A two-step separation technique for fused teeth: clinical report.

An unusual case of fusion combined with concrescence of a supernumerary tooth and a central incisor is presented. In order to prevent a deep periodontal pocket following the separation, a twostep technique was attempted. The first stage consisted of surgical exposure of the roots and separation with closure to allow in-growth of connective tissue. Four weeks later, the fused crowns were separated and one of the teeth was extracted. One year after the separation a periodontal pocket of 3 mm was present at the separation site. Suggestions for use and improvement of the technique are given. fusion has been defined as the dentinal union of two or more originally individual teeth." It may involve a normal and a supernumerary tooth (mesiodens or supplementary tooth). Gemination (Latin, twinning) is believed to be the result of splitting or incomplete division of a single tooth germ.' Tannenbaum and Ailing stated that in gemination, if the bifid tooth is counted as one entity, the total number of teeth in the dental arch is normal. This compares to the fusion of two normal teeth where there should be one fewer tooth in the arch. If the fusion is between a supernumerary and a normal tooth there would be no reduction in the number of teeth. Concrescence is defined as the union of teeth by cementum only. 4 There is disagreement as to whether it happens during or after root formation. Clem and Natkin described the treatment of a supernumerary tooth fused to an incisor tooth. They used a labial flap, removed about 3 mm of crestal bone, separated the two segments and extracted the central incisor, leaving the mesiodens portion because of its more normal position. Good and Berson described a case in which they removed the complete crown and a section of the root of a labially positioned supernumerary tooth to the level of the cementoenamel junction. A periodontal problem developed in this case. In both of these cases, no continuity was found between the pulp chambers and canals of the fused teeth. The purpose of this paper is to report on an unusual case of fusion combined with concrescence and a treatment approach designed to solve the esthetic and potential periodontal problem.