Investigating Bioactive-Glass-Infused Gels for Enamel Remineralization: An In Vitro Study.

OBJECTIVE: Dental hypersensitivity remains widespread, underscoring the need for materials that can effectively seal dental tubules. This study evaluated the potential of bioactive-glass-infused hydroxyethyl cellulose gels in this context. METHODS: Five gels were synthesized, each containing 20% bioactive glass (specifically, 45S5, S53P4, Biomin F, and Biomin C), with an additional blank gel serving as a control. Subjected to two months of accelerated aging at 37 ± 2 °C, these gels were assessed for key properties: viscosity, water disintegration time, pH level, consistency, adhesion to glass, and element release capability. RESULTS: Across the board, the gels facilitated the release of calcium, phosphate, and silicon ions, raising the pH from 9.00 ± 0.10 to 9.7 ± 0.0-a range conducive to remineralization. Dissolution in water occurred within 30-50 min post-application. Viscosity readings showed variability, with 45S5 reaching 6337 ± 24 mPa/s and Biomin F at 3269 ± 18 mPa/s after two months. Initial adhesion for the blank gel was measured at 0.27 ± 0.04 Pa, increasing to 0.73 ± 0.06 Pa for the others over time. Gels can release elements upon contact with water (Ca- Biomin C 104.8 ± 15.7 mg/L; Na- Biomin F 76.30 ± 11.44 mg/L; P- Biomin C 2.623 ± 0.393 mg/L; Si- 45S5-45.15 ± 6.77mg/L, F- Biomin F- 3.256 ± 0.651mg/L; Cl- Biomin C 135.5 ± 20.3 mg/L after 45 min). CONCLUSIONS: These findings highlight the gels' capacity to kickstart the remineralization process by delivering critical ions needed for enamel layer reconstruction. Further exploration in more dynamic, real-world conditions is recommended to fully ascertain their practical utility.

Comparison of Mechanical Properties of Three Tissue Conditioners: An Evaluation In Vitro Study.

Introduction: Tissue conditioners have been widely used in various clinical applications in dentistry, such as treating inflamed alveolar ridges, temporarily relining partial and complete dentures, and the acquisition of functional impressions for denture fabrication. This study aimed to investigate the mechanical properties of the most prevalent tissue conditioner materials on the market, including Tissue Conditioners (TC), Visco Gel (VG), and FITT (F). Materials and Methods: The three tissue conditioners, TC, VG, and F, were assessed based on the parameters mentioned above. The following tests were performed based on the ISO 10139-1 and ISO 10139-2 requirements: Shore A hardness, denture plate adhesion, sorption, water solubility, and contraction after 1 and 3 days in water. Additional tests are described in the literature, such as ethanol content and gelling time. The tests were carried out by storing the materials in water at 37 °C for 7 days. Results: The gel times of all tested materials exceeded 5 min (TC = 300 [s], VG = 350 [s]). In vitro, phthalate-free materials exhibited higher dissolution in water after 14 days (VG = -260.78 ± 11.31 µg/mm2) compared to F (-76.12 ± 7.11 µg/mm2) and experienced faster hardening when stored in distilled water (F = 33.4 ± 0.30 Sh. A, VG = 59.2 ± 0.60 Sh. A). They also showed greater contractions. The connection of all materials to the prosthesis plate was consistent at 0.11 MPa. The highest counterbalance after 3 days was observed in TC = 3.53 ± 1.12%. Conclusions: Materials containing plasticizers that are not phthalates have worse mechanical properties than products containing these substances. Since phthalates are not allowed to be used indefinitely in medical devices, additional research is necessary, especially in vivo, to develop safe materials with superior functional properties to newer-generation alternatives. In vitro results often do not agree fully with those of in vivo outcomes.

Bioactive Glass-Enhanced Resins: A New Denture Base Material.

