Table 1.

Data extraction of all six studies

Year, author, and population	Samples and method	Mean±SD	miR	Sensitivity, specificity, and AUC	Results
Park et al., 2009, 41 Caucasian, 4 Asians, 4 Hispanics, 1 African-American	50 - OSCC 50 - HC RT-preamp qPCR	miR-200a 28.7±3.9	Endogenous miR-191 Exogenous miR-124a miR-200a miR-125a	miR-200a Sensitivity and specificity not mentioned AUC - 0.65	miR-191 degrades at a lower rate than exogenous miR-124a miR-200a and miR-125a reduced in OSCC
Liu et al., 2012, Taiwan	45 - OSCC 10 - OVL 24 - HC RT-qPCR	miR-31-8.3±0.3	miR-16 miR-31	miR-31 Sensitivity - not mentioned Specificity - 100% AUC - 0.71	Levels of salivary miR-31 elevated in OSCC before treatment compared with normal saliva. Saliva of OVL showed no significant difference from normal
Momen-Heravi et al., 2014, Worcester, USA	9 - OSCC 8 - OSCC remission 8 - OLP 9 - HC Nano string miR expression assay and RT-qPCR	Not mentioned	Endogenous miR-191 miR-136 miR-147 miR-1250 miR-632 miR-646 miR-668 miR-877 miR-503 miR-200a miR-323-5p miR-24 miR-27b	miR-27b Sensitivity - 85.71% specificity - 100% AUC - 0.9643	miR 191 most stable hence selected as endogenous marker xyk11 miRs (miR-191, miR-136, miR-147, miR-1250, miR-632, miR-646, miR-668, miR-877, miR-503, miR-200a, miR-323-5) downregulated in OSCC, 2 miRs (miR-24, miR-27b) upregulated in OSCC 7 miRs which distinguished OSCC from OLP miR (over expressed-27b, under epressed-miR-146a, kshv-miR, Hcmv-miR-US5-2, Ebv-miR-BART16, miR-223, miR-29a)
Zahran et al., 2015, Jeddah, Saudi Arabia	20 - HC 20 - OPMD without dysplasia 20 - OPMD with dysplasia 20 - OSCC 20 - RAS qRT-PCR	miR-184-2.5±0.2 miR-21-3.7±0.2 miR-145-0.5±0.04	miR-184 miR-21 miR-145	miR-184 Sensitivity - 80% Specificity - 75% AUC - 0.86 miR-21 Sensitivity - 65% Specificity - 65% AUC - 0.73 miR-145 Sensitivity - 60% Specificity - 70% AUC - 0.78	miR-21 and miR-184 highest in OSCC followed by PMD without dysplasia, PMD with dysplasia, RAS, and HCs miR-145 lowest in OSCC
Al- Malkey et al., 2015, Baghdad, Iraq	35 - OSCC 20 - HC RT-qPCR	miR-31 26.4±16.7	miR-31 Cutoff value - 6.623 Inhibits negative regulators of cancer pathway and promotes cell proliferation	Not mentioned	Fold change was higher in oral cancer group than HC group
Hung et al., 2016 Taipei, Taiwan	46 tissue samples of OPMD 20 saliva samples of OPMD and 24 HC Tissue-in situ hybridization, saliva-qRT-PCR	Not mentioned	miR-21 miR-31	miR-31 Sensitivity - 100% AUC - 0.74 miR-21 Sensitivity - 100% AUC - 0.76	miR-21 and miR-31 significantly increased in saliva of OPMD. miR-31 and epithelial dysplasia significantly associated with disease progression. Neither salivary miR-31 nor epithelial miR-31 significantly increased in dysplasia epithelium

HCs: Healthy controls, OSCC: Oral squamous cell carcinoma, OPMD: Oral potentally malignant disorder, OVL: Oral Verrucous leukoplakia, RAS: Recurrent aphthous stomatitis, miRs: Micro RNAs, RT: Reverse transcription, qPCR: Quantitative polymerase chain reaction, AUC: Area under the curve, OLP: Oral lichen planus, SD: Standard deviation