In situeffect of a commercial CPP-ACP chewing gum on the human enamel initial erosion

Objective This study evaluated thein siturehardening effect of a commercial chewing gum containing casein phosphopeptide - amorphous calcium phosphate (CPP-ACP) on initial erosion lesions. Methods Seventy-two human enamel blocks, after selection (initial surface hardness - SHi) andin vitroshort-term acidic exposure (cola drink for 3min - SHd) were randomly assigned to three groups. The factors under study were treatment (3 levels: GI chewing gum with CPP-ACP, GII chewing gum without CPP-ACP and GIII control group without gum) and intraoral period (2 levels: 2 and 24h). Twelve volunteers wore intraoral palatal devices for 24h in 3 crossover phases. On each phase, after 2h the surface hardness was assessed (SHf1) and the blocks were reinserted and the devices were used for additional 22h (SHf2). In phases of GI and GII volunteers chewed the respective gum during 30min, for 4 times with an interval of 4h. Percentage of surface hardness recovery (%SHR) was calculated after 2 and 24h. The data were analysed by repeated measures ANOVA and Tukey's test. Results Chewing gum with CPP-ACP (2h=50.0%