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The purpose of the present study was to evaluate the effects of different repair resins and surface treatments on the repair strength of a polyamide denture base material. Polyamide resin specimens were prepared and divided into nine groups according to the surface treatments and repair materials. The flexural strengths were measured with a 3-point...
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PURPOSE
Polyamide polymers do not provide sufficient bond strength to auto-polymerized resins for repairing fractured denture or replacing dislodged denture teeth. Limited treatment methods have been developed to improve the bond strength between auto-polymerized reline resins and polyamide denture base materials. The objective of the present study...
The purpose of this study was to evaluate the effect of different polymerization cycles on the flexural strengths and microhardness of two denture base materials (Meliodent and Paladent). Heat-polymerized acrylic resin specimens (65.0 mm long×10.0 mm wide×2.5 mm in height) were prepared using different short and long polymerization cycles. After th...
Citations
... The highest load applied to cause specimen failure was measured in Newtons (N). Flexural strength (FS) was calculated according to the following equation: (20) ...
... Techniques such as sandblasting, air abrasion, or laser treatment can be employed to create micro-roughness on the surface, improving adhesion and bonding strength. Plasma surface treatment involves exposing the polyamide denture base to a low-temperature plasma [14,15]. This treatment modifies the surface chemistry and topography, resulting in improved wettability and adhesion properties. ...
... In an intraoral environment, a denture is subjected to a variety of complicated forces that might result in flexural and impact stresses [12]. Repeated masticatory stresses or significant impact forces that could arise from dropping the prosthesis (especially in elderly people with limited physical dexterity) could cause fractures in the denture base [15,16]. In addition, denture fractures mostly occur as a result of mistakes made in the production of acrylic prostheses, failure to create the appropriate occlusion, loss of fit of the base over time, excessive relief areas, and tissue undercuts [17,18]. ...
... In another study, when repaired using auto-polymerizing acrylic resin, the initial strength ratio of the repaired area was 60-69% [32]. This rate was 54-75% in Neshandar Asli et al. [6] and 8.62-71.15% in Gundogdu et al. [16] In the present study, this ratio was found as 19-32% for heat-polymerized, 16-33% for CAD/CAM milled and, 7.8-45% for 3D groups. The differences in the studies' results from the present study may be due to the composition of the test materials used, the different surface treatments applied, and the thermo- The repair's flexural strength is associated with the base resin and repair material adhering well to one another [15]. ...
... According to some research, exposing the repair surface to monomer improves the bond strength [16,18]. Olvera and de Rijk [34] discovered that 4 min of monomer application and Vallittu et al. [35] discovered that 180 s of immersion of repair surfaces in MMA improved strength. ...
There is limited information on the repairability of prostheses produced with digital technology. This study aims to evaluate various surface treatments on flexural bond strength of repaired dentured base resins produced by digital and conventional methods. A total of 360 samples were prepared from one heat-polymerized, one CAD/CAM milled and one 3D printed denture base materials. All of the test samples were subjected to thermocycling (5–55 °C, 5000 cycles) before and after repair with auto-polymerizing acrylic resin. The test samples were divided into five subgroups according to the surface treatment: grinding with silicon carbide (SC), sandblasting with Al2O3 (SB), Er:YAG laser (L), plasma (P) and negative control (NC) group (no treatment). In addition, the positive control (PC) group consisted of intact samples for the flexural strength test. Surface roughness measurements were performed with a profilometer. After repairing the test samples, a universal test device determined the flexural strength values. Both the surface topography and the fractured surfaces of samples were examined by SEM analysis. The elemental composition of the tested samples was analyzed by EDS. Kruskal–Wallis and Mann–Whitney U tests were performed for statistical analysis of data. SB and L surface treatments statistically significantly increased the surface roughness values of all three materials compared to NC subgroups (p < 0.001). The flexural strength values of the PC groups in all three test materials were significantly higher than those of the other groups (p < 0.001). The repair flexural strength values were statistically different between the SC–SB, L–SB, and NC–SB subgroups for the CAD/CAM groups, and the L–SC and L–NC subgroups for the 3D groups (p < 0.001). The surface treatments applied to the CAD/CAM and heat-polymerized groups did not result in a statistically significant difference in the repair flexural strength values compared to the NC groups (p > 0.05). Laser surface treatment has been the most powerful repair method for 3D printing technique. Surface treatments led to similar repair flexural strengths to untreated groups for CAD/CAM milled and heat-polymerized test samples.