BACKGROUND: The creation of the denture base material with bioactive properties that releases ions and produces hydroxyapatite. METHODS: Acrylic resins were modified by the addition of 20% of four types of bioactive glasses by mixing with powders. Samples were subjected to flexural strength (1, 60 days), sorption and solubility (7 days), and ion release at pH 4 and pH 7 for 42 days. Hydroxyapatite layer formation was measured using infrared. RESULTS: Biomin F glass-containing samples release fluoride ions for a period of 42 days (pH = 4; Ca = 0.62 ± 0.09; P = 30.47 ± 4.35; Si = 22.9 ± 3.44; F = 3.1 ± 0.47 [mg/L]). The Biomin C (contained in the acrylic resin releases (pH = 4; Ca = 41.23 ± 6.19; P = 26.43 ± 3.96; Si = 33.63 ± 5.04 [mg/L]) ions for the same period of time. All samples have a flexural strength greater than 65 MPa after 60 days. CONCLUSION: The addition of partially silanized bioactive glasses allows for obtaining a material that releases ions over a longer period of time. CLINICAL SIGNIFICANCE: This type of material could be used as a denture base material, helping to preserve oral health by preventing the demineralization of the residual dentition through the release of appropriate ions that serve as substrates for hydroxyapatite formation.

Influence of Storing Composite Filling Materials in a Low-pH Artificial Saliva on Their Mechanical Properties-An In Vitro Study.

Restorative composites are subjected to various influences in the oral cavity environment, such as high or low temperatures, the mechanical force generated during mastication, colonization of various microorganisms, and low pH, which may result from ingested food and the influence of microbial flora. This study aimed to investigate the effect of a recently developed commercial artificial saliva (pH = 4, highly acidic) on 17 commercially available restorative materials. After polymerization, the samples were stored in an artificial solution for 3 and 60 days and subjected to crushing resistance and flexural strength tests. The surface additions of the materials were examined in terms of the shapes and sizes of the fillers and elemental composition. When stored in an acidic environment, the resistance of the composite materials was reduced by 2-12%. Larger compressive and flexural strength resistance values were observed for composites that could be bonded to microfilled materials (invented before 2000). This may result from the filler structure taking an irregular form, which results in a faster hydrolysis of silane bonds. All composite materials meet the standard requirements when stored for a long period in an acidic environment. However, storage of the materials in an acid environment has a destructive impact on the materials' properties.

Effects of Surface Preparation Methods on the Color Stability of 3D-Printed Dental Restorations.

BACKGROUND: Color stability is a crucial performance parameter for dental restorations, and limited research exists on how surface preparation methods affect it. The purpose of this study was to test the color stability of three resins intended for 3D printing, which can be used to make dentures or crowns in A2 and A3 colors. MATERIALS AND METHODS: Samples were prepared in the form of incisors; the first group was not subjected to any treatment after curing and washing with alcohol, the second was covered with light-curing varnish, and the third was polished in a standard way. Then, the samples were placed in solutions of coffee, red wine, and distilled water and stored in the laboratory. After 14, 30, and 60 days, color changes were measured (presented as Delta E) compared to material stored in the dark. RESULTS: The greatest changes were observed for samples that were not polished, then were placed in red wine dilutions (ΔE = 18.19 ± 0.16). Regarding the samples covered with varnish, during storage, some parts detached, and the dyes penetrated inside. CONCLUSIONS: 3D-printed material should be polished as thoroughly as possible to limit the adhesion of dyes from food to their surface. Applying varnish may be a temporary solution.

Feldspar-Modified Methacrylic Composite for Fabrication of Prosthetic Teeth.

This study was aimed at investigating poly(methyl methacrylate) (PMMA), modified with a silanized feldspar filler at 10 wt.% and 30 wt.%, as a dental material system for the production of prosthetic teeth. Samples of this composite were subjected to a compressive strength test, three-layer methacrylic teeth were fabricated with the said materials, and their connection to a denture plate was examined. The biocompatibility of the materials was assessed via cytotoxicity tests on human gingival fibroblasts (HGFs) and Chinese hamster ovarian cells (CHO-K1). The addition of feldspar significantly improved the material's compressive strength, with neat PMMA reaching 107 MPa, and the addition of 30% feldspar raising it up to 159 MPa. As observed, composite teeth (cervical part made of neat PMMA, dentin with 10 wt.%, and enamel with 30 wt.% of feldspar) had good adhesion to the denture plate. Neither of the tested materials revealed any cytotoxic effects. In the case of hamster fibroblasts, increased cell viability was observed, with only morphological changes being noticed. Samples containing 10% or 30% of inorganic filler were determined to be safe for treated cells. The use of silanized feldspar to fabricate composite teeth increased their hardness, which is of significant clinical importance for the duration of use of non-retained dentures.

Evaluating the Translucency, Surface Roughness, and Cytotoxicity of a PMMA Acrylic Denture Base Reinforced with Bioactive Glasses.

