Abstract: Objective: To explore the characteristics of chin fractures and the association between the eruption of mandibular canines and the chin fractures in children through the investigation of fracture line position in the chin fracture before and after the eruption of the mandibular canine in children, retrospectively. Methods: Eighty children (age≤12 years old) were collected who were suffered chin fracture (or combined fracture of other parts) from May 2012 to May 2016 in Stomatological Hospital of Wuhan University. The association between the fracture line position and canine tooth germs, median joint, mental foramen was defined by radiological information. The prognosis after operation was recorded. All data were accurately and analyzed using statistical software. Results: A total of 80 children were enrolled in this study, including 57 men and 23 women, with a sex ratio of 2.47:1. The main cause of the injury was inadvertent fall (51.2%). 66.17% of the fracture lines in the non-erupted mandibular canine were on the canine tooth germ, and only 16.67% of the fracture line in the eruption of the canine on the canine. There was statistically significant difference between groups of fracture line in the canine tooth germ and after the eruption of mandibular canine(P=0.003<0.05). There was not statistically significant difference between surgery groups and conservative group (P=1.000). Conclusion: Boys are more likely to have chin fractures than girls. The most important reason is the inadvertent fall. The fracture line of children's chin fracture will change with the eruption of the mandibular canine. If the mandibular canine is not erupted, the fracture will easily occur near the canine tooth germ. However, the fracture was not easily to occur near the canine after the mandibular canine eruption.

Key words: Children, Chin fractures, Mandibular canine eruption