ABSTRACT
Background:
Denture resins made of polymethyl methacrylate (PMMA) are often utilized because of their cost, aesthetic appeal, and simplicity of production. However, their mechanical characteristics, specifically, their flexural strength, are problematic, particularly when used in therapeutic settings for an extended period of time. The flexural strength of three PMMA denture resins that are sold commercially is assessed and contrasted in this research.
Materials and Methods:
In vitro tests were conducted on three different kinds of PMMA denture resins (Brands A, B, and C). By ISO 20795-1:2013 guidelines, 45 specimens (15 in each group) with measurements of 65 mm × 10 mm × 3 mm were created. To replicate oral circumstances, specimens were thermocyclically heated (5°C to 55°C) for 5,000 cycles after being polymerized in accordance with the manufacturer’s instructions. A universal testing machine was used to perform a three-point bending test at a crosshead speed of 5 mm/min to assess flexural strength. Flexural strength (MPa) was calculated by recording the maximal force at fracture. Tukey’s post-hoc test and one-way ANOVA were used for statistical analysis.
Results:
Brands A, B, and C have mean flexural strength values (±SD) of 65.3 ± 5.2 MPa, 72.5 ± 4.8 MPa, and 68.1 ± 6.0 MPa, respectively. The flexural strength of Brand B was substantially greater than that of Brands A and C (P < 0.05). But there was no discernible difference between Brands A and C (P > 0.05).
Conclusion:
In terms of mechanical durability, Brand B is a better option for denture bases since it showed the highest flexural strength among the evaluated materials. To assess other characteristics like impact strength and biocompatibility in clinical settings, further research is advised.
KEYWORDS: Denture resins, flexural strength, in vitro study, polymethyl methacrylate, three-point bending test
INTRODUCTION
Denture bases often employ polymethyl methacrylate (PMMA) because of its advantageous qualities, which include cost-effectiveness, manufacturing convenience, and aesthetically pleasing appearance.[1] However, under functional and parafunctional stresses, its relatively low mechanical strength, especially its flexural strength, presents difficulties for clinical usage.[2,3] Denture base resins’ flexural strength is crucial because it dictates how well they can tolerate occlusal stresses and prevent fractures while in use.[4]
PMMA resins’ mechanical qualities have been improved by several investigations, including additions of fibers, nanoparticles, and other fillers.[5,6] Even though these changes have shown promise, dental professionals still need to choose commercially available PMMA resins since manufacturers provide a variety of formulas, polymerization techniques, and handling qualities.[7]
The purpose of this research is to assess and contrast the flexural strengths of three PMMA denture resins that are sold commercially. The results of this research might help doctors choose the best resin for denture base construction by identifying the material with better flexural capabilities, which would improve clinical outcomes and patient satisfaction.
MATERIALS AND METHODS
For this investigation, three commercially available denture resins made of polymethyl methacrylate (PMMA) were chosen: Brands A, B, and C. The resins were acquired in liquid and powder form and treated in accordance with the guidelines provided by the manufacturers. Following routine laboratory processing, the flexural strength of each brand was evaluated.
Fifteen specimens from each group, totalling forty-five specimens, were produced. The specimens, which were 65 mm by 10 mm by 3 mm, were made in compliance with ISO 20795-1:2013 requirements. To guarantee consistency, stainless steel molds were used. The manufacturer’s instructions were followed while mixing, packing, and polymerizing the PMMA resin. The specimens were polished and trimmed to eliminate surface imperfections after polymerization.
Every specimen was subjected to thermocycling to replicate the oral environment. With a stay period of 30 seconds in each bath and a transfer time of 10 seconds, the specimens underwent 5,000 cycles between 5°C and 55°C.
A universal testing machine’s three-point bending test was used to assess flexural strength. With a crosshead speed of 5 mm/min, a load was applied in the middle of the specimens, which were positioned on two supports with a 50 mm spread.
Tukey’s post-hoc test was used for pairwise comparisons after one-way ANOVA was used to find significant differences between the groups. Statistical significance was defined as a P value of less than 0.05. Statistical software was used for all analyses.
RESULTS
The flexural strength values of the three PMMA denture resins (Brand A, Brand B, and Brand C) were analyzed. The mean flexural strength and standard deviation (SD) of each group are summarized in Table 1. Brand B exhibited the highest mean flexural strength, followed by Brand C and Brand A. A statistically significant difference was observed among the groups (P < 0.05) based on one-way ANOVA, as shown in Table 2.
Table 1.
Mean flexural strength of PMMA denture resins
| Group | Number of Specimens (n) | Mean Flexural Strength (MPa) | Standard Deviation (SD) |
|---|---|---|---|
| Brand A | 15 | 65.3 | 5.2 |
| Brand B | 15 | 72.5 | 4.8 |
| Brand C | 15 | 68.1 | 6.0 |
Table 2.
Statistical analysis of flexural strength
| Comparison | P | Significance |
|---|---|---|
| Brand A vs. Brand B | 0.002 | Significant |
| Brand A vs. Brand C | 0.08 | Not Significant |
| Brand B vs. Brand C | 0.04 | Significant |
Brand B demonstrated significantly higher flexural strength compared to Brand A and Brand C (P < 0.05), as evident from Table 2. However, no statistically significant difference was observed between Brand A and Brand C (P > 0.05). These findings indicate that Brand B is the most mechanically durable PMMA denture resin tested in this study.
The mean flexural strength values and statistical comparisons are detailed in Tables 1 and 2, respectively.
DISCUSSION
The capacity of polymethyl methacrylate (PMMA) denture resins to tolerate masticatory pressures without breaking is determined by their flexural strength, which is an essential characteristic. The flexural strength of three PMMA denture resins that are sold commercially was assessed and contrasted in this research. The findings showed that, out of all the materials tested, Brand B had the greatest flexural strength, followed by Brands C and A.
Variations in the polymer composition, particle size distribution, and degree of polymerization, all of which are known to affect the mechanical characteristics of PMMA resins, could be the cause of Brand B’s better performance.[1,2] PMMA’s mechanical strength can be increased by using several production processes, such as high-impact modification and the addition of cross-linking agents, according to earlier research.[3,4]
Since temperature variations may have a substantial impact on the mechanical characteristics of denture materials, thermocycling was used in this work to replicate the oral environment. According to studies, PMMA may experience decreased flexural strength as a result of microstructural alterations brought on by repetitive heat cycling.[5,6] Nonetheless, the variations in flexural strength shown in this investigation imply that Brand B may be more resilient to these kinds of heat shocks.
In line with earlier research showing that regular PMMA formulations had moderate mechanical capabilities when compared to modified variations,[7] Brand C demonstrated intermediate flexural strength. However, Brand A showed the lowest flexural strength, which would restrict its clinical use, particularly in denture base regions that are subjected to significant stress.[8]
The results of this investigation align with previous studies that found differences in mechanical characteristics across several PMMA brands.[9] For instance, research by Vallittu et al.[10] and Gad et al.[11] highlighted the need for reinforcing techniques, including the addition of fibers or nanoparticles, to improve flexural characteristics. This investigation emphasizes the intrinsic variations among commercially accessible materials, even if it did not include such reinforcements.
CONCLUSION
In summary, Brand B outperformed the other PMMA denture resins in terms of flexural strength, which makes it a better option for clinical settings requiring strong mechanical endurance. These results highlight the need for physicians to carefully choose materials according to their mechanical characteristics in order to guarantee the best possible denture performance.
Conflicts of interest
There are no conflicts of interest.
Funding Statement
Nil.
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