The over-arching objective of this application is the creation of a simple, rapid, inexpensive diagnostic test that can be used during an office visit to detect caries activity before overt carious lesions are apparent so that interventions can be made before permanent damage to the dentition occurs. The specific objective of this application is the clinical validation of an immunoassay measuring GtfB as a saliva-based marker for caries activity in children from a population where Early Childhood Caries (ECC) is prevalent. This method is predicated on an intimate understanding of the pathogenesis of Dental caries. Three glycosyltransferases (GtfB, GtfC and GtfD) are secreted by S. mutans when it colonizes the tooth surface. These enzymes cleave dietary sucrose into its constituent monosaccharides, glucose which is polymerized into soluble and insoluble glucans that create the tightly adherent, bacteria-rich biofilm that characterizes caries, and fructose which is utilized as an energy source and yields enamel-dissolving acids. The central role of Gtfs in disease progression makes them plausible markers for active caries. In a recent cross-sectional clinical trial, the Bowen laboratory distinguished children with ECC from disease-free children with about 80% diagnostic accuracy by measuring the levels of GtfB in their saliva. With such a promising start, two issues become paramount: 1) whether the GtfB immunoassay will be an effective tool for identifying caries-active children prospectively; and 2) ways by which the clinical performance of the assay can be optimized while the method is made useable in an office setting. This application addresses exactly these questions. The focus of Specific Aim 1 is a 100 patient clinical trial to determine whether GtfB measurement can identify children who have the disease Dental caries before they have clinically detectable carious lesions. Clinically caries-free children 24-60 months old will be examined for white spot lesions or frank cavitation every three months for a year. Saliva samples will be taken at the same time and GtfB measured. The clinical question will be: It is not clear whether elevated salivary GtfB values predict the emergence of detectable carious lesions 3, 6 or 9 months later.
Specific Aims 2 and 3 address the creation of additional anti-GtfB monoclonal antibodies and alternative immunoassay formats so we can ultimately make a saliva-based, rapid, inexpensive, instrument-free diagnostic test for incipient Dental caries. Public Health Significance: Use of GtfB as a Diagnostic for Caries Activity. Dental caries remains a major source of morbidity and expense. In the United States alone, $48 billion are spent each year repairing the consequences of this completely preventable disease. A particularly severe form, Early Childhood Caries (ECC) is common in impoverished urban and rural populations creating what the Report of the Surgeon General called a silent epidemic. Among the tools needed for reducing the burden of Dental caries is a simple, inexpensive, in-office, diagnostic test that can identify children with active caries so that interventions can be made before their teeth become irreversibly damaged. The diagnostic must be simple and rapid enough that it can be used in a pediatric or Dental office. The first goal is to validate a saliva-borne, pathogen-derived marker that is the proposed analyte in such a longitudinal test. ? ? ?
