“…Gingivitis was noted in six different types of disadvantaged individuals, two of which showed the highest prevalence, such as alcohol and drug abusers with 82% ([95% CI 43–100%]; 357 patients, three studies, I 2 98.8%) [ 71 , 72 , 75 ] and prisoners with 63% ([95% CI 54–72%]; 802 patients, three studies) [ 22 , 23 , 24 ]. High prevalence values were also found in pregnant women with 41% ([95% CI 34–49%]; 2242 participants, nine studies) [ 53 , 54 , 55 , 83 , 84 , 85 , 86 , 87 , 88 ] ( Figure 3 ) and the elderly with 41% ([95% CI 29–52%];11,048 participants, 15 studies) [ 26 , 28 , 35 , 39 , 43 , 47 , 65 , 66 , 81 , 89 , 90 , 91 , 92 , 93 , 94 ]. Lower prevalence values were found in subjects with low levels of education (19% [95% CI 18–19%]; 75,095 participants, two studies, I 2 = not assessable) [ 95 , 96 ] and low income (19% [95% CI 18–19]; 54,593 participants, two studies, I 2 = 0.00) [ 93 , 94 ] and in immigrants (15% [95% CI 12–18%]; 746 participants, two studies, I 2 = 0.00) [ 39 , 51 ].…”