Diastema. A diastema is a dental term referring to a space or gap between two teeth. It is most commonly applied to the space found between the two maxillary central incisor teeth (upper front teeth). Diastemas can be caused by a number of factors, including genetics, a tooth size discrepancy, a low muscle attachment between teeth known as a frenum, tongue thrusting, or spreading of teeth due to gum disease. There are different treatment options available to correct this condition (such as veneers and orthodontics) and Dr. Sielicki can offer a plan thats best for you.