My son is required to wear masks in school, so about 6 hours in masks. School even stipulates no single layer masks! Shortly after mask-mandated school started, I notice teeth grinding at night, which is liking due to the lack of oxygen. The masks always come back soaking wet and who knows what that can do for dental hygiene like cavities or gum health. Sadly school and majority in my area can’t see the detrimental health effects of masks.