Adherence of Candida albicans on Polymethyl Methacrylate in Probiotics Solution

Abstract

Probiotics are living microorganisms that induce health benefits and advantages on the host, especially when it is used in an adequate amount. Over the years, different definitions of probiotics are established based on their mechanisms, site of action, delivery format, method, or host. As probiotics have various effects, they are used in different areas and one of them is dentistry. Approximately 150 species of yeast are referred to as Candida. Normally, Candida lives without causing harm to its environment which in the most cases is the mucus membranes of various parts of the body, including the ears, eyes, gastrointestinal tract, mouth, nose, reproductive organs, sinuses, skin, stool, and vagina. These mucus membranes are known as beneficial flora and the yeast component in the flora performs important functions in the human body. However, an overgrowth of Candida albicans results from an imbalance in the body’s normal flora. The term is Candidiasis or Thrush. Most common way to treat this condition is by using Nystatin solution. According to new studies, probiotic solutions can be used to reduce the number of Candida albicans adherence and thereby treat Candidiasis or Thrush. We aim to discuss the actual role of probiotic solutions in oral cavity and treatment of Candidiasis.

1. Introduction

The term probiotic comes from the Greek language meaning “for life.” It was first introduced by Lilly and Stillwell in 1965 to describe substances that stimulate the growth of microorganisms. In 1971, Sperti used the probiotic term to define substances secreted by tissue, which have the ability to stimulate microbial growth. Parker first used the term probiotic in relation to its modern usage, defining it as “organisms and substances that contribute to intestinal microbial balance.” Later, Fuller amended this definition by emphasizing the important role of probiotics in establishing the balance of intestinal microbial. This reformed definition emphasizes on the requirement of viability for probiotics and introduces the aspect of a beneficial effect on the host. Havenaar et al. expanded the definition further to include mono or mixed cultures of microorganisms applied to animals or humans that improve the properties of the indigenous microflora. Salminen and Schaafsma further broadened the definition of probiotics to include dairy products such as fermented cereals, sauerkraut, and salami that contain viable probiotic microorganisms. This definition showed that probiotics benefit, effect health and nutrition of the host. Salminen and Schaafsma broadened the definition of probiotics even further by no longer limiting the proposed health effects to influences on the indigenous microflora.

Today, we know that unlike Salminen definition probiotic microorganisms are also can be find in nondairy products [1].

Candida is actually another name for fungi that define over 150 yeast species that exists harmlessly in healthy individuals. An imbalance in normal flora may lead to an overgrowth of one of these species named as Candida albicans, which can cause candidiasis or thrush, a fungal infection that has a widespread impact on the body’s overall health and well-being. Candida is one of the normal flora substances, which is known as “beneficial flora” and also has a useful purpose in the body. When there is an imbalance in the normal flora, it can cause an overgrowth in the number of Candida albicans. The expression used for the overgrowth of Candida albicans that may lead to an infection is Candidiasis or Thrush. This is a fungal infection which is also called Mycosis through any of the species of Candida; however, Candida albicans is the most common one. When this infection happens, it can cause a widespread deterioration to our overall health and well-being of the body.

Oral candidiasis is a common fungal infection in the oral mucosa, caused by Candida albicans. Many people have this organism, and the rate of carriage increases with age [2]. Denture stomatitis, an inflammation of the denture-bearing mucosa affecting two-thirds of elderly denture wearers, is often associated with Candida. It is more common on the palatal mucosa and in female patients [3].

There are different types of denture materials and one of the most common of them is polymethyl methacrylate. Polymethyl methacrylate is a lightweight, synthetic polymer that is an economical alternative to polycarbonate. Unlike polycarbonate, polymethyl methacrylate (PMMA) does not contain potential harmful subunits, such as bisphenol-A, and is easier to handle, process, and less expensive. This chapter aims to discuss the effect of probiotic solutions on the adherence of Candida albicans to polymethyl methacrylate dentures.

