Publications by authors named "Zbigniew Raszewski"

14 Publications

  • Page 1 of 1

Release and Recharge of Fluoride Ions from Acrylic Resin Modified with Bioactive Glass.

Polymers (Basel) 2021 Mar 27;13(7). Epub 2021 Mar 27.

Department of Prosthodontics, Wroclaw Medical University, 50-425 Wroclaw, Poland.

Background: Oral hygiene is essential for maintaining residual dentition of partial denture wearers. The dental material should positively affect the oral environment. Fluoride-releasing dental materials help to inhibit microbial colonization and formation of plaque as well as to initiate the remineralization process in the early cavity area.

Aim: To evaluate fluoride ion release and recharge capacity, sorption, and solubility of polymethyl methacrylate (PMMA) dental resin modified with bioactive glass addition.

Materials And Methods: Two bioactive glass materials (5 wt% Kavitan, 10 wt% Kavitan, and 10 wt% Fritex) and pure 10 wt% NaF were added to dental acrylic resin. After polymerization of the modified resins, the release levels of fluoride anions were measured based on color complex formation by using a spectrophotometer after 7, 14, 28, and 35 days of storage in distilled water at 37 °C. Subsequently, specimens were brushed with a fluoride-containing tooth paste on each side for 30 s, and the fluoride recharge and release potential was investigated after 1, 7, and 14 days. Sorption and solubility after 7 days of storage in distilled water was also investigated.

Results: The acrylic resins with addition of 10% bioactive glass materials released fluoride ions for over 4 weeks (from 0.14 to 2.27 µg/cm). The amount of fluoride ions released from the PMMA resin with addition of 10 wt% Fritex glass was higher than that from the resin with addition of 10 wt% Kavitan. The acrylic resin containing 10 wt% NaF released a high amount of ions over a period of 1 week (1.58 µg/cm), but the amount of released ions decreased rapidly after 14 days of storage. For specimens containing 5 wt% Kavitan glass, the ion-releasing capacity also lasted only for 14 days. Fluoride ion rechargeable properties were observed for the PMMA resin modified with addition of 10 wt% Fritex glass. The ion release levels after recharge ranged from 0.32 to 0.48 µg/cm. Sorption values ranged from 10.23 μm/mm for unmodified PMMA resin to 12.11 μm/mm for specimens modified with 10 wt% Kavitan glass. No significant differences were found regarding solubility levels after 7 days.

Conclusions: The addition of 10 wt% Fritex and 10 wt% Kavitan bioactive glass materials to heat-cured acrylic resin may improve its material properties, with bioactive fluoride ion release ability lasting for over 4 weeks. The resin modified with 10 wt% Fritex glass could absorb fluoride ions from the toothpaste solution and then effectively release them. Addition of fluoride releasing fillers have a small effect on sorption and solubility increase of the modified PMMA resin.

Clinical Significance: The addition of bioactive glass may be promising in the development of the novel bioactive heat-cured denture base resin.
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http://dx.doi.org/10.3390/polym13071054DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8037481PMC
March 2021

Update on acrylic resins used in dentistry.

Mini Rev Med Chem 2021 Feb 26. Epub 2021 Feb 26.

Department of Prosthodontics, Wroclaw Medical University, Wrocław. Poland.

Acrylic resins are the most commonly used materials in prosthetics and orthodontics until now. They have a well-documented history of use as biomaterials in the manufacture of different types of dental appliances. The objective of this study was to describe the properties of acrylic resins and the processing methods used for these materials in dentistry. The review depicts the most important achievements in this area, indicating that the resin technology evolved in different directions. The mechanical and biological properties of acrylic resins were improved by the addition of mineral or natural fibers, and/or fillers including nanofillers, as well as by poly(methyl methacrylate) surface modification. The presence of residual monomer was reduced as a result of postpolymerization activity. New types of acrylic resins were developed for processing Computer-Aided Design/Computer-Aided Manufacturing systems and three-dimensional printing.
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http://dx.doi.org/10.2174/1389557521666210226151214DOI Listing
February 2021

Acrylic resins in the CAD/CAM technology: A systematic literature review.

