RESUMEN
<p><b>OBJECTIVE</b>To identify Streptococcus mutans (S. mutans) strains from clinical samples.</p><p><b>METHODS</b>Plaque samples from caries-active and caries-free sites on enamel surfaces were obtained and cultivated for S. mutans isolation. Morphology, biochemistry, automatic microorganism analysis system and polymerase chain reaction using primers homologous to surface protein antigen I/II (spaP), glucosyltransferase B (gtfB) and dextranase (dexA) were used to identify S. mutans. Genotype of isolated S. mutans was determined by arbitrarily primed polymerase chain reaction.</p><p><b>RESULTS</b>Forty-six strains of S. mutans were obtained from the 32 subjects and were identified as S. mutans by biochemistry, automatic microorganism analysis system and polymerase chain reaction. Five identical genotypes were found by arbitrarily primed polymerase chain reaction.</p><p><b>CONCLUSION</b>Forty-one strains of S. mutans with different genotype were obtained from clinical samples.</p>