... To evaluate the repair strength of the repaired resins, the flexural strength test has been commonly used in previous studies [24][25][26]. Although it mostly mimics the stress that dentures are subjected to in the oral cavity, SBS was recommended for the evaluation of bond strength at the resin-repair interface [15,18,20,[27][28][29]. Based on the objective of this study-examining the bonding strength between repair resins and investigating different denture base resins after surface treatment-the SBS test was selected to compare between the materials. ...
Citation: Gad, M.M.; Albazroun, Z.; Aldajani, F.; Elakel, A.M.; El Zayat, M.; Akhtar, S.; Khan, S.Q.; Ali, S.; Rahoma, A.M. Repair Bond Strength of Conventionally and Digitally Fabricated Denture Base Resins to Auto-Polymerized Acrylic Resin: Surface Treatment Effects In Vitro. Materials 2022, 15, 9062. https://
... Polymethyl methacrylate (PMMA) resin has been used in the fabrication of removable denture prostheses for a long time [1][2][3]. It has several advantages, such as favorable esthetics, biocompatibility, low cost, and simple processing [1,4]. ...
Background
Studies on the antifungal activity, flexural strength, Vickers hardness, and intaglio surface trueness of three-dimensionally printed (3DP) denture bases with microencapsulated phytochemicals with respect to changes in post-polymerization time (PPT) are lacking.
Methods
Specimens of various shapes and dimensions were fabricated with a 3DP denture base resin mixed with 5 wt% phytoncide-filled microcapsules. Each specimen was subjected to different PPT protocols of 5, 10, 20, and 30 min. Specimens without microcapsules with 5-min PPT were used as the negative control group. Cell colonies were counted to evaluate antifungal activity. Three-point bending and Vickers hardness tests were performed to measure the flexural strengths and hardness of the specimens. Fourier-transform infrared spectrometry was used to inspect the degree of conversion (DC). The intaglio surface trueness was measured using root-mean-square estimates calculated by superimposition analysis. A non-parametric Kruskal–Wallis test or one-way analysis of variance was performed (α = 0.05).
Results
The specimens with microcapsules and 10-min PPT showed the highest antifungal activity among the tested groups. Compared with the positive control group (5-min PPT), the specimens with PPTs of 10 min or longer showed significantly higher mean flexural strength, higher DC, greater hardness, and better trueness (all, P < 0.05). Except for the difference in antifungal activity, no statistically significant differences were detected between the specimens subjected to 10-, 20-, and 30-min PPT.
Conclusion
The 3DP denture base filled with microencapsulated phytoncide showed different antifungal activity and physical properties on changing PPT. The 3DP denture base containing phytoncide-filled microcapsules at 5 wt% concentration and subjected to 10-min PPT exhibited sufficient antifungal activity as well as mechanical properties and accuracy within clinical acceptance.
... A load was applied at the midpoint of the prepared area with a crosshead speed of 5 mm/min until the specimen fractured, which is when the fracture load was recorded. The following formula was used to calculate the flexure strength values 21 : ...
Objective The aim of this study was to evaluate the effects of the addition of low-silicon dioxide nanoparticles (nano-SiO2) on the flexural strength and elastic modulus of polymethyl methacrylate (PMMA) denture base material.
Materials and Methods A total of 50 rectangular acrylic specimens (65 × 10 × 2.5 mm3) were fabricated from heat-polymerized acrylic resin. In accordance with the amount of nano-SiO2, specimens were divided into the following five groups (n = 10 per group): a control group with no added SiO2, and four test groups modified with 0.05, 0.25, 0.5, and 1.0 wt% nano-SiO2 of acrylic powder. Flexural strength and elastic modulus were measured by using a 3-point bending test with a universal testing machine. A scanning electron microscope was used for fracture surface analyses. Data analyses were conducted through analysis of variance and Tukey’s post hoc test (α = 0.05).
Results Compared with the control group, flexural strength and modulus of elasticity tended to significantly increase (p ˂ 0.001) with the incorporation of nano-SiO2. In between the reinforced groups, the flexural strength significantly decreased (p ˂ 0.001) as the concentrations increased from 0.25 to 1.0%, with the 1.0% group showing the lowest value. Furthermore, the elastic modulus significantly increased (p ˂ 0.001) at 0.05% followed by 1.0%, 0.25%, 0.5%, and least in control group.
Conclusion A low nano-SiO2 addition increased the flexural strength and elastic modulus of a PMMA denture base resin.
