage at the occlusal margin for either restoration. Statistically significant differences were found among the groups at the gingival margin. No statistically significant difference was observed between the occlusal and gingival margins except in Group IV. The combination of flowable resin composite and hybrid composite light cured separately yielded the best result in this study. The most leakage was observed when this combination was co-cured. The resistance to microleakage of flowable resin composite as a restorative material is similar to that of hybrid resin composite.

Acid Etching, Dental↗
PubMed1979

[Mechanical and dimensional properties of thermosetting resins for crown (author's transl)].

The various mechanical and dimensional properties of seven thermosetting methacrylic resins for crown and one heat-curing methacrylic resin as the control were investigated. The obtained results were as follows. 1. The water sorption, namely amount of sorption water and linear expansion by water sorption of hydrophobic poly-bis-MEPP resins were 50 to 70% of that of the control. But hydrophilic poly-EDMA resins indicated the water sorption about 1 to 1.5 times as much as the control. And a poly-UDMA resin was also hydrophilic as poly-EDMA resins, indicated about 1.3 times as much as the control. 2. The properties of poly-bis-MEPP resins were more excellent than that of poly-EDMA resins especially in the wet condition, at least were equal. 3. A poly-UDMA resin contained so-called organic composite fillers, indicated more excellent properties than other resins on hardness, abrasion resistance, linear coefficient of thermal expansion, compressive strength and bending strength in the dry condition. But, in the wet condition, some of these properties of a poly-UDMA resin were approximately equal to those of other resins.

Acrylates↗
PubMed2006

[Rheological study of hard resin for crown and bridge].

PURPOSE: For the purpose of evaluating the flow properties influencing the formativeness of commercial hard resin pastes used in the construction of crowns and bridges, we examined the behaviors of various resin pastes and their temperature dependence during manipulation. METHODS: Five types of hard resins currently in use for the construction of crowns and bridges in the clinical setting, namely, New Meta Color INFIS, Solidex, Ceramage, Gradia, and Estenia C&B, were examined. The components and flow properties of each resin paste were investigated in relation to the dentine and enamel colors. The viscosities of the resin pastes before curing were measured by a cone-plate viscometer. RESULTS: Each resin paste demonstrated a non-Newtonian flow, and the flow curve showed a hysteresis loop, in which the upward and downward curves were different. When the shear stress at the beginning of the holding time of the flow curve (20 degrees C, 25 degrees C, 30 degrees C) of each resin paste was measured, the shear stress at 20 degrees C was found to be significantly higher than that at 25 degrees C and 30 degrees C, and the shear stress at 25 degrees C was found to be significantly higher than that at 30 degrees C. The viscosity was found to be higher at lower temperatures than at higher temperatures. Comparison of the shear stresses at the beginning and at the end of the holding time revealed that the stress at the beginning of the holding time was significantly higher than that at the end of the holding time for all except the Estenia C&B resin paste. CONCLUSIONS: Each of the resin pastes used in the present study showed temperature dependence of its characteristics in the temperature range examined (20-30 degrees C) and thixotropic fluidity. However, the flow characteristics of these resin pastes differed significantly, suggesting that the flow characteristics may affect the manipulation of resin formativeness.

Color↗
PubMed1990

[Visible light cured resin. Change of quantity of remaining double bonds in the surface low conversion layer by FT-IR method].

The quantity of the remaining double bonds (RDB) in polymerized visible light cured resins has been determined. Five trial unfilled resins, eight commercial composite resins and three commercial crown and bridge resins were investigated by Fourier transform infrared spectrophotometer with the liquid-film method. Infrared absorbance was measured before irradiation and at various times after irradiation. The quantity of RDB was determined and the data expressed as percentage of the total amount of double bonds in the unpolymerized resins. The quantity of RDB of five trial unfilled resins decreased linearly corresponding to the logarithmic time after the start of irradiation. The difference in the quantity of RDB at 5 min and decreasing rate of RDB could be seen in accordance with the kind of monomer. Among five trial unfilled resins, one with BMPEPP (BPE-200) used as monomer gave the smallest RDB, and one with 4 PN-(TF)2-(EMA)6 used as monomer gave the largest value. The quantity of RDB in the unfilled resin with Tri-EDMA at 5 min decreased in accordance with the irradiation time, but after 1 month, it showed almost the same value irrespective of the irradiation time. The quantity of RDB of commercial composite resins and crown and bridge resins decreased linearly corresponding to logarithmic time. In all commercial resins, the quantity of RDB became small when the base monomer was Bis-GMA but large when it was UDMA.

