多生牙也称额外牙,是一种牙齿数目的发育异常,可发生于牙弓的任何部位,其中以上颌前牙区多见,发生在下颌前牙区的比例只占约2%[1]。多生牙可引起邻牙的错位扭转、牙间隙增大、牙列拥挤、邻牙迟萌、牙根吸收和囊肿形成等[2]。本文报道1例因下前牙区多生牙导致侧切牙迟萌,并引起尖牙含牙囊肿,通过正畸开拓间隙并配合外科 Juvenile teeth, also known as extra teeth, is a developmental abnormality in the number of teeth that can occur in any part of the dental arch, most commonly in the anterior maxilla, occurring in the anterior mandibular area accounts for only about 2% [1 ]. Juvenile teeth can cause displacement of adjacent teeth twisted, increased gap, dentition crowded, adjacent teeth late adduction, root resorption and cyst formation [2]. This article reported a case of adduction of the lower anterior teeth area caused by adduction of the lateral incisors, and cause canine cyst, through the orthodontic gap and with surgery