Thermoplastic Denture Base Materials Research Articles

Microbial Adhesion to Different Thermoplastic Denture Base Materials in Kennedy Class I Partially Edentulous Patients.

Introduction Since the polished and fitting surface of the denture base may promote the colonization of microorganisms, it is essential to know how the different types of denture bases prevent or encourage the adhesion of microorganisms. This study aimed to compare the microbial adhesion to the polished and fitting surfaces of thermoplastic nylon, thermoplastic acetal, and thermoplastic acrylic denture bases in Kennedy Class Ⅰ, partially edentulous patients. Materials and methods Thirteen patients were included in the study. The group consisted of eight males (61.54%) and five females (38.46%), with an age range of 41-50 years (mean age 46.1 years). Three types (groups) of removable partial dentures will be made for each patient using different thermoplastic denture base materials: thermoplastic nylon; thermoplastic acetal; and thermoplastic acrylic. The polished and fitting surfaces of the denture bases were swabbed after a one-month follow-up period. Microbial adhesion was evaluated by counting the microorganisms' colony-forming units (CFU) in the collected specimens. The data were collected and statistically analyzed. Results The study revealed no statistically significant difference in microbial adhesion to both polished and fitting surfaces between all types of studied thermoplastic denture base materials. However, the results showed that for the polished surface, the microbial adhesion median of thermoplastic acrylic denture base (40.5 CC x 102/ml) was higher than that of thermoplastic acetal (29.0 CC x 102/ml) and thermoplastic nylon (16.0 CC x 102/ml). Regarding the fitting surface, the microbial adhesion median of thermoplastic acrylic (51.0 CC x 102/ml) is higher than that of thermoplastic acetal (41.0 CC x 102/ml) and thermoplastic nylon (23.0 CC x 102/ml). Conclusion The thermoplastic nylon denture base materials showed less microbial adhesion among the studied thermoplastic materials, so it may be recommended to be used as a denture base material for individuals at high risk of denture stomatitis.

Evaluation Of Silano Adhesive Efficiency in Improvement of Shear Binding Strength of Synthetic Teeth to Thermo-Plastic Denture Material

Background: One of the most serious problems concerning denture performance is the possibility of prosthetic tooth displacement due to increased chewing efficiency. The nature of the mechanical bonding between thermoplastic denture base materials and acrylic teeth has aggravated the problem of tooth debonding. The study aiming to examine the strength of shear bond between prosthetic teeth and thermoplastic base material utilizing silano (silane coupling agent) and mechanical surface modifications (Alumin-ablasting, T. Shape hole) of tooth ridge lap pre and post (100 hrs.) of accelerated ageing conditions. Materials and method: The surface treatments of (120) maxillary central incisors were chosen and grouped into 6 groups of 20 samples each. Each group split into before and after (100hrs.) according to ageing (n=10). Measurement of shear bonding strength applied by a universal testing equipment with 0.5mm/min crosshead speed. Statistical analyses were done using one-way ANOVA test and Tukey’s (HSD) test. Results: Statistics showed high significant variation in average binding force after several surface manipulations in contrast to the control group at (P < 0.000). Regarding surface manipulations, dual treatment of “Alumina-blasting + silano “revealed significant elevation of binding strength in compare to “alumina-blasting” alone (P < 0.001). Similarly, with “T. hole + silano” yielded in greatly increased bonding strength compared to using “T. hole” alone (P < 0.001). a great reduction in bonding strength value was indicated along all treated groups after ageing process (P < 0.000) except the group treated with “T. Hole + silano” show non-significant variations at (p = 0.112). Conclusion: combination treatment (chemo-mechanically) with “T. Hole + silano” improve shear binding strength and not effected with ageing process.

The Effect of Pineapple Peel Extract As a Denture Cleanser on Flexural Strength of Nylon Thermoplastic Denture Base Materials

Background: Nylon thermoplastic has been widely used as denture base material because of its esthetic property, high flexibility, and flexural strength. It is very important to maintain the removable dentures’ cleanliness, which is frequently done with the chemical technique by immersing the denture in a solution. The composition of malic acid and citric acid from pineapple peel extract has antibacterial and antifungal properties, so it can be used not only as a denture cleanser but also affect the flexural strength of denture base material. Objective: To determine the effect of pineapple peel extract as a denture cleanser on the flexural strength of nylon thermoplastic denture base material. Method: This is experimental laboratory research with a post-test-only group design using 36 samples, namely 18 Valplast samples and 18 Lucitone FRS measuring 64mm X 10mm X 2.5mm divided into 4 groups (Valplast control, Valplast experiment, Lucitone FRS control, and Lucitone FRS experiment). The samples were treated by immersing them in sterile distilled water as control, and in 3.5% pineapple peel extract for 15 minutes 3 times a day for 10 days as treatment. Flexural strength measurement using Universal Testing Machine. The data obtained were analyzed by the One Way ANOVA test. Result: There was a decrease in flexural strength in the Valplast and Lucitone FRS groups immersed in 3.5% pineapple peel extract. Lucitone FRS groups had higher flexural strength than Valplast’s. Conclusion: There is a decrease in flexural strength of nylon thermoplastic denture base after being immersed in 3.5% pineapple peel extract.

