Sims teeth health is now monitored and decays over time without dental care interventions. Sims will receive notifications when it's time to attend to their dental needs. Dental care behaviors like regular brushing teeth, using mouthwash, going to the dentist appointments, even popping a mint will help improve teeth health. If Sims don't attend to their teeth health they can get any number of dental issues including cavities, sensitivity, frequent toothaches and require root canals to name a few. If your sim hasn't brushed in over 24 hours their breath will smell bad but a quick mint can help offset the effects but it won't go away until their teeth are brushed. Sims around your sim will feel uncomfortable being around a sim with bad breath.