In this chapter, we aim to talk about the effect of probiotic solutions on adherence of candida albicans to polymethyl methacrylate dentures.

2. Probiotic bacteria

The international definition of probiotics is “a living microorganisms that induce health benefits and advantages on the host, especially when it is used in an adequate amount.” Over the years, different definitions of probiotics are established based on their mechanisms, site of action, delivery format, method, or host. As probiotics have various effects, they are used in different areas [1].

2.1 History

The term probiotic comes from the Greek language meaning “for life.” It was first introduced by Lilly and Stillwell in 1965 to describe substances that stimulate the growth of microorganisms. In 1971, Sperti used the probiotic term to define substances secreted by tissue which have the ability to stimulate microbial growth. Parker first used the term probiotic in relation to its modern usage, defining it as “organisms and substances that contribute to intestinal microbial balance.” Later, Fuller amended this definition by emphasizing the important role of probiotics in establishing the balance of intestinal microbial. This reformed definition emphasizes on the requirement of viability for probiotics and introduces the aspect of a beneficial effect on the host. Havenaar et al. expanded the definition further to include mono or mixed cultures of microorganisms applied to animals or humans that improve the properties of the indigenous microflora. Salminen and Schaafsma further broadened the definition of probiotics to include dairy products such as fermented cereals, sauerkraut, and salami that contain viable probiotic microorganisms. This definition showed that probiotics benefit, effect health and nutrition of the host. Salminen and Schaafsma broadened the definition of probiotics even further by no longer limiting the proposed health effects to influences on the indigenous microflora.

According to today’s definition, probiotics are called “healthy bacteria” with many health benefits such as preventing intestinal infections, improving immunity, lactose intolerance and intestinal microbial balance, and anti-hypercholesterolemia and antihypertensive effect, and reduces traveler’s diarrhea. Recent research has also focused on their use in the treatment of skin and mouth diseases [2].

2.2 Probiotics and oral cavity

Because oral cavity is the first section of the gastrointestinal tract, it is logical to think that some probiotics may affect the oral microbiota. The most commonly used probiotic bacterial strains are the genera Lactobacillus and Bifidobacterium. Specific lactobacilli species are yet to be identified as exclusively in oral microbiota, although some common ones include L. paracasei, L. plantarum, L. rhamnosus, and L. salivarius. Bifidobacteria is among the first anaerobic bacteria to colonize in the oral cavity, and possible species isolated from oral samples are B. bifidum, B. dentium, and B. longum. Culture-based studies confirm that bifidobacteria is among the first anaerobes in the oral cavity. Indeed, both lactobacilli and bifidobacteria can be found in breast milk, suggesting early exposure of the oral cavity to these bacteria [4].

2.3 Potential mechanisms of probiotic effects in the oral cavity

Probiotics can improve oral health through three main mechanisms: normalization of oral microbiota, modulation of the immune response, and metabolic effects. By inhibiting harmful bacteria and promoting beneficial bacteria, probiotics can help restore balance in the mouth and reduce the risk of gum disease and tooth decay. Probiotics can also modulate the immune response and prevent inflammation, particularly in individuals with compromised immune systems. Lastly, probiotics can have metabolic effects that improve overall oral health by breaking down food particles and preventing the buildup of plaque and tartar. In summary, the potential mechanisms of probiotic action in the oral cavity resemble those in the intestine and can benefit oral health significantly [5].

2.4 Observed effects of probiotics on oral health

• Oral candida

• Caries and caries-associated microbes

• Periodontal disease

• Halitosis

(Focus of this chapter is on the effect of probiotic bacteria on adherence of Candida albicans on polymethacrylate denture. However, we will talk about other titles briefly).

3. Candida

Candida refers to a type of fungi that includes over 150 species of yeast. Typically, Candida exists without causing harm in healthy individuals who are not immunosuppressed. It is present in various mucosal areas, such as the ears, eyes, gastrointestinal tract, mouth, nose, reproductive organs, sinuses, skin, stool, and vagina, and is referred to as the “beneficial flora” due to its useful purpose in the body. However, an imbalance in the normal flora can cause Candida albicans, among other species, to overgrow and cause a fungal infection called Candidiasis or Thrush.

