If there are large gaps in the teeth, there are several causes to consider. First, congenital factors. The degree of tooth tightness varies from person to person, mainly based on the germ of the tooth during development and the direction of tooth alignment within the jawbone, and the size of the jawbone. Secondly, partial loss of teeth. When a missing tooth is not set in time, as time goes on, it will be found that the gap between other teeth is getting bigger and the gap between missing teeth is getting smaller. Thirdly, the gap between teeth becomes bigger. It is also possible that there is localized decay, when there is decay on the adjacent surface between two teeth, resulting in enamel and dentin defects, it will also cause the gap between teeth to become larger. The fourth, periodontitis, periodontitis patients periodontal pocket formation, gum recession, alveolar bone resorption, tooth loosening and displacement, tooth gap will also gradually increase.