额外牙又称多生牙.临床中较为常见,但多见于上颌中切牙之间,数目一个或两个,而多发性对称性者少见.笔者曾遇到一例,报告如下.患者男.23岁,于1988年2月7日因右下牙自发性疼。牙龈肿胀二十余日就诊.检查:恒牙列,牙弓整齐,规则,对称,无缺额牙;全口四环素牙.■釉质发育不全; Extra teeth, also known as more raw teeth .Clinical is more common, but more common in the maxillary incisors, the number of one or two, and multiple symmetry are rare .I have encountered a case, the report is as follows.Patients male.23 Year old, on February 7, 1988 due to spontaneous pain in the lower right tooth. Gingival swelling more than 20 days treatment. Examination: permanent dentition, regular arch, regular, symmetrical, no missing teeth; full tetracycline tooth. ■ enamel hypoplasia;