A survey of ponticulus posticus: Radiological analysis of atlas in an orthodontic population based on cone-beam...

The ponticulus posticus (PP; Latin for little posterior bridge) has become an important anomaly of the atlas, as the use of the C1 lateral mass screw has become common in treating atlantoaxial instability.

The purpose of this study was to retrospectively determine the prevalence and morphologic characteristics of PP in an orthodontic patient population using cervical three-dimensional (3-D) cone beam computed tomography (CBCT) images.

A retrospective study was conducted by selecting cervical 3-D CBCT images of 374 adolescent population and examining them for the presence and type of PP.

161 patients with 298 complete or partial or bilateral or unilateral PPs were identified based on the 374 cervical 3-D CBCT scans. The prevalence of posticulus ponticus was founded 43.04% in adolescent population.

Our results show that the presence of this anomaly should be carefully examined using preoperative lateral radiographs before lateral mass screw placement. If a PP is suspected or confirmed on radiographs, 3-D CBCT scanning should be considered before lateral mass screw placement into the posterior arch because of the variation in the size and shape of PPs and the possibility of injury.