RESUMEN
PURPOSE: Based on a case of supernumerary cusp on the bucca of left maxillary second molar diagnosed by cone beam computed tomography (CBCT), its genesis, diagnosis and antidiastole are to be analysed. The clinic implication of CBCT is correspondingly discussed. METHODS: The supernumerary cusp was diagnosed by oral general examination, intra-oral radiograph and CBCT. The features of supernumerary cusp, fused tooth, geminated tooth and concrescence tooth, especially differentiate points among them were discussed. RESULTS: The case of supernumerary cusp on the bucca of left maxillary second molar was diagnosed definitely by the combined application of oral general examination, periapical radiograph and CBCT. CONCLUSION: Supernumerary cusp on the bucca of left maxillary second molar is a rare phenomenon, which is difficult to be differentiated from other tooth deformities. CBCT can improve accuracy of diagnosis.