Periodontal disease, the most common chronic inflammatory condition affecting teeth and supporting tissues, results in gingivitis and periodontitis. Despite its prevalence and growing understanding of its pathophysiology, diagnosis remains based on traditional clinical exams. Metabolomics, a field involving metabolic reactions, has been used to diagnose periodontal disease using saliva and GCF. Techniques like NMR spectroscopy and MS are used to gather data. Metabolomics offers a unique opportunity to impact discovery-driven science, shedding light on the mechanisms underlying periodontal disease development and functional relationships between metabolites. Salivary research is a relatively new field, and this chapter aims to examine metabolomics's use in periodontics and its potential for personalized treatment.
Periodontal disease is a prevalent chronic inflammatory disorder affecting teeth and supporting tissues, often leading to gingivitis and periodontitis. It negatively impacts mastication, aesthetics, and systemic health. The main etiological component is dental biofilms or bacterial plaque, which interact with the host and determine the severity of the disease. Despite increased knowledge of the pathophysiology and incidence of periodontal disease, diagnosis is still based on traditional clinical investigations. An accurate prognostic system is crucial for therapeutic strategies, and there are currently no evidence-based prognostic indicators for periodontitis.
The term 'metabolome' was first coined in the late 1990s and refers to the collection of small molecule metabolites found in an organism or cell, such as glucose, cholesterol, ATP, lipids, amino acids, organic acids, and steroids. The metabolome can be categorized into four groups: intracellular, extracellular, microbial, and xenometabolome.
The omics cascade has revolutionized the study of metabolites, leading to a more informed diagnostic and management process. This concept has led to a paradigm shift in diagnosis, as molecular diagnostics have begun to overweigh clinical diagnostics in periodontal practice. Metabolomics is a comprehensive approach to periodontal diagnostics, focusing on the study of small molecules in biological materials at specific states. These metabolites, which can be found in tissues, cells, or bioorganic fluids, can reveal semi-quantitative data about a person's entire metabolome. Metabolomics monitors and assesses carbohydrates, amino acids, lipids, and their by-products through intracellular processes. Any value that differs significantly from the standard suggests an associated condition, not all of which are limited to periodontal disease.
Metabolomics is a research method that uses samples from various sources, such as cell culture materials, tissues, and biofluids, to study inflammatory pathways. The collection and preparation methods of these samples can significantly affect the data and research conclusions. Various techniques are employed, such as baseline correction, scaling, normalizing, deconvolution, peak or spectrum alignment, and normalization and scaling. Multivariate analysis is the primary data analysis approach used in metabolomics, while univariate methods extract statistical significance. However, this method does not account for interactions between metabolic traits or potential confounding factors, increasing the risk of false positive or false negative results. Combining multivariate and univariate data analysis is recommended to maximize the extraction of significant features from metabolomic datasets.
Metabolomics in Periodontitis:
Periodontitis is influenced by dysbiotic microbiota and periodontal inflammation, leading to disease progression. Metabolomics can establish a connection between biological function in both healthy and pathological states, improving treatment results in personalized medicine. Chronic periodontitis is characterized by the colonization and growth of gram-negative obligatory bacteria, particularly P. gingivalis and other red complex bacteria. These bacteria use exotoxins, enzymes, and toxic metabolites to cause tissue degradation and undermine periodontal tissue integrity. Chronic periodontitis is associated with higher levels of acetone, a significant metabolomics by-product from isopropanol.
Glycerol, a key component of metabolic activities, serves as a signal for the presence of the periodontal pathogenic population. The decreased glycerol levels observed in periodontitis may be due to the use of glycerol as an osmoregulatory agent or carbon source during bacterial colonization. These metabolites may function as diagnostic markers and monitor periodontal disease activity.
Metabolites play a crucial role in the pathophysiology of periodontitis, and GCF is considered the best biofluid for this purpose. Several inflammatory mediators, such as proteins, proteinases, and cytokines, have been identified using GCF. The analysis of biomarkers in GCF could help predict a patient's vulnerability to attachment loss and provide new insights into the biomarkers driving periodontal disease progression.
Salivary metabolic profiling can provide a comprehensive picture of the alterations brought on by periodontal disorders. Salivary indicators in the form of enzymes such as alkaline phosphatase, esterase, glucuronidase, aminopeptidase, immunoglobulins, and steroid hormones are already thought to be the cause of periodontitis. A variety of potential biomarkers, including host or bacterial enzymes and prostaglandin E2, have been proposed as diagnostic candidates. Additionally, 8-hydroxydeoxyguanosine, a byproduct of oxidative DNA damage, has been suggested as a novel salivary diagnostic for periodontitis.
Metabolomics has emerged at the perfect moment, with two primary techniques for gathering information on metabolomics: nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). MS spectroscopy has its main advantage in sensitivity, mass precision, and the ability to examine metabolites in living organisms or intact tissues, as well as in liquid states like serum and urine.
Metabolomics is already having a significant impact in various scientific fields, with methods such as direct infusion-mass spectrometry (DI-MS), liquid chromatography-mass spectrometry (LC-MS), high-sensitivity gas chromatography-mass spectrometry (GC-MS), and high-resolution mass spectrometry (HRMS). These methods provide in situ spatial information for many metabolites while maintaining the morphological integrity of the tissues or cells under investigation. It is a valuable omics-based technology due to its low exposure and high cost. It requires investment in a lab setup and resources for experiments.
However, it is crucial to obtain trial facts as transformation or degradation of metabolites can lead to time loss. Not all naturally occurring metabolites can be commercially measured or evaluated, and kits for such evaluations are still being developed. Quantifying results is challenging due to semi-quantitative data. Currently, the focus is on definitively measuring metabolite quantities, which are easier and more commonly quantified than other biological units. This could be a useful option for periodontal diagnostics in the future.
Future Scope & Trends:
Metabolomics offers a unique opportunity to impact discovery-driven science, surpassing other approaches like transcriptomics, proteomics, and genomes. As metabolomics evolves, it has the potential to combine data from other biomolecules. This will significantly influence public health by translating findings into clinical tests. Healthcare professionals continue to demand disease-specific biomarkers, and omic technologies can meet this need. Metabolomics will resolve the problem of biomarker finding, but integrating genomic and proteomic research data will provide the evidence needed to identify valuable indicators.
Advancements in technology and data analysis in "omics" fields are assisting in assessing and identifying the activity of periodontal disease and its response to diagnostic treatment. Metabolomics is an essential tool for evaluation and diagnosis, as it can reveal inflammation, immune response, and tissue deterioration at the site of periodontal disorders.
Salivary research is a relatively new subject, and the examination of multiple protein metabolites can shed light on the mechanisms underlying periodontal disease development and functional connections among metabolites. Metabolomics may prove useful in diagnostic medicine as a predictor or indication of disease activity. However, it is still a relatively new strategy with its own challenges. Overcoming these obstacles and conducting continuous research is crucial for its integration into clinical periodontal therapy. Metabolomics offers early diagnosis, tracking the course of the illness, identifying various forms of periodontitis, gauging treatment success, determining medication efficacy, and separating systemic and non-systemic periodontitis.