The colonisation of the surface of removable acrylic dentures by various types of microorganisms can lead to the development of various diseases. Therefore, the creation of a bioactive material is highly desirable. This study aimed to develop a denture base material designed to release bioactive ions into the oral environment during use. Four types of bioactive glasses (BAG)-S53P4, Biomin F, 45S5, and Biomin C-were incorporated into the PMMA acrylic resin, with each type constituting 20 wt.% (10 wt.% non-silanised and 10% silanised) of the mixture, while PMMA acrylic resin served as the control group. The specimens were subsequently immersed in distilled water, and pH measurements of the aqueous solutions were taken every seven days for a total of 38 days. Additionally, surface roughness and translucency measurements were recorded both after preparation and following seven days of immersion in distilled water. The cytotoxicity of these materials on human fibroblast cells was evaluated after 24 and 48 h using Direct Contact and MTT assays. Ultimately, the elemental composition of the specimens was determined through energy-dispersive X-ray (EDX) spectroscopy. In general, the pH levels of water solutions containing BAG-containing acrylics gradually increased over the storage period, reaching peak values after 10 days. Notably, S53P4 glass exhibited the most significant increase, with pH levels rising from 5.5 to 7.54. Surface roughness exhibited minimal changes upon immersion in distilled water, while a slight decrease in material translucency was observed, except for Biomin C. However, significant differences in surface roughness and translucency were observed among some of the BAG-embedded specimens under both dry and wet conditions. The composition of elements declared by the glass manufacturer was confirmed by EDX analysis. Importantly, cytotoxicity analysis revealed that specimens containing BAGs, when released into the environment, did not adversely affect the growth of human gingival fibroblast cells after 48 h of exposure. This suggests that PMMA acrylics fabricated with BAGs have the potential to release ions into the environment and can be considered biocompatible materials. Further clinical trials are warranted to explore the practical applications of these materials as denture base materials.

Preparation and characterization of acrylic resins with bioactive glasses.

This study aimed to prepare a bioactive acrylic material by adding different types of glasses. Commercially available polymerized acrylic resin was mixed with 10% of four different types of glasses in the powder form and cured. Flexural strength, sorption, and solubility of the samples were tested according to ISO 20795-1:2013. The total number of samples used in the tests were 60. The materials were placed in artificial saliva of pH 4 and 7, and elution was performed for 0, 1, 28, and 42 days. The collected samples were analyzed using inductively coupled plasma atomic emission spectrometry to detect Ca, P, and Si ions and using ion chromatography to detect F ions. The materials obtained after modification with glasses showed lower compressive strength compared with pure polymethyl methacrylate but met the standard requirements. Two glass types showed higher solubility values compared with the value defined by the ISO standard. Biomin C and S53P4 released Ca, P, and Si ions, respectively, after 42 days in artificial saliva. Acrylic resins modified with 10% Biomin C and S53P4 glasses can be a valuable source of Ca and P ions under acid conditions for 28 and 42 days.

Aspects and Principles of Material Connections in Restorative Dentistry-A Comprehensive Review.

The combination of two dissimilar materials has always been a serious problem in dentistry. In order to meet this challenge, it is necessary to combine both chemical methods (treatment with silanes, (meth)acrylic functional monomers) and the development of the surface of the joined material in a physical way, e.g., by sandblasting with alumina, alumina with silica, acid etching, the use of lasers and other means. The purpose of this literature review is to present all methods of joining dental composites with other materials such as ceramics, metal, another composite material. This review covers articles published within the period 2012-2022 in journals indexed in the PubMed database, written in English and describing joining different dental materials to each other. All the critical steps of new joint preparation have been addressed, including proper cleaning of the joint surface, the application of appropriate primers capable of forming a chemical bond between ceramics, zirconium oxide or metals and alloys, and finally, the application of new composite materials.

Novel Multifunctional Spherosilicate-Based Coupling Agents for Improved Bond Strength and Quality in Restorative Dentistry.

