They are typically detachable, although some grill wearers have had their teeth permanently changed with gold crowns to imitate a grill. The acids can cause tooth decay and gum tissue damage. Bacteria may also play a role in unpleasant breath. They like charcoal grills for food that will not completely burn, so unburned particles pass into the air you breathe out. You can reduce this risk by cleaning the grill regularly. Permanent teeth usually have four surfaces: one is usually flat or slightly curved; the others are slightly raised, giving the tooth its name - "permanent". These surfaces are called occlusal (against which you bite) - they contact the opposing jaw bone; cervical (at the side of the mouth) - these surfaces contact the tongue and other soft tissues; and two more surfaces called apical (apex) - these surfaces point toward the center of the root canal system where bacteria can live if allowed to overflow into that space. If you keep putting excess bacteria into the apex of the tooth, it will eventually die and fall out. The four surfaces of a natural tooth provide many places where bacteria can hide. If you have any missing teeth, then your remaining teeth will have more surface area exposed to the outside environment.