The power of nature in propolis
Improving the durability of acrylic dentures
Dentures are medical devices that must combine several key features: mechanical durability, biological safety, and aesthetics. For decades, polymethyl methacrylate (PMMA) has been the primary material used to make them. This material is well known to both dentists and dental technicians. Although PMMA is a proven and widely used material, it is not without its limitations. Dentures can crack, are susceptible to mechanical damage, and can promote the growth of microorganisms on their surfaces.
In response to these problems, scientists are increasingly seeking ways to modify classic prosthetic materials to improve their properties without compromising their appearance or safety of use. One such solution is propolis, a natural substance produced by bees from plant resins, enriched with waxes, essential oils, and bioactive compounds. The results of research by a team from Iraq, published in the journal Polymers in Medicine of the Medical University of Wrocław and selected as an Editor-in-Chief's Top Pick 2025, show that even a small addition of this substance can significantly improve the quality of prosthetic acrylic.
Propolis – a natural substance with a wide range of applications
Propolis has long been known in natural medicine and dentistry as a substance with antibacterial, antifungal, and anti-inflammatory properties. It is a mixture of plant resins, waxes, and biologically active compounds that bees use to protect their hives from microorganisms. In the context of dental prosthetics, it is particularly important that propolis does not have a strong color, as this can negatively affect the aesthetics of dentures.
Researchers asked whether the biological properties of propolis could be harnessed to improve the mechanical properties of the materials used to make dental prostheses. Unlike previously tested metallic additives, which strengthened acrylic but caused discoloration, propolis enabled durability, naturalness, and an acceptable appearance.
Just 1% of propolis is enough
The study was a strictly controlled laboratory experiment. The researchers prepared samples of prosthetic acrylic subjected to standard thermal polymerization, i.e., as used in everyday prosthetic practice. The material was divided into four groups: one without propolis and three with 1%, 2%, and 3% of the substance added.
Each sample was then tested for properties directly relevant to the use of dentures. Flexural strength, impact resistance, surface hardness, and smoothness were evaluated. These parameters determine not only the durability of the denture, but also patient comfort and ease of hygiene maintenance.
Analysis of the results clearly showed that the material obtained the most favorable properties with the addition of 1% propolis. Importantly, increasing the amount of this substance did not lead to further improvement and, in some cases, even worsened the acrylic's parameters. This means that it is not the fact of using the additive itself that is crucial, but its precisely selected concentration.
“We conducted a pilot study with higher and lower concentrations. We found that 1% propolis does not affect the color of the material, while improving selected mechanical properties, which was crucial for our work," explains study co-author Dr. Intisar J. Ismail from the Department of Dental Prosthetics, Faculty of Medicine and Dentistry, Al-Esraa University in Baghdad.
From the patient's point of view, this means that the denture can be more resistant to damage while maintaining a natural appearance, which is of great importance in everyday use.
Change in properties
The most important improvement was greater resistance to bending, i.e., a lower risk of the denture breaking during chewing or accidental dropping. This is one of the most common causes of denture damage and, at the same time, a major source of patient discomfort.
“The most important property that has been improved is the transverse strength of the material," emphasizes Dr. Intisar J. Ismail.
In addition, the material with 1% propolis showed greater impact resistance and a smoother surface. The latter feature is not only technically important but also has health implications, as smooth surfaces are less susceptible to bacterial and fungal growth.
Although propolis is known for its antibacterial and antifungal properties, the authors of the study emphasize that, in this particular project, these properties, in combination with prosthetic acrylic, have not yet been fully evaluated.
“Its antifungal and antibacterial properties have been confirmed in other studies. We have prepared acrylic samples for such tests, but we need to repeat them,” the researcher points out.
If such effects can be confirmed directly in prosthetic material in the future, dentures could not only be more durable, but also actively reduce the risk of oral infections.
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Next stages of research
The authors indicate that the next step could be the use of so-called coupling agents, which improve the bonding of additives with acrylic. Such a solution could further strengthen the material.
“We have proposed using silane as a coupling agent. We expect that this would improve the mechanical properties, especially impact resistance”, the researcher explains.
The results presented show that natural substances can effectively support the development of modern dental materials when used appropriately. The addition of a small amount of propolis improves the durability of prosthetic acrylic without compromising its appearance, while paving the way for further research into materials that combine mechanical properties with biological potential.
A.Hasiak
FAQ: The power of nature in propolis
What is prosthetic acrylic (PMMA) and why is it so widely used?
Prosthetic acrylic, or polymethyl methacrylate (PMMA), has been used for many years to make dentures. It is relatively light, easy to work with, aesthetic, and well-tolerated by the body. However, its limitations include susceptibility to cracking and mechanical wear over the long term.
What is propolis, and why was it added to acrylic?
Propolis is a natural substance produced by bees, known for its antibacterial, antifungal, and anti-inflammatory properties. Scientists became interested in it as a potential additive to acrylic because it is biocompatible, has a neutral color, and contains chemical compounds that can improve the structure of prosthetic materials.
Why were different concentrations of propolis tested?
The study examined how different amounts of propolis affect the properties of acrylic. It turned out that precise concentration selection is crucial. Too little provides no clear benefits, while too much can degrade the material's properties. The study showed that the best results were obtained with the addition of 1% propolis.
What does the improvement in “flexural strength” mean in practice?
Flexural strength is the ability of a material to resist breakage during chewing or in accidental situations, such as when a denture falls. Increasing it reduces the risk of denture breakage and extends the durability of the prosthetic restoration in everyday use.
Does the addition of propolis change the appearance of the denture?
No. One of the key findings of the study was that adding 1% propolis does not affect the color or aesthetics of acrylic. This is particularly important because many other reinforcing additives, such as metals, can cause unwanted discoloration of the material.
Can dentures with propolis be healthier for the oral cavity?
Propolis is known for its antibacterial and antifungal properties, but this study primarily evaluated its mechanical properties. The authors emphasize that the potential protective effect against oral infections requires additional laboratory and clinical studies.
Are such dentures already available to patients?
No. The study was a laboratory-based (in vitro) study. This means that, before such a solution can be used in everyday prosthetic practice, further research is needed, including biological and clinical tests to confirm the material's safety and effectiveness in real-world conditions.
What could be the next step in this research?
The researchers plan to test whether combining propolis with additional binding substances can further improve the durability of acrylic. In the future, this approach could lead to a new generation of prosthetic materials that are both more durable and more oral health-friendly.
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Editor in Chief's Top Pick 2025
About the journal:
(Polim Med) is a long-established scientific journal, published continuously since 1971. It is currently a semi-annual, peer-reviewed, open-access title, offering free and immediate access to high-quality research for the global scientific and medical community. As an independent, multidisciplinary platform, the journal provides a forum for exchanging scientific knowledge and clinical experience in the rapidly developing field of polymer-based medical technologies. It publishes original research articles (technical, analytical, experimental, and clinical), preliminary communications, and review papers on the design, development, and application of synthetic and natural polymers and advanced biomaterials.
The journal’s growing international visibility is reflected in its current metrics — its CiteScore Tracker is now 4.5. The scope spans medicine and materials science, including pharmaceutics, biotechnology, veterinary science, chemical and physical sciences, with strong coverage of biochemistry, controlled drug delivery, pharmacology, dentistry, implantology, and bioengineering. We welcome interdisciplinary submissions translating polymer research into diagnostics, therapies, and patient care.
This material is based on the article:
Rasha Mehdi, Intisar J. Ismail, Nabaa Al-Nawab, Ban M. Jassim
Polymers in Medicine
DOI: 10.17219/pim/204545
Web. A. Maj
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