Acrylic Resins↗
PubMed2003

A double-blind, multicentre, randomised clinical trial comparing the efficacy and tolerability of aceclofenac with diclofenac resinate in patients with acute low back pain.

The efficacy and tolerability of aceclofenac was compared with diclofenac resinate in a double-blind, multicentre randomised study in patients with acute low back pain suffering from degenerative spinal disorders. The study included 227 patients randomised to receive either aceclofenac 2 x 100 mg daily or diclofenac resinate 2 x 75 mg daily for up to 10 days. The primary objective was to demonstrate the clinical non-inferiority of the analgesic efficacy of aceclofenac compared with diclofenac resinate, as assessed by changes from baseline in the visual analogue scale (0-100 mm) pain score, at rest and at visit 3 (final visit on day's 8-10). Secondary objectives included the time to early cure (resolution of pain) and global assessment of tolerability. Mean change in pain score at rest, and as visit 3, compared with baseline, was 61.6 mm (SD 24.5) for the aceclofenac group ( n = 100) and 57.3 mm (SD 22.8) for the diclofenac resinate group ( n = 105) in the per-protocol population. Similar changes were observed in the intention-to-treat population. Between-group differences of 4.5 mm and 5.5 mm for the per-protocol and intention-to-treat populations, respectively, demonstrated clinical non-inferiority of aceclofenac compared with diclofenac resinate. Furthermore, there was evidence for superiority of aceclofenac over diclofenac resinate in terms of statistical significance, as the one-sided 97.5% confidence interval was above -10 mm and 0 mm. In the intention-to treat population, a total of six aceclofenac-treated patients discontinued their medication owing to early cure, compared with only one patient receiving diclofenac resinate. Seventeen aceclofenac- (14.9%), and 18 diclofenac resinate-treated patients (15.9%) reported at least one adverse event. However, the total number of adverse events reported was lower in patients receiving aceclofenac (22 versus 31 in the diclofenac resinate group). In conclusion, non-inferiority of the analgesic efficacy of aceclofenac compared with diclofenac resinate was demonstrated in patients with localised, uncomplicated acute lumbosacral pain. For the reduction in pain levels from baseline there was also evidence for superiority of aceclofenac compared with diclofenac resinate in terms of statistical significance, although this difference was not considered clinically relevant. The results also showed a trend towards a better safety and tolerability profile of aceclofenac over diclofenac resinate from a clinical point of view.

Acute Disease↗
PubMed2006

Resin composites: strength of the bond to dentin versus mechanical properties.

This study (1) investigated whether the combination of an adhesive system from one manufacturer with a resin composite from the same manufacturer provides superior bonding of the resin composite to dentin compared with the combination of an adhesive system from one manufacturer with a resin composite from another manufacturer, and (2) tested for a possible influence on bond strength of mechanical properties of the resin composite. After application of an adhesive system, a resin composite was bonded to flattened human dentin and tested in shear after 1 week. Five adhesive systems (AdheSE, Adper Prompt L-Pop, Clearfil SE Bond, Optibond Solo Plus, and Xeno III) were tested with each of five resin composites (Tetric Ceram, Filtek Supreme, Clearfil AP-X, Premise, and EsthetX). The mechanical properties flexural strength and flexural modulus were determined by three-point loading. Bond strengths were influenced by the brand of adhesive system (P < 0.0001) and by the brand of resin composite (P < 0.0001), but the combination of an adhesive system from one manufacturer with a resin composite from the same manufacturer did not provide bond strengths that were superior to those obtained when an adhesive system from one manufacturer was combined with a resin composite from another manufacturer. Independent of the brand of resin composite, the adhesive system Clearfil SE Bond mediated the highest bond strength to dentin. For each adhesive system, the resin composite Clearfil AP-X resulted in the highest bond strength to dentin. Significant positive correlations were found between bond strength and flexural strength (P < 0.0026, r = 0.21) and between bond strength and flexural modulus (P < 0.0017, r = 0.22).

Composite Resins↗
PubMed2004

Influence of polymerization mode of dual-polymerized resin direct core foundation systems on bond strengths to bovine dentin.

