Another advantage of saliva as a clinical tool is its greater sensitivity and correlation with levels in blood. With the emergence of promising new technologies, numerous salivary biomarkers for various medical conditions such as cancer, autoimmune, viral, bacterial, cardiovascular, and metabolic diseases have been discovered, making saliva an increasingly valuable tool for diagnosis and monitoring of various diseases. Therefore, it is crucial to diagnose oral diseases, such as dental caries, periodontal disease, and oral cancer, as early as possible because it can lead to better treatment outcomes and prevent further complications. Delayed diagnosis can lead to irreversible damage to the oral tissues and, in some cases, may even spread to other parts of the body. Saliva has been identified as a promising diagnostic fluid for detecting various oral diseases because it is easy to collect and contains a wide range of biomolecules such as proteins, DNA, and RNA. Salivary biomarkers can be used for early detection, diagnosis, and monitoring of disease progression, as well as predicting treatment response. In addition, saliva-based diagnostic tests are non-invasive, painless, and cost-effective, making them ideal for regular screening and monitoring of patients. This review explores the latest advancements in identifying biomarkers for prevalent oral diseases, as well as the biosensing technologies that can detect these biomarkers with enhanced sensitivity, selectivity, accuracy, and practicality.