Objective The objective of this article was to review and analyze the eruption cysts on direct digital panoramic radiographs of 3 182 orthodontic patients, then to analyze the radiographic characters for gaining more knowledge about eruption cysts. Methods Observing the intact and enlarged dental follicles on direct digital panoramic radiographs of orthodontic patients, the largest follicular space was measured by ClinView 6.1.3 analysis software. If both two doctors measured the width and found it was more than 2.5 mm, it would be diagnosed as eruption cyst. Results in 3 182 orthodontic patients, 277 cases involved 164 patients were diagnosed as eruption cysts. 208 cases（75.09%） occurred in the third molars. 55 cases（19.86%） occurred in the second molars. 9 case occurred in the canine（3.25%）, and 2 cases were in the premolar areas（0.72%）. 3 cases involved several teeth （1.08%）. Conclusion Many eruption cysts have been found on direct digital panoramic radiographs. For orthodontic patients, eruption cysts mostly occur on the third molars. Multiple eruption cysts are always bilateral and symmetrical. Most of eruption cysts don′t affect orthodontic therapy, however, dentists should pay more attention to large radiolucent lesions specially when they obstruct the dental eruption, which should combine the surgical treatment.