The aim of this study was to investigate the restorative connections of composite materials after fracture, under controlled conditions of treating the materials with novel, spherosilicate-based (SS) primers bearing both methacryl (MA) and trimethoxysilyl (TMOS) groups. The chemistry of methacrylate group insertion and reactive groups hydrolysis has been studied with the aid of 1H NMR (Nuclear Magnetic Resonance) spectroscopy. The light-cured resin composites were repaired by activating the connection site with the obtained primers and, for comparison, a silane (methacryloxypropyltrimethoxysilane, MATMOS) as a conventional coupling agent bearing the same reactive groups. The resistance of such a joint was tested in a three-point bending test after 24 h and 28 days period of sample conditioning. The effect of bond application was also studied, showing that spherosilicate-based primers may be used more effectively than MATMOS for two-step (primer-composite) restorative process, while for silane, the three-step process with bond application is crucial for satisfactory joint quality. The joint failure mode was determined by microscopic analysis and it was found that SS-4MA-4TMOS and SS-2MA-6TMOS application resulted in mostly composite, and not joint, failure. After 28 days of conditioning, the flexural strength of the joint repaired with SS-4MA-4TMOS was at 94% of the neat, solid material under the same procedure. However, the strength of the neat composite was observed to decline during the conditioning process by ~30%. The joint behavior was explained on the basis of the gradual hydrolysis effect (the greatest decrease being observed for silane).

Mechanical Properties, Cytotoxicity, and Fluoride Ion Release Capacity of Bioactive Glass-Modified Methacrylate Resin Used in Three-Dimensional Printing Technology.

BACKGROUND: Clinically, three-dimensional (3D) printing technology is becoming a popular and efficient dental processing technology. Recently, there has been an increasing demand for dental materials that exhibit bioactive properties. The present study aimed to evaluate the mechanical properties, cytotoxicity, and fluoride ion release capacity of 3D-printed dental resins modified with bioactive glass. MATERIALS AND METHODS: The resin FotoDent splint used in the production of removable orthodontic splints, was modified by the addition of two types of bioactive glasses that are capable of releasing fluoride ions. The novel materials used for the production of dental splints were examined for their mechanical, physical, and biological properties (fracture resistance, sorption, solubility, elution of nonpolymeric substances, and release of fluoride ions over time) and cytotoxic effects on cell cultures. RESULTS: Initially, the fracture toughness of the 3D-printed resin was found to be 55 MPa, but after modification with glass, the resistance was reduced to about 50 MPa. Sorption and solubility values of the materials (19.01 ÷ 21.23 µg/mm3 and 0.42 ÷ 1.12 µg/mm3, respectively) complied with the safety limits imposed by ISO standard. Modified resins were capable of releasing fluoride ions, and the maximum releasing effect was observed after 14 days of incubation. Both the modified resins, after four days of contact with human gingival fibroblasts, exhibited moderate cytotoxic properties. CONCLUSIONS: The experimental results showed that modification of methacrylate resin, used in 3D printing technology, with bioactive glasses produces novel dental materials that possess desirable bioactive properties. The findings of this study indicate the potential ability of modified polymethacrylate resins to release fluoride ions in the oral cavity environment. The modified materials are characterized with a moderate decrease in physical properties and mild cytotoxicity on direct contact with human fibroblasts.

Mechanical Properties and Biocompatibility of 3D Printing Acrylic Material with Bioactive Components.

The aim of this study was to create a 3D printing material with bioactive properties that potentially could be used for a transparent removable orthodontic appliance. MATERIALS AND METHODS: To acrylic monomers, four bioactive glasses at 10% concentration were added, which release Ca, P, Si and F ions. The materials were printed on a 3D printer and tested for flexural strength (24 h and 30 days), sorption and solubility (7 days), ion release to artificial saliva pH = 4 and 7 (42 days) and cytotoxicity in the human fibroblast model. The released ions were determined by plasma spectrometry (Ca, P and Si ions) and ion-selective electrode (F measurement)s. RESULTS: The material obtained released Ca2+ and PO43- ions for a period of 42 days when using glass Biomin C at pH 4. The flexural strength depended on the direction in which the sample was printed relative to the 3D printer platform. Vertically printed samples had a resistance greater than 20%. The 10% Biomin C samples post-cured for 30 min with light had a survival rate of the cells after 72 h of 85%. CONCLUSIONS: Material for 3D printing with bioactive glass in its composition, which releases ions, can be used in the production of orthodontic aligners.

Dynamics of different ion release from denture-base acrylic resins and their mechanical properties after the addition of bioactive materials.