If Candidiasis occurs, it can lead to significant negative impacts on overall health and well-being it and can create a widespread impairment to our overall health and well-being of body.

Oral candidiasis is one of the fungal diseases affecting the oral mucosa. This infection is caused by the yeast Candida albicans. As explained, Candida albicans is one of the normal substances of oral microflora, found in approximately 30 to 50% of people. The carrier increased with the age of the patient. One of the conditions associated with Candida is denture stomatitis [2].

3.1 Denture stomatitis

Denture stomatitis is a term that has been applied to an inflammation of the denture-bearing mucosa, which may affect as many as two-thirds of an elderly population of denture wearers. It is more common on the palatal mucosa and in female patients.

3.1.1 Classification

Classification of denture stomatitis is usually based on the clinical appearance of inflamed mucosa observed beneath maxillary complete dentures. The most commonly used classification system is the one proposed by Newton in 1962. He suggested three different types of denture stomatitis: (1) pinpoint hyperemic foci, (2) diffuse hyperemia of the denture-supporting tissues, and (3) papillary hyperplasia. However, Budtz-Jorgensen and Bertram (1970) used different terms: (1) simple localized inflammation, (2) simple diffuse (generalized) inflammation, and (3) granular inflammation.

3.1.2 Symptoms

Denture stomatitis is a condition that often presents without noticeable symptoms. However, some patients may experience mucosal bleeding and swelling, as well as a burning or painful sensation, halitosis, an unpleasant taste, and dryness in the mouth. Studies have estimated that 28–70% of patients with denture stomatitis may report some levels of oral discomfort.

3.1.3 Etiology

The large majority of scientists believe that the cause of denture stomatitis is multifactorial, some stating that no primary etiological factor exists. However, specific factors have been considered to be more important:

• Denture trauma (including continuous denture wearing);

• Denture cleanness (including reaction to denture plaque);

• Allergic and primary irritant reactions to denture base materials;

• Dietary factors (including resultant hematological deficiencies);

• Candida infection;

• Systemic factors (including predisposing factors);

• Miscellaneous factors.

Regarding that using denture is one of the important causes of denture stomatitis, using specific kind of denture base materials can prevent this disease [6].

4. Different bases of denture

Dentistry as a profession we are familiar with now a day is considered to have begun about 3000 BC. About 2500 BC, the first dental prosthesis has been constructed in Egypt. But by 700 BC, professional dentures were made and during medieval times, dentures were rarely considered as a treatment option. From past to present, different materials have been used to fabricate dentures which are as follows:

• wood

• bone

• ivory

• porcelain (1774)

• gold (1794)

• vulcanite dentures (1839)

• tortoise shell (1850)

• gutta-percha (1851)

• cheoplastic (1856)

• aluminum (1867)

• celluloid (1869)

• bakelite (1909)

• vinyl resin (1930)

• stainless steel and base metal alloys (1937)

• polymethyl methacrylate (1937)

They are some features that are desired for a denture to contain. Dentures should be biocompatible, nontoxic, noncarciogenic, and translucent. The color of the denture should match color of teeth and gums [7].

4.1 Polymethyl methacrylate (PMMA)

Polymethyl methacrylate (PMMA) is a synthetic polymer that is used as an economical alternative to polycarbonate when extremely high strength is not necessary. Unlike polycarbonate, PMMA does not contain potentially harmful subunits like bisphenol-A. Moreover, it is easier to handle, process, and less expensive than polycarbonate, as illustrated in Figure 1.

Figure 1.

Sample of polymethyl methacrylate denture.

