Abstract: Objective To investigate the correlation between unilateral impacted canines and the sum of crown widths by comparing the sum of impacted and non-impacted crown widths of unilateral impacted maxillary canines. Methods From January 2013 to January 2018,we enrolled 30 patients with impacted unilateral maxillary canines (experimental group),30 patients with crowded maxillary dentition accompanied by high eruption of canines (crowd group) and 30 cases with normal eruption of canines and no crowded dentition (healthy group).Then the occlusal models were made for the 90 subjects.The mesiodistal widths of crowns were measured and statistical comparison of the sum of crown widths between both sides was performed. Results In the patients with unilateral impacted canine,the sum of crown width of unilateral arch (51.67±2.33 mm vs 53.43±2.60 mm),anterior area (25.06±1.40 mm vs 26.13±1.38 mm),posterior area (26.61±1.17 mm vs 27.29±1.42 mm),incisor area (16.45±1.11 mm vs 17.28±1.02 mm),anterior molar area (15.61±0.88 mm vs 16.22±0.92 mm),of the impacted were smaller than those of the non-impacted (P<0.05).However,there was no significant difference in the sum of crown widths of each section between the two sides of the health group and the crowed group. Conclusion The sum of crown widths of each section of impacted canine side is smaller than that of non-impacted side,indicating that impacted canine has an inevitable correlation with tooth morphology,which provides clinical evidence for prediction of impacted canine.