The purpose of this study was to evaluate the shape and impacted patterns of mesiodens and associated complications, using threedimensional images produced by dental cone-beam CT. A total of 250 pediatric patients with a chief complain of mesiodens were evaluated; the number, shape, position of mesiodens, and associated complications were investigated using transaxial and threedimensional images. The M/F ratio was 3.1:1. The majority of mesiodens were inverted and conical in shape. The most common locations of the mesiodens was the middle sector (85.2%) in the frontal plane, near the cervical level (60.6%) in the sagittal plane, and at the palatal side (75.1%) in the horizontal plane. Associated complications were present in 47.8% of the mesiodens. The most common complication was a displaced tooth (18.6%), followed by delayed eruption (13.9%). The shape, direction, vertical level, and labio-palatal position of mesiodens showed a correlation with the associated complications. The majority of mesiodens were located at the palatal side of the dental arch and at the height of the cervical level. The shape, direction, vertical level, and labio-palatal position of mesiodens showed a correlation with the associated complications.