Tissue regeneration principles applied to separation of fused teeth

A two-step surgical procedure for separating a central incisor fused to a supernumerary tooth with a 4-year follow-up is described. The fusion was between the crowns and 3/4 of the root length. The roots were connected by web-like radio-opaque tissue. The periodontal ligament could be followed along the lateral aspect of the roots and was continuous along the base of the web. In the first surgical phase, a full-thickness semilunar flap was raised; a fissure bar was cut along and through the web up to the approximate location of the junctional epithelium and the flap was sutured. It was assumed that cells from the bone surrounding the web and/or connective tissue cells from the flap had migrated into contact with the web hard tissue. This resulted in replacement resorption of the web. The connective tissue replacing the web acted as a septum separating the 2 parts of the root. The distal root was extracted. Resorption continued until most of the web disappeared from the wound. At this point, the remaining layer of web tissue was thin enough to allow repopulation of the resorbed surface with periodontal cells from the buccal and palatal sides of the web. The successful clinical outcome supports the assumption that new attachment consisting of periodontal ligament and cementum was formed following the 2-step surgical procedure. Application of the technique is limited by the width of the fusion rather than by its length.