RESUMO
<p><b>OBJECTIVE</b>To preliminarily investigate the relationship between the Lactate dehydrogenase (LDH) activity of Streptococcus mutans (S. mutans) and dental caries initiation.</p><p><b>METHODS</b>100 S. mutans strains derived from caries-active and caries-free individuals were cultured in BHI medium supplemented with glucose. Cells were extracted and ruptured, and the extracted liquid protein was quantified with Coomassie brilliant blue G250 staining methods. LDH activity was assayed using the pyruvate-dependent oxidation of NADH-with and without FDP.</p><p><b>RESULTS</b>LDH activity of the two groups strains had no difference (P > 0.05), but the distribution of differ class enzyme activity strains in the two groups was different (P < 0.05).</p><p><b>CONCLUSION</b>LDH activity of S. mutans is correlated to the initiation of dental caries to some extent. The measurement methods in this study can be applied in preliminary quantitation of LDH activity and the screening of S. mutans strains.</p>