... The denture repair resin should have physical properties similar to those of the denture base resin and must have good denture and bonding strength. In addition, due to the nature of the patient suffering from denture problems, the soft tissue inside the gingiva tends to be damaged (Stipho H D et al., 2001, Gundogdu M et al., 2015 Moreover, we studied the effect of disinfectants on the stability of denture base acrylic resins, and found that they affected their color stability (May KB et al., 1992). Therefore, in this study, the peony extract was prepared by including the denture tissue regulator, and the antibacterial activity, color change and contact angle were analyzed. ...
Candida albicans(C. albicans) is one of the bacteria that resides in the oral cavity, and the ones living in medical and commercial denture resins, commonly cause diseases. Therefore, this study was conducted to confirm the antibacterial activity of C. albicans using a denture base resin containing peony extract with antibacterial properties. For the antibacterial effect, optical density and confocal laser microscopy were used. Contact angle measurements and color change measurements were performed to confirm the physical change of the material added with the antibacterial agent to the denture reline resin. As a result of the antibacterial test, the experimental group exhibited antibacterial activity against C. albicans. Compared to the optical density results, the results of the experimental group showed a significant difference. As a result of Fluorescent images showing (confocal laser microscope), the control group showed a lot of live bacteria, no bacteria appeared in the experimental group. All group did not show any physical changes. As a result of the contact angle measurement, the surface of the experimental group was changed to hydrophilic. In addition, there was no change in the color of the denture reline resin containing peony extract. In conclusion, it was confirmed that the peony extract contained antibacterial activity of the denture resin, and further studies should be conducted on various bacteria for denture base resin disinfection.
... Final strength after repair depends on certain factors like the width of the fracture gap, fracture surface bevelling, and properties of repair resin. So the resistance to fracture of the repaired denture base material is affected by fracture strength and fracture toughness [15]. Dentures made with injectionmolded PMMA thermoplastic resin can also fracture but it is not feasible to repair with the same material. ...
... Chemical surface treatment has been reported to raise the bond strength between the resin used for repair and the denture base [16]. e air blast technique is another surface treatment method, which involves the collision of the accelerated silica-coated alumina particles with the surface which results in the microscopic melting of the treated surface. is process allows the silica-coated alumina particles to penetrate and form an adhesive bond with the surface [18]. e adhesive bond exhibits satisfying strength on initial assessment; however, the aging process has revealed poor outcomes [9]. ...
... is finding 4 International Journal of Dentistry International Journal of Dentistry reveals that the interface of the old and new materials is the site of stress concentration during the transverse strength testing, regardless of the technique and the material used to perform the repair [14]. e validity of the three-point bending test has been closely correlated with the mode of failure of the tested samples [10,18,34]. erefore, the threepoint bending test was utilized for this study. ...
The process of repairing the fractured nylon denture bases and addition of acrylic teeth to the previously worn nylon denture bases has not been widely studied. This study aims to assess the transverse strength of nylon denture bases repaired by various resin materials, different curing techniques, and types of surface treatments. Materials and Methods. One hundred fifty thermoplastic nylon denture base samples were fabricated using plastic patterns measuring 65 × 10 × 2.5 mm (length, width, and thickness, respectively). These samples were then divided into three equal groups. Fifty samples were repaired by microwave heat-polymerization, fifty samples were repaired using the Ivomate autopolymerization, and the other fifty were repaired using light-polymerized acrylic resin. Each of these three groups was further divided into five subgroups of ten samples based on the type of surface treatment. The samples in the control group did not undergo any surface treatment, and the other four groups were chemically surface treated with monomer, acetone, ethyl acetate, and isopropanol, respectively. A three-point bending test was used to calculate the transverse strength values of the samples. Fourier transform infrared (FTIR) analysis was conducted to determine the component of functional groups between the polyamide nylon base and poly(methyl-methacrylate) PMMA repair materials. A polarizing microscope was utilized to investigate the mode of failure at the fracture surfaces. Results. The collected data were analyzed with one-way ANOVA and Sidak’s multiple comparison test to show the differences among different groups. For surface treatments, the highest transverse strength values were obtained by monomer-treated samples (18.29 N/mm²); however, the lowest values were obtained in non-surface treated samples (5.58 N/mm²). While for repair techniques, the highest transverse strength values were obtained by microwave processing, followed by Ivomate and then the light-cured polymerization. The means were found to be significant (). FTIR analysis shows the presence of hydrogen bonding which is due to the ester and amid groups which enhance the bond strength of the surface-treated samples. The interface of the polarizing microscope images revealed a cohesive fracture within repair materials rather than the adhesive nature. Conclusion. The microwave-polymerized resin was considered as the most effective repair technique along with monomer chemical etchant which creates a tight adhesion between PMMA and nylon denture base in comparison to other groups.
