Interaction between the Oral Microbiome and Dental Composite Biomaterials: Where We Are and Where We Should Go

Abstract

Dental composites are routinely placed as part of tooth restoration procedures. The integrity of the restoration is constantly challenged by the metabolic activities of the oral microbiome. This activity directly contributes to a less-than-desirable half-life for the dental composite formulations currently in use. Therefore, many new antimicrobial dental composites are being developed to counteract the microbial challenge. To ensure that these materials will resist microbiome-derived degradation, the model systems used for testing antimicrobial activities should be relevant to the in vivo environment. Here, we summarize the key steps in oral microbial colonization that should be considered in clinically relevant model systems. Oral microbial colonization is a clearly defined developmental process that starts with the formation of the acquired salivary pellicle on the tooth surface, a conditioned film that provides the critical attachment sites for the initial colonizers. Further development includes the integration of additional species and the formation of a diverse, polymicrobial mature biofilm. Biofilm development is discussed in the context of dental composites, and recent research is highlighted regarding the effect of antimicrobial composites on the composition of the oral microbiome. Future challenges are addressed, including the potential of antimicrobial resistance development and how this could be counteracted by detailed studies of microbiome composition and gene expression on dental composites. Ultimately, progress in this area will require interdisciplinary approaches to effectively mitigate the inevitable challenges that arise as new experimental bioactive composites are evaluated for potential clinical efficacy. Success in this area could have the added benefit of inspiring other fields in medically relevant materials research, since microbial colonization of medical implants and devices is a ubiquitous problem in the field.

The Antibacterial Effects of Resin-Based Dental Sealants: A Systematic Review of In Vitro Studies

“…The methods for analyzing the antibacterial activity of restorative materials have been criticized in the literature [ 26 , 41 , 42 ]. This stems from the lack of standardization of the tests, the misinterpretation of purely qualitative analyses or the misuse of quantitative tests.…”

“…The other concern about the antimicrobial activity tests related to the characteristics of the microbial inoculum used [ 26 , 41 , 42 ]. From the nineteen studies selected, seventeen tested the dental sealants against S. mutans .…”

Recent Progress in Antimicrobial Strategies for Resin-Based Restoratives

“…However, these contact-dependent antimicrobial restoratives have several limitations: their antibacterial activity may not be as strong as a free-form coating, due to the heavy dependence on the chemical binding process and the direction of the covalent attachment of the antibacterial agent [ 69 ]; and dead or compromised bacteria and salivary proteins coating the resin surface may lead to the ineffectiveness of surface killing [ 20 ]. The existing problems are introduced in detail below.…”

“…Once a new antimicrobial resin composite has been developed, a series of assessment will be carried out to evaluate whether it holds the promise of inhibiting bacterial adhesion and reducing biofilm formation. Several methods are available to determine bacterial viability, including the gold standard, colony-forming unit [ 20 ] determination, followed by the evaluation of biofilms via microscopy. The other methods include metabolic activity evaluation, inhibition zone testing via disc diffusion and lactic acid production, and measurement of turbidity via spectrophotometry [ 124 ].…”

“…Another strategy is to covalently anchor the antimicrobial agent to the resin matrix by polymerization. In addition, antifouling dental resins to deter microbial adhesion or adjust the composition of biofilms are also common strategies [ 20 ]. In this review, we mainly summarize the articles published predominantly over the past 5 years, and divide the antimicrobial strategies of composite resins into three categories: antimicrobial agent release, contact-dependent strategies and multi-functional strategies.…”