“…Nine studies were excluded due to population (included patients with acute COVID-19, still testing positive in COVID-19 test), two were excluded due to intervention (robot devices, ventilation therapy), one study was excluded due to outcomes (salivary biomarkers), and five due to study design (congress abstract, protocol). Finally, 34 studies were included for qualitative analysis in the present review (20 RCTs and 14 observational studies) [ 36 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 ]. For quantitative analysis, 26 studies were included.…”