STATEMENT OF PROBLEM: Little is known about how various polymerization combinations of dual-polymerized adhesives and resin core foundation pastes affect dentin bond strength. PURPOSE: This study examined the influence of different polymerization modes of dual-polymerized resin direct core foundation systems on dentin bond strength using bovine dentin. MATERIAL AND METHODS: Two commercially available dual-polymerized resin direct core foundation systems, Clearfil DC Core and UniFil Core, were studied. Bovine mandibular incisors were mounted in autopolymerizing resin and the facial dentin surfaces were ground wet on 600-grit SiC paper. Dentin surfaces were treated according to manufacturer's recommendations, and dual-polymerized adhesives were applied and dual-polymerized (control) or only chemically polymerized. The core foundation resins were condensed into the mold (4 x 2-mm) and were also either dual-polymerized or only chemically polymerized. Eighty specimens (n=10) were stored in 37 degrees C water for 24 hours, then shear tested at a crosshead speed of 1.0 mm/min in a universal testing machine. Fourier transformation infrared spectroscopy was used to measure the degree of conversion of dual-polymerized resin core foundation pastes with both modes of polymerization. One- and 2-way ANOVA, Tukey HSD tests, and Student t -tests were performed (alpha=.05). RESULTS: The highest mean bond strengths (+/-SD) were obtained when the adhesives and resin pastes were dual-polymerized for both core foundation systems (14.6 +/- 2.1 MPa for Clearfil DC Core, 15.6 +/- 2.2 MPa for UniFil Core). Chemical polymerization of dual-polymerized adhesives and resin pastes resulted in significantly lower bond strength (2.8 +/- 0.6 MPa for Clearfil DC Core, 8.1 +/- 2.2 MPa for UniFil Core) ( P <.001). The degree of conversion for the resin pastes decreased significantly ( P <.05) when only chemical polymerization was employed, from 81.5% to 76.1% for Clearfil DC Core and 86.7% to 81.2% for UniFil Core. CONCLUSION: The data suggests that the dentin bond strengths of the dual-polymerized resin direct core foundation systems are highest when both adhesive and resin core paste are dual polymerized.

Analysis of Variance↗
PubMed2004

New mechanical retention method for resin and gold alloy bonding.

OBJECTIVE: The purpose of this study was to improve adhesion between dental adhesive resins and 14K gold alloy by creating a sponge-like structure on the alloy surface which enhanced mechanical bonding. METHODS: The internal oxidation particles of Cu oxides precipitated on a 14K gold alloy surface after high-temperature oxidation at 800 degrees C in air were removed by pickling with an acid solution to create a sponge-like structure on the alloy surface. A PMMA resin containing 4-META as an adhesive monomer and a self-cured resin without 4-META were used to examine the effects of mechanical and chemical factors on bond strength. A thiophosphate-type metal primer (M-Primer II) was used in combination with 4-META resin to strengthen the chemical bonding of 4-META resin to the porous alloy surface. The surfaces of the alloy specimen treated by oxidation, pickling, and bonding with 4-META resin were analyzed using an electron probe X-ray micro-analyzer. RESULTS: SEM observation showed many resin tags on the resin side of the bond structure after removal of the gold alloy matrix with aqua regia. The bond strength of 4-META resin to the porous alloy surface was 38+/-3 (mean+/-SD) MPa whereas that to a flat alloy surface with the same composition was 19+/-1 MPa. The bond strength of a self-cured resin without 4-META to the porous alloy surface was 24+/-2 MPa. SIGNIFICANCE: A high bond strength was obtained when 4-META resin was bonded to the porous 14K gold alloy surface treated with M-Primer II.

Acrylic Resins↗
PubMed1999

Bonding procedures for intraoral repair of exposed metal with resin composite.

