Permanent Canine Impaction: A Systematic Review of Incidence, Distribution, and Etiology

Background and Objectives: Tooth impaction is a common developmental dental anomaly characterized by the failure of eruption within the expected physiological timeframe. Permanent canines represent the second most frequently impacted teeth after third molars and may lead to functional, esthetic, and orthodontic complications. This systematic review aimed to synthesize current evidence regarding the incidence, anatomical distribution, etiological determinants, and diagnostic evaluation of permanent canine impaction. Materials and Methods: A systematic literature search was conducted in PubMed, PubMed Central, and ScienceDirect for studies published between December 2009 and December 2025. Studies reporting prevalence data, anatomical positioning, etiological factors, or imaging characteristics of permanent canine impaction were included. Study selection followed PRISMA 2020 guidelines, and 31 studies were included in the qualitative synthesis. Two independent reviewers screened titles, abstracts, and full texts. Methodological quality was assessed using the Joanna Briggs Institute Critical Appraisal Tools. Results: Thirty-one studies met the inclusion criteria and were included in the qualitative synthesis. The reported prevalence of maxillary canine impaction ranged from 0.97% to 7.10%, while mandibular impaction occurred less frequently. Palatal displacement represented the most common positional pattern. Major etiological factors included retained deciduous canines, dental arch constriction, supernumerary teeth, odontomas, and genetic anomalies such as lateral incisor agenesis. Cone-Beam Computed Tomography (CBCT) demonstrated superior diagnostic accuracy compared with panoramic radiography. Conclusions: Permanent canine impaction is a multifactorial condition predominantly influenced by local anatomical and environmental factors, with genetic predisposition acting as a secondary contributor. Early diagnosis and appropriate imaging assessment are essential to prevent complications such as root resorption and to optimize treatment outcomes.