# Concentration in Saliva and Antibacterial Effect of Xylitol Chewing Gum: In Vivo and In Vitro Study
## 3 Results  
No statistically significant differences were found in the xylitol concentration of saliva samples collected before the use of the chewing gums (Table 2).  
The 100% xylitol chewing gum produced the highest salivary concentration after 30 s of use (1.49 \(\pm\) 1.41 logug/L) and then the amount decreased after 1 and 2 min until a second increment was detected at 5 and 10 min (1.28 \(\pm\) 1.10 logug/L and 1.41 \(\pm\) 1.11 logug/L, respectively); after that, a slow decrease until 25 min was found. The 22% xylitol chewing gum produced the highest salivary concentration after 2 min of use (1.21 \(\pm\) 1.24 logug/L) and then gradually decreased in the following evaluations. Statistically significant differences between the concentrations produced by the use of the two Xylitol chewing gums were recorded at all time points (\(p\) = 0.01 for the comparison after 1 min, while \(p\) < 0.01 for all the other times). The modification of the concentration of xylitol in each group during the different times was statistically significant (\(p\) < 0.01). The Cronbach alpha was 0.97 in the 100% xylitol group and 0.95 in the 22% Xylitol group.  
The bacterial concentrations before and after the contact with the two xylitol chewing gums (22% and 100% xylitol) solutions are reported in Table 3. All the considered bacterial strains decreased after the addition of the two chewing gums solutions. The 22% xylitol obtained the highest decrease (except for _B. forysthus_) after 60 min and then increased again at the last evaluation (24 h); the 100% xylitol chewing gum obtained a greater decrease compared to the 22% xylitol at all time points; the highest decrease was recorded after 24 h from the contact for all bacteria strains.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Time** & **100\% Xylitol (logug/L)** & **22\% Xylitol (logug/L)** & _p-Value_ \\ \hline \multirow{3}{*}{Before 30 s} & Mean \(\pm\) sd & mean\(\pm\)sd & \\  & \(-\)0.68 \(\pm\) \(-\)0.66 & \(-\)0.66 \(\pm\) \(-\)0.41 & NS \\  & 1.49 \(\pm\) 1.41 & 0.04 \(\pm\) 1.20 & \(<\) 0.01 \\  & 1.39 \(\pm\) 1.53 & 1.19 \(\pm\) 1.38 & 0.02 \\  & 1.09 \(\pm\) 1.27 & 1.21 \(\pm\) 1.24 & 0.03 \\  & 1.28 \(\pm\) 1.10 & 1.00 \(\pm\) 1.19 & 0.02 \\  & 1.41 \(\pm\) 1.11 & 0.45 \(\pm\) 0.64 & \(<\) 0.01 \\  & 1.19 \(\pm\) 1.12 & \(-\)0.08 \(\pm\) 0.25 & \(<\) 0.01 \\  & 1.07 \(\pm\) 1.03 & \(-\)0.33 \(\pm\) 0.01 & 0.02 \\  & \(-\)0.30 \(\pm\) \(-\)0.92 & \(-\)0.92 \(\pm\) \(-\)1.15 & \(<\) 0.01 \\ p-value & \(<\) 0.01 & \(<\) 0.01 & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Xylitol concentrations in saliva (\(\mu\)g/L). One-way ANOVA for the comparison between the two types of chewing gum and two-way ANOVA for intra-group comparison. The values in bold are the maximum peaks reached.  
\begin{table}
\begin{tabular}{l c c c c c c c c c} \hline
**Bacteria** & **Pre** & **15 min** & \multicolumn{3}{c}{**60 min**} & \multicolumn{3}{c}{**24 h**} & \multicolumn{1}{c}{**p-Value**} \\
**Strain** & **Mean (SD)** & \multicolumn{3}{c}{**Mean (SD)**} & \multicolumn{3}{c}{**Mean (SD)**} & \multicolumn{3}{c}{**Mean (SD)**} & \multicolumn{3}{c}{**p-Value**} \\ \hline  & & 100\% Xylitol & 22\% Xylitol & 100