1. Introduction
Polyamide nylon base is a family of condensation polymers produced from the reaction of a diacid with a diamine monomer to form a variety of polyamides whose physical and mechanical properties are based on the bonding links between the acid group and amine group [1]. Recently, the use of lightweight denture fabrication materials such as thermoplastic nylon has gained a lot of interest. With the technological advancements of prosthetic dentistry, there is a demand to identify the most suitable bonding techniques that can be utilized while performing repairs of these new materials. Optimum performance of the material after such repairs is a key consideration.
Precise and accurate denture bases are fabricated using the thermoplastic resins when prepared utilizing the injection moulding technique which leads to less polymerization shrinkage. Creep resistance, higher fatigue resistance, and dimensional stability are some of the advantages of thermoplastic resins over conventional powder and liquid systems [2–4]. Nylon is a generic name for certain types of thermoplastic polymer belonging to a class of polyamide [5]. Nylon resins have gained popularity and are widely being accepted in clinical practice as a suitable choice of denture base materials. An esthetically favorable outcome, higher elasticity, and sufficient transverse strength than the conventional heat-polymerizing resins advocate its use [5, 6]. Also, thermoplastic nylon resins are a suitable alternative for patients who are allergic to conventional metals and free monomer as studies have revealed a little or almost no free monomer releaser with the use of nylon bases [7].
Various processing techniques such as heat-polymerized, autopolymerized, light-polymerized, or microwave-polymerized acrylic resins have been used to repair the fractured dental prosthesis [8]. However, the autopolymerizing acrylic resin has been commonly utilized for repairing the fractured denture base and chipped artificial teeth. Regarding the surface treatment, a silica-coating by Rocatec® followed by silane coupling to improve the adhesion properties by using the sandblasting method has been used [9, 10].
The adhesion between the nylon base and repair materials can be further enhanced by surface treatment of the denture bases using different chemicals. These chemicals etch the surface and modify the morphology and chemical properties of the denture base [11]. Methyl methacrylate (MMA) has been commonly used for treating the fractured surfaces of the denture bases [12]. However, organic solvents such as acetone, ethyl acetate, isopropanol, toluidine [13], chloroform [14], and methylene chloride [15–17] have also been used to perform the surface treatment. Chemical surface treatment has been reported to raise the bond strength between the resin used for repair and the denture base [16]. The air blast technique is another surface treatment method, which involves the collision of the accelerated silica-coated alumina particles with the surface which results in the microscopic melting of the treated surface. This process allows the silica-coated alumina particles to penetrate and form an adhesive bond with the surface [18]. The adhesive bond exhibits satisfying strength on initial assessment; however, the aging process has revealed poor outcomes [9].
Solvent-assisted bonding is an effective method for repairing thermosetting acrylic resins [19]. Polyamides are generally stable and resistant when exposed to chemical insults. However, the presence of amide groups (-NHCO-) in a solvent makes polyamide prone to absorb water or other solvents and to form hydrogen bonds [20]. Traces of polar molecules in solvents cause plasticization of the polyamide matrix [21]. The plasticization of polyamides disrupts the network of hydrogen bonds which enhances the chain mobility [20]. Propionic acids, acetic acids, and butyric acids promote the adhesion through hydrogen bonding. Also, they cause hydrolysis that breaks the crosslinks and provides swelling generally similar to those of organic solvents [22].
Koodaryan and Hafezeqoran [23] revealed that the surface treatment of polyamide denture base with 5% acetic acid in aqueous ethanol (30/70 by volume) for 10 minutes may be an efficient and cost-effective method for increasing the shear bond strength to the autopolymerized reline resin.
This study aimed to evaluate the physical and mechanical properties for the adhesive bond of the thermoplastic nylon denture base using different resin materials, curing techniques, and chemical surface treatments.