Dent Med Probl 2020 Oct-Dec;57(4):449-454

SpofaDental a.s., Jicin, Czech Republic.

At present, new acrylic plastic technologies are being developed in dentistry. Although this kind of material has been used for dental prostheses for over 80 years, it has been produced in the form of disks with the computer-aided design/computer-aided manufacturing (CAD/CAM) technology for over 15 years. The purpose of the article was to collect information from the literature on acrylic materials processed through the milling technology (CAD/CAM). The publicly available databases PubMed, Google Scholar and Scopus were searched using the key word "acrylic resins, CAD/CAM". All articles describing the application and testing of CAD/CAM disks were selected. Duplicate articles were removed. More than 100 articles that described the use of materials machined using the milling equipment were found. These included works comparing the mechanical properties, biocompatibility and clinical use of the materials. After the initial selection, 36 papers on this subject were included in this review. The number of studies on the processing of acrylic materials with the use of the CAD/CAM technology has been increasing worldwide. Since such materials have better mechanical properties, no polymerization shrinkage occurs during processing, the amount of residual monomer material is very low and they have better color stability than self-curing materials.
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http://dx.doi.org/10.17219/dmp/124697DOI Listing
February 2021

Influence of polymerization method on the cytotoxicity of three different denture base acrylic resins polymerized in different methods.

Saudi J Biol Sci 2020 Oct 1;27(10):2612-2616. Epub 2020 Jun 1.

SpofaDental Kerr Company, Markova 238, 506-01 Jicin, Czech Republic.

Statement Of Problem: Acrylic plastics are used for over 80 years for the manufacture of prostheses. This kind of material has some limitations, one of them is a residual monomer, that remains after the polymerization has been terminated, which can influence the biological properties of the final medical device.

The Purpose: The aim of this investigations was a comparison of the residual monomer concentration and cytotoxic effect of three various acrylic materials which differ in the polymerization method (hot-cured, polymerized under pressure and at lower temperatures).

Material And Methods: The cytotoxicity of three different acrylic resins from the same producer were tested on the in vitro model (VERO CCL-81) by MTT assay. The residual monomer of acrylic materials was detected by gas chromatography.

Results: The Superacryl Plus material polymerized in hot water has a residual monomer concentration of 0.67 ± 0.05%, Superpont C + B hardened under pressure of 2.61 ± 0.208%, and Premacryl Plus after cold curing process has 3.53 ± 0.27% of uncured MMA. The results revealed that the least cytotoxic effect were observed in case of a thermally polymerized material.

Conclusion: Material polymerized in high temperatures has lower residual monomer concentration and not affect cell cultures. Self-curing materials polymerized in lower temperature have a higher concentration of residual monomer, which reduces the number of living cells by 20%, which can cause allergic reaction shortly after new denture was prepared.
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http://dx.doi.org/10.1016/j.sjbs.2020.05.039DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7499378PMC
October 2020

Influence of silanized silica and silanized feldspar addition on the mechanical behavior of polymethyl methacrylate resin denture teeth.

J Prosthet Dent 2020 Apr 28;123(4):647.e1-647.e7. Epub 2020 Feb 28.

Professor, Department of Prosthodontics, Wroclaw Medical University, Wrocław, Poland.

Statement Of Problem: Artificial denture teeth made of polymethyl methacrylate (PMMA) resin have good adhesion to the denture base but are relatively soft and have limited wear resistance during function.

Purpose: The purpose of this in vitro study was to evaluate the influence of the addition of 2 inorganic nanofillers on the flexural strength, maximal displacement, elastic modulus, Isolde impact resistance, and Brinell hardness of acrylic resin denture teeth.