PURPOSE: To determine if tin plating can be recommended for intraoral repair of ceramic veneered cast restorations where metal of unknown composition is exposed by loss of ceramic. This study investigated the effectiveness of surface treatments incorporating tin plating and unfilled resin to enhance the tensile bond strength of a resin composite restorative to three different metal ceramic casting alloys. MATERIALS AND METHODS: Gold-platinum, palladium-tin and nickel-chromium alloys were used to fabricate 120 rods of each alloy, 4 x 15 mm. The end of each rod was ground perpendicular on 600-grit SiC paper and grit blasted with 50-micron alumina. Rods from each alloy were divided into four groups of 30 to receive one of the following treatments before bonding pairs end to end with a visible light-polymerized resin composite (Herculite XRV): 1) direct bonding with the resin composite; 2) tin plating (Micro-Tin) and bonding; 3) application of unfilled resin (Chameleon) and bonding; 4) tin plated, application of unfilled resin and bonding. The bonded samples were stored in distilled water, incubated at 37 degrees C for 24 hours and tested for tensile bond strength at a crosshead speed of 1 mm/min in a Lloyd 1000R machine. The mode of failure was examined using a stereo zoom microscope. RESULTS: A statistically significant increase in tensile bond strength was demonstrated between the control (group 1) and both the gold and palladium alloy treated with tin plating and unfilled resin (group 4). Tin plating, or tin plating with the application of unfilled resin had no statistically significant effect on the tensile bond strength of resin composite to the nickel-chromium alloy. CONCLUSION: The results demonstrate that tin plating, in conjunction with the application of a low-viscosity unfilled resin, optimizes the tensile bond of a resin composite to the three alloys used in the study. This procedure can be recommended for intraoral repair of exposed metal when the type of alloy belongs to one of the investigated alloy groups.

Analysis of Variance↗
PubMedDate not supplied

Flow characteristics and film thickness of flowable resin composites.

Flowable resin composites have been recommended for many clinical uses and have been formulated in a variety of compositions and viscosities to meet various uses. This study compared the variation in viscosity of flowable resin composites using the ADA Flow Test and measured film thickness with a test to simulate flow during cementation. The film thickness test for the flowable resin composites was performed at three different seating pressures to simulate pressure variation during seating of porcelain veneers, one of the potential uses of flowable resin composites that may favor a lower viscosity. The following flowable resin composites were evaluated: Revolution, StarFlow, Aeliteflo LV, Aelite, Flow-It, FloRestore, Versaflo, Durafill Flow and Tetric Flow, with Nexus2, a composite luting resin used as a control. Flow characteristic measurements suggest that resin composites may be divided into high flow (StarFlow, Revolution, Aeliteflo LV), medium flow (FloRestore, Durafill Flow, Flow-It) and low flow (Tetric Flow, Versaflo, Nexus2, Aelite) groupings. The film thickness measurements agreed with the ADA flow test, except for two exceptions. Durafill Flow resin composite had a higher film thickness than expected based on the ADA flow test. Also, Aeliteflo unexpectedly had a lower film thickness. At the lowest seating pressure (.016MPa) tested, eight out of the nine resin composites tested as well as the control luting resin had a film thickness greater than the 25 microns used as the clinical standard for cement film thickness. However, at the highest seating pressure (.038 MPa) tested, only two and the control, Versaflo, Durafill Flow and Nexus2, had film thicknesses significantly greater than 25 microns. The highly filled Nexus2 luting resin had the highest film thickness at all seating pressures.

Analysis of Variance↗
PubMed1990

[The influence of the adhesive resin for the deformation of the metallic plate].

From both vital and denture sides, the design of denture in dental clinic needs taking care of various viewpoints; alleviation of the adverse effect on the periodontium is necessary on the vital side, and prevention of possible rupture of the denture at its functioning and taking hygienic measures are necessary on the denture side. Utilization of the metal and adhesive, 4-META containing resin (hereinafter referred to as adhesive resin) in the design of denture has been reported to be not only hygienically advantageous because of difficult adhesiveness of bacterial flora due to solid union between the metal and the resin, but also less in danger of the denture rupture from its finishing line portion. However, a few reports have been made on the analysis of the correlation between the mechanical strength of the whole of denture and the use of adhesive resin and on the deformation of the metallic frame due to curing shrinkage of adhesive resin. In the present study, in terms of these problems, utilizing the modal analysis applying a vibrato-logical technique and the strain gauge device appropriate for the determination of the time-course, samples of chrome-cobalt alloy and of partial denture were examined for the influence of inserted adhesive and non-adhesive resins upon them. The following results were obtained: 1. The results of the determination by the strain gauge method revealed that the insertion of adhesive resin tended to have more displacement volume for more insertion volume and for thinner chrome-cobalt alloy sample and that of non-adhesive resin had practically no adhesive force, suggesting a small deformation of the sample due to curing shrinkage, with little interlocking force. 2. The results of modal analysis revealed that the insertion of the adhesive resin onto the denture sample led to an increase in mechanical strength and a rigid body modality of the activity at the finishing line portion compared with the non-adhesive resin. 3. From the results of the determination by the strain gauge method and of the modal analysis, the application of adhesive resin was suggested to increase the intensity of denture.