Erratum to: Discolouration of polyamide microcrystalline denture base plates after exposure to filter cigarette smoke [Padjadjaran Journal of Dentistry. 2020;32(2):1-5.

Introduction: Denture users with smoking habit often complain about colour changes in their dentures, especially on the base part. Polyamide microcrystalline is a thermoplastic denture base material and does not undergo many colour changes. The purpose of this study was to analyse the effect of filter cigarettes smoke exposure on the colour of polyamide microcrystalline materials. Methods: This study used posttest only control group design — plate-shaped sample with a size of 2 x 2 x 0.5 cm3. Nine samples as controls were immersed without exposure to the cigarette smoke, and 9 samples were immersed in artificial saliva with exposure to the filter cigarette smoke by six cycles, where one cycle was in the form of smoke exposure from one cigarette at 30-minute intervals. Cigarette exposure lasts for 21 days using a smoking simulation tool. Every seven days of exposure, colours were evaluated using a DSLR camera. The photos were then analysed with Adobe™ Photoshop in the CIELab colour space. The results were analysed afterwards by a one-way ANOVA variant test, and advance difference tests were analysed using a Post-Hoc test. Results: There was a significant colour change after exposure (p < 0.05), but the control group did not experience discolouration. The highest rate of colour change occurred in the second week, while in the third week the colour changes still occurred but tend to be stable. Conclusion: Exposure to the filter cigarette smoke changes the colour of polyamide microcrystalline denture base.

Discolouration of polyamide microcrystalline denture base plates after exposure to filter cigarette smoke

Introduction: Denture users with smoking habit often complain about colour changes in their dentures, especially on the base part. Polyamide microcrystalline is a thermoplastic denture base material and does not undergo many colour changes. The purpose of this study was to analyse the effect of filter cigarettes smoke exposure on the colour of polyamide microcrystalline materials. Methods: This study used posttest only control group design — Plate-Shaped sample with a size of 2 x 2 x 0.5 cm3. Nine samples as controls were immersed without exposure to the cigarette smoke, and 9 samples were immersed in artificial saliva with exposure to the filter cigarette smoke by six cycles, where one cycle was in the form of smoke exposure from one cigarette at 30-minute intervals. Cigarette exposure lasts for 21 days using a smoking simulation tool. Every seven days of exposure, colours were evaluated using a DSLR camera. The photos were then analysed with Adobe™ Photoshop in the CIELab colour space. The results were analysed afterwards by a one-way ANOVA variant test, and advance difference tests were analysed using a Post-Hoc test. Results: There was a significant colour change after exposure (p < 0.05), but the control group did not experience discolouration. The highest rate of colour change occurred in the second week, while in the third week the colour changes still occurred but tend to be stable. Conclusion: Exposure to the filter cigarette smoke changes the colour of polyamide microcrystalline denture base.Keywords: Polyamide microcrystalline, filter cigarette smoke, discolouration, denture base

Physical properties and color stability of injection-molded thermoplastic denture base resins.

PURPOSEThe purpose of this study was to compare mechanical and physical properties of injection-molded thermoplastic denture base resins.MATERIALS AND METHODSIn this study, six commercially available products (VA; Valplast, LC; Lucitone, ST; Smiltone, ES; Estheshot-Bright, AC; Acrytone, WE; Weldenz) were selected from four types of thermoplastic denture base materials (Polyamide, Polyester, Acrylic resin and Polypropylene). The flexural properties and shore D hardness have been investigated and water sorption and solubility, and color stability have evaluated.RESULTSFor the flexural modulus value, ES showed the highest value and WE showed significantly lower value than all other groups (P<.05). Most of experimental groups showed weak color stability beyond the clinically acceptable range.CONCLUSIONWithin the limits of this study, thermoplastic denture base resin did not show sufficient modulus to function as a denture base. In addition, all resins showed discoloration with clinical significance, and especially polyamides showed the lowest color stability.