Material And Methods: Heat polymerizing polymethyl methacrylate resin was mixed with silanized silica or silanized feldspar in concentrations of 5 wt%, 10 wt%, and 15 wt%. The first test was conducted after 24 hours of storage in laboratory conditions, and the second assessment was conducted after 3 months of storage in distilled water at 37 °C. The Brinell hardness was evaluated, and the elastic modulus and maximal displacement at fracture were calculated. The flexural strength and Isolde impact resistance were measured with a 3-point flexural test. Acrylic resin specimens without filler addition were used as a control group. Statistical analysis included 2-way ANOVA for independent variables (α=.05) and the Student t test for time-dependent changes (α=.05). These were performed with Statistica 12 software.

Results: The acrylic resin specimens modified with the addition of silanized feldspar had significantly higher Brinell hardness, elastic modulus, maximal displacement, and flexural strength and also had no adverse effect on Isolde impact resistance compared with the conventional acrylic resin. Silica filler increased the Brinell hardness and elastic modulus of acrylic resins but significantly reduced the flexural strength and Isolde impact resistance.
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http://dx.doi.org/10.1016/j.prosdent.2019.12.007DOI Listing
April 2020

Towards the precise microstructural mapping. Testing new anisotropic phantoms with layered and capillary geometries

Annu Int Conf IEEE Eng Med Biol Soc 2019 Jul;2019:2835-2839

In pursuance of an accurate reality description, more and more physical theories and models are being developed. MRI techniques have superiority in terms of sensitivity to the specific tissue features and their variations. Thus, very precise determination of relaxation and diffusive properties in biological systems may enhance the cellular-level mapping. In this work we present new anisotropic phantoms with layered and capillary geometries, which can contribute to the characterization of biological samples far below the voxel size. Highly advanced manufacturing technique allowed us to obtain well-defined, stable structures, which is undisputable advantage of these models. The phantoms were tested in terms of relaxation and diffusion behavior of water in 50 mT and 0.6 T magnetic field strength. 1D and 2D relaxation experiments revealed many relaxation mechanisms. Diffusion Weighted Imaging confirmed speculations about heterogeneous diffusion coefficient, despite application of the recently proposed BSD-DTI method.
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http://dx.doi.org/10.1109/EMBC.2019.8857065DOI Listing
July 2019

Design and characteristics of new experimental chlorhexidine dental gels with anti-staining properties.

Adv Clin Exp Med 2019 07;28(7):885-890

Department of Dental Prosthetics, Wroclaw Medical University, Poland.

Background: Chlorhexidine-based products are often used in medicine and dentistry as dental hygiene and therapeutic products, especially by patients with various oral tissue diseases. However, these products have disadvantages, such as low stability, as well as discoloration of the teeth and dental reconstruction materials.

Objectives: The aim of this study was to create and evaluate experimental chlorhexidine (CHX) gels with anti-staining properties and to compare them with 3 commercially available products.

Material And Methods: For this study, 4 new formulations containing 1% CHX and different anti-staining agents were developed. The properties of these gels were compared with 3 commercial CHX-based dental products. The pH, viscosity, disintegration in water, and anti-staining properties were evaluated.

Results: The pH level of the 4 new CHX gels ranged from 5.92 to 6.33. The viscosity of the experimental gels was higher (85.7÷217.7 Pa∙s) than the commercial ones (11.6÷72.7 Pa∙s). Among the experimental formulations with 1% CHX, the formulation with 5% polyvinylpyrrolidone (PVP) and 0.2% citric acid and the formulation with 1% citric acid were the most stable in terms of pH and viscosity. The disintegration times of the experimental gels were longer (50-70 min) as compared with the commercial products (approx. 20 min). These 2 CHX gels caused less color change of glass ionomer cements in black tea solution.

Conclusions: To conclude, 2 new experimental dental gels based on 1% CHX, one with 1% citric acid and the second with 5% PVP and 0.2% citric acid, had the most favorable physicochemical properties. Further research is needed to evaluate their therapeutic potential in the treatment of diseases of the oral cavity.
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http://dx.doi.org/10.17219/acem/94152DOI Listing
July 2019

Effect of water quantity and quality on the properties of alginate impression materials.

