If there is something inside the tooth gap, and there is a bad smell, there are two possibilities: 1, usually easy to eat food embedding, stuffed into the tooth gap inside the stuff, slowly fermentation will produce a bad smell. At this time, we need to use dental floss, periodontitis patients can use the gap brush for flossing, usually need to check whether there is food embedded after eating, if there is, remove it in time; 2, it may be that the teeth in the middle of the tooth gap decay, that is, adjacent surface caries. Adjacent surface caries is mainly caused by the food embedded between the teeth, and the bacteria corrode the teeth after long time without removing. At this time, we should take the filling treatment of tooth decay to treat the adjacent caries in the middle of the tooth gap thoroughly.