In clinical practice, PMMA is mostly used as prosthesis for craniofacial tissue defects such as dentures. PMMA has great mechanical properties and low toxicity. PMMA is the most regular substance used to design complete and partial dentures. Despite its great features, it cannot accomplish all mechanical necessities of prosthesis. Flexural fatigue due to repeated masticatory and high-impact forces caused by dropping are the major causes of denture fractures. Features of PMMA denture are summarized in Figure 2 [8].

Figure 2.

PMMA features.

Polymethyl methacrylate (PMMA) is a popular material used in the fabrication of complete dentures, accounting for 95% of cases. This is due to its ease of processing, repair, and polishing, as well as favorable physicochemical properties and acceptable esthetics. For over 80 years, different processing techniques, such as pouring or mold filling (compression and injection molding), have been used to create dentures from PMMA. Each of these techniques presents its own benefits and drawbacks, making them more suitable for certain clinical procedures. Despite these differences, PMMA remains a versatile and popular option in complete denture fabrication because it is light weighted, easy to fabricate, and affordable. However, PMMA has some limitations, including low fracture resistance, poor physical properties in oral fluids, and potential allergic reactions. These limitations can impact clinical performance and denture longevity.

To overcome these drawbacks, several attempts have been made to improve the physical and mechanical properties of PMMA, such as material reinforcements, alternative material use with different compositions, and polymerization techniques, all of which aim to enhance the properties of PMMA to improve the clinical outcomes.

Digital denture fabrication has advanced with the use of computer-aided design and computer-aided manufacturing (CAD-CAM) technology. Two common methods used in this process include subtractive (milled) and additive (3D-printing) approaches.

In the milled method, a pre-polymerized PMMA disc is used to mill the denture base, resulting in high strength and adequate surface properties due to its fabrication under high temperatures and pressures. Compared to conventional fabrication methods, milled denture bases have no polymerization shrinkage and less residual monomer, providing significant advantages.

However, the performance of 3D-printed resins is currently lower than milled and conventional resins. The 3D-printing method builds the denture base layer-by-layer using photo-polymerized fluid resins, which leads to noticeable impacts on the strength and surface properties of the material after thermal cycling. Furthermore, 3D-printed resins exhibit higher levels of water sorption and solubility compared to traditional resins.

Although there are advantages and drawbacks to both the milled and 3D-printed denture base fabrication methods, further research is needed to improve the performance of 3D-printed resins and enhance their potential for use in dentistry [9, 10].

5. Adherence of Candida albicans on PMMA mechanisms

According to hydrophobic proteins on the surface of Candida albicans, this fungus is considered to be a highly hydrophobic substance. The adherence of Candida albicans to denture base surfaces has been associated closely with the hydrophobicity of the microorganism as a significant contributory physiochemical force.

For hydrophobic surfaces such as PMMA, monomer units exposed on the surface have interaction with the hydrophobic domains on a protein of Candida albicans by means of sturdy hydrophobic bonds. Therefore, the attractive hydrophobic interactions could bring about an inclination for Candida albicans to adhere greater with ease to hydrophobic surfaces than to hydrophilic surfaces. The contribution of electrostatic interplay between Candida albicans and polymeric surfaces is secondary to the hydrophobic force, due to the fact the adherence manner takes region in the presence of repulsive pressure [11].

6. Adherence of Candida albicans on PMMA in probiotics solution

It has been strongly counseled that probiotic consumption improves oral healthiness. However, the impact of probiotics at the microbial fame of denture wearers remains blurring. The acrylic prosthesis dentures in edentulous people possess a non-dropping, tough floor thereby facilitating candida adhesion and subsequent fungal colonization. The ability of the yeast to stick to the epithelial cells superficially and to the fitting denture floor remains as the essential key requirement for colonization of candida species and outcomes in making the denture as a store of contamination.

To evaluate the adherence of Candida albicans on PMMA denture base materials, many in vitro studies were conducted. In one study, two groups of PMMA dentures were experimented. First group of PMMA dentures was coated with probiotic solution at varying concentrations dipped in saliva containing candida species, and the other PMMA denture group was dipped in saliva containing candida species without probiotics. The result of this study is shown in Figures 3 and 4, and Tables 1 and 2.

