IL4 and periodontitis: Meta-analysis of the IL-4 -590C/T showed no association between the polymorphism and periodontitis susceptibility (T versus C: OR = 1.12, 95% CI = 0.75–1.66; TT versus CC: OR = 1.44, 95% CI = 0.58–3.57; CT versus CC: OR = 1.26, 95% CI = 0.76–2.10; TT + CT versus CC: OR = 1.30, 95% CI = 0.74–2.26; TT versus CC + CT: OR = 1.2, 95% CI = 0.66–2.19).