BACKGROUND: The denture-base acrylic resins used by partially edentulous patients can cause local demineralization of teeth. Alkali ions released from the bioactive materials that were added to acrylic resins can increase the pH of the oral environment and slow down the demineralization process. AIM OF THE STUDY: This study aimed to create a new denture-base acrylic resin that can release ions. MATERIALS AND METHODS: A total of 222 samples with different fillers (calcium hydrogen phosphate, hydroxyapatite, two kinds of bioactive glasses, and a product obtained by reaction between bioactive glass formed from glass ionomer cement and polyacrylic acid) were prepared for the study. All the materials were tested for mechanical properties and their use as phosphate donors for 3 weeks. The measurements were presented as mean ± SD error of the mean. Data were analyzed by two-way analysis of variance, with a p-value of <0.05 as statistically significant. RESULTS: Acrylic resins obtained after the addition of a small quantity of bioactive materials (2.5-5%) showed similar mechanical properties (such as flexural strength and Izod impact resistance) as non-filled material. However, the hardness of the modified materials was higher compared to pure poly (methyl methacrylate). Samples modified with materials released phosphate ions for a short period. The materials that were identified to be most promising as an ion source were samples containing 5% calcium hydrogen phosphate (p < 0.01). CONCLUSIONS: Based on the results, it can be concluded that denture-base acrylic resins resulting after the addition of different bioactive precursors have improved mechanical properties and can release ions to the oral environment for a short period.

The Effect of Chlorhexidine Disinfectant Gels with Anti-Discoloration Systems on Color and Mechanical Properties of PMMA Resin for Dental Applications.

Chlorhexidine (CHX)-based dental hygiene products are widely used by dental patients. As these products may have long-term contact with denture poly(methyl methacrylate) (PMMA) resin, anti-discoloration systems (ADSs) were included in them to prevent discoloration of the natural teeth and dental materials. Purpose: The aim of this study was to evaluate the effect of two newly designed CHX-containing gels with ADSs and two commercial products with ADSs (Curasept 0.5% and Curasept 1%) in preventing staining and to analyze the mechanical properties of heat-curing PMMA denture base resin. Materials and methods: Twenty-five discs (five for each test group) of PMMA dental resin with a thickness of 1 mm and a diameter of 20 mm were polymerized according to the manufacturer's instructions and stored in distillate water at a temperature of 37 °C. The surface of the specimens was covered with two commercially available gels-Curasept 1% and Curasept 0.5%, or two experimental gel formulations containing 1% CHX. PMMA specimens stored in distilled water were used as control. The initial values of color and Brinell hardness of the specimens were measured immediately after specimen preparation. The changes in color and Brinell hardness, as well as water sorption, and solubility of the specimens were measured after one year of conditioning. Statistical analysis of the obtained data was performed using one-way analysis of variance and Dunn-Bonferroni post hoc tests. Results: In the group of specimens covered with gel 1 with citric acid or Curasept 0.5%, the color change was clinically acceptable (ΔE* < 2.7). In the specimens stored in contact with gel 2 with polyvinylpyrrolidone (PVP) and Curasept 1%, the ΔE* values were 3.6 and 3.67, respectively. In the control group, the level of hardness decreased significantly from 150 to 140 during the experiment. In addition, a statistically significant decrease in hardness was observed in specimens stored with Curasept 1% and gel 2 with PVP. Specimens stored in contact with Curasept 0.5% and gel 1 with citric acid also showed a lower hardness, but the change was not statistically significant. The sorption of all the groups of PMMA specimens ranged from 22.83 to 24.47 µg/mm3, with no significant differences found between them. All the PMMA specimens stored in contact with the tested CHX gels exhibited a significantly higher solubility (6.84 ± 7.91 µg/mm3) compared to the control group (6.74 µg/mm3), with the highest solubility noted for specimens stored with Curasept 1%. Conclusions: The results showed that CHX used in the gel form with ADSs at a concentration of 0.5% and the experimental gel containing 1% CHX with citric acid caused limited changes to the color and mechanical properties of the PMMA denture base resin during the study period. These gels may be safely used by dental patients for oral hygiene regimen even for prolonged periods of time. ADSs contained in these gels seem to be effective in preventing CHX discoloration.

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

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/cm2). 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/cm2), 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/cm2. Sorption values ranged from 10.23 µm/mm3 for unmodified PMMA resin to 12.11 µm/mm3 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.

Update on Acrylic Resins Used in Dentistry.

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 manufacturing 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.

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

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.

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

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.

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

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.

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

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.