Effect of face masks on salivary parameters and halitosis: Randomized controlled crossover trial.

BACKGROUND
Face masking is associated with self-perceived dry mouth and halitosis. Aim of the study was to measure the effect of different face masks on salivary parameters and halitosis.


METHODS
The randomized controlled crossover clinical trial with 4 periods included forty oral healthy participants using different face masks (cloth mask, surgical mask, FFP2 mask) or no mask (control) for 4 hours in random order. Unstimulated salivary flow rate (primary outcome) and stimulated salivary flow rate, salivary pH and buffer capacity of stimulated and unstimulated saliva (secondary outcomes, blinded), and volatile sulfur compounds (secondary outcome) were measured before and after the four-hour periods. Statistical analysis was performed by repeated measures ANOVA (p<0.05).


RESULTS
Of 40 randomized participants, 39 completed the study. Unstimulated salivary flow rate prior to face masking amounted to 0.6±0.3 mL/min. Face masking had no significant effect on unstimulated salivary flow (p=0.550). Face masking had also no significant effect on the other salivary parameters (p≥0.518). The concentration of volatile sulphur compounds (VSC) prior to face masking amounted to 157.3±59.7 ppb. After face masking, the concentration of VSC increased slightly, but not significantly (p=0.055): 168.1±76.3 ppb (control), 199.3±132.7 ppb (cloth masks), 188.5±101.1 ppb (surgical masks), and 189.7±90.1 ppb (FFP2 masks).


CONCLUSION
Four hours of face masking did not change the salivary flow rate, pH, and buffer capacity, and had no significant effect on VSC's levels. Wearing face masks does not seem to result in measurable side-effects on salivary parameters such as a reduced salivary flow rate or VSC's levels.