Early diagnosis and the interception of potential impaction is the most desirable approach for management of impacted canines. Several radiographic predictors have been previously proposed to predict canine impaction. Hence the aim of this systematic review was to identify the most effective radiographic predictors of maxillary canine impaction.

The following databases were searched: PubMed via Medline, Science Direct, LILACS, Cochrane library and Ovid MEDLINE. All comparative studies including observational and interventional studies that compare a canine impacted group versus a control group were included. The primary outcome assessed were the radiographic predictors used for diagnosis of maxillary canine impaction.

Thirteen articles were included in this systematic review. The most commonly used parameters are sector classification, angle formed by the long axis of the canine and the midline, angle formed by the long axis of the canine and the lateral incisor, angle formed by the long axis of the canine and the occlusal plane, and perpendicular distance between the canine cusp tip to the occlusal plane and to the midline. Meta-analysis indicated that the angle formed by the long axis of the canine and the midline with a value of 19.9° and above (95% CI of 6.68 to 33.15), the angle formed by the long axis of the canine and the lateral incisor with a value of 20.01° and above (95% CI of 7.52 to 32.51) favoured canine impaction.

With eleven of the thirteen articles showing a low risk of bias/good quality, it can be concluded that canine impactions can be predicted using various linear and angular parameters measured on different radiographs (orthopantomograms, lateral cephalograms, postero-anterior cephalograms and cone-beam computed tomography). However, further three-dimensional studies are required to accurately predict and diagnose canine impactions.

The study protocol was registered on the International Prospective Register of Systematic Reviews (Reg no: CRD42020200518)