OBJECTIVETo analyze the differences between the oral microbiota of monozygotic and dizygotic twins by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE).

METHODSA total of 20 pairs of twin children were included in this study, in which 10 pairs were monozygotic (MZ) twins, and 10 pairs were dizygotic (DZ) twins. Of the 20 pairs, 10 pairs of twins had primary dentition, and 10 pairs had mixed dentition; 17 children had caries, and 23 children had no caries. Genomic DNA was extracted from saliva samples. The 16s rRNA was amplified and analyzed by PCR-DGGE. The PCR-DGGE band number and Shannon index were calculated.

RESULTSCluster analysis showed high similarity in the oral bacterial community seen in co-twins. However, no significant difference was seen between MZ and DZ twins. In the primary dentition, the PCR-DGGE band number and Shannon index of children with caries (11.00 +/- 1.56, 1.05 +/- 0.36) were lower than those of children without caries (14.00 +/- 2.74, 1.44 +/- 0.37) (P < 0.05). In mixed dentition, the PCR-DGGE band number and Shannon index of children with caries (11.88 +/- 4.05, 1.18 +/- 0.36) were lower than those of children without caries (14.31 +/- 5.71, 1.28 +/- 0.47), but the differences were not statistically significant (P > 0.05).

CONCLUSIONEnvironmental factors may have a stronger effect on the constitution of oral microbiota in children compared with genetic factors. Children without caries may have a richer microbial diversity compared with children with caries.