Vertical Displacement in Unilateral Extension Base Flexible Removable Dentures.

The need for flexible thermoplastic denture base materials has increased due to patient demand for better esthetic outcomes. Designs aimed at improving esthetic outcomes can cause difficulties for prosthodontists, however, from the viewpoint of function and maintenance. Therefore, the purpose of this study was to investigate vertical displacement in unilateral extension base denture models, comparing that obtained by flexible removable dentures with that by conventional metal clasp dentures. Models of unilateral extension base flexible removable dentures for mandibular defects were prepared. Periodontal ligament and jaw mucosa were simulated using a silicone impression material. Four types of flexible removable denture, with or without a metal rest, and two metal clasp dentures made of acrylic resin as a conventional design were used as dental prostheses. The amount of vertical displacement in the defect areas was measured under a load of 50 N at the first and second molars. Among the 6 types of dentures investigated, the amount of vertical displacement was greater with flexible removable dentures than with metal clasp dentures. This vertical displacement tended to decrease significantly, however, with the use of a metal rest with the flexible removable dentures. Esteshot with a metal rest, in particular, showed the smallest amount of displacement in the flexible removable dentures (first molar, 0.265±0.007 mm; second molar, 0.423±0.008 mm). These results indicate the importance of the application of rests in unilateral extension base flexible removable dentures. It may be useful to employ a metal rest in conjunction with a flexible removable denture to reduce load on the underlying mucosa, as is done with conventional partial dentures.

Effect of Two Different Cleansing Agents on Color Stability of Thermoplastic Denture Base Material

Purpose: Researchers tried to improve the mechanical properties of poly methyl methacrylate(PMMA) denture bases. Development of alternative materials such as thermoplastic denture basematerials as polyamide had also been reported in the literature, however, it has not been well studiedregarding color stability. The aim of this in vitro study was to evaluate the effect of two differentcleansing agents on color stability of thermoplastic denture base material. Materials and methods:Thirty samples were fabricated from polyamide (Vertex Thermosens thermoplastic denture basematerial). Samples were divided into Three groups: 10 each. Group I (control group): soaked indistilled water, Group II: soaked in Corega cleansing agent and Group III: soaked in Efferdentcleansing agent. Results: Statistical non-significant results were found. A slight non-significanteffect on color stability was found more with Efferdent than Corega cleansing agent and water.Conclusion: Disinfecting polyamide denture base material (Vertex Thermosens) could be donesafely with Corega and Efferdent cleansing agents.

Evaluation of Different Removable Denture Materials in Kennedy Class I Partially Edentulous Situation Mostafa Abosrie(1), Maged El saadawy (2) and Mohamed Aboshama(3) Codex

BACKGROUND: Although Cast Chromium Cobalt alloy has been the material of choice for fabricating Removable Partial Dentures (RPDs) but it has certain drawbacks. New material like the flexible Nylon based Super Polyamide has been introduced to overcome these drawbacks. The present study compared the above two materials for three clinical parameters. MATERIALS AND METHODS: The study was carried out on 15 patients, the selected cases were Kennedy Class I, with missing teeth first, second and third molars in each distal extension side. These fifteen patients received three RPDs; each one was used for six months. Three types of RPDs were made from different base materials; cobalt chromium alloy and thermoplastic denture base materials, (Group A): RPDs made of cast Cr-Co alloy incorporating RPI clasping system with denture base made of heat cured acrylic resin. (Group B): RPDs made of flexible nylon based super polyamide resin incorporating flexible circumferential clasps and denture bases made of flexible nylon, with metal occlusal rests. (Group C): RPDs made of flexible nylon based super polyamide resin. After insertion of each denture, their Clinical performances were evaluated periodically for six months for the following parameters (Gingival index, plaque index and pocket depth). RESULTS: Statistically significant results were obtained in favor of flexible RPDs, in the parameters of (Gingival index, plaque index and pocket depth).Both groups B and C showed less similar values for (Gingival index, plaque index and pocket depth). during usage’ with the incidence being slightly higher for patients wearing the cast RPDs (Group A). CONCLUSION: Based on the favorable results of this study, it can be summarized that the flexible RPDs is a viable alternative to cast RPDs in Kennedy class I partially edentulous situation in the short term.

