In secondary analyses , the incidence of AOM was 0.53 episodes per 90 days in the xylitol group versus 0.59 in the placebo group ( difference 0.06 ; 95 % CI -0.25 to 0.13 ) ; total antibiotic use was 6.8 days per 90 days in the xylitol group versus 6.4 in the placebo group ( difference 0.4 ; 95 % CI -1.8 to 2.7 ) .