Dent Med Probl 2018 Jan-Mar;55(1):43-48

Department of Dental Prosthetics, Wroclaw Medical University, Poland.

Background: Alginates are impression materials commonly used in prosthodontics and orthodontics. However, all these materials have some disadvantages, such as limited elasticity, tearing resistance and low dimensional stability.

Objectives: The aim of this research was to investigate the effect of various water quantities and qualities on changes in the properties of alginates.

Material And Methods: Two alginates, Neocolloid and Tulip, were mixed with different volumes of water, water with calcium ions, or sparkling water with CO2. The dimensions, setting times, and hardness of the specimens were measured and Young's modulus was calculated. The significance of the difference between the mean values of different groups and the control group was assessed by Student's t-test or the Mann-Whitney U test.

Results: The dimensional stability changes of both alginate impression materials were statistically dependent on the quantity of water used for mixing. Sample storage over 24 h of samples prepared with +15% water led to 5.00% shrinkage for Neocolloid and 4.41% for Tulip. The setting times of Neocolloid and Tulip were significantly prolonged when the alginates were prepared with +15% water; the addition of calcium ions shortened the setting times of both alginates. Specimens mixed with the water containing Ca2+ ions were characterized by greater hardness and Young's modulus values when compared to the alginate mixed with distilled water.

Conclusions: For mixing alginates, it is necessary to use the manufacturers' recommended mixing ratios between powder and water. To obtain the right setting time, hardness and elasticity, the application of distilled or demineralized water is advised.
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http://dx.doi.org/10.17219/dmp/82179DOI Listing
August 2019

Changes in hardness of addition-polymerizing silicone-resilient denture liners after storage in artificial saliva.

J Prosthet Dent 2019 Feb 7;121(2):317-321. Epub 2018 Aug 7.

Professor, Department of Prosthodontics, Wroclaw Medical University, Wrocław, Poland.

Statement Of Problem: The hardness of silicone resilient denture liners was reported to be more stable than that of acrylic resin resilient denture liners. However, the changes in hardness of these materials in artificial saliva are unclear.

Purpose: The purpose of this in vitro study was to evaluate changes in the hardness of addition-polymerizing silicone-resilient denture liners for long-term use after storage in artificial saliva.

Material And Methods: Four addition-polymerizing silicone resilient denture liners were tested: GC Reline Soft, Elite Soft Relining, Megabase, and Mucopren Soft. All were long-term relining materials of the soft type. Fifteen disk-shaped specimens were prepared for each of the tested materials (40 mm in base diameter, 8 mm in thickness). Their initial hardness was assessed with a Shore A durometer, after which they were stored in artificial saliva at a temperature of 37°C. Hardness was examined after 7, 30, and 90 days. Statistical analysis was performed using parametric ANOVA for dependent and independent variables and Tukey honest significant difference (HSD) post hoc tests (α=.05).

Results: All resilient denture liners increased in hardness during the experiment. The change was least for Elite Soft Relining, and GC Reline Soft was the hardest material. Initially, Megabase and Mucopren Soft were significantly softer than the other 2 materials, but their hardness increased rapidly after the first 7 days of specimen conditioning, achieving values close to Elite Soft Relining.

Conclusions: Within the limitations of the study, room temperature vulcanizing addition-polymerizing polyvinyl siloxanes of the soft type have different initial hardness, and this changes with storage time in artificial saliva at the temperature of the oral cavity.
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http://dx.doi.org/10.1016/j.prosdent.2018.05.002DOI Listing
February 2019

Improvements in self-curing composites.

Adv Med Sci 2017 Sep 13;62(2):398-404. Epub 2017 Jun 13.

Department of Materials Science and Biomedical Engineering, Bialystok University of Technology, Faculty of Mechanical Engineering, C, Białystok, Poland. Electronic address:

Purpose: The purpose of this study was to test the influence of a barbituric acid derivative acting as a catalyst and small amounts of pyrolytic silica in acrylic resins on color stability, solubility and sorption of a composite.