2. Materials and Methods
2.1. Sample Grouping
The materials used in this study are listed in Table 1. A total of 150 sample bases of thermoplastic nylon resin were prepared. Fifty sample bases were repaired by microwave (micro) heat-polymerized resin, fifty were repaired using Ivomate (Ivo) autopolymerized resin, and fifty sample bases were repaired using light-polymerized (light) acrylic resin materials. Each of the three groups was further subdivided into five equal groups based on different chemicals used for surface treatment. These included the control group (Cont) without any surface treatment and four chemical groups which were monomer (Mon), acetone (Acet), ethyl acetate (Eth), and isopropanol (Iso).
Material
Brand name
Manufacturer
Batch number
Application
Processing method
Polyamide resin (Nylon 12)
Valplast™
Valplast International Corp., NY, USA
QTY: 10
Denture base material
Injection moulding technique; heating to 288°C under pressure of 0.1 MPa. The screwed flask was placed in hot oven at 75°C for 12 min
Heat-polymerized PMMA acrylic resin
Vertex™ Rapid simplified
Vertex, Netherlands
XX131P11
Repair material
Heat processed with a 500 W for 3 min
Autopolymerized PMMA acrylic resin
Vertex™ Castapress
Vertex, Netherlands
XY441P01
Repair material
Dough material cure at 45°C for 15 min under pressure of 2 bars
Light-polymerized acrylic resin
Unifast LC
GC Corp., Japan
Powder: 0712033
Liquid: 0712122
Repair material
The curing cycle was 470 N wave length for 10 min
Methyl methacrylate monomer
Vertex™ Rapid simplified
Vertex, Netherlands
XX131P11
Surface treatment material
Butt joint surface swabbed with monomer for 60 s
Acetone (CH3)2CO
Acetone
MW:58.08, UK
09200
Surface treatment material
Butt joint surface swabbed with acetone for 30 s
Ethyl acetate (CH3COOC2H5)
Ethyl acetate
MW:88.11, UK
09706
Surface treatment material
Butt joint surface swabbed with ethyl acetate for 120 s
Isopropanol (C3H8O)
Isopropanol
MW:60.10, UK
09200
Surface treatment material
Butt joint surface swabbed with isopropanol for 5 s
PMMA: poly(methyl methacrylate).
... This type of test method is commonly used to measure the bond strength between lining materials and denture resins but in order to obtain accurate results it is necessary to be sensitive to the force applied to the specimens [2,12]. Different surface treatments are required to increase the insufficient bond strength between polyamide resins and auto-polymerized relining resins [9,16,18]. In the present study, the most effective surface treatment was the tribochemical silica coating for group POL-GC. ...
... In this regard, application of ethyl acetate was also proposed to prepare the surfaces of heat-polymerized denture base resins [19]. Also, when ethyl acetate and MMA were compared pretreatment with MMA increased the flexural strength of the polyamide denture base resin [18]. Nevertheless, chemically activated 4-META/MMA-TBB resin bonds to both of the chairside auto-polymerized relining resin and the silica layer [16,20]. ...
This study evaluated the bond strength of relining materials to different denture base materials polyamide and polymethylmethacrylate denture base materials after various surface conditioning methods. Denture base resin specimens (N = 128; n = 8 per group) (10 × 10 × 2.5 mm³) were fabricated out of injection-moulded thermoplastic polyamide resin (POL) (Deflex) and heat-polymerized polymethylmethacrylate (PMMA, Dura Dent) (HC). The specimens were randomly divided into 4 main groups according to different surface conditioning methods: (a) No conditioning, control (C), (b) grinding with green stone (G), (c) application of primer (V), (d) silica coating with Al2O3 particles coated with SiO2 (Rocatec) (R). Half of the specimens in each group received auto-polymerized hard relining resin (GC, GC Reline Hard) and the other half PMMA based relining resin (SC, Dura Dent). After thermocycling (×5000), the bonded specimens were tested under tensile forces (0.5 mm/min). Data (MPa) were analyzed using Mann–Whitney U and Kruskal–Wallis tests (alpha = 0.05). Bond strength of relining resins were significantly higher to PMMA than to POL, regardless of the conditioning method (p < 0.05). While R positively affected the bond strength results (p < 0.05) (4.99 ± 1.65–3.27 ± 1.31), application V or G did not show significant effect to POL-relining resin adhesion. After R conditioning, bond strength values were significantly higher in HC-GC group (7.48 ± 2.32) than POL-GC group (3.27 ± 1.31) (p < 0.05). Adhesion of auto-polymerized relining materials to thermoplastic polyamide or polymethylmethacrylate denture resins could be improved after surface conditioning with silica-coating.
