Short-term effect of chewing gums containing probiotic Lactobacillus reuteri on the levels of inflammatory mediators in gingival crevicular fluid - Twetman, S; Derawi, B; Keller, M; Ekstrand, K; Yucel-Lindberg, T; Stecksen-Blicks, C (Acta Odontol Scand, 2009)