Oral Bacterial Acid–Base Metabolism in Caries Screening: A Proof-Of-Concept Study

The objective of this cross-sectional study was to clinically validate an array of biochemical tests as caries screening tools for oral acid–alkali generation. Adult subjects (n = 185; mean 33.6 ± 10.6 y) were examined clinically for dental caries using the International Caries Detection and Assessment System (ICDAS) criteria. Bitewing radiographs were used to confirm the interproximal surfaces of posterior teeth. For the purposes of this study, subjects were classified as “caries-active” if they had at least one untreated caries lesion with ICDAS 4 or higher. Pooled supragingival plaque and unstimulated saliva samples were collected and assayed for pH changes from sucrose and urea metabolism using colorimetric tests. The validity of each test to discriminate between “caries-inactive” and “caries-active” subjects was assessed and compared with a commercial bacteriological caries-screening test using roc regression and logistic regression models. The areas under the curve (AUCs) (95% CI) of the plaque-urea (PU, 0.59 (0.51 to 0.67)), plaque-urea-glucose (PUG: 0.59 (0.51 to 0.67)) and saliva-urea-glucose (SUG, 0.59 (0.51 to 0.67)) tests did not differ significantly from the bacteriological tests (CRT-mutans, 0.62 (0.54, 0.70); CRT-lactobacillus, 0.63 (0.56 to 0.71) (P > 0.05), but the plaque-glucose (PG), saliva-glucose (SG), saliva-urea (SU) and saliva-plaque-glucose (SPG) tests had significantly smaller AUCs (P < 0.05). The AUCs for PU, PUG, SUG, and the CRT-mutans tests were larger in subjects who had no existing dental restorations (PU, 0.90 (0.77 to 1.04); PUG, 0.90 (0.79 to 1.01); SUG, 0.89 (0.69 to 1.08); CRT-mutans, 0.90 (0.73 to 1.08)). The incorporation of the biochemical tests into a multidimensional bacteriological/psychosocial caries screening model significantly increased the diagnostic value (sensitivity and specificity, 160.6; AUC, 0.846). In conclusion, as a proof-of-concept, the results of this study indicate that measuring urea metabolism together with sugar metabolism by dental plaque and saliva may have a promising role in caries screening either independently or as part of a multidimensional biological test. Knowledge Transfer Statement: The results of this study indicate that assessment of the oral acid/base balance may have a promising role in caries screening either independently, or as part of a multidimensional test.