Materials And Methods: A series of two-component powder/liquid resin systems were prepared. Monomer-like mixtures (bis-GMA, TEGDMA, tertiary amine 60/40) and a quartz powder with additions of various silica and barbituric acid derivatives were used. Temperature of the material during polymerization was measured with the use of a thermometer. In addition, the material's flexural and compressive strength, sorption and solubility were tested pursuant to ISO4049:2009.

Results: The powder-based acrylic composition in a liquid mixed immediately before use, after an addition of a 0.5% barbituric acid derivative, has a lower temperature during the polymerization process (a reduction from 43°C to 37°C), whereas color stability over time is improved, with ΔE=1.81 for samples of powder mixtures containing between 0.45% of BPO and 0.15% of barbituric acid derivatives. For silanized quartz powder with 0.55% BPO and 0.1% BA+0.5% Aerosil R711, the obtained sorption value was 4.57±0.22μg/mm, whereas solubility was 1.60±0.32μg/mm.

Conclusions: New catalytic system with barbituric acid derivative, improves color stability for samples stored at room condition and under light of high intensity. A two-phase composite (bis GMA TEGDMA/Quartz), with a new catalytic system with barbituric acid derivatives, has a lower self-cured temperature. Adding a small quantity of hydrophobic silica (0.5%) has a significant influence, with reduced sorption and solubility of the material.
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http://dx.doi.org/10.1016/j.advms.2017.04.006DOI Listing
September 2017

The Setting Time of Polyether Impression Materials after Contact with Conventional and Experimental Gingival Margin Displacement Agents.

J Prosthodont 2018 Feb 22;27(2):182-188. Epub 2016 Jun 22.

Department of Prosthodontics, Wroclaw Medical University, Wroclaw, Poland.

Purpose: The compatibility of chemical gingival margin displacement agents with polyether impression materials has not been determined. The aim of this study was to evaluate the setting time of polyether impression elastomers after contact with conventional and experimental gingival displacement agents.

Materials And Methods: The study compared the setting time of two polyether impression materials: medium body (Impregum Penta Soft) and light body (Impregum Garant L DuoSoft) after contact with 10 gingival displacement agents, including 5 conventional astringents (10%, 20%, and 25% aluminum chloride, 25% aluminum sulfate, and 15.5% ferric sulfate) and 5 experimental adrenergics (0.1% and 0.01% HCl-epinephrine, 0.05% HCl-tetrahydrozoline, 0.05% HCl-oxymetazoline, and 10% HCl-phenylephrine). As many as 120 specimens (60 light body and 60 medium body) were mixed with 20 μl of each of 10 gingival displacement agents, and the time to achieve maximum viscosity was measured with a viscometer. The setting times of these specimens were compared with the control group of 12 specimens, which were polymerized without contact with the displacement agents. The experiments were performed in two environments: 23°C and 37°C (± 0.1°C). Individual and average polymerization time compatibility indices (PTCI) were calculated. Data were analyzed by 2-way ANOVA (α = 0.05).

Results: The evaluated chemical displacement agents from both groups changed the setting time of light- and medium-body PE. The negative individual PTCI values achieved astringent (20% aluminum chloride) with two PE in both temperature environments. The average PTCI values of the experimental displacement agents at laboratory and intraoral temperatures were significantly higher than the conventional agents.

Conclusions: The present findings suggest that experimental retraction agents can be recommended clinically as gingival margin displacement agents with minimal effects on the setting time of medium- and light-body polyether impression materials; however, direct contact of chemical displacement agents and polyether impression materials can be avoided.
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http://dx.doi.org/10.1111/jopr.12471DOI Listing
February 2018

Anisotropic phantoms in Magnetic Resonance Imaging.