To Compare and Evaluate the Bond Strength of Acrylic Denture Teeth with Heat Cure Acrylic Resin and Thermoplastic Denture Base Material after Different Surface Treatments of Acrylic Teeth - An In Vitro Study

Background: Denture teeth made of acrylic resin are preferred because they chemically bond to denture base material but the problem of debonding is also common with the use of acrylic teeth. Many attempts have been done to improve bond strength of acrylic teeth which involves mechanical and chemical means. With the use of recently introduced thermoplastic denture base materials, the problem of tooth debonding has been increased due to the mechanical nature of the bond between these materials and the acrylic teeth. There is limited literature on bond strength of acrylic teeth and flexible denture materials and the methods to enhance it. The present study evaluates and compares the bond strength between acrylic teeth and heat cure resins and thermoplastic resins after different known denture tooth surface treatment methods, including use of methyl methacrylate; sandblasting and prefabricated vertical groove. Method: A total of 180 maxillary right central incisors were selected and divided into six groups of 30 samples each, according to the surface treatments and denture base material (heat cure or thermoplastic resins) used for processing. The bond strength of all specimens were tested in Universal Testing Machine. The obtained data were subjected to statistical analysis. Result: Results showed that there was statistical significant difference in mean bond strength after various surface treatments and processing of acrylic teeth with either heat cure or flexible denture material. Interpretation &amp; Conclusion: The present findings suggest that vertical groove in the ridge lap area has highest bond strength amongst the groups processed with flexible denture material, and treatment of specimens with methyl methacrylate monomer for 5 sec has highest bond strength amongst all groups.

Effect of Two Cleansing Agents on Water Sorption and Solubility of Two Thermoplastic Denture Base Materials

Aim: Some patients experience adverse reactions to poly (methyl methacrylate)-based (PMMA) dentures. Polyamide (PA) as an alternative to PMMA has, however, not been well documented regarding water sorption and water solubility. The aim of this in vitro study was to evaluate the effect of two different cleansing agents on water sorption and solubility of two different thermoplastic denture base materials. Materials and methods: A total of 60 samples were fabricated from two different thermoplastic denture base materials (i.e. vertex thermosens and breflex). The samples were divided into 3 groups. Each group was including 20 samples, 10 samples from each denture base material. Samples of Group I were subjected to the distilled water as a control group. While samples of Group II were subjected to the Corega as a cleansing agent and samples of Group III were subjected to Fitty dent as the other cleansing agent. Effect of the two cleansing agents on the two-different thermoplastic denture base materials were evaluated and compared with regards water sorption and solubility. Results: Non-significant results were found regarding water sorption and solubility. The fittydent cleansing agent had a slight more non-significant effect on color stability of vertex thermosens and breflex denture base materials than corega cleansing agent and water. The corega and fittydent cleansing agents had a nonsignificant effect on water sorption and solubility of vertex thermosens and breflex denture base materials. Conclusion: Corega and fittydent cleansing agents could be used safely for disinfecting denture base materials (vertex thermosens and breflex) as they had non-significant effect on color stability, water sorbtion and solubility.

Clinical evaluation of chewing efficiency for flexible removable partial dentures in bilateral free-end saddle cases

Statement of problem: Increasing flexibility of removable partial denture increase the patient comfort and esthetics at the cost of bite force and chewing efficiency. Purpose: To compare and study the variation of chewing efficiency in different types of thermoplastic denture base materials used for restoring Kennedy class I removable partial dentures. Materials and Methods: Eight patients were included in the study. Four types (groups) of removable partial dentures will be made for every patient in the test group: thermoplastic Nylon RPD, thermoplastic Acetal RPD, thermoplastic PMMA RPD and thermoplastic PMMA with hard PMMA combination. Nylon and Acetal dentures were made using thermo-injectable technique. F. PMMA and H. & F. PMMA dentures were made using compression moulding technique. Chewing efficiency was measured after 1 week, 3 months and 6 months follow-up period for the two types. Chewing efficiency was evaluated by colored chewing gum and computerized color analysis. The test data were collected and analyzed. Results: H. & F. PMMA and F. PMMA had higher chewing efficiency than Nylon and Acetal 1 week after insertion for all chewing cycles. Only 10 chewing cycles affected by increasing the follow up period and denture adaptation for all types. Conclusion: Combination of flexible denture base materials with hard denture base material is recommended to enhance chewing efficiency.