Acrylic Resins↗
PubMed1999

Flexural and thermal cycling of resins for veneering removable overlay dentures.

OBJECTIVES: This investigation compared the effect of flexural and thermal cycling upon resins, bonded via adhesive primers to cobalt-chromium alloy to identify appropriate materials for veneering overlay dentures which may flex in function. METHODS: The resins investigated were an acrylic resin, a crown and bridge resin, a urethane dimethacrylate and a hybrid composite resin systems. The first three were bonded via an adhesive primer/opaque system based upon 4-methacryloxyethyl trimellitate anhydride (4-META) and the last via one based on 10-methacryloxyldecyl dihydrogen phosphate (MDP). Cast alloy beams 30 x 4 x 0.8 mm with 2 mm resin veneers were stored in H2O for three days or three months, and subjected to 1000 thermo-cycles between 4 and 60 degrees C, and/or 5000 flexural cycles to a displacement of 0.1 mm. Three-point bend testing was carried out in an Instron 4505 UTM. The increase in the flexural moduli of the cast beams, due to the addition of the resin spines, together with the displacements and loads at yield were recorded. RESULTS: The adhesive resin systems varied in their abilities to withstand conditioning stresses, this appeared to reflect the rigidity of the resin component as well as the performance of the adhesive bond. CONCLUSIONS: While the composite/MDP system maintained the highest bond strength throughout the conditioning, its low displacement at yield indicates that it may be more suitable for rigid areas of a removable partial denture. Acrylic resin, with its high load and displacement at yield, make it the material of choice for veneering the more flexible saddle areas of partial dentures.

Acrylic Resins↗
PubMed2000

Effect of surface penetrating sealant on surface texture and microhardness of composite resins.

The application of Fortify (Bisco, Lombard, IL), an unfilled resin, to the surface of composite resin restorations is intended to fill in defects in the surface that persist despite polishing, improve marginal integrity, and increase these materials' resistance to abrasion. The aim of this study was to observe the surface texture by scanning electron microscopy and measure the microhardness of the surface. For each sample of composite resin covered with glaze, 40 measurements were made of the thickness of the resin. Measurements of the Vickers microhardness included three samples of composite resin, three samples of glaze, and six samples of composite resin covered with glaze. A relationship was established between microhardness and thickness. Scanning electron microscopy showed a noticeable improvement in the surface texture. Nevertheless, areas were seen in which glaze seemed very thin or even completely absent. Measurements of the thickness ranged from 0-70 microm. The mean microhardness of composite resin was 65.8 +/- 0.7, while the mean hardness of glaze was 7.3 +/- 0.7. The microhardness of the double layer was reduced, depending on the thickness of the glazing resin. The capacity of glaze to mask surface defects of composite resin was shown, but it was difficult to obtain a regular surface with liquid resin. The application of this product caused a decrease of the microhardness of the composite resin's surface.

Composite Resins↗
PubMed2002

The effect of ajmalicine spiking and resin addition timing on the production of indole alkaloids from Catharanthus roseus cell cultures.

The potential for the feedback inhibition of indole alkaloid synthesis was investigated by spiking suspension cultures of Catharanthus roseus with 0, 9, or 18 mg/L ajmalicine on day 0. The production of ajmalicine, catharanthine, and serpentine were inhibited in a dose-dependent manner. The inhibition was transient as the exogenous ajmalicine was ultimately either metabolized in the medium or within the cell. The addition of neutral resin has previously been shown to enhance ajmalicine production. To minimize product inhibition and product metabolism, Amberlite XAD-7 resin was added to immobilized cultures of C. roseus starting on either day 0, 5, or 15, and fresh resin was exchanged for spent resin every 5 days. The addition of resin did not decrease the viability of the culture. Growth was reduced only in cultures with resin added on day 0. Alkaloid production was enhanced to different extents by the timing of resin addition, suggesting that feedback inhibition or product metabolism was present throughout the culture period. Ajmalicine recovery was nearly 100% when the resin was added initially either on day 0 or day 5. Ajmalicine recovery was reduced to 55% when the resin was added later in the culture period starting on day 15, presumably because of resin saturation or the inaccessibility of alkaloids trapped in the vacuole. Delaying the addition of XAD-7 resin until 5 days after the start of the culture resulted in the highest improvement in ajmalicine production, i.e approximately 70% and also resulted in the complete recovery of ajmalicine from the cell.