Annu Int Conf IEEE Eng Med Biol Soc 2015 Aug;2015:414-7

Even though Magnetic Resonance Imaging (MRI) gives possibility to obtain qualitatively very good images, most quantitative results obtained by means of MRI are biased with high dependence on particular hardware parameters, imaging sequence used, and properties of analysed sample. Thus to enable comparison between results obtained on different scanners a calibration is needed. In one of the approaches to Diffusion Tensor Imaging (DTI), a B-matrix Spatial Distribution DTI (BSD-DTI) anisotropic phantoms are crucial in precise determination of the diffusion tensor. Anisotropic phantoms can be also useful as a porosity models or rock models in geology. The paper focuses on characterization of several anisotropic phantoms and describes their applications in DTI, and other domains related to MRI.
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http://dx.doi.org/10.1109/EMBC.2015.7318387DOI Listing
August 2015

Color change of soft silicone relining materials after storage in artificial saliva.

J Prosthet Dent 2016 Mar 6;115(3):377-80. Epub 2015 Nov 6.

Professor, Department of Prosthodontics, Wroclaw Medical University, Wroclaw, Poland.

Statement Of Problem: The interaction between artificial saliva and color change of silicone soft liners has not been clarified.

Purpose: The purpose of this in vitro study was to investigate the effect of artificial saliva storage on the color stability of soft silicone liners.

Material And Methods: Four silicone-based liners (Elite Soft Relining, GC Reline Soft, Megabase, and Mucopren Soft) (n=10) were tested after 7, 30, and 90 days of storage in artificial saliva at 37°C in darkness. The color of each specimen was measured with a spectrophotometer using the CIELab color scale. Statistical analysis was performed with the nonparametric ANOVA for dependent variables and nonparametric ANOVA for independent variables (α=.05).

Results: The storage in artificial saliva significantly affected the color integrity of 3 of the 4 tested materials. For GC Reline Soft material, the time of storage had no significant effect on color.

Conclusions: Significant differences were found in the color changes of silicone-based denture liners after storage in artificial saliva. With regard to color stability, GC Reline Soft may be recommended for use in dental practices as a silicone soft relining material for long-term applications.
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http://dx.doi.org/10.1016/j.prosdent.2015.08.022DOI Listing
March 2016

Polymerization time compatibility index of polyvinyl siloxane impression materials with conventional and experimental gingival margin displacement agents.

J Prosthet Dent 2014 Aug 23;112(2):168-75. Epub 2014 Jan 23.

Professor, Department of Prosthodontics, Wroclaw Medical University, Poland.

Statement Of Problem: No consensus exists as to the compatibility of chemical agents used with gingival displacement methods with different impression materials.

Purpose: The purpose of this study was to investigate the effect of conventional and experimental gingival displacement agents on the polymerization time of polyvinyl siloxane impression elastomers.

Material And Methods: The study comprised 10 gingival displacement agents, including 5 conventional astringents (10%, 20%, and 25% aluminum chloride, 25% aluminum sulfate, and 15.5% ferric sulfate) and 5 experimental adrenergics (0.1% and 0.01% HCl-epinephrine, 0.05% HCl-tetrahydrozoline, 0.05% HCl-oxymetazoline, and 10% HCl-phenylephrine). The polymerization time of 240 specimens (weight 3.3 g) of 4 polyvinyl siloxane (PVS) impression elastomers, type 3 (Colorise Thermochromic, Hydrorise, Express, and Take 1 Advanced), after mixing with 20 μL of each displacement agent, was measured with a viscometer. The 24 specimens from the control group were polymerized without contact with the displacement agents. The studies were performed at 23°C and 37°C (± 0.1°C).

Results: A polymerization time compatibility index (PTCI) was devised, where the polymerization time of PVS mixed with the displacement agents was expressed as the percentage of the standard polymerization time of the impression material. The PTCI values at 23°C were higher than those at 37°C for both groups of displacement agents. At 37°C, the experimental displacement agents achieved higher PTCI values than the conventional agents.

Conclusions: All of the evaluated displacement agents at laboratory and intraoral temperatures induced changes in the polymerization time of PVS. Therefore, chemical displacement agents should not come into direct contact with PVS impression materials.
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http://dx.doi.org/10.1016/j.prosdent.2013.09.024DOI Listing
August 2014