Abstract: Objective:To report one case of bilateral maxillary fourth molars, and to explore the occurrence and treatment method of additional fourth molar. Methods: The case materials of one patient with bilateral maxillary four molars were collected, and the information was record. Combined with reviewing the relevant literatures, the clinical data, complication and treatment of one patient with bilateral maxillary fourth molars were retrospectively analyzed. Results: The patient was diagnosed due to left maxillary posterior teeth area intermittent pain for several months and the increased pain for 5 d; at the same time,there was no abnormal appearance inducing the symptoms detected by speciality check-up. The pantomography showed the four molars in bilateral maxillary, and the fourth molars impacted the third molar root's absorption. The fourth molar crown was smaller and the root was shorter. The 18,28,29 teeth were removed,and the left maxillary posterior teeth area intermittent pain disppeared. Conclusion: The occurrence of additional fourth molar is a relatively rare demal dysplasia. However,there are some complications following with the fourth molar. Early diagnosis and treatment are essential.

Key words: case report, fourth molar, teeth dysplasia, supemumerary teeth