Figure 3.

The detection rate of candid species was 92.0% in the control group and it was reduced to 16.2% in the test group [12].

Figure 4.

Depicting the comparison of probiotics in varying concentrations against candida species [12].

DISKS	Mean value of C. albicans colony count—without probiotics	Probiotic concentration (Πg/ml)	Mean value of C. albicans colony count—with probiotics
DISK 1	6551	2.5	4551
DISK2	9643	5	4655
DISK3	6777	10	3222
DISK4	8666	15	844
DISK5	5244	20	320

Table 1.

Depicting the comparison of probiotics in varying concentrations against candida species [12].

Probiotic concentration (πg/ml)	2.5	5	10	15	20
Mean value of C. albicans colony count	4551	4655	3222	844	320

Table 2.

Depicting the comparison of Candida albicans colony count in varying probiotic concentrations [12].

This study had two important result:

1. Probiotic application on denture base resin (PMMA) did decrease the Candida albicans count compared to the denture base without probiotic application.

2. As the concentration of probiotic over the denture base increases, the candida cell count decreased respectively [12].

One other study showed that adhesion and colonization of probiotic bacteria on PMMA dentures prevent attachment of Candida albicans through competition for adhesion sites, nutrients, and products of environmental change. In this study, five groups containing 20 PMMA dentures were examined. Each of these groups was dipped in Candida species and then exposed to different substance including the following: (1) probiotic solution of L. rhamnosus GG, (2) probiotic solution of k12 Streptococcus salivarius, (3) sodium hypochlorite solution, (4) normal saline, and (5) nystatin solution. According to the results of this study, probiotic solutions can be used to reduce the number of Candida albicans adhering to the PMMA denture base [13].

7. Probiotic bacteria and oral hygiene

Oral diseases like caries, gingivitis, or periodontitis are associated with a shift in bacterial biofilm composition and subsequent host reactions. Probiotics have been found to be beneficial in preventing or treating these conditions. In vitro studies have demonstrated that probiotic species can have potential effects on cariogenic or periodontal pathogens.

A meta-analysis of studies on the clinical effectiveness of probiotics in treating gingivitis has suggested that probiotics can significantly improve gum condition during therapy. When used regularly during orthodontic treatment, probiotics can reduce the number of bacteria from the Streptococcus mutans group in a patient’s saliva and inhibit the expression of inflammatory mediators and an excessive immune response.

Probiotics eliminate and inhibit the growth of pathogenic microorganisms by competing for receptor sites and secreting metabolites with antibacterial activity. They also stimulate specific and non-specific immune responses by activating T lymphocytes and producing cytokines, allowing their effective use in oral diseases.

Probiotics offer several advantages over conventional antibiotics, including the ability to specifically target harmful bacteria without affecting beneficial bacteria. They restore balance to the oral microbiome and reduce the risk of oral diseases. Regular use of probiotics can be safe and effective for maintaining oral health, particularly in conditions such as gingivitis and periodontitis. However, more research is needed to determine the optimal strains, doses, and duration of probiotic use for specific oral health conditions [14, 15].

7.1 Caries and caries-associated microbes

Dental caries is a complex disease that arises mostly from bacterial infection, resulting in tooth demineralization and destruction (as shown in Figure 5). Tooth decay is a gradual process that occurs when acidogenic bacteria in the bacteria-laden biofilm and remnants of food accumulate on the tooth surface and eventually leads to tooth damage, loss, and infection. These bacteria thrive in microbial communities that form dental plaque accumulating on the tooth surface. Among the bacterial species found in the biofilm are Streptococcus mutans, Streptococcus sobrinus, and Lactobacillus, which produce organic acids as they metabolize fermentable carbohydrates. Organic acid production leads to the undesired low pH levels in the tooth environment, causing demineralization of the tooth structure. Oral bacteria are vital etiological factors in caries development, with S. mutans, the primary causative microorganism discovered in a caries lesion, being the most prominent in dental caries pathogenesis.

