Fusion is the union of two embryologically separate developing teeth. Gemination is the incomplete division of a single tooth bud. Fusion presents clinically as a large bifid crown (with a vertical crease). The geminated crown is smaller but also presents with a vertical crease. Clinically, fusion and germination are usually distinguished by counting the number of teeth in the arch. A deficiency in the normal complement, including the bifid crown, is usually fusion. Typically, fused teeth have two pulp chambers and two canals evident on a dental x-ray. A geminated tooth typically has one pulp chamber and canal.