Dental products come into contact with a diverse array of microorganisms. With over 700 microbial species identified in this environment, it’s a complex ecosystem to navigate. Fahimeh Tabatabaei, a dentist with a PhD in dental biomaterials, explains that not all bacteria residing in the oral cavity pose a threat. ” Some of these microorganisms form part of the normal flora and are routinely present in the oral environment,” she explains. “Termed commensal microorganisms, they play a crucial role in maintaining oral health by stimulating low levels of circulating and secretory antibodies, which may offer cross-reactivity against pathogens”. These microorganisms contribute to the development of oral biofilm on teeth in an organized manner. Under healthy conditions, this biofilm remains relatively stable over time, a phenomenon termed microbial homeostasis. However, when this balance is disrupted, an overgrowth of harmful bacteria can occur, leading to potential oral diseases.

This is where antibacterial dental products come into play. But how effective are they, and what factors should we consider when evaluating one? Dr. Tabatabaei, with her expertise in dental biomaterials and oral biology, will shed light on these questions in the following sections.

Oral Biofilm 

While bacteria can float freely in a fluid environment (planktonic), they tend to adhere to each other and solid surfaces, forming a community interconnected by extracellular matrix. This intricate structure is known as oral biofilm:  a well-organized assembly of living bacteria at various growth stages, firmly adhering to tooth surfaces and embedded within an extracellular matrix. Comprising bacterial products and saliva, this matrix contains proteins, polysaccharides, and lipids, along with cells circulating in saliva like epithelial cells, leukocytes, and macrophages, as well as inorganic components such as calcium and phosphorus.

Fahimeh elucidates that “microbes growing within biofilms exhibit markedly distinct properties compared to those in planktonic form. Notably, microbes in biofilm form consistently demonstrate greater resistance, underscoring the importance of considering biofilm dynamics when evaluating antimicrobial products”.

Oral Biofilm Location and the Relation to Oral Diseases

Any surface with access to the external environment can serve as a suitable substrate for biofilm formation. Fahimeh elaborates that variations in oxygen levels and nutrient sources give rise to distinct microbial communities in different oral locations. Naturally, the tooth surface harbors microorganisms capable of adhering to tooth surfaces (Supragingival) and even colonizing the space between the gums and teeth (Subgingival). While fresh plaque can be effectively removed from tooth surfaces through brushing, the accumulation of thicker plaque can significantly elevate bacterial counts, which are normally kept low.

“Some microorganisms, constituting part of the normal flora, typically exist in small numbers and pose no threat of disease. However, disruptions in microbial homeostasis—such as changes in host defenses, antibiotic treatment, oral hygiene practices, saliva flow, and dietary composition—can lead to their proliferation and subsequent disease onset,” Fahimeh emphasizes. “Moreover, supragingival and subgingival regions aren’t the sole sites susceptible to microbial colonization. Cavities resulting from caries, small gaps between dental fillings and tooth structures, infected root canals, implants, and dental prostheses can all serve as niches for biofilm formation”.

Consequently, various diseases, including caries, periodontitis, periimplantitis, root canal infections, candidiasis, denture stomatitis, and soft tissue infections, are intricately linked to biofilm formation. Prevention of these diseases hinges on the advancement of oral healthcare products and the development of dental materials endowed with antibacterial properties, geared towards prevention or treatment.

Antibacterial Dental Products: A Diverse Arsenal

Antibacterial dental products come in many forms, extending beyond the toothpaste and mouthwash on your bathroom shelf. Dr. Tabatabaei highlights the expanding range of options, including fillings and bonding agents with built-in antibacterial properties. Implants can now be coated for this purpose, and bone grafts or membranes may incorporate antibacterial materials as well. Even targeted treatments for specific bacteria, like enterococcus faecalis in root canals, are being developed. Fahimeh underscores the broad spectrum of antibacterial agents utilized in dental products, each employing distinct mechanisms of action and targeting specific bacteria. She explains her experience about the recent IADR meeting: “It was intriguing to see the plethora of posters at the recent IADR meeting showcasing antimicrobial products. These products utilized a wide array of innovative approaches, including bioactive antimicrobial therapies, anti-biofouling surfaces, novel delivery methods, nanoparticles, bioresponsive or smart products, as well as the integration of different agents into a single carrier or the combination of multiple strategies such as release-killing and contact-killing.”

With such a vast array of dental devices available, Fahimeh underscores the importance of careful classification. Understanding the specific clinical needs and the device’s intended use (preventative or treatment-oriented) is crucial before evaluating its antibacterial capabilities. Testing methodologies must also consider these diverse scenarios and the specific microbiological challenges these products may encounter.

Evaluating Antibacterial Dental Products: A Multifaceted Approach

In dentistry, bacterial infections are a major culprit behind treatment complications. This has led to a surge in antibacterial dental materials. But how do we ensure these products are truly effective? Fahimeh explains the challenges involved in evaluating these products.

“First, we need to understand the complex structure of oral biofilms, the root cause of many dental diseases. Second, we need to develop reliable models that mimic real-world conditions to accurately assess a product’s performance. An important factor is determining the optimal level of antibacterial activity that does not disrupt the delicate balance of oral flora. This depends on various factors like the location of the product in the mouth and the duration of its use.”

Another concern is cytotoxicity, Dr. Tabatabaei emphasizes. “Most antibacterial agents incorporated into dental materials operate through relatively nonspecific mechanisms. As a result, their bactericidal action often entails a comparable impact on cells, leading to cytotoxicity concerns.”

She adds: “These challenges require a blend of expertise. At iFyber, our team includes dental materials specialists, microbiologists, chemists, and molecular biologists. This allows us to take a comprehensive approach, tailoring assays (testing methods) to the specific needs of each product and client. Acknowledging the importance of regulatory considerations, we also leverage ISO standards like ISO 3990, a comprehensive guide for evaluating the antibacterial activity of many dental materials”. However, Fahimeh highlights that certain materials, such as those used for pulp capping, endodontic fillings, dental implants, nightguards, and additive manufactured materials, are not covered under this standard. Therefore, it’s imperative to develop appropriate evaluation methods tailored to these specific products.

As the dental industry continues to innovate, the pursuit of antibacterial dental products remains integral to enhancing patient care and promoting oral health. iFyber is a Contract Research Organization (CRO) specializing in evaluating the safety and efficacy of different biomaterials and medical devices including dental products. By staying at the forefront of research and development, iFyber is proud to contribute to the advancement of antibacterial dental materials, ultimately improving clinical outcomes and fostering better oral health for all.

Contact the team at iFyber to discuss your needs.