Figure 5.

Dental caries, a multifactorial disease.

There is evidence from multiple studies that prebiotic bacteria can inhibit caries development and probiotic supplements seem to reduce caries incidence in preschool children and schoolchildren with a high caries risk. Several studies suggest that consumption of products containing probiotic bacteria (lactobacilli or bifidobacteria) reduces the number of mutans streptococci in saliva causing reduction of dental caries [16, 17, 18].

7.2 Periodontal diseases

Periodontal diseases are prevalent among adults and are divided into two stages: gingivitis and periodontitis based on the presence or absence of attachment loss. Gingivitis is characterized by the presence of gingival inflammation with no loss of connective tissue attachment (as shown in Figure 6). Meanwhile, periodontitis is characterized by gingival inflammation accompanied by attachment loss and the resorption of coronal portions of tooth-supporting alveolar bone (also shown in Figure 6). Plaque bacteria are responsible for both conditions, inducing pathological changes in the tissues, either directly or indirectly. Although conventional therapies are effective, research continues through complementary therapies to improve periodontal treatments. Recently, probiotics have gained considerable interest as a possible management option against periodontal diseases, with several clinical trials conducted to investigate their impact on oral health.

Figure 6.

Normal periodontium, gingivitis, periodontitis.

A new approach of treating gingivitis and periodontitis that has been tried during the last few years is to control a number of infectious diseases through using and consuming of probiotics, so that the disease-causing pathogens are eliminated, promoting the development of a healthy flora, thus leading to restoration of health. Probiotic bacteria, especially lactobacilli, were effective adjunct for treating periodontal disease, particularly when combined with mechanical removal of pathogenic biofilms. Studies indicate that adjunctive use of specific probiotic supplements leads to significant amelioration of disease indices (probing pocket depth, gingival index, plaque index, bleeding on probing, and clinical attachment level), and reduces the need for antibiotics and surgery procedures [19].

7.3 Halitosis

Halitosis is a challenging chronic problem to address in the dental field. Aside from its apparent social impact, it also affects patients psychologically, leading to an increase in demand for dental treatments. Halitosis usually has an oral cause, originating from the breakdown of sulfur-containing amino acids on the tongue and in the periodontal sulcus, leading to the release of volatile sulfur compounds (VSC). Traditional methods such as scaling or root planning and chemotherapeutic solutions like chlorhexidine have shown some effectiveness, but their results are short-lived, and they have negative side effects, such as disrupting the oral cavity’s homeostasis. Therefore, probiotics have emerged as a promising alternative with inhibitory effects on oral halitosis and without any of the side effects associated with the conventional treatments.

A single study suggests that the oral probiotic Streptococcus salivarius, which is found early in healthy individuals as a colonizer of oral surfaces and represents the primary microorganism in the tongue microbiota, has limited capacity to produce volatile sulfur compounds responsible for halitosis. On the other hand, other research advocates for the use of probiotics in managing halitosis. However, the existing evidence is not persuasive enough to support the efficacy of using probiotics for halitosis management. For more effective future studies, standardized recruitment protocols for halitosis subjects and organoleptic measurements are necessary when using probiotics as an intervention for managing halitosis [20, 21].

8. Conclusions

This chapter was written with the goal of evaluating the effect of probiotic solution on the adherence of candida albicans, the most common cause of candidiasis or thrush, on the polymethyl methacrylate denture in patients using partial or complete denture.

Based on the results of this chapter, following conclusion can be drawn:

1. Probiotic solutions can be used to reduce the number of C. albicans adhering to the removable denture base.

2. Probiotic application on PMMA dentures decreased the C. albicans count compared to the denture base without probiotic application.

3. As the concentration of probiotic over the denture base increase, the candida cell count decreased, respectively.