Microarray analysis of microRNA expression in periodontal progenitors from healthy individuals (Con) and animals suffering from periodontal disease (Dis). a Heat map of miRNA expression profiling. miRNAs with a significant level of upregulation or downregulation (P < 0.01) were identified using Student’s t test. Individual upregulated and downregulated genes are listed in Table 1. b Quantitative reverse transcriptase (qRT) polymerase chain reaction verification of selected microRNAs in healthy and periodontal disease tissues. There was a significant difference in miR-21, miR-29b, let-7c and miR-451 gene expression between healthy and diseased tissues.