Salivary Markers as Diagnostic Tool for Dental Caries, Periodontal Disease and Peri-implantitis: A Literature Review

Biomarkers are molecules that can be used in screening, diagnosing, characterising, and monitoring diseases, or as prognostic indicators. There are many salivary molecules that can be used as biomarkers of oral diseases, such as enzymes, specific and nonspecific proteins, antibodies, and other substances. This study aimed to research the effectiveness of using salivary biomarkers as a means of diagnosis and raised the following question that, are salivary biomarkers sufficient to diagnose oral diseases such as caries, periodontal and peri-implant disease, avoiding systemic diseases? Given this question, this study aimed to investigate the topic in recent scientific literature, looking for information that could clarify the issue. Therefore, a bibliographic review on the topic was carried out, and scientific articles were searched in the PubMed database. The findings showed that salivary biomarkers are sufficient to diagnose oral diseases since several biomarkers in saliva have already been identified, which allow the early diagnosis of these conditions, the monitoring of their progression and their response to treatments. This review may be the first to offer a summary classification of existing salivary biomarkers that can be collected by saliva in a simple and noninvasive manner, allowing for early diagnosis. The main finding in this regard was the immune molecules beta-defensin-2 and LL-37, collagen I, fibronectin, soluble Cluster of Differentiation 14 (sCD14) cells, Interleukin (IL)-4, IL-13, Interleukin-2 receptor alpha chain (IL-2 RA) and eotaxin/CCL11 as predictors of dental caries. For periodontal disease, the higher levels of saliva of IL-1 beta, IL-6, MMP-8, MMP-9, MIP-1 alpha, Osteoprotegerin (OPG), Tissue Inhibitors of Metalloproteinases-1(TIMP-1), salivary Total Antioxidant Capacity (TAOC), albumins, uric acid, Superoxide Dismutase (SOD) and peroxidase were related to the pathogenesis of the disease. For peri-implantitis, dysbiosis must be associated with the presence of IL-1 beta, Tumour Necrosis Factor alpha (TNF-alpha), TIMP-2, Vascular Endothelial Growth Factor (VEGF), OPG and procalcitonin. These findings may provide an easier view of the co-presence of other components in the oral environment, such as proteins/cytokines in saliva, transient microbials, which can contribute to the pathogenesis of the disease and date the multifactorial aetiology of oral diseases. This constitutes a personalised medical approach, reinforcing the power of clinical examination and medical history assessments to form an accurate diagnostic tool.