Acrylic Resins↗
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↗
PubMed1991

In vitro two-body wear of inlay-onlay composite resin restoratives.

Inlay-onlay composite resin restorations have been introduced to the profession as alternatives to amalgam and direct composite resins. Two-body wear testing was performed on three inlay-onlay resins and one direct composite resins using a machine designed to produce sliding wear. The composite resins were opposed by human enamel, type III gold alloy, and porcelain. Of the investigated materials, the homogeneously microfilled inlay-onlay material showed significantly less wear. The direct composite resin showed significantly the greatest wear. The hybrid inlay-onlay resins showed intermediate wear. The hybrid inlay-onlay resins and the direct composite (small particle, heavily filled) resin created wear tracks in the opposing surfaces while the homogeneous microfill inlay-onlay resin did not. The depth of the observed wear tracks in the opposing surface was sufficiently substantial to warrant further investigation into the wear of materials that oppose composite resin restorations.

Analysis of Variance↗
PubMed2005

Polymerization characteristics of light- and auto-curing resins for individual splints.

OBJECTIVES: The aim of this in vitro study was to assess different resins for occlusal splints regarding a number of polymerization characteristics. METHODS: One autopolymerizing resin (Palapress) and four light-curing resins (Acrylight, Primosplint, Triad TranSheet Colorless and Pink) were tested for flexural strength, modulus of elasticity, water sorption, volumetric shrinkage, and conversion of double bonds. These resins were polymerized for 10 and 15 min in a light oven at frequencies between 320 and 400 nm or 400 and 500 nm, respectively. Data were treated statistically by ANOVA and by Scheffé test. RESULTS: Concerning flexural strength and modulus of elasticity, Triad TranSheet Colorless showed significantly greater values than Primosplint and Palapress (p<0.05). The light curing resins Acrylight and Primosplint featured significantly higher water sorption when cured for 10 min compared to all other resins (p<0.05). Acrylight displayed significantly higher volumetric shrinkage and a higher quantity of remaining double bonds compared to all other light-curing resins (p<0.05). Primosplint, Triad TranSheet Colorless and Pink showed significantly lower shrinkage values than autopolymerizing Palapress (p<0.05). For all light curing resins, polishing of the samples resulted in a significantly lower quantity of remaining double bonds (p<0.05) compared to unpolished samples. SIGNIFICANCE: With respect to the polymerization properties evaluated, the light-curing resins reached similar material properties to the autopolymerizing resin or even surpassed them. Light-curing resins seem to be suitable for the fabrication of occlusal splints and can been seen as an alternative to autopolymerizing polymethylmethacrylates.

Acrylic Resins↗
PubMed2006

Water sorption/solubility of dental adhesive resins.

OBJECTIVES: This study evaluated the water sorption, solubility and kinetics of water diffusion in commercial and experimental resins that are formulated to be used as dentin and enamel bonding agents. METHODS: Four commercial adhesives were selected along with their solvent-monomer combination: the bonding resins were of Adper Scotchbond Multi-Purpose (MP) and Clearfil SE Bond (SE) systems, and the "one-bottle" systems, Adper Single Bond (SB) and Excite (EX). Five experimental methacrylate-based resins of known hydrophilicities (R1, R2, R3, R4 and R5) were used as reference materials. Specimen disks were prepared by dispensing the uncured resin into a mould (5.8mm x 0.8mm). After desiccation, the cured specimens were weighed and then stored in distilled water for evaluation of the water diffusion kinetics over a 28-day period. RESULTS: Resin composition and hydrophilicity (ranked by their Hoy's solubility parameters) influenced water sorption, solubility and water diffusion in both commercial and experimental dental resins. The most hydrophilic experimental resin, R5, showed the highest water sorption, solubility and water diffusion coefficient. Among the commercial adhesives, the solvated systems, SB and EX, showed water sorption, solubility and water diffusion coefficients significantly greater than those observed for the non-solvated systems, MP and SE (p<0.05). In general, the extent and rate of water sorption increased with the hydrophilicity of the resin blends. SIGNIFICANCE: The extensive amount of water sorption in the current hydrophilic dental resins is a cause of concern. This may affect the mechanical stability of these resins and favor the rapid and catastrophic degradation of resin-dentin bonds.

Absorption↗