Shear Bond Strength of Acrylic Denture Teeth to PMMA and Polyamide Denture Base Materials

Introduction: Detachment of denture teeth from denture base is one of the most common reasons for costly denture repairs .This study aimed at evaluating the bond strength of an acrylic denture tooth to polyamide injection-molded thermoplastic denture base material compared with three conventional polymethylmethacrylate (PMMA) denture base resins. Materials and Method: A total of 40 acrylic denture molar teeth were randomly allocated into four groups (n=10) of heat-polymerized (HP), Auto-polymerized (AP), Injection molded (IM) and Polyamide thermoplastic (PT). All denture base/acrylic teeth combinations underwent 5000 thermal cycles (5-55◦C).Samples were subjected to shear bond strength test by a universal testing machine with a 1 mm/min crosshead speed .Data were analyzed using ANOVA and Tukey’s tests(α=0.05). Results: Mean ±SD of shear bond strength values were (MPa) 4.82±1.21, 4.52±1.67, 3.7±0.84 and 4.13±2.21 for groups HP, AP, IM and PT respectively. No significant difference was found among the experimental groups (P=0.429). Conclusion: Polyamide thermoplastic denture base resin was similar to conventional PMMA denture base materials in terms of bond strength to artificial denture teeth.

Effect of Surface Treatments and Adhesive Materials on the Shear Bond Strength of Artificial Denture Teeth to Denture Base Resins

The purpose of the current study was intended to evaluate the effect of different surface modifications and different adhesive materials on the shear bond strength of artificial teeth to heat-polymerized and thermoplastic denture base materials using different repair techniques. Forty cross-linked artificial teeth used to construct different types of acrylic based denture prosthesis were selected to be bonded to two types of denture base materials, heat-polymerized acrylic resin denture base material, and thermoplastic acrylic resin denture base material. The specimens were divided into four subgroups according to the repair technique and adhesive material used. The base surfaces of all acrylic teeth then were moistened with monomer prior to bonding to the denture base specimens. Then, the specimens were tested using Universal Testing Machine for shear bond strength. The results were analyzed by using two-way analysis of variance (ANOVA) statistical analysis and multiple comparison tests, α ≤ 0.05. The effect of the types of denture base materials vs the surface conditioning methods displayed a statistically significant difference. This study concluded that monomer surface treatment of the bonded surface of artificial denture teeth and the use of cyanoacrylate adhesive followed by additional microwave polymerization displayed better shear bond strength when compared with other repair techniques. Artificial teeth debonding from their denture bases is a common complication in dental practice. The current study evaluates different repairing techniques. Within the limitation of this study, the use of cyanoacrylate adhesive in combination with microwave polymerization is one of the best techniques of repairing denture teeth debonding.

Flexible Thermoplastic Denture Base Materials for Aesthetical Removable Partial Denture Framework

Conventional fixed partial dentures, implant supported Fixed Partial Dentures (FDPs) and removable partial dentures are the most common treatment modalities for the aesthetic and functional rehabilitation of partially edentulous patients. Although implants and FDP have certain advantages over removable partial dentures, in some cases, removable partial dentures may be the only choice which is available. Removable cast partial dentures are used as definitive removable prostheses when indicated, but location of clasps may affect aesthetics. So, when patient is concerned about aesthetics, flexible partial dentures which is aesthetically superior to flipper and cast partial dentures, may be considered. But for the success of flexible removable partial denture, proper diagnosis, treatment planning and insertion technique of this prosthesis is very important, which have been thoroughly described in this article.

Injection Molding Technique for Fabrication of Flexible Prosthesis from Flexible Thermoplastic Denture base Materials

ABSTRACT Purpose To know properties, step-by-step procedure for fabrication and insertion of flexible prosthesis. Background Flexible denture base materials were introduced to dentistry by the name of Valplast and Flexiplast in 1950's. Injection molding technique is used for fabrication of various types of prostheses from these materials and fluid resins. Pryor used injection molding technique for introducing unpolymerized acrylic resin into the mold. In the mid 1970's Ivoclar introduced an injection molding system which used an acrylic resin modified for the injection molding process. Recently, numbers of dental manufacturing companies have introduced injection molding systems. Materials and methods The flexible denture base materials are superpolyamides which are available in the form of granules in cylinders of different sizes. These materials are thermoplastic in nature and needed to be converted into fluid form before pouring into mold under pressure. Each cylinder should be plasticized for 15 to 20 minutes at 550 to 560°F in an electric cartridge furnace before injecting the material into the flask. While injecting, the cylinder should be aligned with opening of flask and the levers of the press should be turned rapidly to apply firm pressure until the springs of the press are fully compressed. The pressure should be maintained for 3 to 5 minutes and the flask should be allowed to bench cool for 15 to 20 minutes before opening. Conclusion This technique can be used for fabrication of different types of prostheses from flexible denture base materials and fluid resins. How to cite this article Singh K, Gupta N. Injection Molding Technique for Fabrication of Flexible Prosthesis from Flexible Thermoplastic Denture base Materials. World J Dent 2012;3(4):303-307.