Cysts of the jaws can be classified according to the origin of the tissue and the site of onset. Cysts evolving from the epithelium or epithelial remnants of adult tissues or teeth are called odontogenic jaw cysts, and cysts due to remnants of epithelium from the embryonic period and cysts of extravasated blood due to injury and aneurysmal bone cysts are called non-odontogenic jaw cysts. (A) Odontogenic maxillary cysts occur in the jawbone and are associated with odontogenic tissues and teeth. According to their sources, they are classified as follows: 1. Apical cysts are due to the stimulation of apical granuloma and chronic inflammation, which cause residual hyperplasia of epithelial senators in the periodontal membrane. Degeneration and liquefaction occur in the center of the proliferating epithelial mass, and the surrounding tissue fluid continuously exudes, gradually forming a cyst, so it can also be called periapical cyst. 2.Primary cyst occurs in the early stage of enamel-forming apparatus development, before the formation of enamel and dentin, after inflammation or injury stimulation, the star reticular layer of the oil-forming apparatus degenerates, and there is fluid exudation, which accumulates and forms cysts. 3, tooth-containing cysts, also known as follicular cysts, occur after the formation of the crown or root of the tooth, and fluid exudation occurs between the shrunken enamel epithelium and the crown surface to form tooth-containing cysts. It can come from 1 tooth germ (containing 1 tooth) or from multiple teeth. 4, odontogenic keratotic cysts are derived from the original tooth germ or tooth plate remnants, which are thought to be the initiating cysts. Keratotic cysts have typical pathological manifestations, the epithelium and fiber envelope of the cyst wall are thin, and the fiber envelope of the cyst wall sometimes contains subcapsules (or satellite cavities) or epithelial islands. The bursa is white or yellow keratinized or oil-like material. (B) Non-dental cysts are developed from the epithelium remaining during embryonic development, so they are also called non-dental ectodermal epithelial cysts. 1, ball maxillary cyst occurs between maxillary lateral incisors and cuspids, the teeth are often displaced by exclusion. x-ray shows that the cyst shadow is between the roots of the teeth, but not in the apical part. The teeth are not decayed and discolored, and the pulp is alive. 2.Nasopalatal cyst located in or near the incisive canal (from the residual epithelium of the incisive canal). 3, Median cyst Located behind the incisal foramen, anywhere in the median suture of the palate, with a round cyst shadow between the sutures visible on X-ray. It can also occur at the median line of the mandible. 4. Nasolacrimal cysts are located at the base of the upper lip and in the nasal vestibule. May arise from the epithelial remnants of the nasolacrimal duct. The cyst is on the surface of the bone and there is no destruction of the bone on the radiograph. The presence of the cyst can be palpated in the lateral aspect of the oral vestibule.