Objective The objective of this study is to investigate with cone-beam computed tomography（CBCT）the tooth length of permanent upper canines near the cleft area in patients with complete unilateral cleft lip palate （UCLP） and to compare the findings with its contralateral tooth, including full length, crown length, root length and top root ratio. Meanwhile, the teeth near the cleft area having anomalies are also recorded. Methods A sample of 20 patients with complete UCLP who accepted the CBCT scan were selected. The raw data were constructed along the longitudinal axis of the upper canines, and the full lengths, crown lengths, root lengths of upper canines of all patients were measured using 3-D measurement software associated to CBCT． The full lengths, crown lengths, root lengths and top root ratios of the upper canines accepted paired-t test. The anterior teeth near the cleft area having anomalies and positions of the clefts were also recorded. Results The full lengths, root lengths and top root ratios of the upper canines had statistical difference between the cleft side and non-cleft side（P0.05）. 20 lateral incisors near the cleft area had anomalies（100%）. Conclusion The lengths of upper canines on
the cleft side are shorter than those of the non-cleft side, and the root lengths are affected more. The teeth near the cleft side prove to be abnormal, especially the lateral incisors.
